<?php
/* $Id: phplot.php,v 1.224 2011/05/27 18:05:16 lbayuk Exp $ */
/*
 * PHPLOT Version 5.4.0
 *
 * A PHP class for creating scientific and business charts
 * Visit http://sourceforge.net/projects/phplot/
 * for PHPlot documentation, downloads, and discussions.
 * ---------------------------------------------------------------------
 * Copyright (C) 1998-2011 Afan Ottenheimer
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 * ---------------------------------------------------------------------
 *
 * Co-author and maintainer (2003-2005)
 * Miguel de Benito Delgado <nonick AT vodafone DOT es>
 *
 * Maintainer (2006-present)
 * <lbayuk AT users DOT sourceforge DOT net>
 *
 * Requires PHP 5.2.x or later. (PHP 4 is unsupported as of Jan 2008)
 */

class PHPlot
{
	const version = "5.4.0";

	/* Declare class variables which are initialized to static values. Many more class variables
	 * are used, defined as needed, but are unset by default.
	 * All these are declared as public. While it is tempting to make them private or protected, this
	 * is avoided for two reasons. First, it will break existing code, since all member variables
	 * were public in PHP4 and who knows what internal variables people used. Second, it makes
	 * testing harder and less effective. Nevertheless, your code should not modify these.
	 */

	public $is_inline = FALSE;             // FALSE = Sends headers, TRUE = sends just raw image data
	public $browser_cache = FALSE;         // FALSE = Sends headers for browser to not cache the image,
										   // (only if is_inline = FALSE also)
	public $print_image = TRUE;            // DrawGraph calls PrintImage. See SetPrintImage

	public $safe_margin = 5;               // Extra margin used in several places, in pixels

	public $x_axis_position = "";          // X axis position in Y world coordinates, blank for default.
	public $y_axis_position = "";          // Y axis position in X world coordinates, blank for default.

	public $xscale_type = "linear";        // linear, log
	public $yscale_type = "linear";

//Fonts
	public $use_ttf  = FALSE;              // Use True Type Fonts by default?
	public $ttf_path = ".";                // Default path to look in for TT Fonts.
	// public $default_ttfont;             // Initialized in GetDefaultTTFont
	public $line_spacing = 4;              // Controls line spacing of multi-line labels

	// Label angles: 0 or 90 degrees for fixed fonts, any for TTF
	public $x_label_angle = 0;             // For X tick labels
	// public $x_data_label_angle;         // For X data labels; defaults to x_label_angle - see CheckLabels()
	public $y_label_angle = 0;             // For Y tick labels
	public $y_data_label_angle = 0;        // For Y data labels

//Formats
	public $file_format = "png";
	public $output_file = "";              // For output to a file instead of stdout

//Data
	public $data_type = "text-data";       // Structure of the data array
	public $plot_type = "linepoints";      // See $plots[] below

	public $label_scale_position = 0.5;    // Shifts data labels in pie charts. 1 = top, 0 = bottom
	public $group_frac_width = 0.7;        // Bars use this fraction (0 to 1) of a group's space
	public $bar_extra_space = 0.5;         // Number of extra bar's worth of space in a group
	public $bar_width_adjust = 1;          // 1 = bars of normal width, must be > 0

// Titles
	public $title_txt = "";

	public $x_title_txt = "";
	public $x_title_pos = "none";          // plotdown, plotup, both, none

	public $y_title_txt = "";
	public $y_title_pos = "none";          // plotleft, plotright, both, none

//Labels
	// There are two types of labels in PHPlot:
	//    Tick labels: Follow the grid, next to ticks in axis.
	//                 Are drawn at grid drawing time, by DrawXTicks() and DrawYTicks()
	//    Data labels: Follow the data points, and can be placed on the axis or the plot (x/y)
	//                 Are drawn at graph plotting time, by Draw*DataLabel(), called by DrawLines(), etc.
	//                 DrawXDataLabel() also draws vertical lines to data points, depending on
	//                 draw_x_data_label_lines.
	// Tick Labels
	// Tick and Data label positions are not initialized, because PHPlot needs to tell if they
	// defaulted or are set by the user. See CheckLabels() for details. The variables and
	// effective defaults are shown here in comments (but CheckLabels adjusts the defaults).
	// public $x_tick_label_pos = 'plotdown';     // X tick label position
	// public $y_tick_label_pos = 'plotleft';     // Y tick label position
	// public $x_data_label_pos = 'plotdown';     // X data label position
	// public $y_data_label_pos = 'none';         // Y data label position

	public $draw_x_data_label_lines = FALSE;   // Draw a line from the data point to the axis?

	// Label format controls: (for tick, data and plot labels)
	// Unset by default, these array members are used as needed for 'x' (x tick labels), 'xd' (x data
	// labels), 'y' (y tick labels), and 'yd' (y data labels).
	//    type, precision, prefix, suffix, time_format, printf_format, custom_callback, custom_arg.
	// These replace the former: x_label_type, x_time_format, x_precision (similar for y), data_units_text.
	public $label_format = ["x" => [], "xd" => [], "y" => [], "yd" => []];
	// data_units_text is retained for backward compatibility, because there was never a function
	// to set it. Use the 'suffix' argument to Set[XY]LabelType instead.
	public $data_units_text = "";              // Units text for 'data' labels (i.e: '¤', '$', etc.)

// Legend
	public $legend = "";                       // An array with legend titles
	// Other legend_* variables are set as needed, unset for default values.

//Ticks
	public $x_tick_length = 5;                 // tick length in pixels for upper/lower axis
	public $y_tick_length = 5;                 // tick length in pixels for left/right axis

	public $x_tick_cross = 3;                  // ticks cross x axis this many pixels
	public $y_tick_cross = 3;                  // ticks cross y axis this many pixels

	public $x_tick_pos = "plotdown";           // plotdown, plotup, both, xaxis, none
	public $y_tick_pos = "plotleft";           // plotright, plotleft, both, yaxis, none

	public $num_x_ticks = "";
	public $num_y_ticks = "";

	public $x_tick_inc = "";                   // Set num_x_ticks or x_tick_inc, not both.
	public $y_tick_inc = "";                   // Set num_y_ticks or y_tick_inc, not both.

	public $skip_top_tick = FALSE;
	public $skip_bottom_tick = FALSE;
	public $skip_left_tick = FALSE;
	public $skip_right_tick = FALSE;

//Grid Formatting
	// public $draw_x_grid = FALSE;            // Default is False except for swapped data type
	// public $draw_y_grid = TRUE;             // Default is True except for swapped data type

	public $dashed_grid = TRUE;
	public $grid_at_foreground = FALSE;        // Chooses whether to draw the grid below or above the graph

//Colors and styles       (all colors can be array (R,G,B) or named color)
	public $color_array = "small";             // 'small', 'large' or array (define your own colors)
											// See rgb.inc.php and SetRGBArray()
	public $default_colors = [       // The default colors for data and error bars
		"SkyBlue", "green", "orange", "blue", "red", "DarkGreen", "purple", "peru",
		"cyan", "salmon", "SlateBlue", "YellowGreen", "magenta", "aquamarine1", "gold", "violet", ];

	// See SetDefaultStyles() for default colors for PHPlot elements.

	public $line_widths = 1;                  // single value or array
	public $line_styles = ["solid", "solid", "dashed"];   // single value or array
	public $dashed_style = "2-4";              // colored dots-transparent dots

	public $point_sizes = [6];            // Array of sizes for points. See CheckPointParams()
	public $point_shapes = [              // Array of point shapes. See SetPointShapes() and DrawDot()
		  "diamond", "dot", "delta", "home", "yield", "box", "circle", "up", "down", "cross",
	   ];

	public $error_bar_size = 5;                // right and left size of tee
	public $error_bar_shape = "tee";           // 'tee' or 'line'
	public $error_bar_line_width = 1;          // single value (or array TODO)

	public $plot_border_type = "sides";        // left, right, top, bottom, sides, none, full; or array
	public $image_border_type = "none";        // 'raised', 'plain', 'none'
	// public $image_border_width;             // NULL, 0, or unset for default. Default depends on type.

	public $shading = 5;                       // 0 for no shading, > 0 is size of shadows in pixels

	public $draw_plot_area_background = FALSE;
	public $draw_broken_lines = FALSE;          // Tells not to draw lines for missing Y data.

//Miscellaneous
	public $callbacks = [                  // Valid callback reasons (see SetCallBack)
		"draw_setup" => NULL,
		"draw_image_background" => NULL,
		"draw_plotarea_background" => NULL,
		"draw_titles" => NULL,
		"draw_axes" => NULL,
		"draw_graph" => NULL,
		"draw_border" => NULL,
		"draw_legend" => NULL,
		"draw_all" => NULL,
		"data_color" => NULL,
		"debug_textbox" => NULL,  // For testing/debugging text box alignment
		"debug_scale" => NULL,    // For testing/debugging scale setup
	];

	// Defined plot types static array:
	// Array key is the plot type. (Upper case letters are not allowed due to CheckOption)
	// Value is an array with these keys:
	//   draw_method (required) : Class method to call to draw the plot.
	//   draw_arg : Optional array of arguments to pass to draw_method.
	//   draw_axes : If FALSE, do not draw X/Y axis lines, labels, ticks, grid, titles.
	//   abs_vals, sum_vals : Data array processing flags. See FindDataLimits().
	static protected $plots = [
		"area" => [
			"draw_method" => "DrawArea",
			"abs_vals" => TRUE,
		],
		"bars" => [
			"draw_method" => "DrawBars",
		],
		"candlesticks" => [
			"draw_method" => "DrawOHLC",
			"draw_arg" => [TRUE, FALSE], // Draw candlesticks, only fill if "closed down"
		],
		"candlesticks2" => [
			"draw_method" => "DrawOHLC",
			"draw_arg" => [TRUE, TRUE], // Draw candlesticks, fill always
		],
		"linepoints" => [
			"draw_method" => "DrawLinePoints",
		],
		"lines" => [
			"draw_method" => "DrawLines",
		],
		"ohlc" => [
			"draw_method" => "DrawOHLC",
			"draw_arg" => [FALSE], // Don't draw candlesticks
		],
		"pie" => [
			"draw_method" => "DrawPieChart",
			"draw_axes" => FALSE,
			"abs_vals" => TRUE,
		],
		"points" => [
			"draw_method" => "DrawDots",
		],
		"squared" => [
			"draw_method" => "DrawSquared",
		],
		"stackedarea" => [
			"draw_method" => "DrawArea",
			"draw_arg" => [TRUE], // Tells DrawArea to draw stacked area plot
			"sum_vals" => TRUE,
			"abs_vals" => TRUE,
		],
		"stackedbars" => [
			"draw_method" => "DrawStackedBars",
			"sum_vals" => TRUE,
		],
		"thinbarline" => [
			"draw_method" => "DrawThinBarLines",
		],
	];

//////////////////////////////////////////////////////
//BEGIN CODE
//////////////////////////////////////////////////////

	/*
	 * Constructor: Setup img resource, colors and size of the image, and font sizes.
	 *
	 *   $which_width : Image width in pixels.
	 *   $which_height : Image height in pixels.
	 *   $which_output_file : Filename for output.
	 *   $which_input_file : Path to a file to be used as background.
	 */
	function PHPlot($which_width=600, $which_height=400, $which_output_file=NULL, $which_input_file=NULL)
	{
		$this->SetRGBArray($this->color_array);

		if ($which_output_file)
			$this->SetOutputFile($which_output_file);

		if ($which_input_file) {
			$this->SetInputFile($which_input_file);
		} else {
			$this->image_width = $which_width;
			$this->image_height = $which_height;

			$this->img = ImageCreate($this->image_width, $this->image_height);
			if (! $this->img)
				return $this->PrintError("PHPlot(): Could not create image resource.");
		}

		$this->SetDefaultStyles();
		$this->SetDefaultFonts();
	}

	/*
	 * Reads an image file. Stores width and height, and returns the image
	 * resource. On error, calls PrintError and returns False.
	 * This is used by the constructor via SetInputFile, and by tile_img().
	 */
	protected function GetImage($image_filename, &$width, &$height)
	{
		$error = "";
		$size = getimagesize($image_filename);
		if (!$size) {
			$error = "Unable to query image file $image_filename";
		} else {
			$image_type = $size[2];
			switch ($image_type) {
			case IMAGETYPE_GIF:
				$img = @ ImageCreateFromGIF ($image_filename);
				break;
			case IMAGETYPE_PNG:
				$img = @ ImageCreateFromPNG ($image_filename);
				break;
			case IMAGETYPE_JPEG:
				$img = @ ImageCreateFromJPEG ($image_filename);
				break;
			default:
				$error = "Unknown image type ($image_type) for image file $image_filename";
				break;
			}
		}
		if (empty($error) && !$img) {
			// getimagesize is OK, but GD won't read it. Maybe unsupported format.
			$error = "Failed to read image file $image_filename";
		}
		if (!empty($error)) {
			return $this->PrintError("GetImage(): $error");
		}
		$width = $size[0];
		$height = $size[1];
		return $img;
	}

	/*
	 * Selects an input file to be used as background for the whole graph.
	 * This resets the graph size to the image's size.
	 * Note: This is used by the constructor. It is deprecated for direct use.
	 */
	function SetInputFile($which_input_file)
	{
		$im = $this->GetImage($which_input_file, $this->image_width, $this->image_height);
		if (!$im)
			return FALSE;  // GetImage already produced an error message.

		// Deallocate any resources previously allocated
		if (isset($this->img))
			imagedestroy($this->img);

		$this->img = $im;

		// Do not overwrite the input file with the background color.
		$this->done["background"] = TRUE;

		return TRUE;
	}

/////////////////////////////////////////////
//////////////                         COLORS
/////////////////////////////////////////////

	/*
	 * Allocate a GD color index for a color specified by a 4 component array.
	 * When a color is requested, it is parsed and checked by SetRGBColor, and then saved as an array
	 * of (R,G,B,A) components. At graph drawing time, this function is used to allocate the color.
	 *   $color : The color specification as a 4 component array: R, G, B, A.
	 * Returns: A GD color index that can be used when drawing.
	 */
	protected function GetColorIndex($color)
	{
		list($r, $g, $b, $a) = $color;
		return imagecolorresolvealpha($this->img, $r, $g, $b, $a);
	}

	/*
	 * Allocate an array of GD color indexes for an array of color specifications.
	 * This is used for the data_colors array, for example.
	 *  $color_array : Array of color specifications, each an array of R,G,B,A components.
	 *     This must use 0-based sequential integer indexes.
	 *  $max_colors : Limit color allocation to no more than this.
	 * Returns an array of GD color indexes.
	 */
	protected function GetColorIndexArray($color_array, $max_colors)
	{
		$n = min(count($color_array), $max_colors);
		$result = [];
		for ($i = 0; $i < $n; $i++)
			$result[] = $this->GetColorIndex($color_array[$i]);
		return $result;
	}

	/*
	 * Allocate an array of GD color indexes for darker shades of an array of color specifications.
	 *  $color_array : Array of color specifications, each an array of R,G,B,A components.
	 *  $max_colors : Limit color allocation to this many colors from the array.
	 * Returns an array of GD color indexes.
	 */
	protected function GetDarkColorIndexArray($color_array, $max_colors)
	{
		$n = min(count($color_array), $max_colors);
		$result = [];
		for ($i = 0; $i < $n; $i++)
			$result[] = $this->GetDarkColorIndex($color_array[$i]);
		return $result;
	}

	/*
	 * Allocate a GD color index for a darker shade of a color specified by a 4 component array.
	 * See notes for GetColorIndex() above.
	 *   $color : The color specification as a 4 component array: R, G, B, A.
	 * Returns: A GD color index that can be used when drawing.
	 */
	protected function GetDarkColorIndex($color)
	{
		list ($r, $g, $b, $a) = $color;
		$r = max(0, $r - 0x30);
		$g = max(0, $g - 0x30);
		$b = max(0, $b - 0x30);
		return imagecolorresolvealpha($this->img, $r, $g, $b, $a);
	}

	/*
	 * Sets/reverts all colors and styles to their defaults.
	 */
	protected function SetDefaultStyles()
	{
		$this->SetDefaultDashedStyle($this->dashed_style);
		$this->SetImageBorderColor([194, 194, 194]);
		$this->SetPlotBgColor("white");
		$this->SetBackgroundColor("white");
		$this->SetTextColor("black");
		$this->SetGridColor("black");
		$this->SetLightGridColor("gray");
		$this->SetTickColor("black");
		$this->SetTitleColor("black");
		// These functions set up the default colors when called without parameters
		$this->SetDataColors();
		$this->SetErrorBarColors();
		$this->SetDataBorderColors();
		return TRUE;
	}

	/*
	 * Set the image background color to $which_color.
	 */
	function SetBackgroundColor($which_color)
	{
		return (bool)($this->bg_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the plot area background color (if enabled) to $which_color.
	 */
	function SetPlotBgColor($which_color)
	{
		return (bool)($this->plot_bg_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the color of the titles (main, X, and Y) to $which_color.
	 * See also SetXTitleColor and SetYTitleColor.
	 */
	function SetTitleColor($which_color)
	{
		return (bool)($this->title_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the color of the X title to $which_color.
	 * This overrides the color set with SetTitleColor.
	 */
	function SetXTitleColor($which_color)
	{
		return (bool)($this->x_title_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the color of the Y title to $which_color.
	 * This overrides the color set with SetTitleColor.
	 */
	function SetYTitleColor($which_color)
	{
		return (bool)($this->y_title_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the color of the axis tick marks to $which_color.
	 */
	function SetTickColor($which_color)
	{
		return (bool)($this->tick_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Deprecated. Use SetTitleColor()
	 */
	function SetLabelColor($which_color)
	{
		return $this->SetTitleColor($which_color);
	}

	/*
	 * Set the general text color (tick and data labels, legend, etc) to $which_color.
	 */
	function SetTextColor($which_color)
	{
		return (bool)($this->text_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the X and Y grid colors to $which_color. Also sets the data label line color.
	 */
	function SetLightGridColor($which_color)
	{
		return (bool)($this->light_grid_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the color used for the X and Y axis, plot border, legend border to $which_color.
	 * Note: This has nothing to do with the grid, and we don't recall where this name came from.
	 */
	function SetGridColor($which_color)
	{
		return (bool)($this->grid_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Set the color used for the image border to $which_color.
	 */
	function SetImageBorderColor($which_color)
	{
		return (bool)($this->i_border = $this->SetRGBColor($which_color));
	}

	/*
	 * Designate color $which_color to be transparent, if supported by the image format.
	 */
	function SetTransparentColor($which_color)
	{
		return (bool)($this->transparent_color = $this->SetRGBColor($which_color));
	}

	/*
	 * Sets the array of colors to be used. It can be user defined, a small predefined one
	 * or a large one included from 'rgb.inc.php'.
	 *
	 *    $which_color_array : A color array, or 'small' or 'large'.
	 * Color arrays map color names into arrays of R, G, B and optionally A values.
	 */
	function SetRGBArray($which_color_array)
	{
		if (is_array($which_color_array)) {           // User defined array
			$this->rgb_array = $which_color_array;
		} elseif ($which_color_array == "small") {      // Small predefined color array
			$this->rgb_array = [
				"white"          => [255, 255, 255],
				"snow"           => [255, 250, 250],
				"PeachPuff"      => [255, 218, 185],
				"ivory"          => [255, 255, 240],
				"lavender"       => [230, 230, 250],
				"black"          => [  0,   0,   0],
				"DimGrey"        => [105, 105, 105],
				"gray"           => [190, 190, 190],
				"grey"           => [190, 190, 190],
				"navy"           => [  0,   0, 128],
				"SlateBlue"      => [106,  90, 205],
				"blue"           => [  0,   0, 255],
				"SkyBlue"        => [135, 206, 235],
				"cyan"           => [  0, 255, 255],
				"DarkGreen"      => [  0, 100,   0],
				"green"          => [  0, 255,   0],
				"YellowGreen"    => [154, 205,  50],
				"yellow"         => [255, 255,   0],
				"orange"         => [255, 165,   0],
				"gold"           => [255, 215,   0],
				"peru"           => [205, 133,  63],
				"beige"          => [245, 245, 220],
				"wheat"          => [245, 222, 179],
				"tan"            => [210, 180, 140],
				"brown"          => [165,  42,  42],
				"salmon"         => [250, 128, 114],
				"red"            => [255,   0,   0],
				"pink"           => [255, 192, 203],
				"maroon"         => [176,  48,  96],
				"magenta"        => [255,   0, 255],
				"violet"         => [238, 130, 238],
				"plum"           => [221, 160, 221],
				"orchid"         => [218, 112, 214],
				"purple"         => [160,  32, 240],
				"azure1"         => [240, 255, 255],
				"aquamarine1"    => [127, 255, 212],
				];
		} elseif ($which_color_array == "large")  {    // Large color array
			if (!@include("rgb.inc.php")) {
				return $this->PrintError("SetRGBArray(): Large color map could not be loaded\n"
									   . "from 'rgb.inc.php'.", );
			}
			$this->rgb_array = $ColorArray;
		} else {                                        // Default to black and white only.
			$this->rgb_array = ["white" => [255, 255, 255], "black" => [0, 0, 0]];
		}

		return TRUE;
	}

	/*
	 * Parse a color description and return the color component values.
	 * Arguments:
	 *   $color_asked : The desired color description, in one of these forms:
	 *       Component notation: array(R, G, B) or array(R, G, B, A) with each
	 *          in the range described below for the return value.
	 *          Examples: (255,255,0)  (204,0,0,30)
	 *       Hex notation: "#RRGGBB" or "#RRGGBBAA" where each pair is a 2 digit hex number.
	 *          Examples: #FF00FF (magenta)   #0000FF40 (Blue with alpha=64/127)
	 *       Named color in the current colormap, with optional suffix ":alpha" for alpha value.
	 *          Examples:  blue   red:60  yellow:20
	 *   $alpha : optional default alpha value. This is applied to the color if it doesn't
	 *       already have an alpha value. If not supplied, colors are opaque (alpha=0) by default.
	 *
	 * Returns an array describing a color as (R, G, B, Alpha).
	 * R, G, and B are integers 0-255, and Alpha is 0 (opaque) to 127 (transparent).
	 * Note: This function should be considered 'protected', and is not documented for public use.
	 */
	function SetRGBColor($color_asked, $alpha = 0)
	{
		if (empty($color_asked)) {
			$ret_val = [0, 0, 0];

		} elseif (is_array($color_asked) && (($n = count($color_asked)) == 3 || $n == 4) ) {
			// Already an array of 3 or 4 elements:
			$ret_val = $color_asked;

		} elseif (preg_match("/^#([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})?$/i",
							 $color_asked, $ss, )) {
			// #RRGGBB or #RRGGBBAA notation:
			$ret_val = [hexdec($ss[1]), hexdec($ss[2]), hexdec($ss[3])];
			if (isset($ss[4])) $ret_val[] = hexdec($ss[4]);

		} elseif (isset($this->rgb_array[$color_asked])) {
			// Color by name:
			$ret_val = $this->rgb_array[$color_asked];

		} elseif (preg_match('/(.+):([\d]+)$/', $color_asked, $ss)
				  && isset($this->rgb_array[$ss[1]])) {
			// Color by name with ":alpha" suffix, alpha is a decimal number:
			$ret_val = $this->rgb_array[$ss[1]];
			$ret_val[3] = (int)$ss[2];

		} else {
			return $this->PrintError("SetRGBColor(): Color '$color_asked' is not valid.");
		}

		// Append alpha if not already provided for:
		if (count($ret_val) == 3)
			$ret_val[] = $alpha;
		return $ret_val;
	}

	/*
	 * Sets the colors for the data, with optional default alpha value
	 * Cases are:
	 *    SetDataColors(array(...))  : Use the supplied array as the color map.
	 *    SetDataColors(colorname)   : Use an array of just colorname as the color map.
	 *    SetDataColors() or SetDataColors(NULL) : Load default color map if no color map is already set.
	 *    SetDataColors('') or SetDataColors(False) : Load default color map (even if one is already set).
	 *  $which_border is passed to SetDataBorderColors, for backward compatibility.
	 *  $alpha is a default Alpha to apply to all data colors that do not have alpha.
	 *    The default for this is NULL, not 0, so we can tell if it was defaulted. But the effective
	 *    default value is 0 (opaque).
	 */
	function SetDataColors($which_data = NULL, $which_border = NULL, $alpha = NULL)
	{
		if (is_array($which_data)) {
			$colors = $which_data;  // Use supplied array
		} elseif (!empty($which_data)) {
			$colors = [$which_data];  // Use supplied single color
		} elseif (empty($this->data_colors) || !is_null($which_data)) {
			$colors = $this->default_colors;  // Use default color array
		} else {
			// which_data is NULL or missing and a color array is already set.
			// The existing color array is left alone, except that if $alpha is
			// given this will replace the alpha value of each existing color.
			// This makes SetDataColors(NULL, NULL, $alpha) work.
			if (isset($alpha)) {
				$n_colors = count($this->data_colors);
				for ($i = 0; $i < $n_colors; $i++) {
					$this->data_colors[$i][3] = $alpha; // Component 3 = alpha value
				}
			}
			// No need to reparse the colors or anything else.
			return TRUE;
		}

		if (!isset($alpha))
			$alpha = 0; // Actual default is opaque colors.

		// Check each color and convert to array (r,g,b,a) form.
		// Use the $alpha argument as a default for the alpha value of each color.
		$this->data_colors = [];
		foreach ($colors as $color) {
			$color_array = $this->SetRGBColor($color, $alpha);
			if (!$color_array) return FALSE; // SetRGBColor already did an error message.
			$this->data_colors[] = $color_array;
		}

		// For past compatibility:
		return $this->SetDataBorderColors($which_border);
	}

	/*
	 * Set the colors for the bars and stacked bars outlines.
	 * Argument usage is similar to SetDataColors(), except the default is just black.
	 */
	function SetDataBorderColors($which_br = NULL)
	{
		if (is_array($which_br)) {
			$colors = $which_br; // Use supplied array
		} elseif (!empty($which_br)) {
			$colors = [$which_br];  // Use supplied single color
		} elseif (empty($this->data_border_colors) || !is_null($which_br)) {
			$colors = ["black"]; // Use default
		} else {
			return TRUE; // Do nothing: which_br is NULL or missing and a color array is already set.
		}

		// Check each color and convert to array (r,g,b,a) form.
		$this->data_border_colors = [];
		foreach ($colors as $color) {
			$color_array = $this->SetRGBColor($color);
			if (!$color_array) return FALSE; // SetRGBColor already did an error message.
			$this->data_border_colors[] = $color_array;
		}
		return TRUE;
	}

	/*
	 * Sets the colors for the data error bars.
	 * Argument usage is the same as SetDataColors().
	 */
	function SetErrorBarColors($which_err = NULL)
	{
		if (is_array($which_err)) {
			$colors = $which_err;  // Use supplied array
		} elseif (!empty($which_err)) {
			$colors = [$which_err];  // Use supplied single color
		} elseif (empty($this->error_bar_colors) || !is_null($which_err)) {
			$colors = $this->default_colors;  // Use default color array
		} else {
			return TRUE; // Do nothing: which_err is NULL or missing and a color array is already set.
		}

		// Check each color and convert to array (r,g,b,a) form.
		$this->error_bar_colors = [];
		foreach ($colors as $color) {
			$color_array = $this->SetRGBColor($color);
			if (!$color_array) return FALSE; // SetRGBColor already did an error message.
			$this->error_bar_colors[] = $color_array;
		}
		return TRUE;
	}

	/*
	 * Sets the default dashed line style.
	 *   $which_style : A string specifying the dashed line style, as alternating numbers
	 *         of the length (in pixels) of lines and spaces, separated by dashes.
	 *   For example: '2-3-1-2' means 2 dots of color, 3 transparent, 1 color, then 2 transparent.
	 *   This builds a string which will evaluate to an array of integers. Each colored dot
	 *   is  '$which_ndxcol' and each transparent dot is 'IMG_COLOR_TRANSPARENT'. When SetDashedStyle()
	 *   eval's this with $which_ndxcol set, the result is a GD line style array.
	 */
	function SetDefaultDashedStyle($which_style)
	{
		// Explode "numcol-numtrans-numcol-numtrans..." into segment counts:
		$asked = explode("-", $which_style);

		if (count($asked) < 2) {
			return $this->PrintError("SetDefaultDashedStyle(): Wrong parameter '$which_style'.");
		}

		// Build the string to be evaluated later by SetDashedStyle() with $which_ndxcolor set.
		$result = "";
		$vals = ["$which_ndxcol,", "IMG_COLOR_TRANSPARENT,"];
		$index = 0;
		foreach ($asked as $n) {
			$result .= str_repeat($vals[$index], $n);
			$index = 1 - $index;
		}
		$this->default_dashed_style = "array($result)";

		return TRUE;
	}

	/*
	 * Sets the style before drawing a dashed line. Defaults to $this->default_dashed_style
	 *    $which_ndxcol : Color index to be used.
	 */
	protected function SetDashedStyle($which_ndxcol)
	{
		// See SetDefaultDashedStyle() to understand this.
		eval ("\$style = $this->default_dashed_style;");
		return imagesetstyle($this->img, $style);
	}

	/*
	 * Set line widths for each data set.
	 *   $which_lw : Array of line widths in pixels, or a single value to use for all data sets.
	 */
	function SetLineWidths($which_lw=NULL)
	{
		if (is_array($which_lw)) {
			$this->line_widths = $which_lw; // Use provided array
		} elseif (!is_null($which_lw)) {
			$this->line_widths = [$which_lw]; // Convert value to array
		}
		return TRUE;
	}

	/*
	 * Set line style ('solid' or 'dashed') for each data set.
	 *   $which_ls : Array of keywords, or a single keyword to use for all data sets.
	 */
	function SetLineStyles($which_ls=NULL)
	{
		if (is_array($which_ls)) {
			$this->line_styles = $which_ls; // Use provided array
		} elseif (!is_null($which_ls)) {
			$this->line_styles = ($which_ls) ? [$which_ls] : ["solid"];
		}
		return TRUE;
	}

/////////////////////////////////////////////
//////////////                 TEXT and FONTS
/////////////////////////////////////////////

	/*
	 * Controls the line spacing of multi-line labels.
	 *   $which_spc : Line spacing factor for text
	 * For GD text, this is the number of pixels between lines.
	 * For TTF text, it controls line spacing in proportion to the normal
	 * spacing defined by the font.
	 */
	function SetLineSpacing($which_spc)
	{
		$this->line_spacing = $which_spc;
		return TRUE;
	}

	/*
	 * Select the default font type to use.
	 *   $which_ttf : True to default to TrueType, False to default to GD (fixed) fonts.
	 * This also resets all font settings to the defaults.
	 */
	function SetUseTTF($which_ttf)
	{
		$this->use_ttf = $which_ttf;
		return $this->SetDefaultFonts();
	}

	/*
	 * Sets the directory name to look into for TrueType fonts.
	 */
	function SetTTFPath($which_path)
	{
		if (!is_dir($which_path) || !is_readable($which_path)) {
			return $this->PrintError("SetTTFPath(): $which_path is not a valid path.");
		}
		$this->ttf_path = $which_path;
		return TRUE;
	}

	/*
	 * Sets the default TrueType font and updates all fonts to that.
	 * The default font might be a full path, or relative to the TTFPath,
	 * so let SetFont check that it exists.
	 * Side effects: Enables use of TrueType fonts as the default font type,
	 * and resets all font settings.
	 */
	function SetDefaultTTFont($which_font)
	{
		$this->default_ttfont = $which_font;
		return $this->SetUseTTF(TRUE);
	}

