Provided by: libgd-graph-perl_1.48-2_all 
NAME
GD::Graph - Graph Plotting Module for Perl 5
SYNOPSIS
use GD::Graph::moduleName;
DESCRIPTION
GD::Graph is a perl5 module to create charts using the GD module. The following classes
for graphs with axes are defined:
"GD::Graph::lines"
Create a line chart.
"GD::Graph::bars" and "GD::Graph::hbars"
Create a bar chart with vertical or horizontal bars.
"GD::Graph::points"
Create an chart, displaying the data as points.
"GD::Graph::linespoints"
Combination of lines and points.
"GD::Graph::area"
Create a graph, representing the data as areas under a line.
"GD::Graph::mixed"
Create a mixed type graph, any combination of the above. At the moment this is fairly
limited. Some of the options that can be used with some of the individual graph types
won't work very well. Bar graphs drawn after lines or points graphs may obscure the
earlier data, and specifying bar_width will not produce the results you probably
expected.
Additional types:
"GD::Graph::pie"
Create a pie chart.
DISTRIBUTION STATUS
Distribution has no releases since 2007. It has new maintainer starting of 1.45 and my
plan is to keep modules backwards compatible as much as possible, fix bugs with test
cases, apply patches and release new versions to the CPAN.
I got repository from Martien without Benjamin's work, Benjamin couldn't find his
repository, so everything else is imported from CPAN and BackPAN. Now it's all on github
<https://github.com/ruz/GDGraph>. May be at some point Benjamin will find his VCS backup
and we can restore full history.
Release 1.44_01 (development release) was released in 2007 by Benjamin, but never made
into production version. This dev version contains very nice changes (truecolor, anti-
aliasing and alpha support), but due to nature of how GD and GD::Graph works authors had
to add third optional argument (truecolor) to all constructors in GD::Graph modules. I
think that this should be and can be adjusted to receive named arguments in constructor
and still be backwards compatible. If you were using that dev release and want to fast
forward inclusion of this work into production release then contact ruz@cpan.org
Martien also has changes in his repository that were never published to CPAN. These are
smaller and well isolated, so I can merge them faster.
My goal at this moment is to merge existing versions together, get rid of CVS reminders,
do some repo cleanup, review existing tickets on rt.cpan.org. Join if you want to help.
EXAMPLES
See the samples directory in the distribution, and read the Makefile there.
USAGE
Fill an array of arrays with the x values and the values of the data sets. Make sure that
every array is the same size, otherwise GD::Graph will complain and refuse to compile the
graph.
@data = (
["1st","2nd","3rd","4th","5th","6th","7th", "8th", "9th"],
[ 1, 2, 5, 6, 3, 1.5, 1, 3, 4],
[ sort { $a <=> $b } (1, 2, 5, 6, 3, 1.5, 1, 3, 4) ]
);
If you don't have a value for a point in a certain dataset, you can use undef, and the
point will be skipped.
Create a new GD::Graph object by calling the new method on the graph type you want to
create (chart is bars, hbars, lines, points, linespoints, mixed or pie).
my $graph = GD::Graph::chart->new(400, 300);
Set the graph options.
$graph->set(
x_label => 'X Label',
y_label => 'Y label',
title => 'Some simple graph',
y_max_value => 8,
y_tick_number => 8,
y_label_skip => 2
) or die $graph->error;
and plot the graph.
my $gd = $graph->plot(\@data) or die $graph->error;
Then do whatever your current version of GD allows you to do to save the file. For
versions of GD older than 1.19 (or more recent than 2.15), you'd do something like:
open(IMG, '>file.gif') or die $!;
binmode IMG;
print IMG $gd->gif;
close IMG;
and for newer versions (1.20 and up) you'd write
open(IMG, '>file.png') or die $!;
binmode IMG;
print IMG $gd->png;
or
open(IMG, '>file.gd2') or die $!;
binmode IMG;
print IMG $gd->gd2;
Then there's also of course the possibility of using a shorter version (for each of the
export functions that GD supports):
print IMG $graph->plot(\@data)->gif;
print IMG $graph->plot(\@data)->png;
print IMG $graph->plot(\@data)->gd;
print IMG $graph->plot(\@data)->gd2;
If you want to write something that doesn't require your code to 'know' whether to use gif
or png, you could do something like:
if ($gd->can('png')) { # blabla }
or you can use the convenience method "export_format":
my $format = $graph->export_format;
open(IMG, ">file.$format") or die $!;
binmode IMG;
print IMG $graph->plot(\@data)->$format();
close IMG;
or for CGI programs:
use CGI qw(:standard);
#...
