10.2. Member Variable Notes

This section contains details on some of the PHPlot class member variables listed in the previous section. Remember that all PHPlot class member variables are meant for internal use only.

10.2.1. fonts[]

The fonts[] array contains information about the fonts to use for text on the plot. The array keys are the element names (such as title or legend) as used in SetFont, SetFontGD, or SetFontTTF. The array values are arrays which contain information about the font to use for that element. The keys and values of the second-level arrays are:

KeyValue for TTFValue for GD Font
ttfTrue for a TrueType fontFalse for a GD font
fontPathname of the font fileFont number: 1 through 5
sizeFont point sizeNot used
heightHeight in pixels of an upper-case "E" in the fontFont height in pixels
widthWidth in pixels of an upper-case "E" in the font.Font width in pixels
spacingFont's built-in inter-line spacingNot used
line_spacingUser-requested inter-line spacing factor.Same as for TTF

For TrueType fonts, the height and width can vary by character. The fonts array stores a height and width value for the font, but these are only used for sizing non-text plot elements (such as the legend color boxes). When PHPlot needs to know the drawn size of a string that will use TTF, it calculates the exact size of that specific string when drawn with the designated font.

GD fonts have fixed character width and height, so the values stored in the fonts array can be used to calculate text string sizes.

The spacing key stores the TrueType font's built-in inter-line spacing. Although TrueType fonts have this information internally, PHP cannot access it, so PHPlot calculates it by taking the height of the string "E\nE" and subtracting twice the height of the letter E.

The line_spacing key stores the user-specified line spacing adjustment for a text element, if any, from SetFont or one of the two related functions. It will be NULL if the spacing was not set for this element, meaning use the default line spacing. See SetLineSpacing for more information on how this is used.

Here is an example of part of a fonts array, for the title element:

$plot->fonts['title'] = array(
    'ttf' => FALSE,          // This element uses a GD font
    'font' => 2,             // Use GD font 2
    'height' => 13,          // Provided by GD
    'width' => 6,            // Provided by GD
    'line_spacing' => NULL,  // Use default line spacing
)

10.2.2. label_format[]

The label_format[] array contains information about how text labels should be formatted. This array has 5 entries, with keys 'x', 'y', 'xd', 'yd', and 'p'. The 'x' and 'y' entries are for tick labels, and the 'xd' and 'yd' entries are for data labels. (Note that PHPlot defaults data label formatting to match tick label formatting, but this is handled in CheckLabels, with the tick label format information copied to the data label format information if necessary.) The 'p' entry is for pie chart labels, and will only exist for pie charts. (The 'p' entry was added in PHPlot-5.6.0.)

The value of each entry in label_format is an array containing formatting information. The arrays are empty by default, meaning there is no special formatting. If formatting has been enabled, for example with SetXLabelType, the arrays can contain the following keys and values:

KeyUsed with typeValue
type Formatting type: data, time, printf, or custom.
precisiondataThe number of decimal positions to produce.
prefixdataA prefix string to append to the label (for example, a currency sign).
suffixdataA suffix string to append to the label (for example, a currency sign or percent sign). This replaces data_units_text (which still works too).
time_formattimeThe date/time format string for the PHP strftime() function.
printf_formatprintfThe format string for the PHP printf() function.
custom_callbackcustomThe function (or array with object and method name) to call to format the label.
custom_argcustomAn additional argument to pass to the custom_callback function.

10.2.3. plots[]

The plots[] array contains information about known plot types. Essentially, it tells FindDataLimits and DrawGraph how to produce the main portion of the plot. This was added in PHPlot-5.3.0. This is a static member variable in the PHPlot class, so it must be accessed as PHPlot::$plots and not through an instance of the class. It has protected visibility, so is not accessible from outside the class or derived classes.

The array keys are the plot types (for example: 'bars', 'linepoints'). These must not include upper case letters. The values are arrays which contain information about the plot type. The keys and values of the second-level arrays are:

KeyValue
draw_methodName of the PHPlot class method (function) to call to draw the 'insides' of the plot. This is the only required entry. The function is responsible for drawing everything inside the plot area. (That is, everything except the plot titles, axis lines, tick marks and tick labels, grid lines, and legend.)
draw_argOptional argument(s) for the drawing method named by draw_method. If present, this must be an array. Each element of the array is passed to the draw_method function as a separate argument. If this is not specified, the drawing method is called with no arguments. This is generally used to 'overload' drawing methods so they handle multiple similar plot types.
draw_axesA flag to indicate if the X axis and Y axis should be drawn. The default is TRUE. This is set to FALSE for pie charts.
abs_valsSpecial data processing flag. If TRUE, this tells FindDataLimits that the plot type will take the absolute value of all dependent variable values in the data array. FindDataLimits needs this information so it knows how to find the minimum and maximum values in the data array. The default if omitted is FALSE.
sum_valsSpecial data processing flag. If TRUE, this tells FindDataLimits that the plot type will sum up the dependent variable values in each row of the data array. FindDataLimits needs this information so it knows how to find the minimum and maximum values in the data array. The default if omitted is FALSE. If both abs_vals and sum_vals are TRUE, this means the plot type sums up the absolute values from the data array. (The stackedarea plot type does this.)

10.2.4. legend_pos[]

The legend_pos[] array contains information about positioning of the legend. This is set by SetLegendPosition, and by the functions which use it (SetLegendPixels and SetLegendWorld). This was added in PHPlot-5.4.0, replacing scalar variables legend_x_pos, legend_y_pos, and legend_xy_world.

The array keys correspond to the arguments to SetLegendPosition and are shown in the following table.

KeysValue
x, yRelative coordinates of a point on the legend box
modeOne of: image, plot, title, or world
x_base, y_baseRelative coordinates of a point on the image, plot, or title, or world coordinates
x_offset, y_offsetPixel offset to be applied last