	/*
	 * Return the default TrueType font name. If no default has been set,
	 * this tries some likely candidates for a font which can be loaded.
	 * If it finds one that works, that becomes the default TT font.
	 * If there is no default and it cannot find a working font, it falls
	 * back to the original PHPlot default (which will not likely work either).
	 */
	protected function GetDefaultTTFont()
	{
		if (!isset($this->default_ttfont)) {
			// No default font yet. Try some common sans-serif fonts.
			$fonts = ["LiberationSans-Regular.ttf",  // For Linux with a correct GD font search path
						   "Verdana.ttf", "Arial.ttf", "Helvetica.ttf", // For Windows, maybe others
						   "ttf-liberation/LiberationSans-Regular.ttf", // For Debian, Ubuntu, and friends
						   "benjamingothic.ttf",  // Original PHPlot default
						  ];
			foreach ($fonts as $font) {
				// First try the font name alone, to see if GD can find and load it.
				if (@imagettfbbox(10, 0, $font, "1") !== False)
					break;
				// If the font wasn't found, try it with the default TTF path in front.
				$font_with_path = $this->ttf_path . DIRECTORY_SEPARATOR . $font;
				if (@imagettfbbox(10, 0, $font_with_path, "1") !== False) {
					$font = $font_with_path;
					break;
				}
			}
			// We either have a working font, or are using the last one regardless.
			$this->default_ttfont = $font;
		}
		return $this->default_ttfont;
	}

	/*
	 * Sets fonts to their defaults
	 */
	protected function SetDefaultFonts()
	{
		// TTF:
		if ($this->use_ttf) {
			return $this->SetFont("generic", "", 8)
				&& $this->SetFont("title", "", 14)
				&& $this->SetFont("legend", "", 8)
				&& $this->SetFont("x_label", "", 6)
				&& $this->SetFont("y_label", "", 6)
				&& $this->SetFont("x_title", "", 10)
				&& $this->SetFont("y_title", "", 10);
		}
		// Fixed GD Fonts:
		return $this->SetFont("generic", 2)
			&& $this->SetFont("title", 5)
			&& $this->SetFont("legend", 2)
			&& $this->SetFont("x_label", 1)
			&& $this->SetFont("y_label", 1)
			&& $this->SetFont("x_title", 3)
			&& $this->SetFont("y_title", 3);
	}

	/*
	 * Select a fixed (GD) font for an element.
	 * This allows using a fixed font, even with SetUseTTF(True).
	 *    $which_elem : The element whose font is to be changed.
	 *       One of: title legend generic x_label y_label x_title y_title
	 *    $which_font : A GD font number 1-5
	 *    $which_spacing (optional) : Line spacing factor
	 */
	function SetFontGD($which_elem, $which_font, $which_spacing = NULL)
	{
		if ($which_font < 1 || 5 < $which_font) {
			return $this->PrintError(__FUNCTION__ . ": Font size must be 1, 2, 3, 4 or 5");
		}
		if (!$this->CheckOption($which_elem,
								"generic, title, legend, x_label, y_label, x_title, y_title",
								__FUNCTION__, )) {
			return FALSE;
		}

		// Store the font parameters: name/size, char cell height and width.
		$this->fonts[$which_elem] = ["ttf" => FALSE,
										  "font" => $which_font,
										  "height" => ImageFontHeight($which_font),
										  "width" => ImageFontWidth($which_font),
										  "line_spacing" => $which_spacing, ];
		return TRUE;
	}

	/*
	 * Select a TrueType font for an element.
	 * This allows using a TrueType font, even with SetUseTTF(False).
	 *    $which_elem : The element whose font is to be changed.
	 *       One of: title legend generic x_label y_label x_title y_title
	 *    $which_font : A TrueType font filename or pathname.
	 *    $which_size : Font point size.
	 *    $which_spacing (optional) : Line spacing factor
	 */
	function SetFontTTF($which_elem, $which_font, $which_size = 12, $which_spacing = NULL)
	{
		if (!$this->CheckOption($which_elem,
								"generic, title, legend, x_label, y_label, x_title, y_title",
								__FUNCTION__, )) {
			return FALSE;
		}

		// Empty font name means use the default font.
		if (empty($which_font))
			$which_font = $this->GetDefaultTTFont();
		$path = $which_font;

		// First try the font name directly, if not then try with path.
		// Use GD imagettfbbox() to determine if this is a valid font.
		// The return $bbox is used below, if valid.
		if (($bbox = @imagettfbbox($which_size, 0, $path, "E")) === False) {
			$path = $this->ttf_path . DIRECTORY_SEPARATOR . $which_font;
			if (($bbox = @imagettfbbox($which_size, 0, $path, "E")) === False) {
				return $this->PrintError(__FUNCTION__ . ": Can't find TrueType font $which_font");
			}
		}

		// Calculate the font height and inherent line spacing. TrueType fonts have this information
		// internally, but PHP/GD has no way to directly access it. So get the bounding box size of
		// an upper-case character without descenders, and the baseline-to-baseline height.
		// Note: In practice, $which_size = $height, maybe +/-1 . But which_size is in points,
		// and height is in pixels, and someday GD may be able to tell the difference.
		// The character width is saved too, but not used by the normal text drawing routines - it
		// isn't necessarily a fixed-space font. It is used in DrawLegend.
		$height = $bbox[1] - $bbox[5];
		$width = $bbox[2] - $bbox[0];
		$bbox = ImageTTFBBox($which_size, 0, $path, "E\nE");
		$spacing = $bbox[1] - $bbox[5] - 2 * $height;

		// Store the font parameters:
		$this->fonts[$which_elem] = ["ttf" => TRUE,
										  "font" => $path,
										  "size" => $which_size,
										  "height" => $height,
										  "width" => $width,
										  "spacing" => $spacing,
										  "line_spacing" => $which_spacing, ];
		return TRUE;
	}

	/*
	 * Select Fixed/TrueType font for an element. Which type of font is
	 * selected depends on the $use_ttf class variable (see SetUseTTF()).
	 * Before PHPlot supported mixing font types, only this function and
	 * SetUseTTF were available to select an overall font type, but now
	 * SetFontGD() and SetFontTTF() can be used for mixing font types.
	 *    $which_elem : The element whose font is to be changed.
	 *       One of: title legend generic x_label y_label x_title y_title
	 *    $which_font : A number 1-5 for fixed fonts, or a TrueType font.
	 *    $which_size : Ignored for Fixed fonts, point size for TrueType.
	 *    $which_spacing (optional) : Line spacing factor
	 */
	function SetFont($which_elem, $which_font, $which_size = 12, $line_spacing = NULL)
	{
		if ($this->use_ttf)
			return $this->SetFontTTF($which_elem, $which_font, $which_size, $line_spacing);
		return $this->SetFontGD($which_elem, $which_font, $line_spacing);
	}

	/*
	 * Return the inter-line spacing for a font.
	 * This is an internal function, used by ProcessText* and DrawLegend.
	 *   $font : A font array variable.
	 * Returns: Spacing, in pixels, between text lines.
	 */
	protected function GetLineSpacing($font)
	{
		// Use the per-font line spacing preference, if set, else the global value:
		if (isset($font["line_spacing"]))
			$line_spacing = $font["line_spacing"];
		else
			$line_spacing = $this->line_spacing;

		// For GD fonts, that is the spacing in pixels.
		// For TTF, adjust based on the 'natural' font spacing (see SetFontTTF):
		if ($font["ttf"]) {
			$line_spacing = (int)($line_spacing * $font["spacing"] / 6.0);
		}
		return $line_spacing;
	}

	/*
	 * Text drawing and sizing functions:
	 * ProcessText is meant for use only by DrawText and SizeText.
	 *    ProcessText(True, ...)  - Draw a block of text
	 *    ProcessText(False, ...) - Just return ($width, $height) of
	 *       the orthogonal bounding box containing the text.
	 * ProcessText is further split into separate functions for GD and TTF
	 * text, due to the size of the code.
	 *
	 * Horizontal and vertical alignment are relative to the drawing. That is:
	 * vertical text (90 deg) gets centered along Y position with
	 * v_align = 'center', and adjusted to the right of X position with
	 * h_align = 'right'.  Another way to look at this is to say
	 * that text rotation happens first, then alignment.
	 *
	 * Original multiple lines code submitted by Remi Ricard.
	 * Original vertical code submitted by Marlin Viss.
	 *
	 * Text routines rewritten by ljb to fix alignment and position problems.
	 * Here is my explanation and notes. More information and pictures will be
	 * placed in the PHPlot Reference Manual.
	 *
	 *    + Process TTF text one line at a time, not as a block. (See below)
	 *    + Flipped top vs bottom vertical alignment. The usual interpretation
	 *  is: bottom align means bottom of the text is at the specified Y
	 *  coordinate. For some reason, PHPlot did left/right the correct way,
	 *  but had top/bottom reversed. I fixed it, and left the default valign
	 *  argument as bottom, but the meaning of the default value changed.
	 *
	 *    For GD font text, only single-line text is handled by GD, and the
	 *  basepoint is the upper left corner of each text line.
	 *    For TTF text, multi-line text could be handled by GD, with the text
	 *  basepoint at the lower left corner of the first line of text.
	 *  (Behavior of TTF drawing routines on multi-line text is not documented.)
	 *  But you cannot do left/center/right alignment on each line that way,
	 *  or proper line spacing.
	 *    Therefore, for either text type, we have to break up the text into
	 *  lines and position each line independently.
	 *
	 *    There are 9 alignment modes: Horizontal = left, center, or right, and
	 *  Vertical = top, center, or bottom. Alignment is interpreted relative to
	 *  the image, not as the text is read. This makes sense when you consider
	 *  for example X axis labels. They need to be centered below the marks
	 *  (center, top alignment) regardless of the text angle.
	 *  'Bottom' alignment really means baseline alignment.
	 *
	 *    GD font text is supported (by libgd) at 0 degrees and 90 degrees only.
	 *  Multi-line or single line text works with any of the 9 alignment modes.
	 *
	 *    TTF text can be at any angle. The 9 alignment modes work for all angles,
	 *  but the results might not be what you expect for multi-line text. See
	 *  the PHPlot Reference Manual for pictures and details. In short, alignment
	 *  applies to the orthogonal (aligned with X and Y axes) bounding box that
	 *  contains the text, and to each line in the multi-line text box. Since
	 *  alignment is relative to the image, 45 degree multi-line text aligns
	 *  differently from 46 degree text.
	 *
	 *    Note that PHPlot allows multi-line text for the 3 titles, and they
	 *  are only drawn at 0 degrees (main and X titles) or 90 degrees (Y title).
	 *  Data labels can also be multi-line, and they can be drawn at any angle.
	 *  -ljb 2007-11-03
	 *
	 */

	/*
	 * ProcessTextGD() - Draw or size GD fixed-font text.
	 * This is intended for use only by ProcessText().
	 *    $draw_it : True to draw the text, False to just return the orthogonal width and height.
	 *    $font : PHPlot font array (with 'ttf' = False) - see SetFontGD()
	 *    $angle : Text angle in degrees. GD only supports 0 and 90. We treat >= 45 as 90, else 0.
	 *    $x, $y : Reference point for the text (ignored if !$draw_it)
	 *    $color : GD color index to use for drawing the text (ignored if !$draw_it)
	 *    $text : The text to draw or size. Put a newline between lines.
	 *    $h_factor : Horizontal alignment factor: 0(left), .5(center), or 1(right) (ignored if !$draw_it)
	 *    $v_factor : Vertical alignment factor: 0(top), .5(center), or 1(bottom) (ignored if !$draw_it)
	 * Returns: True, if drawing text, or an array of ($width, $height) if not.
	 */
	protected function ProcessTextGD($draw_it, $font, $angle, $x, $y, $color, $text, $h_factor, $v_factor)
	{
		// Extract font parameters:
		$font_number = $font["font"];
		$font_width = $font["width"];
		$font_height = $font["height"];
		$line_spacing = $this->GetLineSpacing($font);

		// Break up the text into lines, trim whitespace, find longest line.
		// Save the lines and length for drawing below.
		$longest = 0;
		foreach (explode("\n", $text) as $each_line) {
			$lines[] = $line = trim($each_line);
			$line_lens[] = $line_len = strlen($line);
			if ($line_len > $longest) $longest = $line_len;
		}
		$n_lines = count($lines);

		// Width, height are based on font size and longest line, line count respectively.
		// These are relative to the text angle.
		$total_width = $longest * $font_width;
		$total_height = $n_lines * $font_height + ($n_lines - 1) * $line_spacing;

		if (!$draw_it) {
			if ($angle < 45) return [$total_width, $total_height];
			return [$total_height, $total_width];
		}

		$interline_step = $font_height + $line_spacing; // Line-to-line step

		if ($angle >= 45) {
			// Vertical text (90 degrees):
			// (Remember the alignment convention with vertical text)
			// For 90 degree text, alignment factors change like this:
			$temp = $v_factor;
			$v_factor = $h_factor;
			$h_factor = 1 - $temp;

			$draw_func = "ImageStringUp";

			// Rotation matrix "R" for 90 degrees (with Y pointing down):
			$r00 = 0;  $r01 = 1;
			$r10 = -1; $r11 = 0;

		} else {
			// Horizontal text (0 degrees):
			$draw_func = "ImageString";

			// Rotation matrix "R" for 0 degrees:
			$r00 = 1; $r01 = 0;
			$r10 = 0; $r11 = 1;
		}

		// Adjust for vertical alignment (horizontal text) or horizontal alignment (vertical text):
		$factor = (int)($total_height * $v_factor);
		$xpos = $x - $r01 * $factor;
		$ypos = $y - $r11 * $factor;

		// Debug callback provides the bounding box:
		if ($this->GetCallback("debug_textbox")) {
			if ($angle >= 45) {
				$bbox_width  = $total_height;
				$bbox_height = $total_width;
				$px = $xpos;
				$py = $ypos - (1 - $h_factor) * $total_width;
			} else {
				$bbox_width  = $total_width;
				$bbox_height = $total_height;
				$px = $xpos - $h_factor * $total_width;
				$py = $ypos;
			}
			$this->DoCallback("debug_textbox", $px, $py, $bbox_width, $bbox_height);
		}

		for ($i = 0; $i < $n_lines; $i++) {

			// Adjust for alignment of this line within the text block:
			$factor = (int)($line_lens[$i] * $font_width * $h_factor);
			$x = $xpos - $r00 * $factor;
			$y = $ypos - $r10 * $factor;

			// Call ImageString or ImageStringUp:
			$draw_func($this->img, $font_number, $x, $y, $lines[$i], $color);

			// Step to the next line of text. This is a rotation of (x=0, y=interline_spacing)
			$xpos += $r01 * $interline_step;
			$ypos += $r11 * $interline_step;
		}
		return TRUE;
	}

	/*
	 * ProcessTextTTF() - Draw or size TTF text.
	 * This is intended for use only by ProcessText().
	 *    $draw_it : True to draw the text, False to just return the orthogonal width and height.
	 *    $font : PHPlot font array (with 'ttf' = True) - see SetFontTTF()
	 *    $angle : Text angle in degrees.
	 *    $x, $y : Reference point for the text (ignored if !$draw_it)
	 *    $color : GD color index to use for drawing the text (ignored if !$draw_it)
	 *    $text : The text to draw or size. Put a newline between lines.
	 *    $h_factor : Horizontal alignment factor: 0(left), .5(center), or 1(right) (ignored if !$draw_it)
	 *    $v_factor : Vertical alignment factor: 0(top), .5(center), or 1(bottom) (ignored if !$draw_it)
	 * Returns: True, if drawing text, or an array of ($width, $height) if not.
	 */
	protected function ProcessTextTTF($draw_it, $font, $angle, $x, $y, $color, $text, $h_factor, $v_factor)
	{
		// Extract font parameters (see SetFontTTF):
		$font_file = $font["font"];
		$font_size = $font["size"];
		$font_height = $font["height"];
		$line_spacing = $this->GetLineSpacing($font);

		// Break up the text into lines, trim whitespace.
		// Calculate the total width and height of the text box at 0 degrees.
		// Save the trimmed lines and their widths for later when drawing.
		// To get uniform spacing, don't use the actual line heights.
		// Total height = Font-specific line heights plus inter-line spacing.
		// Total width = width of widest line.
		// Last Line Descent is the offset from the bottom to the text baseline.
		// Note: For some reason, ImageTTFBBox uses (-1,-1) as the reference point.
		//   So 1+bbox[1] is the baseline to bottom distance.
		$total_width = 0;
		$lastline_descent = 0;
		foreach (explode("\n", $text) as $each_line) {
			$lines[] = $line = trim($each_line);
			$bbox = ImageTTFBBox($font_size, 0, $font_file, $line);
			$line_widths[] = $width = $bbox[2] - $bbox[0];
			if ($width > $total_width) $total_width = $width;
			$lastline_descent = 1 + $bbox[1];
		}
		$n_lines = count($lines);
		$total_height = $n_lines * $font_height + ($n_lines - 1) * $line_spacing;

		// Calculate the rotation matrix for the text's angle. Remember that GD points Y down,
		// so the sin() terms change sign.
		$theta = deg2rad($angle);
		$cos_t = cos($theta);
		$sin_t = sin($theta);
		$r00 = $cos_t;    $r01 = $sin_t;
		$r10 = -$sin_t;   $r11 = $cos_t;

		// Make a bounding box of the right size, with upper left corner at (0,0).
		// By convention, the point order is: LL, LR, UR, UL.
		// Note this is still working with the text at 0 degrees.
		// When sizing text (SizeText), use the overall size with descenders.
		//   This tells the caller how much room to leave for the text.
		// When drawing text (DrawText), use the size without descenders - that
		//   is, down to the baseline. This is for accurate positioning.
		$b[0] = 0;
		if ($draw_it) {
			$b[1] = $total_height;
		} else {
			$b[1] = $total_height + $lastline_descent;
		}
		$b[2] = $total_width;  $b[3] = $b[1];
		$b[4] = $total_width;  $b[5] = 0;
		$b[6] = 0;             $b[7] = 0;

		// Rotate the bounding box, then offset to the reference point:
		for ($i = 0; $i < 8; $i += 2) {
			$x_b = $b[$i];
			$y_b = $b[$i+1];
			$c[$i]   = $x + $r00 * $x_b + $r01 * $y_b;
			$c[$i+1] = $y + $r10 * $x_b + $r11 * $y_b;
		}

		// Get an orthogonal (aligned with X and Y axes) bounding box around it, by
		// finding the min and max X and Y:
		$bbox_ref_x = $bbox_max_x = $c[0];
		$bbox_ref_y = $bbox_max_y = $c[1];
		for ($i = 2; $i < 8; $i += 2) {
			$x_b = $c[$i];
			if ($x_b < $bbox_ref_x) $bbox_ref_x = $x_b;
			elseif ($bbox_max_x < $x_b) $bbox_max_x = $x_b;
			$y_b = $c[$i+1];
			if ($y_b < $bbox_ref_y) $bbox_ref_y = $y_b;
			elseif ($bbox_max_y < $y_b) $bbox_max_y = $y_b;
		}
		$bbox_width = $bbox_max_x - $bbox_ref_x;
		$bbox_height = $bbox_max_y - $bbox_ref_y;

		if (!$draw_it) {
			// Return the bounding box, rounded up (so it always contains the text):
			return [(int)ceil($bbox_width), (int)ceil($bbox_height)];
		}

		$interline_step = $font_height + $line_spacing; // Line-to-line step

		// Calculate the offsets from the supplied reference point to the
		// upper-left corner of the text.
		// Start at the reference point at the upper left corner of the bounding
		// box (bbox_ref_x, bbox_ref_y) then adjust it for the 9 point alignment.
		// h,v_factor are 0,0 for top,left, .5,.5 for center,center, 1,1 for bottom,right.
		//    $off_x = $bbox_ref_x + $bbox_width * $h_factor - $x;
		//    $off_y = $bbox_ref_y + $bbox_height * $v_factor - $y;
		// Then use that offset to calculate back to the supplied reference point x, y
		// to get the text base point.
		//    $qx = $x - $off_x;
		//    $qy = $y - $off_y;
		// Reduces to:
		$qx = 2 * $x - $bbox_ref_x - $bbox_width * $h_factor;
		$qy = 2 * $y - $bbox_ref_y - $bbox_height * $v_factor;

		// Check for debug callback. Don't calculate bounding box unless it is wanted.
		if ($this->GetCallback("debug_textbox")) {
			// Calculate the orthogonal bounding box coordinates for debug testing.

			// qx, qy is upper left corner relative to the text.
			// Calculate px,py: upper left corner (absolute) of the bounding box.
			// There are 4 equation sets for this, depending on the quadrant:
			if ($sin_t > 0) {
				if ($cos_t > 0) {
					// Quadrant: 0d - 90d:
					$px = $qx; $py = $qy - $total_width * $sin_t;
				} else {
					// Quadrant: 90d - 180d:
				   $px = $qx + $total_width * $cos_t; $py = $qy - $bbox_height;
				}
			} else {
				if ($cos_t < 0) {
					// Quadrant: 180d - 270d:
					$px = $qx - $bbox_width; $py = $qy + $total_height * $cos_t;
				} else {
					// Quadrant: 270d - 360d:
					$px = $qx + $total_height * $sin_t; $py = $qy;
				}
			}
			$this->DoCallback("debug_textbox", $px, $py, $bbox_width, $bbox_height);
		}

		// Since alignment is applied after rotation, which parameter is used
		// to control alignment of each line within the text box varies with
		// the angle.
		//   Angle (degrees):       Line alignment controlled by:
		//  -45 < angle <= 45          h_align
		//   45 < angle <= 135         reversed v_align
		//  135 < angle <= 225         reversed h_align
		//  225 < angle <= 315         v_align
		if ($cos_t >= $sin_t) {
			if ($cos_t >= -$sin_t) $line_align_factor = $h_factor;
			else $line_align_factor = $v_factor;
		} else {
			if ($cos_t >= -$sin_t) $line_align_factor = 1-$v_factor;
			else $line_align_factor = 1-$h_factor;
		}

		// Now we have the start point, spacing and in-line alignment factor.
		// We are finally ready to start drawing the text, line by line.
		for ($i = 0; $i < $n_lines; $i++) {

			// For drawing TTF text, the reference point is the left edge of the
			// text baseline (not the lower left corner of the bounding box).
			// The following also adjusts for horizontal (relative to
			// the text) alignment of the current line within the box.
			// What is happening is rotation of this vector by the text angle:
			//    (x = (total_width - line_width) * factor, y = font_height)

			$width_factor = ($total_width - $line_widths[$i]) * $line_align_factor;
			$rx = $qx + $r00 * $width_factor + $r01 * $font_height;
			$ry = $qy + $r10 * $width_factor + $r11 * $font_height;

			// Finally, draw the text:
			ImageTTFText($this->img, $font_size, $angle, $rx, $ry, $color, $font_file, $lines[$i]);

			// Step to position of next line.
			// This is a rotation of (x=0,y=height+line_spacing) by $angle:
			$qx += $r01 * $interline_step;
			$qy += $r11 * $interline_step;
		}
		return TRUE;
	}

	/*
	 * ProcessText() - Wrapper for ProcessTextTTF() and ProcessTextGD(). See notes above.
	 * This is intended for use from within PHPlot only, and only by DrawText() and SizeText().
	 *    $draw_it : True to draw the text, False to just return the orthogonal width and height.
	 *    $font : PHPlot font array, or NULL or empty string to use 'generic'
	 *    $angle : Text angle in degrees
	 *    $x, $y : Reference point for the text (ignored if !$draw_it)
	 *    $color : GD color index to use for drawing the text (ignored if !$draw_it)
	 *    $text : The text to draw or size. Put a newline between lines.
	 *    $halign : Horizontal alignment: left, center, or right (ignored if !$draw_it)
	 *    $valign : Vertical alignment: top, center, or bottom (ignored if !$draw_it)
	 *      Note: Alignment is relative to the image, not the text.
	 * Returns: True, if drawing text, or an array of ($width, $height) if not.
	 */
	protected function ProcessText($draw_it, $font, $angle, $x, $y, $color, $text, $halign, $valign)
	{
		// Empty text case:
		if ($text === "") {
			if ($draw_it) return TRUE;
			return [0, 0];
		}

		// Calculate width and height offset factors using the alignment args:
		if ($valign == "top") $v_factor = 0;
		elseif ($valign == "center") $v_factor = 0.5;
		else $v_factor = 1.0; // 'bottom'
		if ($halign == "left") $h_factor = 0;
		elseif ($halign == "center") $h_factor = 0.5;
		else $h_factor = 1.0; // 'right'

		// Apply a default font. This is mostly for external (callback) users.
		if (empty($font)) $font = $this->fonts["generic"];

		if ($font["ttf"]) {
			return $this->ProcessTextTTF($draw_it, $font, $angle, $x, $y, $color, $text,
										 $h_factor, $v_factor, );
		}
		return $this->ProcessTextGD($draw_it, $font, $angle, $x, $y, $color, $text, $h_factor, $v_factor);
	}

	/*
	 * Draws a block of text. See comments above before ProcessText().
	 *    $which_font : PHPlot font array, or NULL or empty string to use 'generic'
	 *    $which_angle : Text angle in degrees
	 *    $which_xpos, $which_ypos: Reference point for the text
	 *    $which_color : GD color index to use for drawing the text
	 *    $which_text :  The text to draw, with newlines (\n) between lines.
	 *    $which_halign : Horizontal (relative to the image) alignment: left, center, or right.
	 *    $which_valign : Vertical (relative to the image) alignment: top, center, or bottom.
	 * Note: This function should be considered 'protected', and is not documented for public use.
	 */
	function DrawText($which_font, $which_angle, $which_xpos, $which_ypos, $which_color, $which_text,
					  $which_halign = "left", $which_valign = "bottom", )
	{
		return $this->ProcessText(TRUE,
						   $which_font, $which_angle, $which_xpos, $which_ypos,
						   $which_color, $which_text, $which_halign, $which_valign, );
	}

	/*
	 * Returns the size of block of text. This is the orthogonal width and height of a bounding
	 * box aligned with the X and Y axes of the text. Only for angle=0 is this the actual
	 * width and height of the text block, but for any angle it is the amount of space needed
	 * to contain the text.
	 *    $which_font : PHPlot font array, or NULL or empty string to use 'generic'
	 *    $which_angle : Text angle in degrees
	 *    $which_text :  The text to draw, with newlines (\n) between lines.
	 * Returns a two element array with: $width, $height.
	 * This is just a wrapper for ProcessText() - see above.
	 * Note: This function should be considered 'protected', and is not documented for public use.
	 */
	function SizeText($which_font, $which_angle, $which_text)
	{
		// Color, position, and alignment are not used when calculating the size.
		return $this->ProcessText(FALSE,
						   $which_font, $which_angle, 0, 0, 1, $which_text, "", "", );
	}

/////////////////////////////////////////////
///////////            INPUT / OUTPUT CONTROL
/////////////////////////////////////////////

	/*
	 * Sets output file format to $format (jpg, png, ...)
	 */
	function SetFileFormat($format)
	{
		$asked = $this->CheckOption($format, "jpg, png, gif, wbmp", __FUNCTION__);
		if (!$asked) return FALSE;
		switch ($asked) {
		case "jpg":
			$format_test = IMG_JPG;
			break;
		case "png":
			$format_test = IMG_PNG;
			break;
		case "gif":
			$format_test = IMG_GIF;
			break;
		case "wbmp":
			$format_test = IMG_WBMP;
			break;
		}
		if (!(imagetypes() & $format_test)) {
			return $this->PrintError("SetFileFormat(): File format '$format' not supported");
		}
		$this->file_format = $asked;
		return TRUE;
	}

	/*
	 * Selects an input file to be used as graph background and scales or tiles this image
	 * to fit the sizes.
	 *   $input_file : Path to the file to be used (jpeg, png and gif accepted)
	 *   $mode : 'centeredtile', 'tile', or 'scale' (the image to the graph's size)
	 */
	function SetBgImage($input_file, $mode="centeredtile")
	{
		$this->bgmode = $this->CheckOption($mode, "tile, centeredtile, scale", __FUNCTION__);
		$this->bgimg  = $input_file;
		return (boolean)$this->bgmode;
	}

	/*
	 * Selects an input file to be used as plot area background and scales or tiles this image
	 * to fit the sizes.
	 *   $input_file : Path to the file to be used (jpeg, png and gif accepted)
	 *   $mode : 'centeredtile', 'tile', or 'scale' (the image to the graph's size)
	 */
	function SetPlotAreaBgImage($input_file, $mode="tile")
	{
		$this->plotbgmode = $this->CheckOption($mode, "tile, centeredtile, scale", __FUNCTION__);
		$this->plotbgimg  = $input_file;
		return (boolean)$this->plotbgmode;
	}

	/*
	 * Sets the name of the file to be used as output file.
	 */
	function SetOutputFile($which_output_file)
	{
		$this->output_file = $which_output_file;
		return TRUE;
	}

	/*
	 * Sets the output image as 'inline', that is: no Content-Type headers are sent
	 * to the browser. Needed if you want to embed the images.
	 */
	function SetIsInline($which_ii)
	{
		$this->is_inline = (bool)$which_ii;
		return TRUE;
	}

	/*
	 * Performs the actual outputting of the generated graph.
	 */
	function PrintImage()
	{
		// Browser cache stuff submitted by Thiemo Nagel
		if ( (! $this->browser_cache) && (! $this->is_inline)) {
			header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
			header("Last-Modified: " . gmdate("D, d M Y H:i:s") . "GMT");
			header("Cache-Control: no-cache, must-revalidate");
			header("Pragma: no-cache");
		}

		switch ($this->file_format) {
		case "png":
			$mime_type = "image/png";
			$output_f = "imagepng";
			break;
		case "jpg":
			$mime_type = "image/jpeg";
			$output_f = "imagejpeg";
			break;
		case "gif":
			$mime_type = "image/gif";
			$output_f = "imagegif";
			break;
		case "wbmp":
			$mime_type = "image/wbmp";
			$output_f = "imagewbmp";
			break;
		default:
			return $this->PrintError("PrintImage(): Please select an image type!");
		}
		if (!$this->is_inline) {
			Header("Content-type: $mime_type");
		}
		if ($this->is_inline && $this->output_file != "") {
			$output_f($this->img, $this->output_file);
		} else {
			$output_f($this->img);
		}
		return TRUE;
	}

	/*
	 *  Error handling for 'fatal' errors:
	 *   $error_message       Text of the error message
	 *  Standard output from PHPlot is expected to be an image file, such as
	 *  when handling an <img> tag browser request. So it is not permitted to
	 *  output text to standard output. (You should have display_errors=off)
	 *  Here is how PHPlot handles fatal errors:
	 *    + Write the error message into an image, and output the image.
	 *    + If no image can be output, write nothing and produce an HTTP
	 *      error header.
	 *    + Trigger a user-level error containing the error message.
	 *      If no error handler was set up, the script will log the
	 *      error and exit with non-zero status.
	 *
	 *  PrintError() and DrawError() are now equivalent. Both are provided for
	 *  compatibility. (In earlier releases, PrintError sent the message to
	 *  stdout only, and DrawError sent it in an image only.)
	 *
	 *  This function does not return, unless the calling script has set up
	 *  an error handler which does not exit. In that case, PrintError will
	 *  return False. But not all of PHPlot will handle this correctly, so
	 *  it is probably a bad idea for an error handler to return.
	 */
	protected function PrintError($error_message)
	{
		// Be sure not to loop recursively, e.g. PrintError - PrintImage - PrintError.
		if (isset($this->in_error)) return FALSE;
		$this->in_error = TRUE;

		// Output an image containing the error message:
		if (!empty($this->img)) {
			$ypos = $this->image_height/2;
			$xpos = $this->image_width/2;
			$bgcolor = ImageColorResolve($this->img, 255, 255, 255);
			$fgcolor = ImageColorResolve($this->img, 0, 0, 0);
			ImageFilledRectangle($this->img, 0, 0, $this->image_width, $this->image_height, $bgcolor);

			// Switch to built-in fonts, in case of error with TrueType fonts:
			$this->SetUseTTF(FALSE);

			$this->DrawText($this->fonts["generic"], 0, $xpos, $ypos, $fgcolor,
							wordwrap($error_message), "center", "center", );