my $format = $graph->export_format;
print header("image/$format");
binmode STDOUT;
print $graph->plot(\@data)->$format();
(the parentheses after $format are necessary, to help the compiler decide that you mean a
method name there)
See under "SEE ALSO" for references to other documentation, especially the FAQ.
METHODS
Methods for all graphs
GD::Graph::chart->new([width,height])
Create a new object $graph with optional width and height. Default width = 400,
default height = 300. chart is either bars, lines, points, linespoints, area, mixed or
pie.
$graph->set_text_clr(colour name)
Set the colour of the text. This will set the colour of the titles, labels, and axis
labels to colour name. Also see the options textclr, labelclr and axislabelclr.
$graph->set_title_font(font specification)
Set the font that will be used for the title of the chart. See "FONTS".
$graph->plot(\@data)
Plot the chart, and return the GD::Image object.
$graph->set(attrib1 => value1, attrib2 => value2 ...)
Set chart options. See OPTIONS section.
$graph->get(attrib1, attrib2)
Returns a list of the values of the attributes. In scalar context returns the value of
the first attribute only.
$graph->gd()
Get the GD::Image object that is going to be used to draw on. You can do this either
before or after calling the plot method, to do your own drawing.
Note: as of the current version, this GD::Image object will always be palette-based,
even if the installed version of GD supports true-color images.
Note also that if you draw on the GD::Image object before calling the plot method, you
are responsible for making sure that the background colour is correct and for setting
transparency.
$graph->export_format()
Query the export format of the GD library in use. In scalar context, it returns
'gif', 'png' or undefined, which is sufficient for most people's use. In a list
context, it returns a list of all the formats that are supported by the current
version of GD. It can be called as a class or object method
$graph->can_do_ttf()
Returns true if the current GD library supports TrueType fonts, False otherwise. Can
also be called as a class method or static method.
Methods for Pie charts
$graph->set_label_font(font specification)
$graph->set_value_font(font specification)
Set the font that will be used for the label of the pie or the values on the pie. See
"FONTS".
Methods for charts with axes.
$graph->set_x_label_font(font specification)
$graph->set_y_label_font(font specification)
$graph->set_x_axis_font(font specification)
$graph->set_y_axis_font(font specification)
$graph->set_values_font(font specification)
Set the font for the x and y axis label, the x and y axis value labels, and for the
values printed above the data points. See "FONTS".
$graph->get_hotspot($dataset, $point)
Experimental: Return a coordinate specification for a point in a dataset. Returns a
list. If the point is not specified, returns a list of array references for all points
in the dataset. If the dataset is also not specified, returns a list of array
references for each data set. See "HOTSPOTS".
$graph->get_feature_coordinates($feature_name)
Experimental: Return a coordinate specification for a certain feature in the chart.
Currently, features that are defined are axes, the coordinates of the rectangle within
the axes; x_label, y1_label and y2_label, the labels printed along the axes, with
y_label provided as an alias for y1_label; and title which is the title text box. See
"HOTSPOTS".
OPTIONS
Options for all graphs
width, height
The width and height of the canvas in pixels Default: 400 x 300. NB At the moment,
these are read-only options. If you want to set the size of a graph, you will have to
do that with the new method.
t_margin, b_margin, l_margin, r_margin
Top, bottom, left and right margin of the canvas. These margins will be left blank.
Default: 0 for all.
logo
Name of a logo file. Generally, this should be the same format as your version of GD
exports images in. Currently, this file may be in any format that GD can import, but
please see GD if you use an XPM file and get unexpected results.
Default: no logo.
logo_resize, logo_position
Factor to resize the logo by, and the position on the canvas of the logo. Possible
values for logo_position are 'LL', 'LR', 'UL', and 'UR'. (lower and upper left and
right). Default: 'LR'.
transparent
If set to a true value, the produced image will have the background colour marked as
transparent (see also option bgclr). Default: 1.
interlaced
If set to a true value, the produced image will be interlaced. Default: 1.
Note: versions of GD higher than 2.0 (that is, since GIF support was restored after
being removed owing to patent issues) do not support interlacing of GIF images.
Support for interlaced PNG and progressive JPEG images remains available using this
option.
Colours
bgclr, fgclr, boxclr, accentclr, shadowclr
Drawing colours used for the chart: background, foreground (axes and grid), axis box
fill colour, accents (bar, area and pie outlines), and shadow (currently only for
bars).
All colours should have a valid value as described in "COLOURS", except boxclr, which
can be undefined, in which case the box will not be filled.
shadow_depth
Depth of a shadow, positive for right/down shadow, negative for left/up shadow, 0 for
no shadow (default). Also see the "shadowclr" and "bar_spacing" options.
labelclr, axislabelclr, legendclr, valuesclr, textclr
Text Colours used for the chart: label (labels for the axes or pie), axis label
(misnomer: values printed along the axes, or on a pie slice), legend text, shown
values text, and all other text.
All colours should have a valid value as described in "COLOURS".
dclrs (short for datacolours)
This controls the colours for the bars, lines, markers, or pie slices. This should be
a reference to an array of colour names as defined in GD::Graph::colour
("perldoc GD::Graph::colour" for the names available).
$graph->set( dclrs => [ qw(green pink blue cyan) ] );
The first (fifth, ninth) data set will be green, the next pink, etc.
A colour can be "undef", in which case the data set will not be drawn. This can be
useful for cumulative bar sets where you want certain data series (often the first
one) not to show up, which can be used to emulate error bars (see examples 1-7 and 6-3
in the distribution).
Default: [ qw(lred lgreen lblue lyellow lpurple cyan lorange) ]
borderclrs
This controls the colours of the borders of the bars data sets. Like dclrs, it is a
reference to an array of colour names as defined in GD::Graph::colour. Setting a
border colour to "undef" means the border will not be drawn.
cycle_clrs
If set to a true value, bars will not have a colour from "dclrs" per dataset, but per
point. The colour sequence will be identical for each dataset. Note that this may have
a weird effect if you are drawing more than one data set. If this is set to a value
larger than 1 the border colour of the bars will cycle through the colours in
"borderclrs".
accent_treshold
Not really a colour, but it does control a visual aspect: Accents on bars are only
drawn when the width of a bar is larger than this number of pixels. Accents inside
areas are only drawn when the horizontal distance between points is larger than this
number. Default 4
Options for graphs with axes.
options for bars, lines, points, linespoints, mixed and area charts.
x_label, y_label
The labels to be printed next to, or just below, the axes. Note that if you use the
two_axes option that you need to use y1_label and y2_label.
long_ticks, tick_length
If long_ticks is a true value, ticks will be drawn the same length as the axes.
Otherwise ticks will be drawn with length tick_length. if tick_length is negative, the
ticks will be drawn outside the axes. Default: long_ticks = 0, tick_length = 4.
These attributes can also be set for x and y axes separately with x_long_ticks,
y_long_ticks, x_tick_length and y_tick_length.
x_ticks
If x_ticks is a true value, ticks will be drawn for the x axis. These ticks are
subject to the values of long_ticks and tick_length. Default: 1.
y_tick_number
Number of ticks to print for the Y axis. Use this, together with y_label_skip to
control the look of ticks on the y axis. Default: 5.