			$this->PrintImage();
		} elseif (! $this->is_inline) {
			Header("HTTP/1.0 500 Internal Server Error");
		}
		trigger_error($error_message, E_USER_ERROR);
		unset($this->in_error);
		return FALSE;  // In case error handler returns, rather than doing exit().
	}

	/*
	 * Display an error message and exit.
	 * This is provided for backward compatibility only. Use PrintError() instead.
	 *   $error_message       Text of the error message
	 *   $where_x, $where_y   Ignored, provided for compatibility.
	 */
	protected function DrawError($error_message, $where_x = NULL, $where_y = NULL)
	{
		return $this->PrintError($error_message);
	}

/////////////////////////////////////////////
///////////                            LABELS
/////////////////////////////////////////////

	/*
	 * Sets position for X data labels.
	 * For vertical plots, these are X axis data labels, showing label strings from the data array.
	 *    Accepted positions are: plotdown, plotup, both, none.
	 * For horizontal plots (bar, stackedbar only), these are X data value labels, show the data values.
	 *    Accepted positions are: plotin, plotstack, none.
	 */
	function SetXDataLabelPos($which_xdlp)
	{
		$which_xdlp = $this->CheckOption($which_xdlp, "plotdown, plotup, both, none, plotin, plotstack",
										 __FUNCTION__, );
		if (!$which_xdlp) return FALSE;
		$this->x_data_label_pos = $which_xdlp;

		return TRUE;
	}

	/*
	 * Sets position for Y data labels.
	 * For vertical plots (where available), these are Y data value labels, showing the data values.
	 *    Accepted positions are: plotin, plotstack, none.
	 * For horizontal plots, these are Y axis data labels, showing label strings from the data array.
	 *    Accepted positions are: plotleft, plotright, both, none.
	 */
	function SetYDataLabelPos($which_ydlp)
	{
		$which_ydlp = $this->CheckOption($which_ydlp, "plotleft, plotright, both, none, plotin, plotstack",
										  __FUNCTION__, );
		if (!$which_ydlp) return FALSE;
		$this->y_data_label_pos = $which_ydlp;

		return TRUE;
	}

	/*
	 * Set position for X tick labels.
	 */
	function SetXTickLabelPos($which_xtlp)
	{
		$which_xtlp = $this->CheckOption($which_xtlp, "plotdown, plotup, both, xaxis, none",
										 __FUNCTION__, );
		if (!$which_xtlp) return FALSE;
		$this->x_tick_label_pos = $which_xtlp;

		return TRUE;
	}

	/*
	 * Set position for Y tick labels.
	 */
	function SetYTickLabelPos($which_ytlp)
	{
		$which_ytlp = $this->CheckOption($which_ytlp, "plotleft, plotright, both, yaxis, none",
										 __FUNCTION__, );
		if (!$which_ytlp) return FALSE;
		$this->y_tick_label_pos = $which_ytlp;

		return TRUE;
	}

	/*
	 * Set formatting type for tick and data labels on X or Y axis.
	 * This implements the 4 functions Set[XY]LabelType() and Set[XY]DataLabelType().
	 *    $mode  : 'x', 'y', 'xd', or 'yd' - which type of label to configure.
	 *        'x' and 'y' set the type for tick labels, and the default type for data labels
	 *        if they are not separately configured. 'xd' and 'yd' set the type for data labels.
	 *    $args  : Variable arguments, passed as an array.
	 *       [0] = $type (required) : Label type. 'data', 'time', 'printf', or 'custom'.
	 *     For type 'data':
	 *       [1] = $precision (optional). Numeric precision. Can also be set by SetPrecision[XY]().
	 *       [2] = $prefix (optional) - prefix string for labels.
	 *       [3] = $suffix (optional) - suffix string for labels. This replaces data_units_text.
	 *     For type 'time':
	 *       [1] = $format for strftime (optional). Can also be set by Set[XY]TimeFormat().
	 *     For type 'printf':
	 *       [1] = $format (optional) for sprintf.
	 *     For type 'custom':
	 *       [1] = $callback (required) - Custom function or array of (instance,method) to call.
	 *       [2] = $argument (optional) - Pass-through argument for the formatting function.
	 */
	protected function SetLabelType($mode, $args)
	{
		if (!$this->CheckOption($mode, "x, y, xd, yd", __FUNCTION__))
			return FALSE;

		$type = $args[0] ?? "";
		$format =& $this->label_format[$mode];  // Shorthand reference to format storage variables
		switch ($type) {
		case "data":
			if (isset($args[1]))
				$format["precision"] = $args[1];
			elseif (!isset($format["precision"]))
				$format["precision"] = 1;
			$format["prefix"] = $args[2] ?? "";
			$format["suffix"] = $args[3] ?? "";
			break;

		case "time":
			if (isset($args[1]))
				$format["time_format"] = $args[1];
			elseif (!isset($format["time_format"]))
				$format["time_format"] = "%H:%M:%S";
			break;

		case "printf":
			if (isset($args[1]))
				$format["printf_format"] = $args[1];
			elseif (!isset($format["printf_format"]))
				$format["printf_format"] = "%e";
			break;

		case "custom":
			if (isset($args[1])) {
				$format["custom_callback"] = $args[1];
				$format["custom_arg"] = $args[2] ?? NULL;
			} else {
				$type = ""; // Error, 'custom' without a function, set to no-format mode.
			}
			break;

		case "":
		case "title":   // Retained for backwards compatibility?
			break;

		default:
			$this->CheckOption($type, "data, time, printf, custom", __FUNCTION__);
			$type = "";
		}
		$format["type"] = $type;
		return (boolean)$type;
	}

	/*
	 * Select label formating for X tick labels, and for X data labels
	 * (unless SetXDataLabelType was called).
	 * See SetLabelType() for details.
	 */
	function SetXLabelType()  // Variable arguments: $type, ...
	{
		$args = func_get_args();
		return $this->SetLabelType("x", $args);
	}

	/*
	 * Select label formatting for X data labels, overriding SetXLabelType.
	 */
	function SetXDataLabelType()  // Variable arguments: $type, ...
	{
		$args = func_get_args();
		return $this->SetLabelType("xd", $args);
	}

	/*
	 * Select label formating for Y tick labels, and for Y data labels
	 * (unless SetYDataLabelType was called).
	 * See SetLabelType() for details.
	 */
	function SetYLabelType()  // Variable arguments: $type, ...
	{
		$args = func_get_args();
		return $this->SetLabelType("y", $args);
	}

	/*
	 * Select label formatting for Y data labels, overriding SetYLabelType.
	 */
	function SetYDataLabelType()  // Variable arguments: $type, ...
	{
		$args = func_get_args();
		return $this->SetLabelType("yd", $args);
	}

	/*
	 * Set the date/time format code for X labels.
	 * Note: Use of SetXLabelType('time', $which_xtf) is preferred, because
	 * SetXTimeFormat does not also enable date/time formatting.
	 */
	function SetXTimeFormat($which_xtf)
	{
		$this->label_format["x"]["time_format"] = $which_xtf;
		return TRUE;
	}

	/*
	 * Set the date/time format code for Y labels.
	 * Note: Use of SetYLabelType('time', $which_ytf) is preferred, because
	 * SetYTimeFormat does not also enable date/time formatting.
	 */
	function SetYTimeFormat($which_ytf)
	{
		$this->label_format["y"]["time_format"] = $which_ytf;
		return TRUE;
	}

	/*
	 * Set number format parameters (decimal point and thousands separator) for
	 * 'data' mode label formatting, overriding the locale-defaults.
	 */
	function SetNumberFormat($decimal_point, $thousands_sep)
	{
		$this->decimal_point = $decimal_point;
		$this->thousands_sep = $thousands_sep;
		return TRUE;
	}

	/*
	 * Set the text angle for X labels to $which_xla degrees.
	 */
	function SetXLabelAngle($which_xla)
	{
		$this->x_label_angle = $which_xla;
		return TRUE;
	}

	/*
	 * Set the text angle for Y labels to $which_xla degrees.
	 */
	function SetYLabelAngle($which_yla)
	{
		$this->y_label_angle = $which_yla;
		return TRUE;
	}

	/*
	 * Set the angle for X Data Labels to $which_xdla degrees.
	 * If not used, this defaults to the value set with SetXLabelAngle.
	 */
	function SetXDataLabelAngle($which_xdla)
	{
		$this->x_data_label_angle = $which_xdla;
		return TRUE;
	}

	/*
	 * Set the angle for Y Data Labels to $which_ydla degrees.
	 * If not used, this defaults to zero (unlike X data labels).
	 */
	function SetYDataLabelAngle($which_ydla)
	{
		$this->y_data_label_angle = $which_ydla;
		return TRUE;
	}

/////////////////////////////////////////////
///////////                              MISC
/////////////////////////////////////////////

	/*
	 * Checks the validity of an option.
	 *   $which_opt  String to check, such as the provided value of a function argument.
	 *   $which_acc  String of accepted choices. Must be lower-case, and separated
	 *               by exactly ', ' (comma, space).
	 *   $which_func Name of the calling function, for error messages.
	 * Returns the supplied option value, downcased and trimmed, if it is valid.
	 * Reports an error if the supplied option is not valid.
	 */
	protected function CheckOption($which_opt, $which_acc, $which_func)
	{
		$asked = strtolower(trim($which_opt));

		// Look for the supplied value in a comma/space separated list.
		if (strpos(", $which_acc,", ", $asked,") !== FALSE)
			return $asked;

		$this->PrintError("$which_func(): '$which_opt' not in available choices: '$which_acc'.");
		return NULL;
	}

	/*
	 * Checks the validity of an array of options.
	 *   $opt  Array or string to check.
	 *   $acc  String of accepted choices. Must be lower-case, and separated
	 *               by exactly ', ' (comma, space).
	 *   $func Name of the calling function, for error messages.
	 * Returns a array option value(s), downcased and trimmed, if all entries in $opt are valid.
	 * Reports an error if any supplied option is not valid. Returns NULL if the error handler returns.
	 */
	protected function CheckOptionArray($opt, $acc, $func)
	{
		$opt_array = (array)$opt;
		$result = [];
		foreach ($opt_array as $option) {
			$choice = $this->CheckOption($option, $acc, $func);
			if (is_null($choice)) return NULL; // In case CheckOption error handler returns
			$result[] = $choice;
		}
		return $result;
	}

	/*
	 * Check compatibility of a plot type and data type.
	 * This is called by the plot-type-specific drawing functions.
	 *   $valid_types  String of supported data types. Multiple values must be
	 *      separated by exactly ', ' (comma, space).
	 * Returns True if the type is valid for this plot.
	 * Reports an error if the data type is not value. If the error is handled and
	 *   the handler returns, this returns False.
	 */
	protected function CheckDataType($valid_types)
	{
		if (strpos(", $valid_types,", ", $this->data_type,") !== FALSE)
			return TRUE;

		$this->PrintError("Data type '$this->data_type' is not valid for '$this->plot_type' plots."
			   . " Supported data type(s): '$valid_types'", );
		return FALSE;
	}

	/*
	 * Decode the data type into variables used to determine how to process a data array.
	 * The goal is minimize which functions understand the actual data type values.
	 * This sets the datatype_* variables for use by other member functions.
	 *   datatype_implied : Implicit independent variable (e.g. text-data vs data-data)
	 *   datatype_swapped_xy : Swapped X/Y (horizontal plot)
	 *   datatype_error_bars : Data array has error bar data
	 *   datatype_pie_single : Data array is for a pie chart with one row per slice
	 */
	protected function DecodeDataType()
	{
		$dt = $this->data_type;

		$this->datatype_implied = ($dt == "text-data" || $dt == "text-data-single"
								|| $dt == "text-data-yx");
		$this->datatype_swapped_xy = ($dt == "text-data-yx" || $dt == "data-data-yx");
		$this->datatype_error_bars = ($dt == "data-data-error");
		$this->datatype_pie_single = ($dt == "text-data-single");
	}

	/*
	 * Make sure the data array is populated, and calculate the number of columns.
	 * This is called from DrawGraph. Calculates data_columns, which is the
	 * maximum number of dependent variable values (usually Y) in the data array rows.
	 * (For pie charts, this is the number of slices.)
	 * This depends on the data_type, unlike records_per_group (which was
	 * previously used to pad style arrays, but is not accurate).
	 * Returns True if the data array is OK, else reports an error (and may return False).
	 * Note error messages refer to the caller, the public DrawGraph().
	 */
	protected function CheckDataArray()
	{
		// Test for missing image, which really should never happen.
		if (!$this->img) {
			return $this->PrintError("DrawGraph(): No image resource allocated");
		}

		// Test for missing or empty data array:
		if (empty($this->data) || !is_array($this->data)) {
			return $this->PrintError("DrawGraph(): No data array");
		}
		if ($this->total_records == 0) {
			return $this->PrintError("DrawGraph(): Empty data set");
		}

		// Decode the data type into functional flags.
		$this->DecodeDataType();

		// Calculate the maximum number of dependent values per independent value
		// (e.g. Y for each X), or the number of pie slices.
		if ($this->datatype_pie_single) {
			$this->data_columns = $this->num_data_rows; // Special case for 1 type of pie chart.
		} else {
			$skip = $this->datatype_implied ? 1 : 2; // Skip data label and independent variable if used
			$this->data_columns = $this->records_per_group - $skip;
			if ($this->datatype_error_bars) // Each Y has +err and -err along with it
				$this->data_columns = (int)($this->data_columns / 3);
		}
		return TRUE;
	}

	/*
	 * Control headers for browser-side image caching.
	 *   $which_browser_cache : True to allow browsers to cache the image.
	 */
	function SetBrowserCache($which_browser_cache)
	{
		$this->browser_cache = $which_browser_cache;
		return TRUE;
	}

	/*
	 * Set whether DrawGraph automatically outputs the image too.
	 *   $which_pi : True to have DrawGraph call PrintImage at the end.
	 */
	function SetPrintImage($which_pi)
	{
		$this->print_image = $which_pi;
		return TRUE;
	}

	/*
	 * Set border for the plot area.
	 * Accepted values are: left, right, top, bottom, sides, none, full or an array of those.
	 */
	function SetPlotBorderType($pbt)
	{
		$this->plot_border_type = $this->CheckOptionArray($pbt, "left, right, top, bottom, sides, none, full",
														  __FUNCTION__, );
		return !empty($this->plot_border_type);
	}

	/*
	 * Set border style for the image.
	 * Accepted values are: raised, plain, solid, none
	 *  'solid' is the same as 'plain' except it fixes the color (see DrawImageBorder)
	 */
	function SetImageBorderType($sibt)
	{
		$this->image_border_type = $this->CheckOption($sibt, "raised, plain, solid, none", __FUNCTION__);
		return (boolean)$this->image_border_type;
	}

	/*
	 * Set border width for the image to $width in pixels.
	 */
	function SetImageBorderWidth($width)
	{
		$this->image_border_width = $width;
		return TRUE;
	}

	/*
	 * Enable or disable drawing of the plot area background color.
	 */
	function SetDrawPlotAreaBackground($dpab)
	{
		$this->draw_plot_area_background = (bool)$dpab;
		return TRUE;
	}

	/*
	 * Enable or disable drawing of the X grid lines.
	 */
	function SetDrawXGrid($dxg)
	{
		$this->draw_x_grid = (bool)$dxg;
		return TRUE;
	}

	/*
	 * Enable or disable drawing of the Y grid lines.
	 */
	function SetDrawYGrid($dyg)
	{
		$this->draw_y_grid = (bool)$dyg;
		return TRUE;
	}

	/*
	 * Select dashed or solid grid lines.
	 *   $ddg : True for dashed grid lines, false for solid grid lines.
	 */
	function SetDrawDashedGrid($ddg)
	{
		$this->dashed_grid = (bool)$ddg;
		return TRUE;
	}

	/*
	 * Enable or disable drawing of X Data Label Lines.
	 */
	function SetDrawXDataLabelLines($dxdl)
	{
		$this->draw_x_data_label_lines = (bool)$dxdl;
		return TRUE;
	}

	/*
	 * Set the main title text for the plot.
	 */
	function SetTitle($which_title)
	{
		$this->title_txt = $which_title;
		return TRUE;
	}

	/*
	 * Set the X axis title and position.
	 */
	function SetXTitle($which_xtitle, $which_xpos = "plotdown")
	{
		if ($which_xtitle == "")
			$which_xpos = "none";

		$this->x_title_pos = $this->CheckOption($which_xpos, "plotdown, plotup, both, none", __FUNCTION__);
		if (!$this->x_title_pos) return FALSE;
		$this->x_title_txt = $which_xtitle;
		return TRUE;
	}

	/*
	 * Set the Y axis title and position.
	 */
	function SetYTitle($which_ytitle, $which_ypos = "plotleft")
	{
		if ($which_ytitle == "")
			$which_ypos = "none";

		$this->y_title_pos = $this->CheckOption($which_ypos, "plotleft, plotright, both, none", __FUNCTION__);
		if (!$this->y_title_pos) return FALSE;
		$this->y_title_txt = $which_ytitle;
		return TRUE;
	}

	/*
	 * Set the size of the drop shadow for bar and pie charts.
	 *   $which_s : Size of the drop shadow in pixels.
	 */
	function SetShading($which_s)
	{
		$this->shading = (int)$which_s;
		return TRUE;
	}

	/*
	 * Set the plot type (bars, points, ...)
	 */
	function SetPlotType($which_pt)
	{
		$avail_plot_types = implode(", ", array_keys(PHPlot::$plots)); // List of known plot types
		$this->plot_type = $this->CheckOption($which_pt, $avail_plot_types, __FUNCTION__);
		return (boolean)$this->plot_type;
	}

	/*
	 * Set the position of the X axis.
	 *  $pos : Axis position in world coordinates (as an integer).
	 */
	function SetXAxisPosition($pos="")
	{
		$this->x_axis_position = ($pos === "") ? $pos : (int)$pos;
		return TRUE;
	}

	/*
	 * Set the position of the Y axis.
	 *  $pos : Axis position in world coordinates (as an integer).
	 */
	function SetYAxisPosition($pos="")
	{
		$this->y_axis_position = ($pos === "") ? $pos : (int)$pos;
		return TRUE;
	}

	/*
	 * Enable or disable drawing of the X axis line.
	 *  $draw : True to draw the axis (default if not called), False to suppress it.
	 * This controls drawing of the axis line only, and not the ticks, labels, or grid.
	 */
	function SetDrawXAxis($draw)
	{
		$this->suppress_x_axis = !$draw; // See DrawXAxis()
		return TRUE;
	}

	/*
	 * Enable or disable drawing of the Y axis line.
	 *  $draw : True to draw the axis (default if not called), False to suppress it.
	 * This controls drawing of the axis line only, and not the ticks, labels, or grid.
	 */
	function SetDrawYAxis($draw)
	{
		$this->suppress_y_axis = !$draw; // See DrawYAxis()
		return TRUE;
	}

	/*
	 * Select linear or log scale for the X axis.
	 */
	function SetXScaleType($which_xst)
	{
		$this->xscale_type = $this->CheckOption($which_xst, "linear, log", __FUNCTION__);
		return (boolean)$this->xscale_type;
	}

	/*
	 * Select linear or log scale for the Y axis.
	 */
	function SetYScaleType($which_yst)
	{
		$this->yscale_type = $this->CheckOption($which_yst, "linear, log",  __FUNCTION__);
		return (boolean)$this->yscale_type;
	}

	/*
	 * Set the precision for numerically formatted X labels.
	 *   $which_prec : Number of digits to display.
	 * Note: This is equivalent to: SetXLabelType('data', $which_prec)
	 */
	function SetPrecisionX($which_prec)
	{
		return $this->SetXLabelType("data", $which_prec);
	}

	/*
	 * Set the precision for numerically formatted Y labels.
	 *   $which_prec : Number of digits to display.
	 * Note: This is equivalent to: SetYLabelType('data', $which_prec)
	 */
	function SetPrecisionY($which_prec)
	{
		return $this->SetYLabelType("data", $which_prec);
	}

	/*
	 * Set the line width (in pixels) for error bars.
	 */
	function SetErrorBarLineWidth($which_seblw)
	{
		$this->error_bar_line_width = $which_seblw;
		return TRUE;
	}

	/*
	 * Set the position for pie chart percentage labels.
	 *   $which_blb : Real number between 0 and 1.
	 *      Smaller values move the labels in towards the center.
	 */
	function SetLabelScalePosition($which_blp)
	{
		$this->label_scale_position = $which_blp;
		return TRUE;
	}

	/*
	 * Set the size (in pixels) of the "T" in error bars.
	 */
	function SetErrorBarSize($which_ebs)
	{
		$this->error_bar_size = $which_ebs;
		return TRUE;
	}

	/*
	 * Set the shape of the in error bars.
	 *   $which_ebs : Error bar shape, 'tee' or 'line'.
	 */
	function SetErrorBarShape($which_ebs)
	{
		$this->error_bar_shape = $this->CheckOption($which_ebs, "tee, line", __FUNCTION__);
		return (boolean)$this->error_bar_shape;
	}

	/*
	 * Synchronize the point shape and point size arrays.
	 * This is called just before drawing any plot that needs 'points'.
	 */
	protected function CheckPointParams()
	{
		// Make both point_shapes and point_sizes the same size, by padding the smaller.
		$ps = count($this->point_sizes);
		$pt = count($this->point_shapes);

		if ($ps < $pt) {
			$this->pad_array($this->point_sizes, $pt);
			$this->point_counts = $pt;
		} elseif ($ps > $pt) {
			$this->pad_array($this->point_shapes, $ps);
			$this->point_counts = $ps;
		} else {
			$this->point_counts = $ps;
		}

		// Note: PHPlot used to check and adjust point_sizes to be an even number here,
		// for all 'diamond' and 'triangle' shapes. The reason for this having been
		// lost, and the current maintainer seeing no sense it doing this for only
		// some shapes, the code has been removed. But see what DrawDot() does.
	}

	/*
	 * Set the point shape for each data set.
	 *   $which_pt : Array (or single value) of valid point shapes. See also DrawDot() for valid shapes.
	 * The point shape and point sizes arrays are synchronized before drawing a graph
	 * that uses points. See CheckPointParams()
	 */
	function SetPointShapes($which_pt)
	{
		$this->point_shapes = $this->CheckOptionArray($which_pt, "halfline, line, plus, cross, rect,"
					   . " circle, dot, diamond, triangle, trianglemid, delta, yield, star, hourglass,"
					   . " bowtie, target, box, home, up, down, none", __FUNCTION__, );
		return !empty($this->point_shapes);
	}

	/*
	 * Set the point size for point plots.
	 *   $which_ps : Array (or single value) of point sizes in pixels.
	 * The point shape and point sizes arrays are synchronized before drawing a graph
	 * that uses points. See CheckPointParams()
	 */
	function SetPointSizes($which_ps)
	{
		if (is_array($which_ps)) {
			// Use provided array:
			$this->point_sizes = $which_ps;
		} elseif (!is_null($which_ps)) {
			// Make the single value into an array:
			$this->point_sizes = [$which_ps];
		}
		return TRUE;
	}

	/*
	 * Sets whether lines should be broken at missing data.
	 *   $bl : True to break the lines, false to connect around missing data.
	 * This only works with 'lines' and 'squared' plots.
	 */
	function SetDrawBrokenLines($bl)
	{
		$this->draw_broken_lines = (bool)$bl;
		return TRUE;
	}

	/*
	 * Set the data type, which defines the structure of the data array
	 *  text-data: ('label', y1, y2, y3, ...)
	 *  text-data-single: ('label', data), for some pie charts.
	 *  data-data: ('label', x, y1, y2, y3, ...)
	 *  data-data-error: ('label', x1, y1, e1+, e2-, y2, e2+, e2-, y3, e3+, e3-, ...)
	 *  data-data-yx: ('label', y, x1, x2, x3, ..)
	 *  text-data-yx: ('label', x1, x2, x3, ...)
	 */
	function SetDataType($which_dt)
	{
		//The next four lines are for past compatibility.
		if ($which_dt == "text-linear") $which_dt = "text-data";
		elseif ($which_dt == "linear-linear") $which_dt = "data-data";
		elseif ($which_dt == "linear-linear-error") $which_dt = "data-data-error";
		elseif ($which_dt == "text-data-pie") $which_dt = "text-data-single";

		$this->data_type = $this->CheckOption($which_dt, "text-data, text-data-single, ".
														 "data-data, data-data-error, ".
														 "data-data-yx, text-data-yx",
														 __FUNCTION__, );
		return (boolean)$this->data_type;
	}

	/*
	 * Copy the array passed as data values. We convert to numerical indexes, for its
	 * use for (or while) loops, which sometimes are faster. Performance improvements
	 * vary from 28% in DrawLines() to 49% in DrawArea() for plot drawing functions.
	 */
	function SetDataValues($which_dv)
	{
		$this->num_data_rows = count($which_dv);
		$this->total_records = 0;
		$this->data = [];
		$this->num_recs = [];
		for ($i = 0; $i < $this->num_data_rows; $i++) {
			$this->data[$i] = array_values($which_dv[$i]);   // convert to numerical indices.

			// Count size of each row, and total for the array.
			$recs = count($this->data[$i]);
			$this->total_records += $recs;
			$this->num_recs[$i] = $recs;
		}
		// This is the size of the widest row in the data array
		// Note records_per_group isn't used much anymore. See data_columns in CheckDataArray()
		$this->records_per_group = max($this->num_recs);
		return TRUE;
	}

	/*
	 * Pad styles arrays for later use by plot drawing functions:
	 * This removes the need for $max_data_colors, etc. and $color_index = $color_index % $max_data_colors
	 * in DrawBars(), DrawLines(), etc.
	 * The arrays are padded to data_columns which is the maximum number of data sets.
	 * See CheckDataArray() for the calculation.
	 */
	protected function PadArrays()
	{
		$this->pad_array($this->line_widths, $this->data_columns);
		$this->pad_array($this->line_styles, $this->data_columns);
		$this->pad_array($this->ndx_data_colors, $this->data_columns);
		$this->pad_array($this->ndx_data_border_colors, $this->data_columns);
		// Other data color arrays are handled in the Need*Colors() functions.

		return TRUE;
	}

	/*
	 * Pads an array with itself. This only works on 0-based sequential integer indexed arrays.
	 *    $arr : The array (or scalar) to pad. This argument is modified.
	 *    $size : Minimum size of the resulting array.
	 * If $arr is a scalar, it will be converted first to a single element array.
	 * If $arr has at least $size elements, it is unchanged.
	 * Otherwise, append elements of $arr to itself until it reaches $size elements.
	 */
	protected function pad_array(&$arr, $size)
	{
		if (! is_array($arr)) {
			$arr = [$arr];
		}
		$n = count($arr);
		$base = 0;
		while ($n < $size) $arr[$n++] = $arr[$base++];
	}

	/*
	 * Format a floating-point number.
	 *   $number : A floating point number to format
	 *   $decimals : Number of decimal places in the result
	 *   Returns the formatted result.
	 * This is like PHP's number_format, but uses class variables for separators.
	 * The separators will default to locale-specific values, if available.
	 */
	protected function number_format($number, $decimals=0)
	{
		if (!isset($this->decimal_point) || !isset($this->thousands_sep)) {
			// Load locale-specific values from environment, unless disabled:
			if (empty($this->locale_override))
				@setlocale(LC_ALL, "");
			// Fetch locale settings:
			$locale = @localeconv();
			if (isset($locale["decimal_point"]) && isset($locale["thousands_sep"])) {
				$this->decimal_point = $locale["decimal_point"];
				$this->thousands_sep = $locale["thousands_sep"];
			} else {
				// Locale information not available.
				$this->decimal_point = ".";
				$this->thousands_sep = ",";
			}
		}
		return number_format($number, $decimals, $this->decimal_point, $this->thousands_sep);
	}

	/*
	 * Register a callback (hook) function
	 *   $reason : A pre-defined name where a callback can be defined.
	 *   $function : The name of a function to register for callback, or an instance/method
	 *      pair in an array (see 'callbacks' in the PHP reference manual).
	 *   $arg : Optional argument to supply to the callback function when it is triggered.
	 *      (Often called "clientData")
	 *   Returns True if the callback reason is valid, else False.
	 */
	function SetCallback($reason, $function, $arg = NULL)
	{
		// Use array_key_exists because valid reason keys have NULL as value.
		if (!array_key_exists($reason, $this->callbacks))
			return FALSE;
		$this->callbacks[$reason] = [$function, $arg];
		return TRUE;
	}

	/*
	 * Return the name of a function registered for callback. See SetCallBack.
	 *   $reason - A pre-defined name where a callback can be defined.
	 *   Returns the current callback function (name or array) for the given reason,
	 *   or False if there was no active callback or the reason is not valid.
	 * Note you can safely test the return value with a simple 'if', as
	 * no valid function name evaluates to false.
	 */
	function GetCallback($reason)
	{
		if (isset($this->callbacks[$reason]))
			return $this->callbacks[$reason][0];
		return FALSE;
	}

	/*
	 * Un-register (remove) a function registered for callback.
	 *   $reason - A pre-defined name where a callback can be defined.
	 *   Returns: True if it was a valid callback reason, else False.
	 * Note: Returns True whether or not there was a callback registered.
	 */
	function RemoveCallback($reason)
	{
		if (!array_key_exists($reason, $this->callbacks))
			return FALSE;
		$this->callbacks[$reason] = NULL;
		return TRUE;
	}

	/*
	 * Invoke a callback, if one is registered.
	 * Accepts a variable number of arguments >= 1:
	 *   $reason : A string naming the callback.
	 *   ... : Zero or more additional arguments to be passed to the
	 *         callback function, after the passthru argument:
	 *           callback_function($image, $passthru, ...)
	 *   Returns: whatever value (if any) was returned by the callback.
	 */
	protected function DoCallback() // Note: Variable arguments
	{
		$args = func_get_args();
		$reason = $args[0];
		if (!isset($this->callbacks[$reason]))
			return;
		list($function, $args[0]) = $this->callbacks[$reason];
		array_unshift($args, $this->img);
		// Now args[] looks like: img, passthru, extra args...
		return call_user_func_array($function, $args);
	}

	/*
	 * Allocate colors for the plot.
	 * This is called by DrawGraph to allocate the colors needed for the plot.  Each selectable
	 * color has already been validated, parsed into an array (r,g,b,a), and stored into a member
	 * variable. Now the GD color indexes are assigned and stored into the ndx_*_color variables.
	 * This is deferred here to avoid allocating unneeded colors and to avoid order dependencies,
	 * especially with the transparent color.
	 *
	 * For drawing data elements, only the main data colors and border colors are allocated here.
	 * Dark colors and error bar colors are allocated by Need*Color() functions.
	 * (Data border colors default to just black, so there is no cost to always allocating.)
	 *
	 * Data color allocation works as follows. If there is a data_color callback, then allocate all
	 * defined data colors (because the callback can use them however it wants). Otherwise, only allocate
	 * the number of colors that will be used. This is the larger of the number of data sets and the
	 * number of legend lines.
	 */
	protected function SetColorIndexes()
	{
		$this->ndx_bg_color         = $this->GetColorIndex($this->bg_color); // Background first
		$this->ndx_plot_bg_color    = $this->GetColorIndex($this->plot_bg_color);
		if ($this->image_border_type != "none") {
			$this->ndx_i_border         = $this->GetColorIndex($this->i_border);
			$this->ndx_i_border_dark    = $this->GetDarkColorIndex($this->i_border);
		}

		// Handle defaults for X and Y title colors.
		$this->ndx_title_color      = $this->GetColorIndex($this->title_color);
		if (empty($this->x_title_color)) {
			$this->ndx_x_title_color = $this->ndx_title_color;
		} else {
			$this->ndx_x_title_color = $this->GetColorIndex($this->x_title_color);
		}
		if (empty($this->y_title_color)) {
			$this->ndx_y_title_color = $this->ndx_title_color;
		} else {
			$this->ndx_y_title_color = $this->GetColorIndex($this->y_title_color);
		}