y_number_format
This can be either a string, or a reference to a subroutine. If it is a string, it
will be taken to be the first argument to a sprintf, with the value as the second
argument:
$label = sprintf( $s->{y_number_format}, $value );
If it is a code reference, it will be executed with the value as the argument:
$label = &{$s->{y_number_format}}($value);
This can be useful, for example, if you want to reformat your values in currency, with
the - sign in the right spot. Something like:
sub y_format
{
my $value = shift;
my $ret;
if ($value >= 0)
{
$ret = sprintf("\$%d", $value * $refit);
}
else
{
$ret = sprintf("-\$%d", abs($value) * $refit);
}
return $ret;
}
$graph->set( 'y_number_format' => \&y_format );
(Yes, I know this can be much shorter and more concise)
Default: undef.
y1_number_format, y2_number_format
As with y_number_format, these can be either a string, or a reference to a subroutine.
These are used as formats for graphs with two y-axis scales so that independent
formats can be used.
For compatibility purposes, each of these will fall back on y_number_format if not
specified.
Default: undef for both.
x_label_skip, y_label_skip
Print every x_label_skipth number under the tick on the x axis, and every
y_label_skipth number next to the tick on the y axis. Default: 1 for both.
x_last_label_skip
By default, when x_label_skip is set to something higher than 1, the last label on the
axis will be printed, even when it doesn't belong to the normal series that should be
printed. Setting this to a true value prevents that.
For example, when your X values are the months of the year (i.e. Jan - Dec), and you
set x_label_skip to 3, the months printed on the axis will be Jan, Apr, Jul, Oct and
Dec; even though Dec does not really belong to that sequence. If you do not like the
last month to be printed, set x_last_label_skip to a true value.
This option has no effect in other circumstances. Also see x_tick_offset for another
method to make this look better. Default: 0 for both
x_tick_offset
When x_label_skip is used, this will skip the first x_tick_offset values in the labels
before starting to print. Let me give an example. If you have a series of X labels
like
qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec)
and you set x_label_skip to 3, you will see ticks on the X axis for Jan, Apr, Jul, Oct
and Dec. This is not always what is wanted. If you set x_tick_offset to 1, you get
Feb, May, Aug, Nov and Dec, and if you set it to 2, you get Mar, Jun Sep and Dec, and
this last one definitely looks better. A combination of 6 and 5 also works nice for
months.
Note that the value for x_tick_offset is periodical. This means that it will have the
same effect for each integer n in x_tick_offset + n * x_label_skip.
Also see x_last_label_skip for another method to influence this.
x_all_ticks
Force a print of all the x ticks, even if x_label_skip is set to a value Default: 0.
x_label_position
Controls the position of the X axis label (title). The value for this should be
between 0 and 1, where 0 means aligned to the left, 1 means aligned to the right, and
1/2 means centered. Default: 3/4
y_label_position
Controls the position of both Y axis labels (titles). The value for this should be
between 0 and 1, where 0 means aligned to the bottom, 1 means aligned to the top, and
1/2 means centered. Default: 1/2
x_labels_vertical
If set to a true value, the X axis labels will be printed vertically. This can be
handy in case these labels get very long. Default: 0.
x_plot_values, y_plot_values
If set to a true value, the values of the ticks on the x or y axes will be plotted
next to the tick. Also see x_label_skip, y_label_skip. Default: 1 for both.
box_axis
Draw the axes as a box, if true. Default: 1.
no_axes
Draw no axes at all. If this is set to undef, all axes are drawn. If it is set to 0,
the zero axis will be drawn, for bar charts only. If this is set to a true value, no
axes will be drawn at all. Value labels on the axes and ticks will also not be drawn,
but axis lables are drawn. Default: undef.
two_axes
Use two separate axes for the first and second data set. The first data set will be
set against the left axis, the second against the right axis. If more than two data
sets are being plotted, the use_axis option should be used to specify which data sets
use which axis.
Note that if you use this option, that you need to use y1_label and y2_label, instead
of just y_label, if you want the two axes to have different labels. The same goes for
some other options starting with the letter 'y' and an underscore.
Default: 0.
use_axis
If two y-axes are in use and more than two datasets are specified, set this option to
an array reference containing a value of 1 or 2 (for the left and right scales
respectively) for each dataset being plotted. That is, to plot three datasets with
the second on a different scale than the first and third, set this to "[1,2,1]".
Default: [1,2].
zero_axis
If set to a true value, the axis for y values of 0 will always be drawn. This might be
useful in case your graph contains negative values, but you want it to be clear where
the zero value is. (see also zero_axis_only and box_axes). Default: 0.
zero_axis_only
If set to a true value, the zero axis will be drawn (see zero_axis), and no axis at
the bottom of the graph will be drawn. The labels for X values will be placed on the
zero axis. Default: 0.
y_max_value, y_min_value
Maximum and minimum value displayed on the y axis. If two_axes is a true value, then
y1_min_value, y1_max_value (for the left axis), and y2_min_value, y2_max_value (for
the right axis) take precedence over these.
The range (y_min_value..y_max_value) has to include all the values of the data points,
or GD::Graph will die with a message.
For bar and area graphs, the range (y_min_value..y_max_value) has to include 0. If it
doesn't, the values will be adapted before attempting to draw the graph.
Default: Computed from data sets.
axis_space
This space will be left blank between the axes and the tick value text. Default: 4.
text_space
This space will be left open between text elements and the graph (text elements are
title and axis labels.
Default: 8.
cumulate
If this attribute is set to a true value, the data sets will be cumulated. This means
that they will be stacked on top of each other. A side effect of this is that
"overwrite" will be set to a true value.
Notes: This only works for bar and area charts at the moment.
If you have negative values in your data sets, setting this option might produce odd
results. Of course, the graph itself would be quite meaningless.
overwrite
If set to 0, bars of different data sets will be drawn next to each other. If set to
1, they will be drawn in front of each other. Default: 0.
Note: Setting overwrite to 2 to produce cumulative sets is deprecated, and may
disappear in future versions of GD::Graph. Instead see the "cumulate" attribute.
correct_width
If this is set to a true value and "x_tick_number" is false, then the width of the
graph (or the height for rotated graphs like "GD::Graph::hbar") will be recalculated
to make sure that each data point is exactly an integer number of pixels wide. You
probably never want to fiddle with this.
When this value is true, you will need to make sure that the number of data points is
smaller than the number of pixels in the plotting area of the chart. If you get errors
saying that your horizontal size if too small, you may need to manually switch this
off, or consider using something else than a bar type for your chart.
Default: 1 for bar, calculated at runtime for mixed charts, 0 for others.
Plotting data point values with the data point
Sometimes you will want to plot the value of a data point or bar above the data point for
clarity. GD::Graph allows you to control this in a generic manner, or even down to the
single point.
show_values
Set this to 1 to display the value of each data point above the point or bar itself.
No effort is being made to ensure that there is enough space for the text.
Set this to a GD::Graph::Data object, or an array reference of the same shape, with
the same dimensions as your data object that you pass in to the plot method. The
reason for this option is that it allows you to make a copy of your data set, and
selectively set points to "undef" to disable plotting of them.
my $data = GD::Graph::Data->new(
[ [ 'A', 'B', 'C' ], [ 1, 2, 3 ], [ 11, 12, 13 ] ]);
my $values = $data->copy;
$values->set_y(1, 1, undef);
$values->set_y(2, 0, undef);
$graph->set(show_values => $values);
$graph->plot($data);
Default: 0.
values_vertical
If set to a true value, the values will be printed vertically, instead of
horizontally. This can be handy if the values are long numbers. Default: 0.
values_space
Space to insert between the data point and the value to print. Default: 4.
values_format
How to format the values for display. See y_number_format for more information.
Default: undef.
hide_overlapping_values
If set to a true value, the values that goes out of graph space are hidden. Option is
EXPERIMENTAL, works only for bars, text still can overlap with other bars and labels,
most useful only with text in the same direction as bars. Default: undef
Options for graphs with a numerical X axis
First of all: GD::Graph does not support numerical x axis the way it should. Data for X
axes should be equally spaced. That understood: There is some support to make the printing
of graphs with numerical X axis values a bit better, thanks to Scott Prahl. If the option
"x_tick_number" is set to a defined value, GD::Graph will attempt to treat the X data as
numerical.