		$this->ndx_text_color       = $this->GetColorIndex($this->text_color);
		$this->ndx_grid_color       = $this->GetColorIndex($this->grid_color);
		$this->ndx_light_grid_color = $this->GetColorIndex($this->light_grid_color);
		$this->ndx_tick_color       = $this->GetColorIndex($this->tick_color);

		// Maximum number of data & border colors to allocate:
		if ($this->GetCallback("data_color")) {
			$n_data = count($this->data_colors); // Need all of them
			$n_border = count($this->data_border_colors);
		} else {
			$n_data = max($this->data_columns, empty($this->legend) ? 0 : count($this->legend));
			$n_border = $n_data; // One border color per data color
		}

		// Allocate main data colors. For other colors used for data, see the functions which follow.
		$this->ndx_data_colors = $this->GetColorIndexArray($this->data_colors, $n_data);
		$this->ndx_data_border_colors = $this->GetColorIndexArray($this->data_border_colors, $n_border);

		// Set up a color as transparent, if SetTransparentColor was used.
		if (!empty($this->transparent_color)) {
			imagecolortransparent($this->img, $this->GetColorIndex($this->transparent_color));
		}
	}

	/*
	 * Allocate dark-shade data colors. Called if needed by graph drawing functions.
	 */
	protected function NeedDataDarkColors()
	{
		// This duplicates the calculation in SetColorIndexes() for number of data colors to allocate.
		if ($this->GetCallback("data_color")) {
			$n_data = count($this->data_colors);
		} else {
			$n_data = max($this->data_columns, empty($this->legend) ? 0 : count($this->legend));
		}
		$this->ndx_data_dark_colors = $this->GetDarkColorIndexArray($this->data_colors, $n_data);
		$this->pad_array($this->ndx_data_dark_colors, $this->data_columns);
	}

	/*
	 * Allocate error bar colors. Called if needed by graph drawing functions.
	 */
	protected function NeedErrorBarColors()
	{
		// This is similar to the calculation in SetColorIndexes() for number of data colors to allocate.
		if ($this->GetCallback("data_color")) {
			$n_err = count($this->error_bar_colors);
		} else {
			$n_err = max($this->data_columns, empty($this->legend) ? 0 : count($this->legend));
		}
		$this->ndx_error_bar_colors = $this->GetColorIndexArray($this->error_bar_colors, $n_err);
		$this->pad_array($this->ndx_error_bar_colors, $this->data_columns);
	}

	/*
	 * Determine if, and where, to draw Data Value Labels.
	 *   $label_control : Label position control. Either x_data_label_pos or y_data_label_pos.
	 *   &$x_adj, &$y_adj : Returns X,Y adjustments (offset in pixels) to the text position.
	 *   &$h_align, &$v_align : Returns horizontal and vertical alignment for the label.
	 *      The above 4 argument values should be passed to DrawDataValueLabel()
	 * Returns True if data value labels should be drawn (based on $label_control), else False.
	 * This is used for plot types other than bars/stackedbars (which have their own way of doing it).
	 * It uses two member variables (unset by default): data_value_label_angle and data_value_label_distance
	 * to define the vector to the label. Default is 90 degrees at 5 pixels.
	 */
	protected function CheckDataValueLabels($label_control, &$x_adj, &$y_adj, &$h_align, &$v_align)
	{
		if ($label_control != "plotin")
			return FALSE; // No data value labels
		$angle = deg2rad($this->data_value_label_angle ?? 90);
		$radius = $this->data_value_label_distance ?? 5;
		$cos = cos($angle);
		$sin = sin($angle);
		$x_adj = (int)($radius * $cos);
		$y_adj = -(int)($radius * $sin); // Y is reversed in device coordinates

		// Choose from 8 (not 9, center/center can't happen) text alignments based on angle:
		if ($sin >= 0.383) $v_align = "bottom"; // 0.383 = sin(360deg / 16)
		elseif ($sin >= -0.383) $v_align = "center";
		else $v_align = "top";
		if ($cos >= 0.383) $h_align = "left";
		elseif ($cos >= -0.383) $h_align = "center";
		else $h_align = "right";
		return TRUE;
	}

//////////////////////////////////////////////////////////
///////////         DATA ANALYSIS, SCALING AND TRANSLATION
//////////////////////////////////////////////////////////

	/*
	 * Analyzes the data array and calculates the minimum and maximum values.
	 * In this function, IV refers to the independent variable, and DV the dependent variable.
	 * For most plots, IV is X and DV is Y. For swapped X/Y plots, IV is Y and DV is X.
	 * At the end of the function, IV and DV ranges get assigned into X or Y.
	 *
	 * The data type mostly determines the data array structure, but some plot types do special
	 * things such as sum the values in a row. This information is in the plots[] array.
	 *
	 * This calculates min_x, max_x, min_y, and max_y. It also calculates two arrays
	 * data_min[] and data_max[] with per-row min and max values. These are used for
	 * data label lines. For normal (unswapped) data, these are the Y range for each X.
	 * For swapped X/Y data, they are the X range for each Y.
	 */
	protected function FindDataLimits()
	{
		// Does this plot type need special processing of the data values?
		$sum_vals = !empty(PHPlot::$plots[$this->plot_type]["sum_vals"]); // Add up values in each row
		$abs_vals = !empty(PHPlot::$plots[$this->plot_type]["abs_vals"]); // Take absolute values

		// These need to be initialized in case there are multiple plots and missing data points.
		$this->data_min = [];
		$this->data_max = [];

		// Independent values are in the data array or assumed?
		if ($this->datatype_implied) {
			$all_iv = [0, $this->num_data_rows - 1];
		} else {
			$all_iv = [];
		}

		// Process all rows of data:
		for ($i = 0; $i < $this->num_data_rows; $i++) {
			$n_vals = $this->num_recs[$i];
			$j = 1; // Skips label at [0]

			if (!$this->datatype_implied) {
				$all_iv[] = (double)$this->data[$i][$j++];
			}

			if ($sum_vals) {
				$all_dv = [0, 0]; // One limit is 0, other calculated below
			} else {
				$all_dv = [];
			}
			while ($j < $n_vals) {
				if (is_numeric($this->data[$i][$j])) {
					$val = (double)$this->data[$i][$j++];

					if ($this->datatype_error_bars) {
						$all_dv[] = $val + (double)$this->data[$i][$j++];
						$all_dv[] = $val - (double)$this->data[$i][$j++];
					} else {
						if ($abs_vals) {
							$val = abs($val); // Use absolute values
						}
						if ($sum_vals) {
							$all_dv[1] += $val;  // Sum of values
						} else {
							$all_dv[] = $val; // List of all values
						}
					}
				} else {    // Missing DV value
				  $j++;
				  if ($this->datatype_error_bars) $j += 2;
				}
			}
			if (!empty($all_dv)) {
				$this->data_min[$i] = min($all_dv);  // Store per-row DV range
				$this->data_max[$i] = max($all_dv);
			}
		}

		if ($this->datatype_swapped_xy) {
			// Assign min and max for swapped X/Y plots: IV=Y and DV=X
			$this->min_y = min($all_iv);
			$this->max_y = max($all_iv);
			if (empty($this->data_min)) { // Guard against regressive case: No X at all
				$this->min_x = 0;
				$this->max_x = 0;
			} else {
				$this->min_x = min($this->data_min);  // Store global X range
				$this->max_x = max($this->data_max);
			}
		} else {
			// Assign min and max for normal plots: IV=X and DV=Y
			$this->min_x = min($all_iv);
			$this->max_x = max($all_iv);
			if (empty($this->data_min)) { // Guard against regressive case: No Y at all
				$this->min_y = 0;
				$this->max_y = 0;
			} else {
				$this->min_y = min($this->data_min);  // Store global Y range
				$this->max_y = max($this->data_max);
			}
		}

		if ($this->GetCallback("debug_scale")) {
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"min_x" => $this->min_x, "min_y" => $this->min_y,
				"max_x" => $this->max_x, "max_y" => $this->max_y, ]);
		}
		return TRUE;
	}

	/*
	 * Calculates image margins on the fly from title positions and sizes,
	 * and tick labels positions and sizes.
	 *
	 * A picture of the locations of elements and spacing can be found in the
	 * PHPlot Reference Manual.
	 *
	 * Calculates the following (class variables unless noted):
	 *
	 * Plot area margins (see note below):
	 *     y_top_margin
	 *     y_bot_margin
	 *     x_left_margin
	 *     x_right_margin
	 *
	 * Title sizes (these are now local, not class variables, since they are not used elsewhere):
	 *     title_height : Height of main title
	 *     x_title_height : Height of X axis title, 0 if no X title
	 *     y_title_width : Width of Y axis title, 0 if no Y title
	 *
	 * Tick/Data label offsets, relative to plot_area:
	 *     x_label_top_offset, x_label_bot_offset, x_label_axis_offset
	 *     y_label_left_offset, y_label_right_offset, y_label_axis_offset
	 *
	 * Title offsets, relative to plot area:
	 *     x_title_top_offset, x_title_bot_offset
	 *     y_title_left_offset, y_title_left_offset
	 *     title_offset (for main title, relative to image edge)
	 *
	 *  Note: The margins are calculated, but not stored, if margins or plot area were
	 *  set by the user with SetPlotAreaPixels or SetMarginsPixels. The margin
	 *  calculation is mixed in with the offset variables, so it doesn't seem worth the
	 *  trouble to separate them.
	 *
	 * If the $maximize argument is true, we use the full image size, minus safe_margin
	 * and main title, for the plot. This is for pie charts which have no axes or X/Y titles.
	 */
	protected function CalcMargins($maximize)
	{
		// This is the line-to-line or line-to-text spacing:
		$gap = $this->safe_margin;
		// Initial margin on each side takes into account a possible image border.
		// For compatibility, if border is 1 or 2, don't increase the margins.
		$base_margin = max($gap, $this->GetImageBorderWidth() + 3);
		$this->title_offset = $base_margin;  // For use in DrawTitle

		// Minimum margin on each side. This reduces the chance that the
		// right-most tick label (for example) will run off the image edge
		// if there are no titles on that side.
		$min_margin = 2 * $gap + $base_margin;

		// Calculate the title sizes:
		list($unused, $title_height) = $this->SizeText($this->fonts["title"], 0, $this->title_txt);
		list($unused, $x_title_height) = $this->SizeText($this->fonts["x_title"], 0, $this->x_title_txt);
		list($y_title_width, $unused) = $this->SizeText($this->fonts["y_title"], 90, $this->y_title_txt);

		// Special case for maximum area usage with no X/Y titles or labels, only main title:
		if ($maximize) {
			if (!isset($this->x_left_margin))
				$this->x_left_margin = $base_margin;
			if (!isset($this->x_right_margin))
				$this->x_right_margin = $base_margin;
			if (!isset($this->y_top_margin)) {
				$this->y_top_margin = $base_margin;
				if ($title_height > 0)
					$this->y_top_margin += $title_height + $gap;
			}
			if (!isset($this->y_bot_margin))
				$this->y_bot_margin = $base_margin;

			return TRUE;
		}

		// Make local variables for these. (They get used a lot and I'm tired of this, this, this.)
		$x_tick_label_pos = $this->x_tick_label_pos;
		$x_data_label_pos = $this->x_data_label_pos;
		$x_tick_pos       = $this->x_tick_pos;
		$x_tick_len       = $this->x_tick_length;
		$y_tick_label_pos = $this->y_tick_label_pos;
		$y_tick_pos       = $this->y_tick_pos;
		$y_tick_len       = $this->y_tick_length;
		$y_data_label_pos = $this->y_data_label_pos;

		// For X/Y tick and label position of 'xaxis' or 'yaxis', determine if the axis happens to be
		// on an edge of a plot. If it is, we need to account for the margins there.
		if ($this->x_axis_position <= $this->plot_min_y)
			$x_axis_pos = "bottom";
		elseif ($this->x_axis_position >= $this->plot_max_y)
			$x_axis_pos = "top";
		else
			$x_axis_pos = "none";
		if ($this->y_axis_position <= $this->plot_min_x)
			$y_axis_pos = "left";
		elseif ($this->y_axis_position >= $this->plot_max_x)
			$y_axis_pos = "right";
		else
			$y_axis_pos = "none";

		// Calculate the heights for X tick and data labels, and the max (used if they are overlaid):
		$x_data_label_height = ($x_data_label_pos == "none") ? 0 : $this->CalcMaxDataLabelSize("x");
		$x_tick_label_height = ($x_tick_label_pos == "none") ? 0 : $this->CalcMaxTickLabelSize("x");
		$x_max_label_height = max($x_data_label_height, $x_tick_label_height);

		// Calculate the space needed above and below the plot for X tick and X data labels:

		// Above the plot:
		$tick_labels_above = ($x_tick_label_pos == "plotup" || $x_tick_label_pos == "both"
						  || ($x_tick_label_pos == "xaxis" && $x_axis_pos == "top"));
		$data_labels_above = ($x_data_label_pos == "plotup" || $x_data_label_pos == "both");
		if ($tick_labels_above) {
			if ($data_labels_above) {
				$label_height_above = $x_max_label_height;
			} else {
				$label_height_above = $x_tick_label_height;
			}
		} elseif ($data_labels_above) {
			$label_height_above = $x_data_label_height;
		} else {
			$label_height_above = 0;
		}

		// Below the plot:
		$tick_labels_below = ($x_tick_label_pos == "plotdown" || $x_tick_label_pos == "both"
						  || ($x_tick_label_pos == "xaxis" && $x_axis_pos == "bottom"));
		$data_labels_below = ($x_data_label_pos == "plotdown" || $x_data_label_pos == "both");
		if ($tick_labels_below) {
			if ($data_labels_below) {
				$label_height_below = $x_max_label_height;
			} else {
				$label_height_below = $x_tick_label_height;
			}
		} elseif ($data_labels_below) {
			$label_height_below = $x_data_label_height;
		} else {
			$label_height_below = 0;
		}

		// Calculate the width for Y tick and data labels, if on, and the max:
		// Note CalcMaxDataLabelSize('y') returns 0 except for swapped X/Y plots.
		$y_data_label_width = ($y_data_label_pos == "none") ? 0 : $this->CalcMaxDataLabelSize("y");
		$y_tick_label_width = ($y_tick_label_pos == "none") ? 0 : $this->CalcMaxTickLabelSize("y");
		$y_max_label_width = max($y_data_label_width, $y_tick_label_width);

		// Calculate the space needed left and right of the plot for Y tick and Y data labels:
		// (Y data labels here are for swapped X/Y plots such has horizontal bars)

		// Left of the plot:
		$tick_labels_left = ($y_tick_label_pos == "plotleft" || $y_tick_label_pos == "both"
						 || ($y_tick_label_pos == "yaxis" && $y_axis_pos == "left"));
		$data_labels_left = ($y_data_label_pos == "plotleft" || $y_data_label_pos == "both");
		if ($tick_labels_left) {
			if ($data_labels_left) {
				$label_width_left = $y_max_label_width;
			} else {
				$label_width_left = $y_tick_label_width;
			}
		} elseif ($data_labels_left) {
			$label_width_left = $y_data_label_width;
		} else {
			$label_width_left = 0;
		}

		// Right of the plot:
		$tick_labels_right = ($y_tick_label_pos == "plotright" || $y_tick_label_pos == "both"
						  || ($y_tick_label_pos == "yaxis" && $y_axis_pos == "right"));
		$data_labels_right = ($y_data_label_pos == "plotright" || $y_data_label_pos == "both");
		if ($tick_labels_right) {
			if ($data_labels_right) {
				$label_width_right = $y_max_label_width;
			} else {
				$label_width_right = $y_tick_label_width;
			}
		} elseif ($data_labels_right) {
			$label_width_right = $y_data_label_width;
		} else {
			$label_width_right = 0;
		}

		///////// Calculate margins:

		// Calculating Top and Bottom margins:
		// y_top_margin: Main title, Upper X title, X ticks and tick labels, and X data labels:
		// y_bot_margin: Lower title, ticks and tick labels, and data labels:
		$top_margin = $base_margin;
		$bot_margin = $base_margin;
		$this->x_title_top_offset = $gap;
		$this->x_title_bot_offset = $gap;

		// Space for main title?
		if ($title_height > 0)
			$top_margin += $title_height + $gap;

		// Space for X Title?
		if ($x_title_height > 0) {
			$pos = $this->x_title_pos;
			if ($pos == "plotup" || $pos == "both")
				$top_margin += $x_title_height + $gap;
			if ($pos == "plotdown" || $pos == "both")
				$bot_margin += $x_title_height + $gap;
		}

		// Space for X Labels above the plot?
		if ($label_height_above > 0) {
			$top_margin += $label_height_above + $gap;
			$this->x_title_top_offset += $label_height_above + $gap;
		}

		// Space for X Labels below the plot?
		if ($label_height_below > 0) {
			$bot_margin += $label_height_below + $gap;
			$this->x_title_bot_offset += $label_height_below + $gap;
		}

		// Space for X Ticks above the plot?
		if ($x_tick_pos == "plotup" || $x_tick_pos == "both"
		   || ($x_tick_pos == "xaxis" && $x_axis_pos == "top")) {
			$top_margin += $x_tick_len;
			$this->x_label_top_offset = $x_tick_len + $gap;
			$this->x_title_top_offset += $x_tick_len;
		} else {
			// No X Ticks above the plot:
			$this->x_label_top_offset = $gap;
		}

		// Space for X Ticks below the plot?
		if ($x_tick_pos == "plotdown" || $x_tick_pos == "both"
		   || ($x_tick_pos == "xaxis" && $x_axis_pos == "bottom")) {
			$bot_margin += $x_tick_len;
			$this->x_label_bot_offset = $x_tick_len + $gap;
			$this->x_title_bot_offset += $x_tick_len;
		} else {
			// No X Ticks below the plot:
			$this->x_label_bot_offset = $gap;
		}
		// Label offsets for on-axis ticks:
		if ($x_tick_pos == "xaxis") {
			$this->x_label_axis_offset = $x_tick_len + $gap;
		} else {
			$this->x_label_axis_offset = $gap;
		}

		// Calculating Left and Right margins:
		// x_left_margin: Left Y title, Y ticks and tick labels:
		// x_right_margin: Right Y title, Y ticks and tick labels:
		$left_margin = $base_margin;
		$right_margin = $base_margin;
		$this->y_title_left_offset = $gap;
		$this->y_title_right_offset = $gap;

		// Space for Y Title?
		if ($y_title_width > 0) {
			$pos = $this->y_title_pos;
			if ($pos == "plotleft" || $pos == "both")
				$left_margin += $y_title_width + $gap;
			if ($pos == "plotright" || $pos == "both")
				$right_margin += $y_title_width + $gap;
		}

		// Space for Y Labels left of the plot?
		if ($label_width_left > 0) {
			$left_margin += $label_width_left + $gap;
			$this->y_title_left_offset += $label_width_left + $gap;
		}

		// Space for Y Labels right of the plot?
		if ($label_width_right > 0) {
			$right_margin += $label_width_right + $gap;
			$this->y_title_right_offset += $label_width_right + $gap;
		}

		// Space for Y Ticks left of plot?
		if ($y_tick_pos == "plotleft" || $y_tick_pos == "both"
		   || ($y_tick_pos == "yaxis" && $y_axis_pos == "left")) {
			$left_margin += $y_tick_len;
			$this->y_label_left_offset = $y_tick_len + $gap;
			$this->y_title_left_offset += $y_tick_len;
		} else {
			// No Y Ticks left of plot:
			$this->y_label_left_offset = $gap;
		}

		// Space for Y Ticks right of plot?
		if ($y_tick_pos == "plotright" || $y_tick_pos == "both"
		   || ($y_tick_pos == "yaxis" && $y_axis_pos == "right")) {
			$right_margin += $y_tick_len;
			$this->y_label_right_offset = $y_tick_len + $gap;
			$this->y_title_right_offset += $y_tick_len;
		} else {
			// No Y Ticks right of plot:
			$this->y_label_right_offset = $gap;
		}

		// Label offsets for on-axis ticks:
		if ($x_tick_pos == "yaxis") {
			$this->y_label_axis_offset = $y_tick_len + $gap;
		} else {
			$this->y_label_axis_offset = $gap;
		}

		// Apply the minimum margins and store in the object.
		// Do not set margins which were user-defined (see note at top of function).
		if (!isset($this->y_top_margin))
			$this->y_top_margin = max($min_margin, $top_margin);
		if (!isset($this->y_bot_margin))
			$this->y_bot_margin = max($min_margin, $bot_margin);
		if (!isset($this->x_left_margin))
			$this->x_left_margin = max($min_margin, $left_margin);
		if (!isset($this->x_right_margin))
			$this->x_right_margin = max($min_margin, $right_margin);

		if ($this->GetCallback("debug_scale")) {
			// (Too bad compact() doesn't work on class member variables...)
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"label_height_above" => $label_height_above,
				"label_height_below" => $label_height_below,
				"label_width_left" => $label_width_left,
				"label_width_right" => $label_width_right,
				"x_tick_len" => $x_tick_len,
				"y_tick_len" => $y_tick_len,
				"x_left_margin" => $this->x_left_margin,
				"x_right_margin" => $this->x_right_margin,
				"y_top_margin" => $this->y_top_margin,
				"y_bot_margin" => $this->y_bot_margin,
				"x_label_top_offset" => $this->x_label_top_offset,
				"x_label_bot_offset" => $this->x_label_bot_offset,
				"y_label_left_offset" => $this->y_label_left_offset,
				"y_label_right_offset" => $this->y_label_right_offset,
				"x_title_top_offset" => $this->x_title_top_offset,
				"x_title_bot_offset" => $this->x_title_bot_offset,
				"y_title_left_offset" => $this->y_title_left_offset,
				"y_title_right_offset" => $this->y_title_right_offset, ]);
		}

		return TRUE;
	}

	/*
	 * Calculate the plot area (device coordinates) from the margins.
	 * (This used to be part of SetPlotAreaPixels.)
	 * The margins might come from SetMarginsPixels, SetPlotAreaPixels,
	 * or CalcMargins.
	 */
	protected function CalcPlotAreaPixels()
	{
		$this->plot_area = [$this->x_left_margin, $this->y_top_margin,
								 $this->image_width - $this->x_right_margin,
								 $this->image_height - $this->y_bot_margin, ];
		$this->plot_area_width = $this->plot_area[2] - $this->plot_area[0];
		$this->plot_area_height = $this->plot_area[3] - $this->plot_area[1];

		$this->DoCallback("debug_scale", __FUNCTION__, $this->plot_area);
		return TRUE;
	}

	/*
	 * Set the margins in pixels (left, right, top, bottom)
	 * This determines the plot area, equivalent to SetPlotAreaPixels().
	 * Deferred calculations now occur in CalcPlotAreaPixels().
	 */
	function SetMarginsPixels($which_lm = NULL, $which_rm = NULL, $which_tm = NULL, $which_bm = NULL)
	{
		$this->x_left_margin = $which_lm;
		$this->x_right_margin = $which_rm;
		$this->y_top_margin = $which_tm;
		$this->y_bot_margin = $which_bm;

		return TRUE;
	}

	/*
	 * Sets the limits for the plot area.
	 * This stores the margins, not the area. That may seem odd, but
	 * the idea is to make SetPlotAreaPixels and SetMarginsPixels two
	 * ways to accomplish the same thing, and the deferred calculations
	 * in CalcMargins and CalcPlotAreaPixels don't need to know which
	 * was used.
	 *   (x1, y1) - Upper left corner of the plot area
	 *   (x2, y2) - Lower right corner of the plot area
	 */
	function SetPlotAreaPixels($x1 = NULL, $y1 = NULL, $x2 = NULL, $y2 = NULL)
	{
		$this->x_left_margin = $x1;
		if (isset($x2)) $this->x_right_margin = $this->image_width - $x2;
		else unset($this->x_right_margin);
		$this->y_top_margin = $y1;
		if (isset($y2)) $this->y_bot_margin = $this->image_height - $y2;
		else unset($this->y_bot_margin);

		return TRUE;
	}

	/*
	 * Calculate the World Coordinate limits of the plot area.
	 * This goes with SetPlotAreaWorld, but the calculations are
	 * deferred until the graph is being drawn.
	 * Uses and sets: plot_min_x, plot_max_x, plot_min_y, plot_max_y
	 * These can be user-supplied or NULL to auto-calculate.
	 * Pre-requisites: FindDataLimits() calculates min_x, max_x, min_y, max_y
	 * which are the limits of the data to be plotted.
	 *
	 * The general method is this:
	 *   If any part of the range is user-defined (via SetPlotAreaWorld),
	 *      use the user-defined value.
	 *   Else, if this is an implicitly-defined independent variable,
	 *      use the fixed range of 0 to (max+1).
	 *   Else, if this is an explicitly-defined independent variable,
	 *      use the exact data range (min to max).
	 *   Else, this is the dependent variable, so define a range which
	 *      includes and exceeds the data range by a bit.
	 */
	protected function CalcPlotAreaWorld()
	{
		// Data array omits X or Y?
		$implied_x = $this->datatype_implied && !$this->datatype_swapped_xy;
		$implied_y = $this->datatype_implied && $this->datatype_swapped_xy;

		if (isset($this->plot_min_x) && $this->plot_min_x !== "")
			$xmin = $this->plot_min_x; // Use user-provided value
		elseif ($implied_x)
			$xmin = 0;          // Implied X starts at zero
		elseif ($this->datatype_swapped_xy)
			// If X is the dependent variable, leave some room below.
			$xmin = floor($this->min_x - abs($this->min_x) * 0.1);
		else
			$xmin = $this->min_x;  // Otherwise just start at the min data X

		if (isset($this->plot_max_x) && $this->plot_max_x !== "")
			$xmax = $this->plot_max_x; // Use user-provided value
		elseif ($implied_x)
			$xmax = $this->max_x + 1; // Implied X ends after last value
		elseif ($this->datatype_swapped_xy)
			// If X is the dependent variable, leave some room above.
			$xmax = ceil($this->max_x + abs($this->max_x) * 0.1);
		else
			$xmax = $this->max_x; // Otherwise just end at the max data X

		if (isset($this->plot_min_y) && $this->plot_min_y !== "")
			$ymin = $this->plot_min_y;  // Use user-provided value
		elseif ($implied_y)
			$ymin = 0;    // Implied Y starts at zero
		elseif ($this->datatype_swapped_xy)
			$ymin = $this->min_y; // Start at min data Y
		else
			// If Y is the dependent variable, leave some room below.
			$ymin = floor($this->min_y - abs($this->min_y) * 0.1);

		if (isset($this->plot_max_y) && $this->plot_max_y !== "")
			$ymax = $this->plot_max_y; // Use user-provided value
		elseif ($implied_y)
			$ymax = $this->max_y + 1; // Implied Y ends after last value
		elseif ($this->datatype_swapped_xy)
			$ymax = $this->max_y;  // End at max data Y
		else
			// If Y is the dependent variable, leave some room above.
			$ymax = ceil($this->max_y + abs($this->max_y) * 0.1);

		// Error checking

		if ($ymin == $ymax)
			$ymax++;
		if ($xmin == $xmax)
			$xmax++;

		if ($this->yscale_type == "log") {
			if ($ymin <= 0) {
				$ymin = 1;
			}
			if ($ymax <= 0) {
				// Note: Error messages reference the user function, not this function.
				return $this->PrintError("SetPlotAreaWorld(): Log plots need data greater than 0");
			}
		}

		if ($ymax <= $ymin) {
			return $this->PrintError("SetPlotAreaWorld(): Error in data - max not greater than min");
		}

		$this->plot_min_x = $xmin;
		$this->plot_max_x = $xmax;
		$this->plot_min_y = $ymin;
		$this->plot_max_y = $ymax;
		if ($this->GetCallback("debug_scale")) {
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"plot_min_x" => $this->plot_min_x, "plot_min_y" => $this->plot_min_y,
				"plot_max_x" => $this->plot_max_x, "plot_max_y" => $this->plot_max_y, ]);
		}
		return TRUE;
	}

	/*
	 * Stores the desired World Coordinate range of the plot.
	 * The user calls this to force one or more of the range limits to
	 * specific values. Anything not set will be calculated in CalcPlotAreaWorld().
	 */
	function SetPlotAreaWorld($xmin=NULL, $ymin=NULL, $xmax=NULL, $ymax=NULL)
	{
		$this->plot_min_x = $xmin;
		$this->plot_max_x = $xmax;
		$this->plot_min_y = $ymin;
		$this->plot_max_y = $ymax;
		return TRUE;
	}

	/*
	 * Calculate the width (or height) of bars for bar plots.
	 *   $stacked : If true, this is a stacked bar plot (1 bar per group).
	 *   $verticals : If false, this is a horizontal bar plot.
	 * This calculates:
	 *    record_bar_width : Allocated width for each bar (including gaps)
	 *    actual_bar_width : Actual drawn width of each bar
	 *    bar_adjust_gap  : Gap on each side of each bar (0 if they touch)
	 * For the case $verticals=False, horizontal bars are being drawn,
	 * but the same variable names are used. Think of "bar_width" as being
	 * the width if you are standing on the Y axis looking towards positive X.
	 */
	protected function CalcBarWidths($stacked, $verticals)
	{
		// group_width is the width of a group, including padding
		if ($verticals) {
			$group_width = $this->plot_area_width / $this->num_data_rows;
		} else {
			$group_width = $this->plot_area_height / $this->num_data_rows;
		}

		// Actual number of bar spaces in the group. This includes the drawn bars, and
		// 'bar_extra_space'-worth of extra bars.
		if ($stacked) {
			$num_spots = 1 + $this->bar_extra_space;
		} else {
			$num_spots = $this->data_columns + $this->bar_extra_space;
		}

		// record_bar_width is the width of each bar's allocated area.
		// If bar_width_adjust=1 this is the width of the bar, otherwise
		// the bar is centered inside record_bar_width.
		// The equation is:
		//   group_frac_width * group_width = record_bar_width * num_spots
		$this->record_bar_width = $this->group_frac_width * $group_width / $num_spots;

		// Note that the extra space due to group_frac_width and bar_extra_space will be
		// evenly divided on each side of the group: the drawn bars are centered in the group.