Extra options are:
x_tick_number
If set to 'auto', GD::Graph will attempt to format the X axis in a nice way, based on
the actual X values. If set to a number, that's the number of ticks you will get. If
set to undef, GD::Graph will treat X data as labels. Default: undef.
x_min_value, x_max_value
The minimum and maximum value to use for the X axis. Default: computed.
x_number_format
See y_number_format
x_label_skip
See y_label_skip
Options for graphs with bars
bar_width
The width of a bar in pixels. Also see "bar_spacing". Use "bar_width" If you want to
have fixed-width bars, no matter how wide the chart gets. Default: as wide as
possible, within the constraints of the chart size and "bar_spacing" setting.
bar_spacing
Number of pixels to leave open between bars. This works well in most cases, but on
some platforms, a value of 1 will be rounded off to 0. Use "bar_spacing" to get a
fixed amount of space between bars, with variable bar widths, depending on the width
of the chart. Note that if "bar_width" is also set, this setting will be ignored, and
automatically calculated. Default: 0
bargroup_spacing
Number of pixels (in addition to whatever is specified in "bar_spacing") to leave
between groups of bars when multiple datasets are being displayed. Unlike
"bar_spacing", however, this parameter will hold its value if "bar_width" is set.
Options for graphs with lines
line_types
Which line types to use for lines and linespoints graphs. This should be a reference
to an array of numbers:
$graph->set( line_types => [3, 2, 4] );
Available line types are 1: solid, 2: dashed, 3: dotted, 4: dot-dashed.
Default: [1] (always use solid)
line_type_scale
Controls the length of the dashes in the line types. default: 6.
line_width
The width of the line used in lines and linespoints graphs, in pixels. Default: 1.
skip_undef
For all other axes graph types, the default behaviour is (by their nature) to not draw
a point when the Y value is "undef". For line charts the point gets skipped as well,
but the line is drawn between the points n-1 to n+1 directly. If "skip_undef" has a
true value, there will be a gap in the chart where a Y value is undefined.
Note that a line will not be drawn unless there are at least two consecutive data
points exist that have a defined value. The following data set will only plot a very
short line towards the end if "skip_undef" is set:
@data = (
[ qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct ) ],
[ 1, undef, 2, undef, 3, undef, 4, undef, 5, 6 ]
);
This option is useful when you have a consecutive gap in your data, or with
linespoints charts. If you have data where you have intermittent gaps, be careful when
you use this. Default value: 0
Options for graphs with points
markers
This controls the order of markers in points and linespoints graphs. This should be a
reference to an array of numbers:
$graph->set( markers => [3, 5, 6] );
Available markers are: 1: filled square, 2: open square, 3: horizontal cross, 4:
diagonal cross, 5: filled diamond, 6: open diamond, 7: filled circle, 8: open circle,
9: horizontal line, 10: vertical line. Note that the last two are not part of the
default list.
Default: [1,2,3,4,5,6,7,8]
marker_size
The size of the markers used in points and linespoints graphs, in pixels. Default: 4.
Options for mixed graphs
types
A reference to an array with graph types, in the same order as the data sets. Possible
values are:
$graph->set( types => [qw(lines bars points area linespoints)] );
$graph->set( types => ['lines', undef, undef, 'bars'] );
values that are undefined or unknown will be set to "default_type".
Default: all set to "default_type"
default_type
The type of graph to draw for data sets that either have no type set, or that have an
unknown type set.
Default: lines
Graph legends (axestype graphs only)
At the moment legend support is minimal.
Methods
$graph->set_legend(@legend_keys);
Sets the keys for the legend. The elements of @legend_keys correspond to the data sets
as provided to plot().
If a key is undef or an empty string, the legend entry will be skipped.
$graph->set_legend_font(font name);
Sets the font for the legend text (see "FONTS"). Default: GD::gdTinyFont.
Options
legend_placement
Where to put the legend. This should be a two letter key of the form: 'B[LCR]|R[TCB]'.
The first letter indicates the placement (Bottom or Right), and the second letter the
alignment (Left, Right, Center, Top, or Bottom). Default: 'BC'
If the legend is placed at the bottom, some calculations will be made to ensure that
there is some 'intelligent' wrapping going on. if the legend is placed at the right,
all entries will be placed below each other.
legend_spacing
The number of pixels to place around a legend item, and between a legend 'marker' and
the text. Default: 4
legend_marker_width, legend_marker_height
The width and height of a legend 'marker' in pixels. Defaults: 12, 8
lg_cols
If you, for some reason, need to force the legend at the bottom to have a specific
number of columns, you can use this. Default: computed
Options for pie graphs
3d If set to a true value, the pie chart will be drawn with a 3d look. Default: 1.
pie_height
The thickness of the pie when 3d is true. Default: 0.1 x height.
start_angle
The angle at which the first data slice will be displayed, with 0 degrees being "6
o'clock". Default: 0.
suppress_angle
If a pie slice is smaller than this angle (in degrees), a label will not be drawn on
it. Default: 0.
label
Print this label below the pie. Default: undef.
COLOURS
All references to colours in the options for this module have been shortened to clr. The
main reason for this was that I didn't want to support two spellings for the same word
('colour' and 'color')
Wherever a colour is required, a colour name should be used from the package
GD::Graph::colour. "perldoc GD::Graph::colour" should give you the documentation for that
module, containing all valid colour names. I will probably change this to read the systems
rgb.txt file if it is available.
FONTS
Depending on your version of GD, this accepts both GD builtin fonts or the name of a
TrueType font file. In the case of a TrueType font, you must specify the font size. See
GD::Text for more details and other things, since all font handling in GD::Graph is
delegated to there.
Examples:
$graph->set_title_font('/fonts/arial.ttf', 18);
$graph->set_legend_font(gdTinyFont);
$graph->set_legend_font(
['verdana', 'arial', gdMediumBoldFont], 12)
(The above discussion is based on GD::Text 0.65. Older versions have more restrictive
behaviour).
HOTSPOTS
Note that this is an experimental feature, and its interface may, and likely will, change
in the future. It currently does not work for area charts or pie charts.
A known problem with hotspots for GD::Graph::hbars is that the x and y coordinate come out
transposed. This probably won't be fixed until the redesign of this section
GD::Graph keeps an internal set of coordinates for each data point and for certain
features of a chart, like the title and axis labels. This specification is very similar to
the HTML image map specification, and in fact exists mainly for that purpose. You can get
at these hotspots with the "get_hotspot" method for data point, and
"get_feature_coordinates" for the chart features.
The <get_hotspot> method accepts two optional arguments, the number of the dataset you're
interested in, and the number of the point in that dataset you're interested in. When
called with two arguments, the method returns a list of one of the following forms:
'rect', x1, y1, x2, y2
'poly', x1, y1, x2, y2, x3, y3, ....
'line', xs, ys, xe, ye, width
The parameters for "rect" are the coordinates of the corners of the rectangle, the
parameters for "poly" are the coordinates of the vertices of the polygon, and the
parameters for the "line" are the coordinates for the start and end point, and the line
width. It should be possible to almost directly translate these lists into HTML image map
specifications.
If the second argument to "get_hotspot" is omitted, a list of references to arrays will be
returned. This list represents all the points in the dataset specified, and each array
referred to is of the form outlined above.
['rect', x1, y1, x2, y2 ], ['rect', x1, y1, x2, y2], ...
if both arguments to "get_hotspot" are omitted, the list that comes back will contain
references to arrays for each data set, which in turn contain references to arrays for
each point.
[
['rect', x1, y1, x2, y2 ], ['rect', x1, y1, x2, y2], ...
],
[
['line', xs, ys, xe, ye, w], ['line', xs, ys, xe, ye, w], ...
],...
The "get_feature" method, when called with the name of a feature, returns a single array
reference with a type and coordinates as described above. When called with no arguments, a
hash reference is returned with the keys being all the currently defined and set features,
and the values array references with the type and coordinates for each of those features.