		// Within each bar's allocated space, if bar_width_adjust=1 the bar fills the
		// space, otherwise it is centered.
		// This is the actual drawn bar width:
		$this->actual_bar_width = $this->record_bar_width * $this->bar_width_adjust;
		// This is the gap on each side of the bar (0 if bar_width_adjust=1):
		$this->bar_adjust_gap = ($this->record_bar_width - $this->actual_bar_width) / 2;

		if ($this->GetCallback("debug_scale")) {
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"record_bar_width" => $this->record_bar_width,
				"actual_bar_width" => $this->actual_bar_width,
				"bar_adjust_gap" => $this->bar_adjust_gap, ]);
		}
		return TRUE;
	}

	/*
	 * Calculate X and Y Axis Positions, world coordinates.
	 * This needs the min/max x/y range set by CalcPlotAreaWorld.
	 * It adjusts or sets x_axis_position and y_axis_position per the data.
	 * Empty string means the values need to be calculated; otherwise they
	 * are supplied but need to be validated against the World area.
	 *
	 * Note: This used to be in CalcTranslation, but CalcMargins needs it too.
	 * This does not calculate the pixel values of the axes. That happens in
	 * CalcTranslation, after scaling is set up (which has to happen after
	 * margins are set up).
	 *
	 * For vertical plots, the X axis defaults to Y=0 if that is inside the plot range, else whichever
	 * of the top or bottom that has the smallest absolute value (that is, the value closest to 0).
	 * The Y axis defaults to the left edge. For horizontal plots, the axis roles and defaults are switched.
	 */
	protected function CalcAxisPositions()
	{
		// Validate user-provided X axis position, or calculate a default if not provided:
		if ($this->x_axis_position !== "") {
			// Force user-provided X axis position to be within the plot range:
			$this->x_axis_position = min(max($this->plot_min_y, $this->x_axis_position), $this->plot_max_y);
		} elseif ($this->yscale_type == "log") {
			// Always use 1 for X axis position on log scale plots.
			$this->x_axis_position = 1;
		} elseif ($this->datatype_swapped_xy || $this->plot_min_y > 0) {
			// Horizontal plot, or Vertical Plot with all Y > 0: Place X axis on the bottom.
			$this->x_axis_position = $this->plot_min_y;
		} elseif ($this->plot_max_y < 0) {
			// Vertical plot with all Y < 0, so place the X axis at the top.
			$this->x_axis_position = $this->plot_max_y;
		} else {
			// Vertical plot range includes Y=0, so place X axis at 0.
			$this->x_axis_position = 0;
		}

		// Validate user-provided Y axis position, or calculate a default if not provided:
		if ($this->y_axis_position !== "") {
			// Force user-provided Y axis position to be within the plot range:
			$this->y_axis_position = min(max($this->plot_min_x, $this->y_axis_position), $this->plot_max_x);
		} elseif ($this->xscale_type == "log") {
			// Always use 1 for Y axis position on log scale plots.
			$this->y_axis_position = 1;
		} elseif (!$this->datatype_swapped_xy || $this->plot_min_x > 0) {
			// Vertical plot, or Horizontal Plot with all X > 0: Place Y axis on left side.
			$this->y_axis_position = $this->plot_min_x;
		} elseif ($this->plot_max_x < 0) {
			// Horizontal plot with all X < 0, so place the Y axis on the right side.
			$this->y_axis_position = $this->plot_max_x;
		} else {
			// Horizontal plot range includes X=0: place Y axis at 0.
			$this->y_axis_position = 0;
		}

		if ($this->GetCallback("debug_scale")) {
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"x_axis_position" => $this->x_axis_position,
				"y_axis_position" => $this->y_axis_position, ]);
		}

		return TRUE;
	}

	/*
	 * Calculates scaling stuff...
	 */
	protected function CalcTranslation()
	{
		if ($this->plot_max_x - $this->plot_min_x == 0) { // Check for div by 0
			$this->xscale = 0;
		} else {
			if ($this->xscale_type == "log") {
				$this->xscale = $this->plot_area_width /
								(log10($this->plot_max_x) - log10($this->plot_min_x));
			} else {
				$this->xscale = $this->plot_area_width / ($this->plot_max_x - $this->plot_min_x);
			}
		}

		if ($this->plot_max_y - $this->plot_min_y == 0) { // Check for div by 0
			$this->yscale = 0;
		} else {
			if ($this->yscale_type == "log") {
				$this->yscale = $this->plot_area_height /
								(log10($this->plot_max_y) - log10($this->plot_min_y));
			} else {
				$this->yscale = $this->plot_area_height / ($this->plot_max_y - $this->plot_min_y);
			}
		}
		// GD defines x = 0 at left and y = 0 at TOP so -/+ respectively
		if ($this->xscale_type == "log") {
			$this->plot_origin_x = $this->plot_area[0] - ($this->xscale * log10($this->plot_min_x) );
		} else {
			$this->plot_origin_x = $this->plot_area[0] - ($this->xscale * $this->plot_min_x);
		}
		if ($this->yscale_type == "log") {
			$this->plot_origin_y = $this->plot_area[3] + ($this->yscale * log10($this->plot_min_y));
		} else {
			$this->plot_origin_y = $this->plot_area[3] + ($this->yscale * $this->plot_min_y);
		}

		// Convert axis positions to device coordinates:
		$this->y_axis_x_pixels = $this->xtr($this->y_axis_position);
		$this->x_axis_y_pixels = $this->ytr($this->x_axis_position);

		if ($this->GetCallback("debug_scale")) {
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"xscale" => $this->xscale, "yscale" => $this->yscale,
				"plot_origin_x" => $this->plot_origin_x, "plot_origin_y" => $this->plot_origin_y,
				"y_axis_x_pixels" => $this->y_axis_x_pixels,
				"x_axis_y_pixels" => $this->x_axis_y_pixels, ]);
		}

		return TRUE;
	}

	/*
	 * Translate X world coordinate into pixel coordinate
	 * See CalcTranslation() for calculation of xscale.
	 * Note: This function should be 'protected', but is left public for historical reasons.
	 * See GetDeviceXY() for a preferred public method.
	 */
	function xtr($x_world)
	{
		if ($this->xscale_type == "log") {
			$x_pixels = $this->plot_origin_x + log10($x_world) * $this->xscale ;
		} else {
			$x_pixels = $this->plot_origin_x + $x_world * $this->xscale ;
		}
		return round($x_pixels);
	}

	/*
	 * Translate Y world coordinate into pixel coordinate.
	 * See CalcTranslation() for calculation of yscale.
	 * Note: This function should be 'protected', but is left public for historical reasons.
	 * See GetDeviceXY() for a preferred public method.
	 */
	function ytr($y_world)
	{
		if ($this->yscale_type == "log") {
			//minus because GD defines y = 0 at top. doh!
			$y_pixels =  $this->plot_origin_y - log10($y_world) * $this->yscale ;
		} else {
			$y_pixels =  $this->plot_origin_y - $y_world * $this->yscale ;
		}
		return round($y_pixels);
	}

	/* A public interface to xtr and ytr. Translates (x,y) in world coordinates
	 * to (x,y) in device coordinates and returns them as an array.
	 * Usage is: list($x_pixel, $y_pixel) = $plot->GetDeviceXY($x_world, $y_world)
	 */
	function GetDeviceXY($x_world, $y_world)
	{
		if (!isset($this->xscale)) {
			return $this->PrintError("GetDeviceXY() was called before translation factors were calculated");
		}
		return [$this->xtr($x_world), $this->ytr($y_world)];
	}

	/*
	 * Calculate tick parameters: Start, end, and delta values. This is used
	 * by both DrawXTicks() and DrawYTicks().
	 * This currently uses the same simplistic method previously used by
	 * PHPlot (basically just range/10), but splitting this out into its
	 * own function is the first step in replacing the method.
	 * This is also used by CalcMaxTickSize() for CalcMargins().
	 *
	 *   $which : 'x' or 'y' : Which tick parameters to calculate
	 *
	 * Returns an array of 3 elements: tick_start, tick_end, tick_step
	 */
	protected function CalcTicks($which)
	{
		if ($which == "x") {
			$num_ticks = $this->num_x_ticks;
			$tick_inc = $this->x_tick_inc;
			$data_max = $this->plot_max_x;
			$data_min = $this->plot_min_x;
			$skip_lo = $this->skip_left_tick;
			$skip_hi = $this->skip_right_tick;
			$anchor = &$this->x_tick_anchor; // Use reference because this might not be set
		} elseif ($which == "y") {
			$num_ticks = $this->num_y_ticks;
			$tick_inc = $this->y_tick_inc;
			$data_max = $this->plot_max_y;
			$data_min = $this->plot_min_y;
			$skip_lo = $this->skip_bottom_tick;
			$skip_hi = $this->skip_top_tick;
			$anchor = &$this->y_tick_anchor; // Use reference because this might not be set
		} else {
			return $this->PrintError("CalcTicks: Invalid usage ($which)");
		}

		if (!empty($tick_inc)) {
			$tick_step = $tick_inc;
		} elseif (!empty($num_ticks)) {
			$tick_step = ($data_max - $data_min) / $num_ticks;
		} else {
			$tick_step = ($data_max - $data_min) / 10;
		}

		// NOTE: When working with floats, because of approximations when adding $tick_step,
		// the value may not quite reach the end, or may exceed it very slightly.
		// So apply a "fudge" factor.
		$tick_start = (double)$data_min;
		$tick_end = (double)$data_max + ($data_max - $data_min) / 10000.0;

		// If a tick anchor was given, adjust the start of the range so the anchor falls
		// at an exact tick mark (or would, if it was within range).
		if (isset($anchor)) {
			$tick_start = $anchor - $tick_step * floor(($anchor - $tick_start) / $tick_step);
		}

		// Lastly, adjust for option to skip left/bottom or right/top tick marks:
		if ($skip_lo)
			$tick_start += $tick_step;
		if ($skip_hi)
			$tick_end -= $tick_step;

		return [$tick_start, $tick_end, $tick_step];
	}

	/*
	 * Calculate the size of the biggest tick label. This is used by CalcMargins().
	 * For 'x' ticks, it returns the height . For 'y' ticks, it returns the width.
	 * This means height along Y, or width along X - not relative to the text angle.
	 * That is what we need to calculate the needed margin space.
	 * (Previous versions of PHPlot estimated this, using the maximum X or Y value,
	 * or maybe the longest string. That doesn't work. -10 is longer than 9, etc.
	 * So this gets the actual size of each label, slow as that may be.
	 */
	protected function CalcMaxTickLabelSize($which)
	{
		list($tick_start, $tick_end, $tick_step) = $this->CalcTicks($which);

		if ($which == "x") {
			$font = $this->fonts["x_label"];
			$angle = $this->x_label_angle;
		} elseif ($which == "y") {
			$font = $this->fonts["y_label"];
			$angle = $this->y_label_angle;
		} else {
			return $this->PrintError("CalcMaxTickLabelSize: Invalid usage ($which)");
		}

		$max_width = 0;
		$max_height = 0;

		// Loop over ticks, same as DrawXTicks and DrawYTicks:
		// Avoid cumulative round-off errors from $val += $delta
		$n = 0;
		$tick_val = $tick_start;
		while ($tick_val <= $tick_end) {
			$tick_label = $this->FormatLabel($which, $tick_val);
			list($width, $height) = $this->SizeText($font, $angle, $tick_label);
			if ($width > $max_width) $max_width = $width;
			if ($height > $max_height) $max_height = $height;
			$tick_val = $tick_start + ++$n * $tick_step;
		}
		if ($this->GetCallback("debug_scale")) {
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"which" => $which, "height" => $max_height, "width" => $max_width, ]);
		}

		if ($which == "x")
			return $max_height;
		return $max_width;
	}

	/*
	 * Calculate the size of the biggest data label. This is used by CalcMargins().
	 * For $which='x', it returns the height of labels along the top or bottom.
	 * For $which='y', it returns the width of labels along the left or right sides.
	 * There is only one set of data labels (the first position in each data record).
	 * They normally go along the top or bottom (or both). If the data type indicates
	 * X/Y swapping (which is used for horizontal bar charts), the data labels go
	 * along the sides instead. So CalcMaxDataLabelSize('x') returns 0 if the
	 * data is X/Y swapped, and CalcMaxDataLabelSize('y') returns 0 if the data is
	 * is not X/Y swapped.
	 */
	protected function CalcMaxDataLabelSize($which = "x")
	{
		if ($which == "x") {
		  if ($this->datatype_swapped_xy)
			  return 0; // Shortcut: labels aren't on top/bottom.
		  $font = $this->fonts["x_label"];
		  $angle = $this->x_data_label_angle;
		  $format_code = "xd";
		} elseif ($which == "y") {
		  if (!$this->datatype_swapped_xy)
			  return 0; // Shortcut: labels aren't on left/right.
		  $font = $this->fonts["y_label"];
		  $angle = $this->y_data_label_angle;
		  $format_code = "yd";
		} else {
		  return $this->PrintError("CalcMaxDataLabelSize: Invalid usage ($which)");
		}
		$max_width = 0;
		$max_height = 0;

		// Loop over all data labels and find the biggest:
		for ($i = 0; $i < $this->num_data_rows; $i++) {
			$label = $this->FormatLabel($format_code, $this->data[$i][0]);
			list($width, $height) = $this->SizeText($font, $angle, $label);
			if ($width > $max_width) $max_width = $width;
			if ($height > $max_height) $max_height = $height;
		}
		if ($this->GetCallback("debug_scale")) {
			$this->DoCallback("debug_scale", __FUNCTION__, [
				"height" => $max_height, "width" => $max_width, ]);
		}

		if ($this->datatype_swapped_xy)
			return $max_width;
		return $max_height;
	}

	/*
	 * Set grid control defaults.
	 * X grid defaults off, Y grid defaults on, except the reverse is true
	 * with swapped graphs such as horizontal bars.
	 */
	protected function CalcGridSettings()
	{
		if (!isset($this->draw_x_grid))
			$this->draw_x_grid = $this->datatype_swapped_xy;
		if (!isset($this->draw_y_grid))
			$this->draw_y_grid = !$this->datatype_swapped_xy;
	}

	/*
	 * Helper for CheckLabels() - determine if there are any non-empty labels.
	 * Returns True if all data labels are empty, else False.
	 */
	protected function CheckLabelsAllEmpty()
	{
		for ($i = 0; $i < $this->num_data_rows; $i++)
			if ($this->data[$i][0] !== "") return FALSE;
		return TRUE;
	}

	/*
	 * Check and set label parameters. This handles deferred processing for label
	 * positioning and other label-related parameters.
	 *   Copy label_format from 'x' to 'xd', and 'y' to 'yd', if not already set.
	 *   Set x_data_label_angle from x_label_angle, if not already set.
	 *   Apply defaults to X and Y tick and data label positions.
	 * Note: the label strings in the data array are used as X data labels in
	 * the normal case, but as Y data labels in the swapped X/Y case.
	 */
	protected function CheckLabels()
	{
		// The X and Y data labels are formatted the same as X and Y tick labels,
		// unless overridden. Check and apply defaults for FormatLabel here:
		if (empty($this->label_format["xd"]) && !empty($this->label_format["x"]))
			$this->label_format["xd"] = $this->label_format["x"];
		if (empty($this->label_format["yd"]) && !empty($this->label_format["y"]))
			$this->label_format["yd"] = $this->label_format["y"];

		// The X tick label angle setting controls X data label angles too,
		// unless overridden. Check and apply the default here:
		if (!isset($this->x_data_label_angle))
			$this->x_data_label_angle = $this->x_label_angle;
		// Note: Y data label angle defaults to zero, unlike X,
		// for compatibility with older releases.

		// X Label position fixups, for x_data_label_pos and x_tick_label_pos:
		if ($this->datatype_swapped_xy) {
			// Just apply defaults - there is no position conflict for X labels.
			if (!isset($this->x_tick_label_pos))
				$this->x_tick_label_pos = "plotdown";
			if (!isset($this->x_data_label_pos))
				$this->x_data_label_pos = "none";
		} else {
			// Apply defaults but do not allow conflict between tick and data labels.
			if (isset($this->x_data_label_pos)) {
				if (!isset($this->x_tick_label_pos)) {
					// Case: data_label_pos is set, tick_label_pos needs a default:
					if ($this->x_data_label_pos == "none")
						$this->x_tick_label_pos = "plotdown";
					else
						$this->x_tick_label_pos = "none";
				}
			} elseif (isset($this->x_tick_label_pos)) {
				// Case: tick_label_pos is set, data_label_pos needs a default:
				if ($this->x_tick_label_pos == "none")
					$this->x_data_label_pos = "plotdown";
				else
					$this->x_data_label_pos = "none";
			} else {
				// Case: Neither tick_label_pos nor data_label_pos is set.
				// We do not want them to be both on (as PHPlot used to do in this case).
				// Turn on data labels if any were supplied, else tick labels.
				if ($this->CheckLabelsAllEmpty()) {
					$this->x_data_label_pos = "none";
					$this->x_tick_label_pos = "plotdown";
				} else {
					$this->x_data_label_pos = "plotdown";
					$this->x_tick_label_pos = "none";
				}
			}
		}

		// Y Label position fixups, for y_data_label_pos and y_tick_label_pos:
		if (!$this->datatype_swapped_xy) {
			// Just apply defaults - there is no position conflict.
			if (!isset($this->y_tick_label_pos))
				$this->y_tick_label_pos = "plotleft";
			if (!isset($this->y_data_label_pos))
				$this->y_data_label_pos = "none";
		} else {
			// Apply defaults but do not allow conflict between tick and data labels.
			if (isset($this->y_data_label_pos)) {
				if (!isset($this->y_tick_label_pos)) {
					// Case: data_label_pos is set, tick_label_pos needs a default:
					if ($this->y_data_label_pos == "none")
						$this->y_tick_label_pos = "plotleft";
					else
						$this->y_tick_label_pos = "none";
				}
			} elseif (isset($this->y_tick_label_pos)) {
				// Case: tick_label_pos is set, data_label_pos needs a default:
				if ($this->y_tick_label_pos == "none")
					$this->y_data_label_pos = "plotleft";
				else
					$this->y_data_label_pos = "none";
			} else {
				// Case: Neither tick_label_pos nor data_label_pos is set.
				// Turn on data labels if any were supplied, else tick labels.
				if ($this->CheckLabelsAllEmpty()) {
					$this->y_data_label_pos = "none";
					$this->y_tick_label_pos = "plotleft";
				} else {
					$this->y_data_label_pos = "plotleft";
					$this->y_tick_label_pos = "none";
				}
			}
		}
		return TRUE;
	}

	/*
	 * Formats a tick or data label.
	 *    which_pos - 'x', 'xd', 'y', or 'yd', selects formatting controls.
	 *        x, y are for tick labels; xd, yd are for data labels.
	 *    which_lab - String to format as a label.
	 * Credits: Time formatting suggested by Marlin Viss
	 *          Custom formatting suggested by zer0x333
	 * Notes:
	 *   Type 'title' is obsolete and retained for compatibility.
	 *   Class variable 'data_units_text' is retained as a suffix for 'data' type formatting for
	 *      backward compatibility. Since there was never a function/method to set it, there
	 *      could be somebody out there who sets it directly in the object.
	 */
	protected function FormatLabel($which_pos, $which_lab)
	{
		// Assign a reference shortcut to the label format controls.
		// Note CheckLabels() made sure the 'xd' and 'yd' arrays are set.
		$format =& $this->label_format[$which_pos];

		// Don't format empty strings (especially as time or numbers), or if no type was set.
		if ($which_lab !== "" && !empty($format["type"])) {
			switch ($format["type"]) {
			case "title":  // Note: This is obsolete
				$which_lab = @ $this->data[$which_lab][0];
				break;
			case "data":
				$which_lab = $format["prefix"]
						   . $this->number_format($which_lab, $format["precision"])
						   . $this->data_units_text  // Obsolete
						   . $format["suffix"];
				break;
			case "time":
				$which_lab = strftime($format["time_format"], $which_lab);
				break;
			case "printf":
				$which_lab = sprintf($format["printf_format"], $which_lab);
				break;
			case "custom":
				$which_lab = call_user_func($format["custom_callback"], $which_lab, $format["custom_arg"]);
				break;

			}
		}
		return $which_lab;
	}

/////////////////////////////////////////////
///////////////                         TICKS
/////////////////////////////////////////////

	/*
	 * Set the step (interval) between X ticks.
	 * Use either this or SetNumXTicks(), not both, to control the X tick marks.
	 */
	function SetXTickIncrement($which_ti="")
	{
		$this->x_tick_inc = $which_ti;
		if (!empty($which_ti)) {
			$this->num_x_ticks = "";
		}
		return TRUE;
	}

	/*
	 * Set the step (interval) between Y ticks.
	 * Use either this or SetNumYTicks(), not both, to control the Y tick marks.
	 */
	function SetYTickIncrement($which_ti="")
	{
		$this->y_tick_inc = $which_ti;
		if (!empty($which_ti)) {
			$this->num_y_ticks = "";
		}
		return TRUE;
	}

	/*
	 * Set the number of X tick marks.
	 * Use either this or SetXTickIncrement(), not both, to control the X tick marks.
	 */
	function SetNumXTicks($which_nt="")
	{
		$this->num_x_ticks = $which_nt;
		if (!empty($which_nt)) {
			$this->x_tick_inc = "";
		}
		return TRUE;
	}

	/*
	 * Set the number of Y tick marks.
	 * Use either this or SetYTickIncrement(), not both, to control the Y tick marks.
	 */
	function SetNumYTicks($which_nt="")
	{
		$this->num_y_ticks = $which_nt;
		if (!empty($which_nt)) {
			$this->y_tick_inc = "";  //either use num_y_ticks or y_tick_inc, not both
		}
		return TRUE;
	}

	/*
	 * Set the position for the X tick marks.
	 * These can be above the plot, below, both positions, at the X axis, or suppressed.
	 */
	function SetXTickPos($which_tp)
	{
		$this->x_tick_pos = $this->CheckOption($which_tp, "plotdown, plotup, both, xaxis, none",
											   __FUNCTION__, );
		return (boolean)$this->x_tick_pos;
	}

	/*
	 * Set the position for the Y tick marks.
	 * These can be left of the plot, right, both positions, at the Y axis, or suppressed.
	 */
	function SetYTickPos($which_tp)
	{
		$this->y_tick_pos = $this->CheckOption($which_tp, "plotleft, plotright, both, yaxis, none",
											  __FUNCTION__, );
		return (boolean)$this->y_tick_pos;
	}

	/*
	 * Skip the top-most Y axis tick mark and label if $skip is true.
	 */
	function SetSkipTopTick($skip)
	{
		$this->skip_top_tick = (bool)$skip;
		return TRUE;
	}

	/*
	 * Skip the bottom-most Y axis tick mark and label if $skip is true.
	 */
	function SetSkipBottomTick($skip)
	{
		$this->skip_bottom_tick = (bool)$skip;
		return TRUE;
	}

	/*
	 * Skip the left-most X axis tick mark and label if $skip is true.
	 */
	function SetSkipLeftTick($skip)
	{
		$this->skip_left_tick = (bool)$skip;
		return TRUE;
	}

	/*
	 * Skip the right-most X axis tick mark and label if $skip is true.
	 */
	function SetSkipRightTick($skip)
	{
		$this->skip_right_tick = (bool)$skip;
		return TRUE;
	}

	/*
	 * Set the outer length of X tick marks to $which_xln pixels.
	 * This is the part of the tick mark that sticks out from the plot area.
	 */
	function SetXTickLength($which_xln)
	{
		$this->x_tick_length = $which_xln;
		return TRUE;
	}

	/*
	 * Set the outer length of Y tick marks to $which_yln pixels.
	 * This is the part of the tick mark that sticks out from the plot area.
	 */
	function SetYTickLength($which_yln)
	{
		$this->y_tick_length = $which_yln;
		return TRUE;
	}

	/*
	 * Set the crossing length of X tick marks to $which_xc pixels.
	 * This is the part of the tick mark that sticks into the plot area.
	 */
	function SetXTickCrossing($which_xc)
	{
		$this->x_tick_cross = $which_xc;
		return TRUE;
	}

	/*
	 * Set the crossing length of Y tick marks to $which_yc pixels.
	 * This is the part of the tick mark that sticks into the plot area.
	 */
	function SetYTickCrossing($which_yc)
	{
		$this->y_tick_cross = $which_yc;
		return TRUE;
	}

	/*
	 * Set an anchor point for X tick marks. There will be an X tick mark at
	 * this exact value (if the data range were extended to include it).
	 */
	function SetXTickAnchor($xta = NULL)
	{
		$this->x_tick_anchor = $xta;
		return TRUE;
	}

	/*
	 * Set an anchor point for Y tick marks. There will be a Y tick mark at
	 * this exact value (if the data range were extended to include it).
	 */
	function SetYTickAnchor($yta = NULL)
	{
		$this->y_tick_anchor = $yta;
		return TRUE;
	}

/////////////////////////////////////////////
////////////////////          GENERIC DRAWING
/////////////////////////////////////////////

	/*
	 * Fill the image background, with a tiled image file or solid color.
	 */
	protected function DrawBackground()
	{
		// Don't draw this twice if drawing two plots on one image
		if (empty($this->done["background"])) {
			if (isset($this->bgimg)) {    // If bgimg is defined, use it
				$this->tile_img($this->bgimg, 0, 0, $this->image_width, $this->image_height, $this->bgmode);
			} else {                        // Else use solid color
				ImageFilledRectangle($this->img, 0, 0, $this->image_width, $this->image_height,
									 $this->ndx_bg_color, );
			}
			$this->done["background"] = TRUE;
		}
		return TRUE;
	}

	/*
	 * Fill the plot area background, with a tiled image file or solid color.
	 */
	protected function DrawPlotAreaBackground()
	{
		if (isset($this->plotbgimg)) {
			$this->tile_img($this->plotbgimg, $this->plot_area[0], $this->plot_area[1],
							$this->plot_area_width, $this->plot_area_height, $this->plotbgmode, );
		} elseif ($this->draw_plot_area_background) {
			ImageFilledRectangle($this->img, $this->plot_area[0], $this->plot_area[1],
								 $this->plot_area[2], $this->plot_area[3], $this->ndx_plot_bg_color, );
		}
		return TRUE;
	}

	/*
	 * Tiles an image at some given coordinates.
	 *   $file : Filename of the picture to be used as tile.
	 *   $xorig : X device coordinate of where the tile is to begin.
	 *   $yorig : Y device coordinate of where the tile is to begin.
	 *   $width : Width of the area to be tiled.
	 *   $height : Height of the area to be tiled.
	 *   $mode : Tiling mode. One of 'centeredtile', 'tile', 'scale'.
	 */
	protected function tile_img($file, $xorig, $yorig, $width, $height, $mode)
	{
		$im = $this->GetImage($file, $tile_width, $tile_height);
		if (!$im)
			return FALSE;  // GetImage already produced an error message.

		if ($mode == "scale") {
			imagecopyresampled($this->img, $im, $xorig, $yorig, 0, 0, $width, $height,
							   $tile_width, $tile_height, );
			return TRUE;
		}

		if ($mode == "centeredtile") {
			$x0 = - floor($tile_width/2);   // Make the tile look better
			$y0 = - floor($tile_height/2);
		} else {      // Accept anything else as $mode == 'tile'
			$x0 = 0;
			$y0 = 0;
		}

		// Draw the tile onto a temporary image first.
		$tmp = imagecreate($width, $height);
		if (! $tmp)
			return $this->PrintError("tile_img(): Could not create image resource.");

		for ($x = $x0; $x < $width; $x += $tile_width)
			for ($y = $y0; $y < $height; $y += $tile_height)
				imagecopy($tmp, $im, $x, $y, 0, 0, $tile_width, $tile_height);

		// Copy the temporary image onto the final one.
		imagecopy($this->img, $tmp, $xorig, $yorig, 0,0, $width, $height);

		// Free resources
		imagedestroy($tmp);
		imagedestroy($im);

		return TRUE;
	}

	/*
	 * Return the image border width.
	 * This is used by CalcMargins() and DrawImageBorder().
	 */
	protected function GetImageBorderWidth()
	{
		if ($this->image_border_type == "none")
			return 0; // No border
		if (!empty($this->image_border_width))
			return $this->image_border_width; // Specified border width
		if ($this->image_border_type == "raised")
			return 2; // Default for raised border is 2 pixels.
		return 1; // Default for other border types is 1 pixel.
	}

	/*
	 * Draws a border around the final image.
	 * Note: 'plain' draws a flat border using the dark shade of the border color.
	 * This probably should have been written to use the actual border color, but
	 * it is too late to fix it without changing plot appearances. Therefore a
	 * new type 'solid' was added to use the SetImageBorderColor color.
	 */
	protected function DrawImageBorder()
	{
		// Do nothing if already drawn, or if no border has been set.
		if ($this->image_border_type == "none" || !empty($this->done["border"]))
			return TRUE;
		$width = $this->GetImageBorderWidth();
		$color1 = $this->ndx_i_border;
		$color2 = $this->ndx_i_border_dark;
		$ex = $this->image_width - 1;
		$ey = $this->image_height - 1;
		switch ($this->image_border_type) {
		case "raised":
			// Top and left lines use border color, right and bottom use the darker shade.
			// Drawing order matters in the upper right and lower left corners.
			for ($i = 0; $i < $width; $i++, $ex--, $ey--) {
				imageline($this->img, $i,  $i,  $ex, $i,  $color1); // Top
				imageline($this->img, $ex, $i,  $ex, $ey, $color2); // Right
				imageline($this->img, $i,  $i,  $i,  $ey, $color1); // Left
				imageline($this->img, $i,  $ey, $ex, $ey, $color2); // Bottom
			}
			break;
		case "plain": // See note above re colors
			$color1 = $color2;
			// Fall through
		case "solid":
			for ($i = 0; $i < $width; $i++, $ex--, $ey--) {
				imagerectangle($this->img, $i, $i, $ex, $ey, $color1);
			}
			break;
		default:
			return $this->PrintError(
						  "DrawImageBorder(): unknown image_border_type: '$this->image_border_type'", );
		}
		$this->done["border"] = TRUE; // Border should only be drawn once per image.
		return TRUE;
	}

	/*
	 * Draws the main title on the graph.
	 * The title must not be drawn more than once (in the case of multiple plots
	 * on the image), because TTF text antialiasing makes it look bad.
	 */
	protected function DrawTitle()
	{
		if (!empty($this->done["title"]) || $this->title_txt === "")
			return TRUE;

		// Center of the image:
		$xpos = $this->image_width / 2;

		// Place it at almost at the top
		$ypos = $this->title_offset;

		$this->DrawText($this->fonts["title"], 0, $xpos, $ypos,
						$this->ndx_title_color, $this->title_txt, "center", "top", );

		$this->done["title"] = TRUE;
		return TRUE;
	}

	/*
	 * Draws the X-Axis Title
	 */
	protected function DrawXTitle()
	{
		if ($this->x_title_pos == "none")
			return TRUE;

		// Center of the plot
		$xpos = ($this->plot_area[2] + $this->plot_area[0]) / 2;

		// Upper title
		if ($this->x_title_pos == "plotup" || $this->x_title_pos == "both") {
			$ypos = $this->plot_area[1] - $this->x_title_top_offset;
			$this->DrawText($this->fonts["x_title"], 0, $xpos, $ypos, $this->ndx_x_title_color,
							$this->x_title_txt, "center", "bottom", );
		}
		// Lower title
		if ($this->x_title_pos == "plotdown" || $this->x_title_pos == "both") {
			$ypos = $this->plot_area[3] + $this->x_title_bot_offset;
			$this->DrawText($this->fonts["x_title"], 0, $xpos, $ypos, $this->ndx_x_title_color,
							$this->x_title_txt, "center", "top", );
		}
		return TRUE;
	}

	/*
	 * Draws the Y-Axis Title
	 */
	protected function DrawYTitle()
	{
		if ($this->y_title_pos == "none")
			return TRUE;

		// Center the title vertically to the plot area
		$ypos = ($this->plot_area[3] + $this->plot_area[1]) / 2;

		if ($this->y_title_pos == "plotleft" || $this->y_title_pos == "both") {
			$xpos = $this->plot_area[0] - $this->y_title_left_offset;
			$this->DrawText($this->fonts["y_title"], 90, $xpos, $ypos, $this->ndx_y_title_color,
							$this->y_title_txt, "right", "center", );
		}
		if ($this->y_title_pos == "plotright" || $this->y_title_pos == "both") {
			$xpos = $this->plot_area[2] + $this->y_title_right_offset;
			$this->DrawText($this->fonts["y_title"], 90, $xpos, $ypos, $this->ndx_y_title_color,
							$this->y_title_txt, "left", "center", );
		}

		return TRUE;
	}

	/*
	 * Draw the X axis, including ticks and labels, and X (vertical) grid lines.
	 */
	protected function DrawXAxis()
	{
		// Draw ticks, labels and grid
		$this->DrawXTicks();

		//Draw X Axis at Y = x_axis_y_pixels, unless suppressed (See SetXAxisPosition)
		if (empty($this->suppress_x_axis)) {
			ImageLine($this->img, $this->plot_area[0]+1, $this->x_axis_y_pixels,
					  $this->plot_area[2]-1, $this->x_axis_y_pixels, $this->ndx_grid_color, );
		}
		return TRUE;
	}

	/*
	 * Draw the Y axis, including ticks and labels, and Y (horizontal) grid lines.
	 * Horizontal grid lines overwrite horizontal axis with y=0, so call this first, then DrawXAxis()
	 */
	protected function DrawYAxis()
	{
		// Draw ticks, labels and grid
		$this->DrawYTicks();