ERROR HANDLING
GD::Graph objects inherit from the GD::Graph::Error class (not the other way around), so
they behave in the same manner. The main feature of that behaviour is that you have the
error() method available to get some information about what went wrong. The GD::Graph
methods all return undef if something went wrong, so you should be able to write safe
programs like this:
my $graph = GD::Graph->new() or die GD::Graph->error;
$graph->set( %attributes ) or die $graph->error;
$graph->plot($gdg_data) or die $graph->error;
More advanced usage is possible, and there are some caveats with this error handling,
which are all explained in GD::Graph::Error.
Unfortunately, it is almost impossible to gracefully recover from an error in GD::Graph,
so you really should get rid of the object, and recreate it from scratch if you want to
recover. For example, to adjust the correct_width attribute if you get the error
"Horizontal size too small" or "Vertical size too small" (in the case of hbar), you could
do something like:
sub plot_graph
{
my $data = shift;
my %attribs = @_;
my $graph = GD::Graph::bars->new()
or die GD::Graph->error;
$graph->set(%attribs) or die $graph->error;
$graph->plot($data) or die $graph->error;
}
my $gd;
eval { $gd = plot_graph(\@data, %attribs) };
if ($@)
{
die $@ unless $@ =~ /size too small/;
$gd = plot_graph(\@data, %attribs, correct_width => 0);
}
Of course, you could also adjust the width this way, and you can check for other errors.
NOTES
As with all Modules for Perl: Please stick to using the interface. If you try to fiddle
too much with knowledge of the internals of this module, you could get burned. I may
change them at any time.
BUGS
GD::Graph objects cannot be reused. To create a new plot, you have to create a new
GD::Graph object.
Rotated charts (ones with the X axis on the left) can currently only be created for bars.
With a little work, this will work for all others as well. Please, be patient :)
Other outstanding bugs can (alas) probably be found in the RT queue for this distribution,
at http://rt.cpan.org/Public/Dist/Display.html?Name=GDGraph
If you think you have found a bug, please check first to see if it has already been
reported. If it has not, please do (you can use the web interface above or send e-mail to
<bug-GDGraph@rt.cpan.org>). Bug reports should contain as many as possible of the
following:
• a concise description of the buggy behavior and how it differs from what you expected,
• the versions of Perl, GD::Graph and GD that you are using,
• a short demonstration script that shows the bug in action,
• a patch that fixes it. :-)
Of all of these, the third is probably the single most important, since producing a test
case generally makes the explanation much more concise and understandable, as well as
making it much simpler to show that the bug has been fixed. As an incidental benefit, if
the bug is in fact caused by some code outside of GD::Graph, it will become apparent while
you are writing the test case, thereby saving time and confusion for all concerned.
AUTHOR
Martien Verbruggen <mgjv@tradingpost.com.au>
Current maintenance (including this release) by Benjamin Warfield <bwarfield@cpan.org>
Copyright
GIFgraph: Copyright (c) 1995-1999 Martien Verbruggen.
Chart::PNGgraph: Copyright (c) 1999 Steve Bonds.
GD::Graph: Copyright (c) 1999 Martien Verbruggen.
All rights reserved. This package is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
Acknowledgements
Thanks to Steve Bonds for releasing Chart::PNGgraph, and keeping the code alive when GD
reached version 1.20, and I didn't have time to do something about it.
Thanks to the following people for contributing code, or sending me fixes: Dave Belcher,
Steve Bonds, Mike Bremford, Damon Brodie, Gary Deschaines, brian d foy, Edwin Hildebrand,
Ari Jolma, Tim Meadowcroft, Honza Pazdziora, Scott Prahl, Ben Tilly, Vegard Vesterheim,
Jeremy Wadsack.
And some people whose real name I don't know, and whose email address I'd rather not
publicise without their consent.
SEE ALSO
GD::Graph::FAQ, GD::Graph::Data, GD::Graph::Error, GD::Graph::colour