		// Draw Y axis at X = y_axis_x_pixels, unless suppressed (See SetYAxisPosition)
		if (empty($this->suppress_y_axis)) {
			ImageLine($this->img, $this->y_axis_x_pixels, $this->plot_area[1],
					  $this->y_axis_x_pixels, $this->plot_area[3], $this->ndx_grid_color, );
		}
		return TRUE;
	}

	/*
	 * Draw one X tick mark and its tick label.
	 *   $which_xlab : Formatted X value for the label.
	 *   $which_xpix : X device coordinate for this tick mark.
	 */
	protected function DrawXTick($which_xlab, $which_xpix)
	{
		// Ticks on X axis
		if ($this->x_tick_pos == "xaxis") {
			ImageLine($this->img, $which_xpix, $this->x_axis_y_pixels - $this->x_tick_cross,
					  $which_xpix, $this->x_axis_y_pixels + $this->x_tick_length, $this->ndx_tick_color, );
		}

		// Ticks on top of the Plot Area
		if ($this->x_tick_pos == "plotup" || $this->x_tick_pos == "both") {
			ImageLine($this->img, $which_xpix, $this->plot_area[1] - $this->x_tick_length,
					  $which_xpix, $this->plot_area[1] + $this->x_tick_cross, $this->ndx_tick_color, );
		}

		// Ticks on bottom of Plot Area
		if ($this->x_tick_pos == "plotdown" || $this->x_tick_pos == "both") {
			ImageLine($this->img, $which_xpix, $this->plot_area[3] + $this->x_tick_length,
					  $which_xpix, $this->plot_area[3] - $this->x_tick_cross, $this->ndx_tick_color, );
		}

		// Label on X axis
		if ($this->x_tick_label_pos == "xaxis") {
			$this->DrawText($this->fonts["x_label"], $this->x_label_angle,
							$which_xpix, $this->x_axis_y_pixels + $this->x_label_axis_offset,
							$this->ndx_text_color, $which_xlab, "center", "top", );
		}

		// Label on top of the Plot Area
		if ($this->x_tick_label_pos == "plotup" || $this->x_tick_label_pos == "both") {
			$this->DrawText($this->fonts["x_label"], $this->x_label_angle,
							$which_xpix, $this->plot_area[1] - $this->x_label_top_offset,
							$this->ndx_text_color, $which_xlab, "center", "bottom", );
		}

		// Label on bottom of the Plot Area
		if ($this->x_tick_label_pos == "plotdown" || $this->x_tick_label_pos == "both") {
			$this->DrawText($this->fonts["x_label"], $this->x_label_angle,
							$which_xpix, $this->plot_area[3] + $this->x_label_bot_offset,
							$this->ndx_text_color, $which_xlab, "center", "top", );
		}
		return TRUE;
	}

	/*
	 * Draw one Y tick mark and its tick label. Called from DrawYTicks() and DrawXAxis()
	 *   $which_ylab : Formatted Y value for the label.
	 *   $which_ypix : Y device coordinate for this tick mark.
	 */
	protected function DrawYTick($which_ylab, $which_ypix)
	{
		// Ticks on Y axis
		if ($this->y_tick_pos == "yaxis") {
			ImageLine($this->img, $this->y_axis_x_pixels - $this->y_tick_length, $which_ypix,
					  $this->y_axis_x_pixels + $this->y_tick_cross, $which_ypix, $this->ndx_tick_color, );
		}

		// Ticks to the left of the Plot Area
		if (($this->y_tick_pos == "plotleft") || ($this->y_tick_pos == "both") ) {
			ImageLine($this->img, $this->plot_area[0] - $this->y_tick_length, $which_ypix,
					  $this->plot_area[0] + $this->y_tick_cross, $which_ypix, $this->ndx_tick_color, );
		}

		// Ticks to the right of the Plot Area
		if (($this->y_tick_pos == "plotright") || ($this->y_tick_pos == "both") ) {
			ImageLine($this->img, $this->plot_area[2] + $this->y_tick_length, $which_ypix,
					  $this->plot_area[2] - $this->y_tick_cross, $which_ypix, $this->ndx_tick_color, );
		}

		// Labels on Y axis
		if ($this->y_tick_label_pos == "yaxis") {
			$this->DrawText($this->fonts["y_label"], $this->y_label_angle,
							$this->y_axis_x_pixels - $this->y_label_axis_offset, $which_ypix,
							$this->ndx_text_color, $which_ylab, "right", "center", );
		}

		// Labels to the left of the plot area
		if ($this->y_tick_label_pos == "plotleft" || $this->y_tick_label_pos == "both") {
			$this->DrawText($this->fonts["y_label"], $this->y_label_angle,
							$this->plot_area[0] - $this->y_label_left_offset, $which_ypix,
							$this->ndx_text_color, $which_ylab, "right", "center", );
		}
		// Labels to the right of the plot area
		if ($this->y_tick_label_pos == "plotright" || $this->y_tick_label_pos == "both") {
			$this->DrawText($this->fonts["y_label"], $this->y_label_angle,
							$this->plot_area[2] + $this->y_label_right_offset, $which_ypix,
							$this->ndx_text_color, $which_ylab, "left", "center", );
		}
		return TRUE;
	}

	/*
	 * Draws Grid, Ticks and Tick Labels along X-Axis
	 * Ticks and tick labels can be down of plot only, up of plot only,
	 * both on up and down of plot, or crossing a user defined X-axis
	 *
	 * Original vertical code submitted by Marlin Viss
	 */
	protected function DrawXTicks()
	{
		// Sets the line style for IMG_COLOR_STYLED lines (grid)
		if ($this->dashed_grid) {
			$this->SetDashedStyle($this->ndx_light_grid_color);
			$style = IMG_COLOR_STYLED;
		} else {
			$style = $this->ndx_light_grid_color;
		}

		// Calculate the tick start, end, and step:
		list($x_start, $x_end, $delta_x) = $this->CalcTicks("x");

		// Loop, avoiding cumulative round-off errors from $x_tmp += $delta_x
		$n = 0;
		$x_tmp = $x_start;
		while ($x_tmp <= $x_end) {
			$xlab = $this->FormatLabel("x", $x_tmp);
			$x_pixels = $this->xtr($x_tmp);

			// Vertical grid lines
			if ($this->draw_x_grid) {
				ImageLine($this->img, $x_pixels, $this->plot_area[1], $x_pixels, $this->plot_area[3], $style);
			}

			// Draw tick mark(s)
			$this->DrawXTick($xlab, $x_pixels);

			// Step to next X, without accumulating error
			$x_tmp = $x_start + ++$n * $delta_x;
		}
		return TRUE;
	}

	/*
	 * Draw the grid, ticks, and tick labels along the Y axis.
	 * Ticks and tick labels can be left of plot only, right of plot only,
	 * both on the left and right of plot, or crossing a user defined Y-axis
	 */
	protected function DrawYTicks()
	{
		// Sets the line style for IMG_COLOR_STYLED lines (grid)
		if ($this->dashed_grid) {
			$this->SetDashedStyle($this->ndx_light_grid_color);
			$style = IMG_COLOR_STYLED;
		} else {
			$style = $this->ndx_light_grid_color;
		}

		// Calculate the tick start, end, and step:
		list($y_start, $y_end, $delta_y) = $this->CalcTicks("y");

		// Loop, avoiding cumulative round-off errors from $y_tmp += $delta_y
		$n = 0;
		$y_tmp = $y_start;
		while ($y_tmp <= $y_end) {
			$ylab = $this->FormatLabel("y", $y_tmp);
			$y_pixels = $this->ytr($y_tmp);

			// Horizontal grid line
			if ($this->draw_y_grid) {
				ImageLine($this->img, $this->plot_area[0]+1, $y_pixels, $this->plot_area[2]-1,
						  $y_pixels, $style, );
			}

			// Draw tick mark(s)
			$this->DrawYTick($ylab, $y_pixels);

			// Step to next Y, without accumulating error
			$y_tmp = $y_start + ++$n * $delta_y;
		}
		return TRUE;
	}

	/*
	 *  Draw a border around the plot area. See SetPlotBorderType.
	 *  Note: SetPlotBorderType sets plot_border_type to an array, but
	 *  it won't be an array if it defaults or is set directly (backward compatibility).
	 */
	protected function DrawPlotBorder()
	{
		$pbt = (array)$this->plot_border_type;
		$sides = 0;  // Bitmap: 1=left 2=top 4=right 8=bottom
		$map = ["left" => 1, "plotleft" => 1, "right" => 4, "plotright" => 4, "top" => 2,
					  "bottom" => 8, "both" => 5, "sides" => 5, "full" => 15, "none" => 0, ];
		foreach ($pbt as $option) $sides |= $map[$option];
		if ($sides == 15) { // Border on all 4 sides
			imagerectangle($this->img, $this->plot_area[0], $this->plot_area[1],
						   $this->plot_area[2], $this->plot_area[3], $this->ndx_grid_color, );
		} else {
			if ($sides & 1) // Left
				imageline($this->img, $this->plot_area[0], $this->plot_area[1],
									  $this->plot_area[0], $this->plot_area[3], $this->ndx_grid_color, );
			if ($sides & 2) // Top
				imageline($this->img, $this->plot_area[0], $this->plot_area[1],
									  $this->plot_area[2], $this->plot_area[1], $this->ndx_grid_color, );
			if ($sides & 4) // Right
				imageline($this->img, $this->plot_area[2], $this->plot_area[1],
									  $this->plot_area[2], $this->plot_area[3], $this->ndx_grid_color, );
			if ($sides & 8) // Bottom
				imageline($this->img, $this->plot_area[0], $this->plot_area[3],
									  $this->plot_area[2], $this->plot_area[3], $this->ndx_grid_color, );
		}
		return TRUE;
	}

	/*
	 * Draw the data value label associated with a point in the plot.
	 * These are labels that show the value (dependent variable, usually Y) of the data point,
	 * and are drawn within the plot area (not to be confused with axis data labels).
	 *
	 *    $x_or_y : Specify 'x' or 'y' labels. This selects font, angle, and formatting.
	 *    $x_world, $y_world : World coordinates of the text (see also x/y_adjustment).
	 *    $text : The text to draw, after formatting with FormatLabel().
	 *    $halign, $valign : Selects from 9-point text alignment.
	 *    $x_adjustment, $y_adjustment : Text position offsets, in device coordinates.
	 *    $min_width, $min_height : If supplied, suppress the text if it will not fit.
	 * Returns True, if the text was drawn, or False, if it will not fit.
	 */
	protected function DrawDataValueLabel($x_or_y, $x_world, $y_world, $text, $halign, $valign,
					  $x_adjustment=0, $y_adjustment=0, $min_width=NULL, $min_height=NULL, )
	{
		if ($x_or_y == "x") {
			$angle = $this->x_data_label_angle;
			$font = $this->fonts["x_label"];
			$formatted_text = $this->FormatLabel("xd", $text);
		} else { // Assumed 'y'
			$angle = $this->y_data_label_angle;
			$font = $this->fonts["y_label"];
			$formatted_text = $this->FormatLabel("yd", $text);
		}
		$color = $this->ndx_title_color; // Currently this is the same for X and Y labels

		// Check to see if the text fits in the available space, if requested.
		if (isset($min_width) || isset($min_height)) {
			list($width, $height) = $this->SizeText($font, $angle, $formatted_text);
			if ((isset($min_width) && ($min_width - $width)  < 2)
				|| (isset($min_height) && ($min_height - $height) < 2))
				return FALSE;
		}

		$this->DrawText($font, $angle, $this->xtr($x_world) + $x_adjustment,
						$this->ytr($y_world) + $y_adjustment,
						$color, $formatted_text, $halign, $valign, );
		return TRUE;
	}

	/*
	 * Draws the axis data label associated with a point in the plot.
	 * This is different from x_labels drawn by DrawXTicks() and care
	 * should be taken not to draw both, as they'd probably overlap.
	 * Calling of this function in DrawLines(), etc is decided after x_data_label_pos value.
	 * Leave the last parameter out, to avoid the drawing of vertical lines, no matter
	 * what the setting is (for plots that need it, like DrawSquared())
	 */
	protected function DrawXDataLabel($xlab, $xpos, $row=FALSE)
	{
		$xlab = $this->FormatLabel("xd", $xlab);

		// Labels below the plot area
		if ($this->x_data_label_pos == "plotdown" || $this->x_data_label_pos == "both")
			$this->DrawText($this->fonts["x_label"], $this->x_data_label_angle,
							$xpos, $this->plot_area[3] + $this->x_label_bot_offset,
							$this->ndx_text_color, $xlab, "center", "top", );

		// Labels above the plot area
		if ($this->x_data_label_pos == "plotup" || $this->x_data_label_pos == "both")
			$this->DrawText($this->fonts["x_label"], $this->x_data_label_angle,
							$xpos, $this->plot_area[1] - $this->x_label_top_offset,
							$this->ndx_text_color, $xlab, "center", "bottom", );

		// $row=0 means this is the first row. $row=FALSE means don't do any rows.
		if ($row !== FALSE && $this->draw_x_data_label_lines)
			$this->DrawXDataLine($xpos, $row);
		return TRUE;
	}

	/*
	 * Draw a data label along the Y axis or side.
	 * This is used by horizontal plots.
	 */
	protected function DrawYDataLabel($ylab, $ypos)
	{
		$ylab = $this->FormatLabel("yd", $ylab);

		// Labels left of the plot area
		if ($this->y_data_label_pos == "plotleft" || $this->y_data_label_pos == "both")
			$this->DrawText($this->fonts["y_label"], $this->y_data_label_angle,
							$this->plot_area[0] - $this->y_label_left_offset, $ypos,
							$this->ndx_text_color, $ylab, "right", "center", );

		// Labels right of the plot area
		if ($this->y_data_label_pos == "plotright" || $this->y_data_label_pos == "both")
			$this->DrawText($this->fonts["y_label"], $this->y_data_label_angle,
							$this->plot_area[2] + $this->y_label_right_offset, $ypos,
							$this->ndx_text_color, $ylab, "left", "center", );
		return TRUE;
	}

	/*
	 * Draws Vertical lines from data points up and down.
	 * Which lines are drawn depends on the value of x_data_label_pos,
	 * and whether this is at all done or not, on draw_x_data_label_lines
	 *
	 *   $xpos : position in pixels of the line.
	 *   $row : index of the data row being drawn.
	 */
	protected function DrawXDataLine($xpos, $row)
	{
		// Sets the line style for IMG_COLOR_STYLED lines (grid)
		if ($this->dashed_grid) {
			$this->SetDashedStyle($this->ndx_light_grid_color);
			$style = IMG_COLOR_STYLED;
		} else {
			$style = $this->ndx_light_grid_color;
		}

		if ($this->x_data_label_pos == "both") {
			// Lines from the bottom up
			ImageLine($this->img, $xpos, $this->plot_area[3], $xpos, $this->plot_area[1], $style);
		} elseif ($this->x_data_label_pos == "plotdown" && isset($this->data_max[$row])) {
			// Lines from the bottom of the plot up to the max Y value at this X:
			$ypos = $this->ytr($this->data_max[$row]);
			ImageLine($this->img, $xpos, $ypos, $xpos, $this->plot_area[3], $style);
		} elseif ($this->x_data_label_pos == "plotup" && isset($this->data_min[$row])) {
			// Lines from the top of the plot down to the min Y value at this X:
			$ypos = $this->ytr($this->data_min[$row]);
			ImageLine($this->img, $xpos, $this->plot_area[1], $xpos, $ypos, $style);
		}
		return TRUE;
	}

/////////////////////////////////////////////
///////////////                        LEGEND
/////////////////////////////////////////////

	/*
	 * Set text to display in the graph's legend.
	 *   $which_leg : Array of strings for the complete legend, or a single string
	 *                to be appended to the legend.
	 *                Or NULL (or an empty array) to cancel the legend.
	 */
	function SetLegend($which_leg)
	{
		if (is_array($which_leg)) {           // use array (or cancel, if empty array)
			$this->legend = $which_leg;
		} elseif (!is_null($which_leg)) {     // append string
			$this->legend[] = $which_leg;
		} else {
			$this->legend = "";  // Reinitialize to empty, meaning no legend.
		}
		return TRUE;
	}

	/*
	 * Specifies the position of the legend's upper/leftmost corner, in pixel (device) coordinates.
	 * Both X and Y must be provided, or both omitted (or use NULL) to restore auto-positioning.
	 */
	function SetLegendPixels($which_x=NULL, $which_y=NULL)
	{
		return $this->SetLegendPosition(0, 0, "image", 0, 0, $which_x, $which_y);
	}

	/*
	 * Specifies the position of the legend's upper/leftmost corner, in world (data space) coordinates.
	 */
	function SetLegendWorld($which_x, $which_y)
	{
		return $this->SetLegendPosition(0, 0, "world", $which_x, $which_y);
	}

	/*
	 * Specifies the position of the legend. This includes SetLegendWorld(), SetLegendPixels(), and
	 * additional choices using relative coordinates, with optional pixel offset.
	 *   $x, $y : Relative coordinates of a point on the legend box. (See below)
	 *   $relative_to : What to position the legend relative to: 'image', 'plot', 'world', or 'title'.
	 *   $x_base, $y_base : Base point for positioning.
	 *      If $relative_to is 'world', then this is a world coordinate position.
	 *      Otherwise, this is a relative coordinate position on the $relative_to element.
	 *   $x_offset, $y_offset : Additional legend box offset in device coordinates (pixels).
	 *  The legend is positioned so that point ($x,$y) is at ($x_base, $y_base).
	 *  'Relative coordinates' means: (0,0) is the upper left corner, and (1,1) is the lower right corner
	 *  of the element (legend, image, plot, or title area), regardless of its size. These are floating
	 *  point values, each usually in the range [0,1], but they can be negative or greater than 1.
	 *  If any of x, y, x_offset, or y_offset are NULL, default legend positioning is restored.
	 */
	function SetLegendPosition($x, $y, $relative_to, $x_base, $y_base, $x_offset = 0, $y_offset = 0)
	{
		// Special case: NULL means restore the default positioning.
		if (!isset($x, $y, $x_offset, $y_offset)) {
			unset($this->legend_pos);
		} else {
			$mode = $this->CheckOption($relative_to, "image, plot, title, world", __FUNCTION__);
			if (empty($mode))
				return FALSE;
			// Save all values for use by GetLegendPosition()
			$this->legend_pos = compact("x", "y", "mode", "x_base", "y_base", "x_offset", "y_offset");
		}
		return TRUE;
	}

	/*
	 * Set legend text alignment, color box alignment, and style options.
	 *   $text_align : Alignment of the text, 'left' or 'right'.
	 *   $colorbox_align : Alignment of the color boxes, 'left', 'right', 'none', or missing/empty.
	 *       If missing or empty, the same alignment as $text_align is used. Color box is positioned first.
	 */
	function SetLegendStyle($text_align, $colorbox_align = "")
	{
		$this->legend_text_align = $this->CheckOption($text_align, "left, right", __FUNCTION__);
		if (empty($colorbox_align))
			$this->legend_colorbox_align = $this->legend_text_align;
		else
			$this->legend_colorbox_align = $this->CheckOption($colorbox_align, "left, right, none",
															  __FUNCTION__, );
		return ((boolean)$this->legend_text_align && (boolean)$this->legend_colorbox_align);
	}

	/*
	 * Use color boxes or point shapes (for points and linepoints plots only) in the legend.
	 *   $use_shapes : True to use point shapes, false to use color boxes.
	 */
	function SetLegendUseShapes($use_shapes)
	{
		$this->legend_use_shapes = (bool)$use_shapes;
		return TRUE;
	}

	/*
	 * Get legend sizing parameters.
	 * This is used internally by DrawLegend(), and also by the public GetLegendSize().
	 * It returns information based on any SetLegend*() calls already made. It does not use
	 * legend position or data scaling, so it can be called before data scaling is set up.
	 * Returns an associative array with these entries describing legend sizing:
	 *    'width', 'height' : Overall legend box size in pixels.
	 *    'char_w', 'char_h' : Width and height of 'E' in legend text font. (Used to size color boxes)
	 *    'v_margin' : Inside margin for legend
	 *    'text_align', 'colorbox_align' : Same as the class variables, with default applied.
	 *    'draw_colorbox' : True if color boxes will be drawn.
	 *    'dot_height' : Height of color boxes (even if not drawn), for line spacing.
	 *    'colorbox_width' : Width of color boxes.
	 */
	protected function GetLegendSizeParams()
	{
		$font = &$this->fonts["legend"]; // Shortcut to font info array

		// Find maximum legend label line width.
		$max_width = 0;
		foreach ($this->legend as $line) {
			list($width, $unused) = $this->SizeText($font, 0, $line);
			if ($width > $max_width) $max_width = $width;
		}

		// Font parameters are used to size the color boxes:
		$char_w = $font["width"];
		$char_h = $font["height"];
		$line_spacing = $this->GetLineSpacing($font);

		// Apply defaults to text alignment and colorbox alignment variables:
		$text_align = $this->legend_text_align ?? "right";
		$colorbox_align = $this->legend_colorbox_align ?? "right";
		$draw_colorbox = ($colorbox_align != "none");

		// Sizing parameters:
		$v_margin = $char_h / 2;                 // Between vertical borders and labels
		$dot_height = $char_h + $line_spacing;   // Height of the color boxes (even if not drawn)
		$colorbox_width = $char_w;               // Base color box width
		if (isset($this->legend_colorbox_width))
			$colorbox_width *= $this->legend_colorbox_width; // Adjustment to color box width

		// Calculate overall legend box width and height.
		// Width is e.g.: "| space colorbox space text space |" where each space adds $char_w,
		// and colorbox (if drawn) adds $char_w * its width adjustment.
		if ($draw_colorbox) {
			$width = $max_width + 3 * $char_w + $colorbox_width;
		} else {
			$width = $max_width + 2 * $char_w;
		}
		$height = $dot_height * count($this->legend) + 2 * $v_margin;

		return compact("width", "height", "char_w", "char_h", "v_margin",
			  "text_align", "colorbox_align", "draw_colorbox", "dot_height", "colorbox_width", );
	}

	/*
	 * Get legend box size. This can be used to adjust the plot margins, for example.
	 * Returns: Array of ($width, $height) of the legend box in pixels.
	 */
	function GetLegendSize()
	{
		$params = $this->GetLegendSizeParams();
		return [$params["width"], $params["height"]];
	}

	/*
	 * Get legend location in device coordinates. This is a helper for DrawLegend, and is only
	 * called if there is a legend. See SetLegendWorld(), SetLegendPixels(), SetLegendPosition().
	 *   $width, $height : Width and height of the legend box.
	 * Returns: coordinates of the upper left corner of the legend box as an array ($x, $y)
	 */
	protected function GetLegendPosition($width, $height)
	{
		// Extract variables set by SetLegend*(): $mode, $x, $y, $x_base, $y_base, $x_offset, $y_offset
		if (isset($this->legend_pos["mode"]))
			extract($this->legend_pos);
		else
			$mode = ""; // Default legend position mode.

		switch ($mode) {

		case "plot": // SetLegendPosition with mode='plot', relative coordinates over plot area.
			return [(int)($x_base * $this->plot_area_width - $x * $width)
						  + $this->plot_area[0] + $x_offset,
						 (int)($y_base * $this->plot_area_height - $y * $height)
						  + $this->plot_area[1] + $y_offset, ];

		case "world": // User-defined position in world-coordinates (SetLegendWorld), using x_base, y_base
			return [$this->xtr($x_base) + $x_offset - (int)($x * $width),
						 $this->ytr($y_base) + $y_offset - (int)($y * $height), ];

		case "image": // SetLegendPosition with mode='image', relative coordinates over image area.
					  // SetLegendPixels() uses this too, with x=y=0.
			return [(int)($x_base * $this->image_width - $x * $width) + $x_offset,
						 (int)($y_base * $this->image_height - $y * $height) + $y_offset, ];

		case "title": // SetLegendPosition with mode='title', relative to main title.
			// Recalculate main title position/size, since CalcMargins does not save it. See DrawTitle()
			list($title_width, $title_height) = $this->SizeText($this->fonts["title"], 0, $this->title_txt);
			$title_x = (int)(($this->image_width - $title_width) / 2);
			return [(int)($x_base * $title_width - $x * $width) + $title_x + $x_offset,
						 (int)($y_base * $title_height - $y * $height) + $this->title_offset + $y_offset, ];

		default: // If mode is unset (or invalid), use default position.
			return  [$this->plot_area[2] - $width - $this->safe_margin,
						  $this->plot_area[1] + $this->safe_margin, ];
		}
	}

	/*
	 * Draws the graph legend
	 * This is called by DrawGraph only if $this->legend is not empty.
	 * Base code submitted by Marlin Viss
	 */
	protected function DrawLegend()
	{
		$font = &$this->fonts["legend"]; // Shortcut to font info array

		// Calculate legend box sizing parameters:
		// See GetLegendSizeParams() to see what variables are set by this.
		extract($this->GetLegendSizeParams());

		// Get legend box position:
		list($box_start_x, $box_start_y) = $this->GetLegendPosition($width, $height);
		$box_end_y = $box_start_y + $height;
		$box_end_x = $box_start_x + $width;

		// Draw outer box
		ImageFilledRectangle($this->img, $box_start_x, $box_start_y, $box_end_x, $box_end_y,
							 $this->ndx_bg_color, );
		ImageRectangle($this->img, $box_start_x, $box_start_y, $box_end_x, $box_end_y,
					   $this->ndx_grid_color, );

		$color_index = 0;
		$max_color_index = count($this->ndx_data_colors) - 1;

		// Calculate color box and text horizontal positions.
		if (!$draw_colorbox) {
			if ($text_align == "left")
				$x_pos = $box_start_x + $char_w;
			else
				$x_pos = $box_end_x - $char_w;
			$dot_left_x = 0; // Not used directly if color boxes/shapes are off, but referenced below.
		} elseif ($colorbox_align == "left") {
			$dot_left_x = $box_start_x + $char_w;
			$dot_right_x = $dot_left_x + $colorbox_width;
			if ($text_align == "left")
				$x_pos = $dot_right_x + $char_w;
			else
				$x_pos = $box_end_x - $char_w;
		} else {      // $colorbox_align == 'right'
			$dot_right_x = $box_end_x - $char_w;
			$dot_left_x = $dot_right_x - $colorbox_width;
			if ($text_align == "left")
				$x_pos = $box_start_x + $char_w;
			else
				$x_pos = $dot_left_x - $char_w;
		}

		// $y_pos is the bottom of each color box. $yc is the vertical center of the color box or
		// the point shape (if drawn). The text is centered vertically on $yc.
		$y_pos = $box_start_y + $v_margin + $dot_height;
		$yc = (int)($y_pos - $dot_height / 2);
		$xc = (int)($dot_left_x + $colorbox_width / 2);   // Horizontal center for point shape if drawn
		$shape_index = 0;  // Shape number index, if drawing point shapes

		// Option to use point shapes rather than solid boxes. Disallow this if the shapes array
		// has not been initialized (see CheckPointParams). Only works with 'points' or 'linepoints' plots.
		$use_shapes = !empty($this->legend_use_shapes) && !empty($this->point_counts);

		foreach ($this->legend as $leg) {
			// Draw text with requested alignment:
			$this->DrawText($font, 0, $x_pos, $yc, $this->ndx_text_color, $leg, $text_align, "center");
			if ($draw_colorbox) {
				$y1 = $y_pos - $dot_height + 1;
				$y2 = $y_pos - 1;
				if ($use_shapes) {
					// Draw a point shape in the data color
					// If plot area background is on, use that as the shape background:
					if ($this->draw_plot_area_background) {
						ImageFilledRectangle($this->img, $dot_left_x, $y1, $dot_right_x, $y2,
											 $this->ndx_plot_bg_color, );
					}
					// Draw the shape. DrawShape() takes shape_index modulo number of defined shapes.
					$this->DrawShape($xc, $yc, $shape_index++, $this->ndx_data_colors[$color_index]);
				} else {
					// Draw color boxes:
					ImageFilledRectangle($this->img, $dot_left_x, $y1, $dot_right_x, $y2,
										 $this->ndx_data_colors[$color_index], );
				   // Draw a rectangle around the box
				   ImageRectangle($this->img, $dot_left_x, $y1, $dot_right_x, $y2, $this->ndx_text_color);
				}
			}
			$y_pos += $dot_height;
			$yc += $dot_height;
			if (++$color_index > $max_color_index)
				$color_index = 0;
		}
		return TRUE;
	}

/////////////////////////////////////////////
////////////////////     PLOT DRAWING HELPERS
/////////////////////////////////////////////

	/*
	 * Get data color to use for plotting.
	 *   $row, $idx : Index arguments for the current data point.
	 *   &$vars : Variable storage. Caller makes an empty array, and this function uses it.
	 *   &$data_color : Returned result - Color index for the data point.
	 *   $extra : Extra info flag passed through to data color callback.
	 */
	protected function GetDataColor($row, $idx, &$vars, &$data_color, $extra = 0)
	{
		// Initialize or extract variables:
		if (empty($vars)) {
			$custom_color = (bool)$this->GetCallback("data_color");
			$num_data_colors = count($this->ndx_data_colors);
			$vars = compact("custom_color", "num_data_colors");
		} else {
			extract($vars);
		}

		// Select the colors.
		if ($custom_color) {
			$col_i = $this->DoCallback("data_color", $row, $idx, $extra); // Custom color index
			$data_color = $this->ndx_data_colors[$col_i % $num_data_colors];
		} else {
			$data_color = $this->ndx_data_colors[$idx];
		}
	}

	/*
	 * Get data color and error bar color to use for plotting.
	 *   $row, $idx : Index arguments for the current bar.
	 *   &$vars : Variable storage. Caller makes an empty array, and this function uses it.
	 *   &$data_color : Returned result - Color index for the data (bar fill)
	 *   &$error_color : Returned result - Color index for the error bars
	 *   $extra : Extra info flag passed through to data color callback.
	 */
	protected function GetDataErrorColors($row, $idx, &$vars, &$data_color, &$error_color, $extra = 0)
	{
		// Initialize or extract variables:
		if (empty($vars)) {
			$this->NeedErrorBarColors();   // This plot needs error bar colors.
			$custom_color = (bool)$this->GetCallback("data_color");
			$num_data_colors = count($this->ndx_data_colors);
			$num_error_colors = count($this->ndx_error_bar_colors);
			$vars = compact("custom_color", "num_data_colors", "num_error_colors");
		} else {
			extract($vars);
		}

		// Select the colors.
		if ($custom_color) {
			$col_i = $this->DoCallback("data_color", $row, $idx, $extra); // Custom color index
			$data_color = $this->ndx_data_colors[$col_i % $num_data_colors];
			$error_color = $this->ndx_error_bar_colors[$col_i % $num_error_colors];
		} else {
			$data_color = $this->ndx_data_colors[$idx];
			$error_color = $this->ndx_error_bar_colors[$idx];
		}
	}

	/*
	 * Get colors to use for a bar chart. There is a data color, and either a border color
	 * or a shading color (data dark color).
	 *   $row, $idx : Index arguments for the current bar.
	 *   &$vars : Variable storage. Caller makes an empty array, and this function uses it.
	 *   &$data_color : Returned result - Color index for the data (bar fill).
	 *   &$alt_color : Returned result - Color index for the shading or outline.
	 */
	protected function GetBarColors($row, $idx, &$vars, &$data_color, &$alt_color)
	{
		// Initialize or extract variables:
		if (empty($vars)) {
			if ($this->shading > 0)    // This plot needs dark colors if shading is on.
				$this->NeedDataDarkColors();
			$custom_color = (bool)$this->GetCallback("data_color");
			$num_data_colors = count($this->ndx_data_colors);
			$num_border_colors = count($this->ndx_data_border_colors);
			$vars = compact("custom_color", "num_data_colors", "num_border_colors");
		} else {
			extract($vars);
		}

		// Select the colors.
		if ($custom_color) {
			$col_i = $this->DoCallback("data_color", $row, $idx); // Custom color index
			$i_data = $col_i % $num_data_colors; // Index for data colors and dark colors
			$i_border = $col_i % $num_border_colors; // Index for data borders (if used)
		} else {
			$i_data = $i_border = $idx;
		}
		$data_color = $this->ndx_data_colors[$i_data];
		if ($this->shading > 0) {
			$alt_color = $this->ndx_data_dark_colors[$i_data];
		} else {
			$alt_color = $this->ndx_data_border_colors[$i_border];
		}
	}

	/*
	 * Draw a shape (dot, point). This is the bottom half of DrawDot, and is also
	 * used by legend drawing. Unlike DrawDot this takes device coordinates.
	 * The list of supported shapes can also be found in SetPointShapes().
	 *   $x, $y - Device coordinates of the center of the shape
	 *   $record - Index into point_shapes[] and point_sizes[]. This is taken modulo the array sizes.
	 *   $color - Shape color to use.
	 */
	protected function DrawShape($x, $y, $record, $color)
	{
		$index = $record % $this->point_counts;
		$point_size = $this->point_sizes[$index];
		$half_point = (int)($point_size / 2);

		$x1 = $x - $half_point;
		$x2 = $x + $half_point;
		$y1 = $y - $half_point;
		$y2 = $y + $half_point;

		switch ($this->point_shapes[$index]) {
		case "halfline":
			ImageLine($this->img, $x1, $y, $x, $y, $color);
			break;
		case "line":
			ImageLine($this->img, $x1, $y, $x2, $y, $color);
			break;
		case "plus":
			ImageLine($this->img, $x1, $y, $x2, $y, $color);
			ImageLine($this->img, $x, $y1, $x, $y2, $color);
			break;
		case "cross":
			ImageLine($this->img, $x1, $y1, $x2, $y2, $color);
			ImageLine($this->img, $x1, $y2, $x2, $y1, $color);
			break;
		case "circle":
			ImageArc($this->img, $x, $y, $point_size, $point_size, 0, 360, $color);
			break;
		case "dot":
			ImageFilledEllipse($this->img, $x, $y, $point_size, $point_size, $color);
			break;
		case "diamond":
			$arrpoints = [$x1, $y, $x, $y1, $x2, $y, $x, $y2];
			ImageFilledPolygon($this->img, $arrpoints, 4, $color);
			break;
		case "triangle":
			$arrpoints = [$x1, $y, $x2, $y, $x, $y2];
			ImageFilledPolygon($this->img, $arrpoints, 3, $color);
			break;
		case "trianglemid":
			$arrpoints = [$x1, $y1, $x2, $y1, $x, $y];
			ImageFilledPolygon($this->img, $arrpoints, 3, $color);
			break;
		case "yield":
			$arrpoints = [$x1, $y1, $x2, $y1, $x, $y2];
			ImageFilledPolygon($this->img, $arrpoints, 3, $color);
			break;
		case "delta":
			$arrpoints = [$x1, $y2, $x2, $y2, $x, $y1];
			ImageFilledPolygon($this->img, $arrpoints, 3, $color);
			break;
		case "star":
			ImageLine($this->img, $x1, $y, $x2, $y, $color);
			ImageLine($this->img, $x, $y1, $x, $y2, $color);
			ImageLine($this->img, $x1, $y1, $x2, $y2, $color);
			ImageLine($this->img, $x1, $y2, $x2, $y1, $color);
			break;
		case "hourglass":
			$arrpoints = [$x1, $y1, $x2, $y1, $x1, $y2, $x2, $y2];
			ImageFilledPolygon($this->img, $arrpoints, 4, $color);
			break;
		case "bowtie":
			$arrpoints = [$x1, $y1, $x1, $y2, $x2, $y1, $x2, $y2];
			ImageFilledPolygon($this->img, $arrpoints, 4, $color);
			break;
		case "target":
			ImageFilledRectangle($this->img, $x1, $y1, $x, $y, $color);
			ImageFilledRectangle($this->img, $x, $y, $x2, $y2, $color);
			ImageRectangle($this->img, $x1, $y1, $x2, $y2, $color);
			break;
		case "box":
			ImageRectangle($this->img, $x1, $y1, $x2, $y2, $color);
			break;
		case "home": /* As in: "home plate" (baseball), also looks sort of like a house. */
			$arrpoints = [$x1, $y2, $x2, $y2, $x2, $y, $x, $y1, $x1, $y];
			ImageFilledPolygon($this->img, $arrpoints, 5, $color);
			break;
		case "up":
			ImagePolygon($this->img, [$x, $y1, $x2, $y2, $x1, $y2], 3, $color);
			break;
		case "down":
			ImagePolygon($this->img, [$x, $y2, $x1, $y1, $x2, $y1], 3, $color);
			break;
		case "none": /* Special case, no point shape here */
			break;
		default: /* Also 'rect' */
			ImageFilledRectangle($this->img, $x1, $y1, $x2, $y2, $color);
			break;
		}
		return TRUE;
	}

	/*
	 * Draws a styled dot. Uses world coordinates.
	 * Note: DrawShape() does all the work.
	 */
	protected function DrawDot($x_world, $y_world, $record, $color)
	{
		return $this->DrawShape($this->xtr($x_world), $this->ytr($y_world), $record, $color);
	}

	/*
	 * Draw a bar (or segment of a bar), with optional shading or border.
	 * This is used by the bar and stackedbar plots, vertical and horizontal.
	 *   $x1, $y1 : One corner of the bar.
	 *   $x2, $y2 : Other corner of the bar.
	 *   $data_color : Color index to use for the bar fill.
	 *   $alt_color : Color index to use for the shading (if shading is on), else for the border.
	 *      Note the same color is NOT used for shading and border - just the same argument.
	 *      See GetBarColors() for where these arguments come from.
	 *   $shade_top : Shade the top? (Suppressed for downward stack segments except first.)
	 *   $shade_side : Shade the right side? (Suppressed for leftward stack segments except first.)
	 *      Only one of $shade_top or $shade_side can be FALSE. Both default to TRUE.
	 */
	protected function DrawBar($x1, $y1, $x2, $y2, $data_color, $alt_color,
			$shade_top = TRUE, $shade_side = TRUE, )
	{
		// Sort the points so x1,y1 is upper left and x2,y2 is lower right. This
		// is needed in order to get the shading right, and imagerectangle may require it.
		if ($x1 > $x2) {
			$t = $x1; $x1 = $x2; $x2 = $t;
		}
		if ($y1 > $y2) {
			$t = $y1; $y1 = $y2; $y2 = $t;
		}

		// Draw the bar
		ImageFilledRectangle($this->img, $x1, $y1, $x2, $y2, $data_color);

		// Draw a shade, or a border.
		if (($shade = $this->shading) > 0) {
			if ($shade_top && $shade_side) {
				$npts = 6;
				$pts = [$x1, $y1, $x1 + $shade, $y1 - $shade, $x2 + $shade, $y1 - $shade,
							 $x2 + $shade, $y2 - $shade, $x2, $y2, $x2, $y1, ];
			} else {
				$npts = 4;
				if ($shade_top) { // Suppress side shading
					$pts = [$x1, $y1, $x1 + $shade, $y1 - $shade, $x2 + $shade, $y1 - $shade, $x2, $y1];
				} else { // Suppress top shading
					$pts = [$x2, $y2, $x2, $y1, $x2 + $shade, $y1 - $shade, $x2 + $shade, $y2 - $shade];
				}
			}
			ImageFilledPolygon($this->img, $pts, $npts, $alt_color);
		} else {
			ImageRectangle($this->img, $x1, $y1, $x2,$y2, $alt_color);
		}
	}

	/*
	 *  Draw an Error Bar set. Used by DrawDotsError and DrawLinesError
	 */
	protected function DrawYErrorBar($x_world, $y_world, $error_height, $error_bar_type, $color)
	{
		$x1 = $this->xtr($x_world);
		$y1 = $this->ytr($y_world);
		$y2 = $this->ytr($y_world+$error_height) ;

		ImageSetThickness($this->img, $this->error_bar_line_width);
		ImageLine($this->img, $x1, $y1 , $x1, $y2, $color);
		if ($error_bar_type == "tee") {
			ImageLine($this->img, $x1-$this->error_bar_size, $y2, $x1+$this->error_bar_size, $y2, $color);
		}
		ImageSetThickness($this->img, 1);
		return TRUE;
	}

/////////////////////////////////////////////
////////////////////             PLOT DRAWING
/////////////////////////////////////////////

	/*
	 * Draws a pie chart. Data is 'text-data', 'data-data', or 'text-data-single'.
	 *
	 *  For text-data-single, the data array contains records with an ignored label,
	 *  and one Y value. Each record defines a sector of the pie, as a portion of
	 *  the sum of all Y values.
	 *
	 *  For text-data and data-data, the data array contains records with an ignored label,
	 *  an ignored X value (for data-data only), and N (N>=1) Y values per record.
	 *  The pie chart will be produced with N segments. The relative size of the first
	 *  sector of the pie is the sum of the first Y data value in each record, etc.
	 *
	 *  Note: With text-data-single, the data labels could be used, but are not currently.
	 *
	 *  If there are no valid data points > 0 at all, just draw nothing. It may seem more correct to
	 *  raise an error, but all of the other plot types handle it this way implicitly. DrawGraph
	 *  checks for an empty data array, but this is different: a non-empty data array with no Y values,
	 *  or all Y=0.
	 */
	protected function DrawPieChart()
	{
		if (!$this->CheckDataType("text-data, text-data-single, data-data"))
			return FALSE;

		// Allocate dark colors only if they will be used for shading.
		if ($this->shading > 0)
			$this->NeedDataDarkColors();

		$xpos = $this->plot_area[0] + $this->plot_area_width/2;
		$ypos = $this->plot_area[1] + $this->plot_area_height/2;
		$diameter = min($this->plot_area_width, $this->plot_area_height);
		$radius = $diameter/2;

		$num_slices = $this->data_columns;  // See CheckDataArray which calculates this for us.
		if ($num_slices < 1) return TRUE;   // Give up early if there is no data at all.
		$sumarr = array_fill(0, $num_slices, 0);

		if ($this->datatype_pie_single) {
			// text-data-single: One data column per row, one pie slice per row.
			for ($i = 0; $i < $num_slices; $i++) {
				// $legend[$i] = $this->data[$i][0];                // Note: Labels are not used yet
				if (is_numeric($this->data[$i][1]))
					$sumarr[$i] = abs($this->data[$i][1]);
			}
		} else {
			// text-data: Sum each column (skipping label), one pie slice per column.
			// data-data: Sum each column (skipping X value and label), one pie slice per column.
			$skip = ($this->datatype_implied) ? 1 : 2; // Leading values to skip in each row.
			for ($i = 0; $i < $this->num_data_rows; $i++) {
				for ($j = $skip; $j < $this->num_recs[$i]; $j++) {
					if (is_numeric($this->data[$i][$j]))
						$sumarr[$j-$skip] += abs($this->data[$i][$j]);
				}
			}
		}

		$total = array_sum($sumarr);

		if ($total == 0) {
			// There are either no valid data points, or all are 0.
			// See top comment about why not to make this an error.
			return TRUE;
		}

		if ($this->shading) {
			$diam2 = $diameter / 2;
		} else {
			$diam2 = $diameter;
		}
		$max_data_colors = count($this->ndx_data_colors);

		// Use the Y label format precision, with default value:
		if (isset($this->label_format["y"]["precision"]))
			$precision = $this->label_format["y"]["precision"];
		else
			$precision = 1;

		for ($h = $this->shading; $h >= 0; $h--) {
			$color_index = 0;
			$start_angle = 0;
			$end_angle = 0;
			for ($j = 0; $j < $num_slices; $j++) {
				$val = $sumarr[$j];

				// For shaded pies: the last one (at the top of the "stack") has a brighter color:
				if ($h == 0)
					$slicecol = $this->ndx_data_colors[$color_index];
				else
					$slicecol = $this->ndx_data_dark_colors[$color_index];

				$label_txt = $this->number_format(($val / $total * 100), $precision) . "%";
				$val = 360 * ($val / $total);

				// NOTE that imagefilledarc measures angles CLOCKWISE (go figure why),
				// so the pie chart would start clockwise from 3 o'clock, would it not be
				// for the reversal of start and end angles in imagefilledarc()
				// Also note ImageFilledArc only takes angles in integer degrees, and if the
				// the start and end angles match then you get a full circle not a zero-width
				// pie. This is bad. So skip any zero-size wedge. On the other hand, we cannot
				// let cumulative error from rounding to integer result in missing wedges. So
				// keep the running total as a float, and round the angles. It should not
				// be necessary to check that the last wedge ends at 360 degrees.
				$start_angle = $end_angle;
				$end_angle += $val;
				// This method of conversion to integer - truncate after reversing it - was
				// chosen to match the implicit method of PHPlot<=5.0.4 to get the same slices.
				$arc_start_angle = (int)(360 - $start_angle);
				$arc_end_angle = (int)(360 - $end_angle);

				if ($arc_start_angle > $arc_end_angle) {
					$mid_angle = deg2rad($end_angle - ($val / 2));

					// Draw the slice
					ImageFilledArc($this->img, $xpos, $ypos+$h, $diameter, $diam2,
								   $arc_end_angle, $arc_start_angle,
								   $slicecol, IMG_ARC_PIE, );

					// Draw the labels only once
					if ($h == 0) {
						// Draw the outline
						if (! $this->shading)
							ImageFilledArc($this->img, $xpos, $ypos+$h, $diameter, $diam2,
										   $arc_end_angle, $arc_start_angle, $this->ndx_grid_color,
										   IMG_ARC_PIE | IMG_ARC_EDGED |IMG_ARC_NOFILL, );

						// The '* 1.2' trick is to get labels out of the pie chart so there are more
						// chances they can be seen in small sectors.
						$label_x = $xpos + ($diameter * 1.2 * cos($mid_angle)) * $this->label_scale_position;
						$label_y = $ypos+$h - ($diam2 * 1.2 * sin($mid_angle)) * $this->label_scale_position;

						$this->DrawText($this->fonts["generic"], 0, $label_x, $label_y, $this->ndx_grid_color,
										$label_txt, "center", "center", );
					}
				}
				if (++$color_index >= $max_data_colors)
					$color_index = 0;
			}   // end for
		}   // end for
		return TRUE;
	}

	/*
	 * Draw the points and errors bars for an error plot of types points and linepoints
	 * Supports only data-data-error format, with each row of the form
	 *   array("title", x, y1, error1+, error1-, y2, error2+, error2-, ...)
	 * This is called from DrawDots, with data type already checked.
	 *   $paired is true for linepoints error plots, to make sure elements are
	 *       only drawn once.  If true, data labels are drawn by DrawLinesError, and error
	 *       bars are drawn by DrawDotsError. (This choice is for backwards compatibility.)
	 */
	protected function DrawDotsError($paired = FALSE)
	{
		// Adjust the point shapes and point sizes arrays:
		$this->CheckPointParams();

		$gcvars = []; // For GetDataErrorColors, which initializes and uses this.
		// Special flag for data color callback to indicate the 'points' part of 'linepoints':
		$alt_flag = $paired ? 1 : 0;

		for ($row = 0, $cnt = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                // Skip record #0 (title)

			$x_now = $this->data[$row][$record++];  // Read it, advance record index

			$x_now_pixels = $this->xtr($x_now);             // Absolute coordinates.

			// Draw X Data labels?
			if ($this->x_data_label_pos != "none" && !$paired)
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels, $row);

			// Now go for Y, E+, E-
			for ($idx = 0; $record < $this->num_recs[$row]; $idx++) {
				if (is_numeric($this->data[$row][$record])) {         // Allow for missing Y data

					// Select the colors:
					$this->GetDataErrorColors($row, $idx, $gcvars, $data_color, $error_color, $alt_flag);

					// Y:
					$y_now = $this->data[$row][$record++];
					$this->DrawDot($x_now, $y_now, $idx, $data_color);

					// Error +
					$val = $this->data[$row][$record++];
					$this->DrawYErrorBar($x_now, $y_now, $val, $this->error_bar_shape, $error_color);
					// Error -
					$val = $this->data[$row][$record++];
					$this->DrawYErrorBar($x_now, $y_now, -$val, $this->error_bar_shape, $error_color);
				} else {
					$record += 3;  // Skip over missing Y and its error values
				}
			}
		}
		return TRUE;
	}

	/*
	 * Draw a points plot, or the points for a linepoints plot
	 * Data format can be text-data (label, y1, y2, ...) or data-data (label, x, y1, y2, ...)
	 * Points plot with error bars (data-data-error format) is redirected to DrawDotsError.
	 *   $paired is true for linepoints plots, to make sure elements are only drawn once.
	 */
	protected function DrawDots($paired = FALSE)
	{
		if (!$this->CheckDataType("text-data, data-data, data-data-error"))
			return FALSE;
		if ($this->datatype_error_bars)
			return $this->DrawDotsError($paired); // Redirect for points+errorbars plot

		// Adjust the point shapes and point sizes arrays:
		$this->CheckPointParams();

		$gcvars = []; // For GetDataColor, which initializes and uses this.
		// Special flag for data color callback to indicate the 'points' part of 'linepoints':
		$alt_flag = $paired ? 1 : 0;

		// Data Value Labels? (Skip if doing the points from a linepoints plot)
		$do_dvls = !$paired && $this->CheckDataValueLabels($this->y_data_label_pos,
					  $dvl_x_off, $dvl_y_off, $dvl_h_align, $dvl_v_align, );

		for ($row = 0, $cnt = 0; $row < $this->num_data_rows; $row++) {
			$rec = 1;                    // Skip record #0 (data label)

			if ($this->datatype_implied)                    // Implied X values?
				$x_now = 0.5 + $cnt++;                      // Place text-data at X = 0.5, 1.5, 2.5, etc...
			else
				$x_now = $this->data[$row][$rec++];         // Read it, advance record index

			$x_now_pixels = $this->xtr($x_now);

			// Draw X Data labels?
			if (!$paired && $this->x_data_label_pos != "none")
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels, $row);

			// Proceed with Y values
			for ($idx = 0;$rec < $this->num_recs[$row]; $rec++, $idx++) {
				if (is_numeric($this->data[$row][$rec])) {              // Allow for missing Y data
					$y_now = (double)$this->data[$row][$rec];

					// Select the color:
					$this->GetDataColor($row, $idx, $gcvars, $data_color, $alt_flag);
					// Draw the marker:
					$this->DrawDot($x_now, $y_now, $idx, $data_color);

					// Draw data value labels?
					if ($do_dvls) {
						$this->DrawDataValueLabel("y", $x_now, $y_now, $y_now, $dvl_h_align, $dvl_v_align,
												  $dvl_x_off, $dvl_y_off, );
					}
				}
			}
		}
		return TRUE;
	}

	/*
	 * Draw a Thin Bar Line plot, also known as an Impulse plot.
	 * A clean, fast routine for when you just want charts like stock volume charts.
	 * Supports data-data and text-data formats for vertical plots,
	 * and data-data-yx and text-data-yx for horizontal plots.
	 * Note that although this plot type supports multiple data sets, it rarely makes
	 * sense to have more than 1, because the lines will overlay.
	 * This one function does both vertical and horizontal plots. "iv" is used for the
	 * independent variable (X for vertical plots, Y for horizontal) and "dv" is used
	 * for the dependent variable (Y for vertical plots, X for horizontal).
	 */
	protected function DrawThinBarLines()
	{
		if (!$this->CheckDataType("text-data, data-data, text-data-yx, data-data-yx"))
			return FALSE;

		$gcvars = []; // For GetDataColor, which initializes and uses this.

		for ($row = 0, $cnt = 0; $row < $this->num_data_rows; $row++) {
			$rec = 1;                    // Skip record #0 (data label)

			if ($this->datatype_implied)                    // Implied independent variable values?
				$iv_now = 0.5 + $cnt++;                     // Place text-data at 0.5, 1.5, 2.5, etc...
			else
				$iv_now = $this->data[$row][$rec++];        // Read it, advance record index

			if ($this->datatype_swapped_xy) {
				$y_now_pixels = $this->ytr($iv_now);
				// Draw Y Data labels?
				if ($this->y_data_label_pos != "none")
					$this->DrawYDataLabel($this->data[$row][0], $y_now_pixels);
			} else {
				$x_now_pixels = $this->xtr($iv_now);
				// Draw X Data labels?
				if ($this->x_data_label_pos != "none")
					$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels);
			}

			// Proceed with dependent values
			for ($idx = 0; $rec < $this->num_recs[$row]; $rec++, $idx++) {
				if (is_numeric($this->data[$row][$rec])) {              // Allow for missing data
					$dv = $this->data[$row][$rec];
					ImageSetThickness($this->img, $this->line_widths[$idx]);

					// Select the color:
					$this->GetDataColor($row, $idx, $gcvars, $data_color);

					if ($this->datatype_swapped_xy) {
						// Draw a line from user defined y axis position right (or left) to xtr($dv)
						ImageLine($this->img, $this->y_axis_x_pixels, $y_now_pixels,
											  $this->xtr($dv), $y_now_pixels, $data_color, );
					} else {
						// Draw a line from user defined x axis position up (or down) to ytr($dv)
						ImageLine($this->img, $x_now_pixels, $this->x_axis_y_pixels,
											  $x_now_pixels, $this->ytr($dv), $data_color, );
				   }
				}
			}
		}

		ImageSetThickness($this->img, 1);
		return TRUE;
	}

	/*
	 * Draw an 'area' or 'stacked area' plot.
	 * Both of these fill the area between lines, but in the stacked area graph the Y values
	 * are accumulated for each X, same as stacked bars. In the regular area graph, the areas
	 * are filled in order from the X axis up to each Y (so the Y values for each X need to be
	 * in decreasing order in this case).
	 * Data format can be text-data (label, y1, y2, ...) or data-data (label, x, y1, y2, ...)
	 * Notes:
	 *   All Y values must be >= 0. (If any Y<0 the absolute value is used.)
	 *   Missing data points are NOT handled. (They are counted as 0.)
	 *   All rows must have the same number of Y points, or an error image will be produced.
	 */
	protected function DrawArea($do_stacked = FALSE)
	{
		if (!$this->CheckDataType("text-data, data-data"))
			return FALSE;

		$n = $this->num_data_rows;  // Number of X values

		// These arrays store the device X and Y coordinates for all lines:
		$xd = [];
		$yd = [];

		// Make sure each row has the same number of values. Note records_per_group is max(num_recs).
		if ($this->records_per_group != min($this->num_recs)) {
			return $this->PrintError("DrawArea(): Data array must contain the same number"
					  . " of Y values for each X", );
		}

		// Calculate the Y value for each X, and store the device
		// coordinates into the xd and yd arrays.
		// For stacked area plots, the Y values accumulate.
		for ($row = 0; $row < $n; $row++) {
			$rec = 1;                                       // Skip record #0 (data label)

			if ($this->datatype_implied)                    // Implied X values?
				$x_now = 0.5 + $row;                        // Place text-data at X = 0.5, 1.5, 2.5, etc...
			else
				$x_now = $this->data[$row][$rec++];         // Read it, advance record index

			$x_now_pixels = $this->xtr($x_now);

			if ($this->x_data_label_pos != "none")          // Draw X Data labels?
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels);

			// Store the X value.
			// There is an artificial Y value at the axis. For 'area' it goes
			// at the end; for stackedarea it goes before the start.
			$xd[$row] = $x_now_pixels;
			$yd[$row] = [];
			if ($do_stacked)
				$yd[$row][] = $this->x_axis_y_pixels;

			// Store the Y values for this X.
			// All Y values are clipped to the x axis which should be zero but can be moved.
			$y = 0;
			while ($rec < $this->records_per_group) {
				if (is_numeric($this->data[$row][$rec])) {  // Treat missing values as 0.
					$y += abs($this->data[$row][$rec]);
				}
				$yd[$row][] = $this->ytr(max($this->x_axis_position, $y));
				if (!$do_stacked) $y = 0;
				$rec++;
			}

			if (!$do_stacked)
				$yd[$row][] = $this->x_axis_y_pixels;
		}

		// Now draw the filled polygons.
		// Note data_columns is the number of Y points (columns excluding label and X), and the
		// number of entries in the yd[] arrays is data_columns+1.
		$prev_row = 0;
		for ($row = 1; $row <= $this->data_columns; $row++) { // 1 extra for X axis artificial row
			$pts = [];
			// Previous data set forms top (for area) or bottom (for stackedarea):
			for ($j = 0; $j < $n; $j++) {
				$pts[] = $xd[$j];
				$pts[] = $yd[$j][$prev_row];
			}
			// Current data set forms bottom (for area) or top (for stackedarea):
			for ($j = $n- 1; $j >= 0; $j--) {
				$pts[] = $xd[$j];
				$pts[] = $yd[$j][$row];
			}
			// Draw it:
			ImageFilledPolygon($this->img, $pts, $n * 2, $this->ndx_data_colors[$prev_row]);

			$prev_row = $row;
		}
		return TRUE;
	}

	/*
	 * Draw a line plot, or the lines part of a linepoints plot
	 * Data format can be text-data (label, y1, y2, ...) or data-data (label, x, y1, y2, ...)
	 * Line plot with error bars (data-data-error format) is redirected to DrawLinesError.
	 *   $paired is true for linepoints plots, to make sure elements are only drawn once.
	 */
	protected function DrawLines($paired = FALSE)
	{
		if (!$this->CheckDataType("text-data, data-data, data-data-error"))
			return FALSE;
		if ($this->datatype_error_bars)
			return $this->DrawLinesError($paired); // Redirect for lines+errorbar plot

		// Flag array telling if the current point is valid, one element per plot line.
		// If start_lines[i] is true, then (lastx[i], lasty[i]) is the previous point.
		$start_lines = array_fill(0, $this->data_columns, FALSE);

		$gcvars = []; // For GetDataColor, which initializes and uses this.

		// Data Value Labels?
		$do_dvls = $this->CheckDataValueLabels($this->y_data_label_pos,
					  $dvl_x_off, $dvl_y_off, $dvl_h_align, $dvl_v_align, );

		for ($row = 0, $cnt = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			if ($this->datatype_implied)                    // Implied X values?
				$x_now = 0.5 + $cnt++;                      // Place text-data at X = 0.5, 1.5, 2.5, etc...
			else
				$x_now = $this->data[$row][$record++];      // Read it, advance record index

			$x_now_pixels = $this->xtr($x_now);             // Absolute coordinates

			if ($this->x_data_label_pos != "none")          // Draw X Data labels?
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels, $row);

			for ($idx = 0; $record < $this->num_recs[$row]; $record++, $idx++) {
				if (($line_style = $this->line_styles[$idx]) == "none")
					continue; //Allow suppressing entire line, useful with linepoints
				if (is_numeric($this->data[$row][$record])) {           //Allow for missing Y data
					$y_now = (double)$this->data[$row][$record];
					$y_now_pixels = $this->ytr($y_now);

					if ($start_lines[$idx]) {
						// Set line width, revert it to normal at the end
						ImageSetThickness($this->img, $this->line_widths[$idx]);

						// Select the color:
						$this->GetDataColor($row, $idx, $gcvars, $data_color);

						if ($line_style == "dashed") {
							$this->SetDashedStyle($data_color);
							$data_color = IMG_COLOR_STYLED;
						}
						ImageLine($this->img, $x_now_pixels, $y_now_pixels,
								  $lastx[$idx], $lasty[$idx], $data_color, );
					}

					// Draw data value labels?
					if ($do_dvls) {
						$this->DrawDataValueLabel("y", $x_now, $y_now, $y_now, $dvl_h_align, $dvl_v_align,
												  $dvl_x_off, $dvl_y_off, );
					}

					$lasty[$idx] = $y_now_pixels;
					$lastx[$idx] = $x_now_pixels;
					$start_lines[$idx] = TRUE;
				} elseif ($this->draw_broken_lines) {  // Y data missing, leave a gap.
					$start_lines[$idx] = FALSE;
				}
			}   // end for
		}   // end for

		ImageSetThickness($this->img, 1);       // Revert to original state for lines to be drawn later.
		return TRUE;
	}

	/*
	 * Draw lines with error bars for an error plot of types lines and linepoints
	 * Supports only data-data-error format, with each row of the form
	 *   array("title", x, y1, error1+, error1-, y2, error2+, error2-, ...)
	 * This is called from DrawLines, with data type already checked.
	 *   $paired is true for linepoints error plots, to make sure elements are
	 *       only drawn once.  If true, data labels are drawn by DrawLinesError, and error
	 *       bars are drawn by DrawDotsError. (This choice is for backwards compatibility.)
	 */
	protected function DrawLinesError($paired = FALSE)
	{
		$start_lines = array_fill(0, $this->data_columns, FALSE);

		$gcvars = []; // For GetDataErrorColors, which initializes and uses this.

		for ($row = 0, $cnt = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			$x_now = $this->data[$row][$record++];          // Read X value, advance record index

			$x_now_pixels = $this->xtr($x_now);             // Absolute coordinates.

			if ($this->x_data_label_pos != "none")          // Draw X Data labels?
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels, $row);

			// Now go for Y, E+, E-
			for ($idx = 0; $record < $this->num_recs[$row]; $idx++) {
				if (($line_style = $this->line_styles[$idx]) == "none")
					continue; //Allow suppressing entire line, useful with linepoints
				if (is_numeric($this->data[$row][$record])) {    // Allow for missing Y data

					// Select the colors:
					$this->GetDataErrorColors($row, $idx, $gcvars, $data_color, $error_color);

					// Y
					$y_now = $this->data[$row][$record++];
					$y_now_pixels = $this->ytr($y_now);

					if ($start_lines[$idx]) {
						ImageSetThickness($this->img, $this->line_widths[$idx]);

						if ($line_style == "dashed") {
							$this->SetDashedStyle($data_color);
							$data_color = IMG_COLOR_STYLED;
						}
						ImageLine($this->img, $x_now_pixels, $y_now_pixels,
								  $lastx[$idx], $lasty[$idx], $data_color, );
					}

					if ($paired) {
						$record += 2; // Skip error bars - done in the 'points' part of 'linepoints'.
					} else {
						// Error+
						$val = $this->data[$row][$record++];
						$this->DrawYErrorBar($x_now, $y_now, $val, $this->error_bar_shape, $error_color);

						// Error-
						$val = $this->data[$row][$record++];
						$this->DrawYErrorBar($x_now, $y_now, -$val, $this->error_bar_shape, $error_color);
					}

					// Update indexes:
					$start_lines[$idx] = TRUE;   // Tells us if we already drew the first column of points,
											 // thus having $lastx and $lasty ready for the next column.
					$lastx[$idx] = $x_now_pixels;
					$lasty[$idx] = $y_now_pixels;

				} else {
					$record += 3;  // Skip over missing Y and its error values
					if ($this->draw_broken_lines) {
						$start_lines[$idx] = FALSE;
					}
				}
			}   // end for
		}   // end for

		ImageSetThickness($this->img, 1);   // Revert to original state for lines to be drawn later.
		return TRUE;
	}

	/*
	 * Draw a Lines+Points plot (linepoints).
	 * This just uses DrawLines and DrawDots. They handle the error-bar case themselves.
	 */
	protected function DrawLinePoints()
	{
		// This check is redundant, as DrawLines and DrawDots do it, but left here as insurance.
		if (!$this->CheckDataType("text-data, data-data, data-data-error"))
			return FALSE;
		$this->DrawLines(TRUE);
		$this->DrawDots(TRUE);
		return TRUE;
	}

	/*
	 * Draw a Squared Line plot.
	 * Data format can be text-data (label, y1, y2, ...) or data-data (label, x, y1, y2, ...)
	 * This is based on DrawLines(), with one more line drawn for each point.
	 */
	protected function DrawSquared()
	{
		if (!$this->CheckDataType("text-data, data-data"))
			return FALSE;

		// Flag array telling if the current point is valid, one element per plot line.
		// If start_lines[i] is true, then (lastx[i], lasty[i]) is the previous point.
		$start_lines = array_fill(0, $this->data_columns, FALSE);

		$gcvars = []; // For GetDataColor, which initializes and uses this.

		// Data Value Labels?
		$do_dvls = $this->CheckDataValueLabels($this->y_data_label_pos,
					  $dvl_x_off, $dvl_y_off, $dvl_h_align, $dvl_v_align, );

		for ($row = 0, $cnt = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			if ($this->datatype_implied)                    // Implied X values?
				$x_now = 0.5 + $cnt++;                      // Place text-data at X = 0.5, 1.5, 2.5, etc...
			else
				$x_now = $this->data[$row][$record++];      // Read it, advance record index

			$x_now_pixels = $this->xtr($x_now);             // Absolute coordinates

			if ($this->x_data_label_pos != "none")          // Draw X Data labels?
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels); // notice there is no last param.

			// Draw Lines
			for ($idx = 0; $record < $this->num_recs[$row]; $record++, $idx++) {
				if (is_numeric($this->data[$row][$record])) {               // Allow for missing Y data
					$y_now = (double)$this->data[$row][$record];
					$y_now_pixels = $this->ytr($y_now);

					if ($start_lines[$idx]) {
						// Set line width, revert it to normal at the end
						ImageSetThickness($this->img, $this->line_widths[$idx]);

						// Select the color:
						$this->GetDataColor($row, $idx, $gcvars, $data_color);

						if ($this->line_styles[$idx] == "dashed") {
							$this->SetDashedStyle($data_color);
							$data_color = IMG_COLOR_STYLED;
						}
						ImageLine($this->img, $lastx[$idx], $lasty[$idx],
								  $x_now_pixels, $lasty[$idx], $data_color, );
						ImageLine($this->img, $x_now_pixels, $lasty[$idx],
								  $x_now_pixels, $y_now_pixels, $data_color, );
					}

					// Draw data value labels?
					if ($do_dvls) {
						$this->DrawDataValueLabel("y", $x_now, $y_now, $y_now, $dvl_h_align, $dvl_v_align,
												  $dvl_x_off, $dvl_y_off, );
					}

					$lastx[$idx] = $x_now_pixels;
					$lasty[$idx] = $y_now_pixels;
					$start_lines[$idx] = TRUE;
				} elseif ($this->draw_broken_lines) {  // Y data missing, leave a gap.
					$start_lines[$idx] = FALSE;
				}
			}
		}   // end while

		ImageSetThickness($this->img, 1);
		return TRUE;
	}

	/*
	 * Draw a Bar chart
	 * Supports text-data format, with each row in the form array(label, y1, y2, y3, ...)
	 * Horizontal bars (text-data-yx format) are sent to DrawHorizBars() instead.
	 */
	protected function DrawBars()
	{
		if (!$this->CheckDataType("text-data, text-data-yx"))
			return FALSE;
		if ($this->datatype_swapped_xy)
			return $this->DrawHorizBars();
		$this->CalcBarWidths(FALSE, TRUE); // Calculate bar widths for unstacked, vertical

		// This is the X offset from the bar group's label center point to the left side of the first bar
		// in the group. See also CalcBarWidths above.
		$x_first_bar = ($this->data_columns * $this->record_bar_width) / 2 - $this->bar_adjust_gap;

		$gcvars = []; // For GetBarColors, which initializes and uses this.

		for ($row = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			$x_now_pixels = $this->xtr(0.5 + $row);         // Place text-data at X = 0.5, 1.5, 2.5, etc...

			if ($this->x_data_label_pos != "none")          // Draw X Data labels?
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels);

			// Lower left X of first bar in the group:
			$x1 = $x_now_pixels - $x_first_bar;

			// Draw the bars in the group:
			for ($idx = 0; $record < $this->num_recs[$row]; $record++, $idx++) {
				if (is_numeric($this->data[$row][$record])) {       // Allow for missing Y data
					$y = $this->data[$row][$record];
					$x2 = $x1 + $this->actual_bar_width;

					if (($upgoing_bar = $y >= $this->x_axis_position)) {
						$y1 = $this->ytr($y);
						$y2 = $this->x_axis_y_pixels;
					} else {
						$y1 = $this->x_axis_y_pixels;
						$y2 = $this->ytr($y);
					}

					// Select the colors:
					$this->GetBarColors($row, $idx, $gcvars, $data_color, $alt_color);

					// Draw the bar, and the shade or border:
					$this->DrawBar($x1, $y1, $x2, $y2, $data_color, $alt_color);

					// Draw optional data labels above the bars (or below, for negative values).
					if ( $this->y_data_label_pos == "plotin") {
						if ($upgoing_bar) {
						  $v_align = "bottom";
						  $y_offset = -5 - $this->shading;
						} else {
						  $v_align = "top";
						  $y_offset = 2;
						}
						$this->DrawDataValueLabel("y", $row+0.5, $y, $y, "center", $v_align,
								($idx + 0.5) * $this->record_bar_width - $x_first_bar, $y_offset, );
					}
				}
				// Step to next bar in group:
				$x1 += $this->record_bar_width;
			}   // end for
		}   // end for
		return TRUE;
	}

	/*
	 * Draw a Horizontal Bar chart
	 * Supports only text-data-yx format, with each row in the form array(label, x1, x2, x3, ...)
	 * Note that the data values are X not Y, and the bars are drawn horizontally.
	 * This is called from DrawBars, which has already checked the data type.
	 */
	protected function DrawHorizBars()
	{
		$this->CalcBarWidths(FALSE, FALSE); // Calculate bar widths for unstacked, vertical

		// This is the Y offset from the bar group's label center point to the bottom of the first bar
		// in the group. See also CalcBarWidths above.
		$y_first_bar = ($this->data_columns * $this->record_bar_width) / 2 - $this->bar_adjust_gap;

		$gcvars = []; // For GetBarColors, which initializes and uses this.

		for ($row = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			$y_now_pixels = $this->ytr(0.5 + $row);         // Place bars at Y=0.5, 1.5, 2.5, etc...

			if ($this->y_data_label_pos != "none")          // Draw Y Data Labels?
				$this->DrawYDataLabel($this->data[$row][0], $y_now_pixels);

			// Lower left Y of first bar in the group:
			$y1 = $y_now_pixels + $y_first_bar;

			// Draw the bars in the group:
			for ($idx = 0; $record < $this->num_recs[$row]; $record++, $idx++) {
				if (is_numeric($this->data[$row][$record])) {       // Allow for missing X data
					$x = $this->data[$row][$record];
					$y2 = $y1 - $this->actual_bar_width;

					if (($rightwards_bar = $x >= $this->y_axis_position)) {
						$x1 = $this->xtr($x);
						$x2 = $this->y_axis_x_pixels;
					} else {
						$x1 = $this->y_axis_x_pixels;
						$x2 = $this->xtr($x);
					}

					// Select the colors:
					$this->GetBarColors($row, $idx, $gcvars, $data_color, $alt_color);

					// Draw the bar, and the shade or border:
					$this->DrawBar($x1, $y1, $x2, $y2, $data_color, $alt_color);

					// Draw optional data labels to the right of the bars (or left, if the bar
					// goes left of the Y axis line).
					if ($this->x_data_label_pos == "plotin") {
						if ($rightwards_bar) {
						  $h_align = "left";
						  $x_offset = 5 + $this->shading;
						} else {
						  $h_align = "right";
						  $x_offset = -2;
						}
						$this->DrawDataValueLabel("x", $x, $row+0.5, $x, $h_align, "center",
								$x_offset, $y_first_bar - ($idx + 0.5) * $this->record_bar_width, );
					}

				}
				// Step to next bar in group:
				$y1 -= $this->record_bar_width;
			}   // end for
		}   // end for

		return TRUE;
	}

	/*
	 * Draw a Stacked Bar chart
	 * Supports text-data format, with each row in the form array(label, y1, y2, y3, ...)
	 * Horizontal stacked bars (text-data-yx format) are sent to DrawHorizStackedBars() instead.
	 * Original stacked bars idea by Laurent Kruk < lolok at users.sourceforge.net >
	 */
	protected function DrawStackedBars()
	{
		if (!$this->CheckDataType("text-data, text-data-yx"))
			return FALSE;
		if ($this->datatype_swapped_xy)
			return $this->DrawHorizStackedBars();
		$this->CalcBarWidths(TRUE, TRUE); // Calculate bar widths for stacked, vertical

		// This is the X offset from the bar's label center point to the left side of the bar.
		$x_first_bar = $this->record_bar_width / 2 - $this->bar_adjust_gap;

		$gcvars = []; // For GetBarColors, which initializes and uses this.

		// Determine if any data labels are on:
		$data_labels_within = ($this->y_data_label_pos == "plotstack");
		$data_labels_end = $data_labels_within || ($this->y_data_label_pos == "plotin");
		$data_label_y_offset = -5 - $this->shading; // For upward labels only.

		for ($row = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			$x_now_pixels = $this->xtr(0.5 + $row);         // Place text-data at X = 0.5, 1.5, 2.5, etc...

			if ($this->x_data_label_pos != "none")          // Draw X Data labels?
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels);

			// Determine bar direction based on 1st non-zero value. Note the bar direction is
			// based on zero, not the axis value.
			$n_recs = $this->num_recs[$row];
			$upward = TRUE; // Initialize this for the case of all segments = 0
			for ($i = $record; $i < $n_recs; $i++) {
				if (is_numeric($this_y = $this->data[$row][$i]) && $this_y != 0) {
					$upward = ($this_y > 0);
					break;
				}
			}

			$x1 = $x_now_pixels - $x_first_bar;  // Left X of bars in this stack
			$x2 = $x1 + $this->actual_bar_width; // Right X of bars in this stack
			$wy1 = 0;                            // World coordinates Y1, current sum of values
			$wy2 = $this->x_axis_position;       // World coordinates Y2, last drawn value

			// Draw bar segments and labels in this stack.
			$first = TRUE;
			for ($idx = 0; $record < $n_recs; $record++, $idx++) {

				// Skip missing Y values. Process Y=0 values due to special case of moved axis.
				if (is_numeric($this_y = $this->data[$row][$record])) {

					$wy1 += $this_y;    // Keep the running total for this bar stack

					// Draw nothing if this segment would not increase the bar height.
					// Upward bars: draw if wy1>wy2.  Downward bars: Draw if wy1<wy2.
					if (($wy1 < $wy2) XOR $upward) {

						$y1 = $this->ytr($wy1); // Convert to device coordinates. $y1 is outermost value.
						$y2 = $this->ytr($wy2); // $y2 is innermost (closest to axis).

						// Select the colors:
						$this->GetBarColors($row, $idx, $gcvars, $data_color, $alt_color);

						// Draw the bar, and the shade or border:
						$this->DrawBar($x1, $y1, $x2, $y2, $data_color, $alt_color,
							// Only shade the top for upward bars, or the first segment of downward bars:
							$upward || $first, TRUE, );

						// Draw optional data label for this bar segment just inside the end.
						// Text value is the current Y, but position is the cumulative Y.
						// The label is only drawn if it fits in the segment height |y2-y1|.
						if ($data_labels_within) {
							$this->DrawDataValueLabel("y", $row+0.5, $wy1, $this_y,
													  "center", $upward ? "top" : "bottom",
													  0, $upward ? 3 : -3, NULL, abs($y1 - $y2), );
						}
						// Mark the new end of the bar, conditional on segment height > 0.
						$wy2 = $wy1;
						$first = FALSE;
					}
				}
			}   // end for

			// Draw optional data label above the bar with the total value.
			// Value is wy1 (total value), but position is wy2 (end of the bar stack).
			// These differ only with wrong-direction segments, or a stack completely clipped by the axis.
			if ($data_labels_end) {
				$this->DrawDataValueLabel("y", $row+0.5, $wy2, $wy1, "center", $upward ? "bottom" : "top",
										  0, $upward ? $data_label_y_offset : 5, );
			}
		}   // end for
		return TRUE;
	}

	/*
	 * Draw a Horizontal Stacked Bar chart
	 * Supports only text-data-yx format, with each row in the form array(label, x1, x2, x3, ...)
	 * Note that the data values are X not Y, and the bars are drawn horizontally.
	 * This is called from DrawStackedBars, which has already checked the data type.
	 */
	protected function DrawHorizStackedBars()
	{
		$this->CalcBarWidths(TRUE, FALSE); // Calculate bar widths for stacked, horizontal

		// This is the Y offset from the bar's label center point to the bottom of the bar
		$y_first_bar = $this->record_bar_width / 2 - $this->bar_adjust_gap;

		$gcvars = []; // For GetBarColors, which initializes and uses this.

		// Determine if any data labels are on:
		$data_labels_within = ($this->x_data_label_pos == "plotstack");
		$data_labels_end = $data_labels_within || ($this->x_data_label_pos == "plotin");
		$data_label_x_offset = 5 + $this->shading; // For rightward labels only

		for ($row = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			$y_now_pixels = $this->ytr(0.5 + $row);         // Place bars at Y=0.5, 1.5, 2.5, etc...

			if ($this->y_data_label_pos != "none")          // Draw Y Data labels?
				$this->DrawYDataLabel($this->data[$row][0], $y_now_pixels);

			// Determine bar direction based on 1st non-zero value. Note the bar direction is
			// based on zero, not the axis value.
			$n_recs = $this->num_recs[$row];
			$rightward = TRUE; // Initialize this for the case of all segments = 0
			for ($i = $record; $i < $n_recs; $i++) {
				if (is_numeric($this_x = $this->data[$row][$i]) && $this_x != 0) {
					$rightward = ($this_x > 0);
					break;
				}
			}

			// Lower left and upper left Y of the bars in this stack:
			$y1 = $y_now_pixels + $y_first_bar;  // Lower Y of bars in this stack
			$y2 = $y1 - $this->actual_bar_width; // Upper Y of bars in this stack
			$wx1 = 0;                            // World coordinates X1, current sum of values
			$wx2 = $this->y_axis_position;       // World coordinates X2, last drawn value

			// Draw bar segments and labels in this stack.
			$first = TRUE;
			for ($idx = 0; $record < $this->num_recs[$row]; $record++, $idx++) {

				// Skip missing X values. Process Y=0 values due to special case of moved axis.
				if (is_numeric($this_x = $this->data[$row][$record])) {

					$wx1 += $this_x;  // Keep the running total for this bar stack

					// Draw nothing if this segment would not increase the bar length.
					// Rightward bars: draw if wx1>wx2. Leftward bars: Draw if wx1<wx2.
					if (($wx1 < $wx2) XOR $rightward) {

						$x1 = $this->xtr($wx1); // Convert to device coordinates. $x1 is outermost value.
						$x2 = $this->xtr($wx2); // $x2 is innermost (closest to axis).

						// Select the colors:
						$this->GetBarColors($row, $idx, $gcvars, $data_color, $alt_color);

						// Draw the bar, and the shade or border:
						$this->DrawBar($x1, $y1, $x2, $y2, $data_color, $alt_color,
							// Only shade the side for rightward bars, or the first segment of leftward bars:
							TRUE, $rightward || $first, );
						// Draw optional data label for this bar segment just inside the end.
						// Text value is the current X, but position is the cumulative X.
						// The label is only drawn if it fits in the segment width |x2-x1|.
						if ($data_labels_within) {
							$this->DrawDataValueLabel("x", $wx1, $row+0.5, $this_x,
													  $rightward ? "right" : "left", "center",
													  $rightward ? -3 : 3, 0, abs($x1 - $x2), NULL, );
						}
						// Mark the new end of the bar, conditional on segment width > 0.
						$wx2 = $wx1;
						$first = FALSE;
					}
				}
			}   // end for

			// Draw optional data label right of the bar with the total value.
			// Value is wx1 (total value), but position is wx2 (end of the bar stack).
			// These differ only with wrong-direction segments, or a stack completely clipped by the axis.
			if ($data_labels_end) {
				$this->DrawDataValueLabel("x", $wx2, $row+0.5, $wx1, $rightward ? "left" : "right", "center",
										  $rightward ? $data_label_x_offset : -5, 0, );
			}
		}   // end for
		return TRUE;
	}

	/*
	 * Draw a financial "Open/High/Low/Close" (OHLC) plot, including candlestick plots.
	 * Data format can be text-data (label, Yo, Yh, Yl, Yc) or data-data (label, X, Yo, Yh, Yl, Yc).
	 * Yo="Opening price", Yc="Closing price", Yl="Low price", Yh="High price".
	 * Each row must have exactly 4 Y values. No multiple data sets, no missing values.
	 * There are 3 subtypes, selected by $draw_candles and $always_fill.
	 *   $draw_candles  $always_fill  Description:
	 *    FALSE          N/A          A basic OHLC chart with a vertical line for price range, horizontal
	 *                                tick marks on left for opening price and right for closing price.
	 *    TRUE           FALSE        A candlestick plot with filled body indicating close down, outline
	 *                                for closing up, and vertical wicks for low and high prices.
	 *    TRUE           TRUE         A candlestick plot where the candle bodies are always filled.
	 * These map to 3 plot types per the $plots[] array.
	 *
	 * Data color usage:                        If closes down:   If closes up or unchanged:
	 *    Candlestick body, ohlc range line:      color 0           color 1
	 *    Candlestick wicks, ohlc tick marks:     color 2           color 3
	 * There are three member variables that control the width (candlestick body or tick marks):
	 *     ohlc_max_width, ohlc_min_width, ohlc_frac_width
	 * (There is no API to change them at this time.)
	 */
	protected function DrawOHLC($draw_candles, $always_fill = FALSE)
	{
		if (!$this->CheckDataType("text-data, data-data"))
			return FALSE;

		// Assign name of GD function to draw candlestick bodies for stocks that close up.
		$draw_body_close_up = $always_fill ? "imagefilledrectangle" : "imagerectangle";

		// These 3 variables control the calculation of the half-width of the candle body, or length of
		// the tick marks. This is scaled based on the plot density, but within tight limits.
		$min_width = $this->ohlc_min_width ?? 2;
		$max_width = $this->ohlc_max_width ?? 8;
		$width_factor = $this->ohlc_frac_width ?? 0.3;
		$dw = max($min_width, min($max_width,
					 (int)($width_factor * $this->plot_area_width / $this->num_data_rows), ));

		// Get line widths to use: index 0 for body/stroke, 1 for wick/tick.
		list($body_thickness, $wick_thickness) = $this->line_widths;

		$gcvars = []; // For GetDataColor, which initializes and uses this.

		for ($row = 0, $cnt = 0; $row < $this->num_data_rows; $row++) {
			$record = 1;                                    // Skip record #0 (data label)

			if ($this->datatype_implied)                    // Implied X values?
				$x_now = 0.5 + $cnt++;                      // Place text-data at X = 0.5, 1.5, 2.5, etc...
			else
				$x_now = $this->data[$row][$record++];      // Read it, advance record index

			$x_now_pixels = $this->xtr($x_now);             // Convert X to device coordinates
			$x_left = $x_now_pixels - $dw;
			$x_right = $x_now_pixels + $dw;

			if ($this->x_data_label_pos != "none")          // Draw X Data labels?
				$this->DrawXDataLabel($this->data[$row][0], $x_now_pixels, $row);

			// Require and use 4 numeric values in each row.
			if ($this->num_recs[$row] - $record != 4
					|| !is_numeric($yo = $this->data[$row][$record++])
					|| !is_numeric($yh = $this->data[$row][$record++])
					|| !is_numeric($yl = $this->data[$row][$record++])
					|| !is_numeric($yc = $this->data[$row][$record++])) {
				return $this->PrintError("DrawOHLC: row $row must have 4 values.");
			}

			// Set device coordinates for each value and direction flag:
			$yh_pixels = $this->ytr($yh);
			$yl_pixels = $this->ytr($yl);
			$yc_pixels = $this->ytr($yc);
			$yo_pixels = $this->ytr($yo);
			$closed_up = $yc >= $yo;

			// Get data colors and line thicknesses:
			if ($closed_up) {
				$this->GetDataColor($row, 1, $gcvars, $body_color); // Color 1 for body, closing up
				$this->GetDataColor($row, 3, $gcvars, $ext_color);  // Color 3 for wicks/ticks
			} else {
				$this->GetDataColor($row, 0, $gcvars, $body_color); // Color 0 for body, closing down
				$this->GetDataColor($row, 2, $gcvars, $ext_color);  // Color 2 for wicks/ticks
			}
			imagesetthickness($this->img, $body_thickness);

			if ($draw_candles) {
				// Note: Unlike ImageFilledRectangle, ImageRectangle 'requires' its arguments in
				// order with upper left corner first.
				if ($closed_up) {
					$yb1_pixels = $yc_pixels; // Upper body Y
					$yb2_pixels = $yo_pixels; // Lower body Y
					$draw_body = $draw_body_close_up;
					// Avoid a PHP/GD bug resulting in "T"-shaped ends to zero height unfilled rectangle:
					if ($yb1_pixels == $yb2_pixels)
						$draw_body = "imagefilledrectangle";
				} else {
					$yb1_pixels = $yo_pixels;
					$yb2_pixels = $yc_pixels;
					$draw_body = "imagefilledrectangle";
				}

				// Draw candle body
				$draw_body($this->img, $x_left, $yb1_pixels, $x_right, $yb2_pixels, $body_color);

				// Draw upper and lower wicks, if they have height. (In device coords, that's dY<0)
				imagesetthickness($this->img, $wick_thickness);
				if ($yh_pixels < $yb1_pixels) {
					imageline($this->img, $x_now_pixels, $yb1_pixels, $x_now_pixels, $yh_pixels, $ext_color);
				}
				if ($yl_pixels > $yb2_pixels) {
					imageline($this->img, $x_now_pixels, $yb2_pixels, $x_now_pixels, $yl_pixels, $ext_color);
				}
			} else {
				// Basic OHLC
				imageline($this->img, $x_now_pixels, $yl_pixels, $x_now_pixels, $yh_pixels, $body_color);
				imagesetthickness($this->img, $wick_thickness);
				imageline($this->img, $x_left, $yo_pixels, $x_now_pixels, $yo_pixels, $ext_color);
				imageline($this->img, $x_right, $yc_pixels, $x_now_pixels, $yc_pixels, $ext_color);
			}
			imagesetthickness($this->img, 1);
		}
		return TRUE;
	}

	/*
	 * Draw the graph.
	 * This is the function that performs the actual drawing, after all
	 * the parameters and data are set up.
	 * It also outputs the finished image, unless told not to.
	 * Note: It is possible for this to be called multiple times.
	 */
	function DrawGraph()
	{
		// Test for missing image, missing data, empty data:
		if (!$this->CheckDataArray())
			return FALSE; // Error message already reported.

		// Set defaults then import plot type configuration:
		$draw_axes = TRUE;
		$draw_arg = []; // Default is: no arguments to the drawing function
		extract(PHPlot::$plots[$this->plot_type]);

		// Allocate colors for the plot:
		$this->SetColorIndexes();

		// Get maxima and minima for scaling:
		if (!$this->FindDataLimits())
			return FALSE;

		// Set plot area world values (plot_max_x, etc.):
		if (!$this->CalcPlotAreaWorld())
			return FALSE;

		// Calculate X and Y axis positions in World Coordinates:
		$this->CalcAxisPositions();

		// Process label-related parameters:
		$this->CheckLabels();

		// Apply grid defaults:
		$this->CalcGridSettings();

		// Calculate the plot margins, if needed.
		// For pie charts, set the $maximize argument to maximize space usage.
		$this->CalcMargins(!$draw_axes);

		// Calculate the actual plot area in device coordinates:
		$this->CalcPlotAreaPixels();

		// Calculate the mapping between world and device coordinates:
		$this->CalcTranslation();

		// Pad color and style arrays to fit records per group:
		$this->PadArrays();
		$this->DoCallback("draw_setup");

		$this->DrawBackground();
		$this->DrawImageBorder();
		$this->DoCallback("draw_image_background");

		$this->DrawPlotAreaBackground();
		$this->DoCallback("draw_plotarea_background", $this->plot_area);

		$this->DrawTitle();
		if ($draw_axes) {  // If no axes (pie chart), no axis titles either
			$this->DrawXTitle();
			$this->DrawYTitle();
		}
		$this->DoCallback("draw_titles");

		if ($draw_axes && ! $this->grid_at_foreground) {   // Usually one wants grids to go back, but...
			$this->DrawYAxis();     // Y axis must be drawn before X axis (see DrawYAxis())
			$this->DrawXAxis();
			$this->DoCallback("draw_axes");
		}

		// Call the plot-type drawing method:
		call_user_func_array([$this, $draw_method], $draw_arg);
		$this->DoCallback("draw_graph", $this->plot_area);

		if ($draw_axes && $this->grid_at_foreground) {   // Usually one wants grids to go back, but...
			$this->DrawYAxis();     // Y axis must be drawn before X axis (see DrawYAxis())
			$this->DrawXAxis();
			$this->DoCallback("draw_axes");
		}

		if ($draw_axes) {
			$this->DrawPlotBorder();
			$this->DoCallback("draw_border");
		}

		if ($this->legend) {
			$this->DrawLegend();
			$this->DoCallback("draw_legend");
		}
		$this->DoCallback("draw_all", $this->plot_area);

		if ($this->print_image && !$this->PrintImage())
			return FALSE;

		return TRUE;
	}

/////////////////////////////////////////////
//////////////////         DEPRECATED METHODS
/////////////////////////////////////////////

	/*
	 * Note on deprecated methods - as these pre-date the PHPlot Reference
	 * Manual, and there is minimal documentation about them, I have neither
	 * removed them nor changed them. They are not tested or documented, and
	 * should not be used.
	 */

	/*
	 * Deprecated, use SetYTickPos()
	 */
	function SetDrawVertTicks($which_dvt)
	{
		if ($which_dvt != 1)
			$this->SetYTickPos("none");
		return TRUE;
	}

	/*
	 * Deprecated, use SetXTickPos()
	 */
	function SetDrawHorizTicks($which_dht)
	{
		if ($which_dht != 1)
		   $this->SetXTickPos("none");
		return TRUE;
	}

	/*
	 * Deprecated - use SetNumXTicks()
	 */
	function SetNumHorizTicks($n)
	{
		return $this->SetNumXTicks($n);
	}

	/*
	 * Deprecated - use SetNumYTicks()
	 */
	function SetNumVertTicks($n)
	{
		return $this->SetNumYTicks($n);
	}

	/*
	 * Deprecated - use SetXTickIncrement()
	 */
	function SetHorizTickIncrement($inc)
	{
		return $this->SetXTickIncrement($inc);
	}

	/*
	 * Deprecated - use SetYTickIncrement()
	 */
	function SetVertTickIncrement($inc)
	{
		return $this->SetYTickIncrement($inc);
	}

	/*
	 * Deprecated - use SetYTickPos()
	 */
	function SetVertTickPosition($which_tp)
	{
		return $this->SetYTickPos($which_tp);
	}

	/*
	 * Deprecated - use SetXTickPos()
	 */
	function SetHorizTickPosition($which_tp)
	{
		return $this->SetXTickPos($which_tp);
	}

	/*
	 * Deprecated - use SetFont()
	 */
	function SetTitleFontSize($which_size)
	{
		return $this->SetFont("title", $which_size);
	}

	/*
	 * Deprecated - use SetFont()
	 */
	function SetAxisFontSize($which_size)
	{
		$this->SetFont("x_label", $which_size);
		$this->SetFont("y_label", $which_size);
	}

	/*
	 * Deprecated - use SetFont()
	 */
	function SetSmallFontSize($which_size)
	{
		return $this->SetFont("generic", $which_size);
	}

	/*
	 * Deprecated - use SetFont()
	 */
	function SetXLabelFontSize($which_size)
	{
		return $this->SetFont("x_title", $which_size);
	}

	/*
	 * Deprecated - use SetFont()
	 */
	function SetYLabelFontSize($which_size)
	{
		return $this->SetFont("y_title", $which_size);
	}

	/*
	 * Deprecated - use SetXTitle()
	 */
	function SetXLabel($which_xlab)
	{
		return $this->SetXTitle($which_xlab);
	}

	/*
	 * Deprecated - use SetYTitle()
	 */
	function SetYLabel($which_ylab)
	{
		return $this->SetYTitle($which_ylab);
	}

	/*
	 * Deprecated - use SetXTickLength() and SetYTickLength() instead.
	 */
	function SetTickLength($which_tl)
	{
		$this->SetXTickLength($which_tl);
		$this->SetYTickLength($which_tl);
		return TRUE;
	}

	/*
	 * Deprecated - use SetYLabelType()
	 */
	function SetYGridLabelType($which_yglt)
	{
		return $this->SetYLabelType($which_yglt);
	}

	/*
	 * Deprecated - use SetXLabelType()
	 */
	function SetXGridLabelType($which_xglt)
	{
		return $this->SetXLabelType($which_xglt);
	}
	/*
	 * Deprecated - use SetYTickLabelPos()
	 */
	function SetYGridLabelPos($which_yglp)
	{
		return $this->SetYTickLabelPos($which_yglp);
	}
	/*
	 * Deprecated - use SetXTickLabelPos()
	 */
	function SetXGridLabelPos($which_xglp)
	{
		return $this->SetXTickLabelPos($which_xglp);
	}

	/*
	 * Deprecated - use SetXtitle()
	 */
	function SetXTitlePos($xpos)
	{
		$this->x_title_pos = $xpos;
		return TRUE;
	}

	/*
	 * Deprecated - use SetYTitle()
	 */
	function SetYTitlePos($xpos)
	{
		$this->y_title_pos = $xpos;
		return TRUE;
	}

	/*
	 * Deprecated - use SetXDataLabelPos()
	 */
	function SetDrawXDataLabels($which_dxdl)
	{
		if ($which_dxdl == "1" )
			$this->SetXDataLabelPos("plotdown");
		else
			$this->SetXDataLabelPos("none");
	}

	/*
	 * Deprecated - use SetPlotAreaPixels()
	 */
	function SetNewPlotAreaPixels($x1, $y1, $x2, $y2)
	{
		return $this->SetPlotAreaPixels($x1, $y1, $x2, $y2);
	}

	/*
	 * Deprecated - use SetLineWidths().
	 */
	function SetLineWidth($which_lw)
	{

		$this->SetLineWidths($which_lw);

		if (!$this->error_bar_line_width) {
			$this->SetErrorBarLineWidth($which_lw);
		}
		return TRUE;
	}

	/*
	 * Deprecated - use SetPointShapes().
	 */
	function SetPointShape($which_pt)
	{
		$this->SetPointShapes($which_pt);
		return TRUE;
	}

	/*
	 * Deprecated - use SetPointSizes().
	 */
	function SetPointSize($which_ps)
	{
		$this->SetPointSizes($which_ps);
		return TRUE;
	}
}

/*
 * The PHPlot_truecolor class extends PHPlot to use GD truecolor images.
 */

class PHPlot_truecolor extends PHPlot
{
	/*
	 * PHPlot Truecolor variation constructor: Create a PHPlot_truecolor object and initialize it.
	 * Note this does NOT call the parent (PHPlot) constructor. It duplicates the code here.
	 * Everything is the same as the PHPlot constructor except for imagecreatetruecolor.
	 *
	 * Parameters are the same as PHPlot:
	 *   $which_width : Image width in pixels.
	 *   $which_height : Image height in pixels.
	 *   $which_output_file : Filename for output.
	 *   $which_input_file : Path to a file to be used as background.
	 */
	function __construct($which_width=600, $which_height=400, $which_output_file=NULL, $which_input_file=NULL)
	{
		$this->SetRGBArray($this->color_array);

		if ($which_output_file)
			$this->SetOutputFile($which_output_file);

		if ($which_input_file) {
			$this->SetInputFile($which_input_file);
		} else {
			$this->image_width = $which_width;
			$this->image_height = $which_height;

			$this->img = imagecreatetruecolor($this->image_width, $this->image_height);
			if (! $this->img)
				return $this->PrintError("PHPlot_truecolor(): Could not create image resource.");
		}

		$this->SetDefaultStyles();
		$this->SetDefaultFonts();
	}
}
