NAME
URI::GoogleChart - Generate Google Chart URIs
SYNOPSIS
use URI::GoggleChart;
my $chart = URI::GoogleChart->new("line", 300, 100,
data => [45, 80, 100, 33],
);
DESCRIPTION
This module provide a constructor method for Google Chart URIs. Google
will serve back PNG images of charts controlled by the provided
parameters when these URI are dereferenced. Normally these URIs will be
embedded as "" tags in HTML documents.
The Google Chart service is described at
and these pages also define the API
in terms of the parameters these URIs take. This module make it easier
to generate URIs that conform to this API as it automatically takes care
of data encoding and scaling, as well as hiding most of the cryptic
parameter names that the API uses in order to generate shorter URIs.
The following constructor method is provided:
$uri = URI::GoogleChart->new( $type, $width, $height, %opt )
The constructor method's 3 first arguments are mandatory and they
define the type of chart to generate and the dimension of the image
in pixels. The rest of the arguments are provided as key/value
pairs. The return value is an HTTP URI object, which can also be
treated as a string.
The $type argument can either be one of the type code documented at
the Google Charts page or one of the following more readable
aliases:
lines
sparklines
xy-lines
horizontal-stacked-bars
vertical-stacked-bars
horizontal-grouped-bars
vertical-grouped-bars
pie
pie-3d
concentric-pie
venn
scatter-plot
radar
radar-splines
google-o-meter
world
africa
asia
europe
middle_east
south_america
usa
The key/value pairs can either be one of the "chXXX" codes
documented on the Google Chart pages or one of the following:
data => [{ v => [$v1, $v2,...], %opt }, ...]
data => [[$v1, $v2,...], [$v1, $v2,...], ...]
data => [$v1, $v2,...]
data => $v1
The data to be charted is provided as an array of data series.
Each series is defined by a hash with the "v" element being an
array of data points in the series. Missing data points should
be provided as "undef". Other hash elements can be provided to
define various properties of the series. These are described
below.
As a short hand when you don't need to define other properties
besides the data points you can just provide an array of numbers
instead of the series hash.
As a short hand when you only have a single data series, you can
just provide a single array of numbers, and finally if you only
have a single number you can provide it without wrapping it in
an array.
The following data series properties can be provided.
The "group" property can be used to group data series together.
Series that have the same group value belong to the same group.
Values in the same group are scaled based on the minimum and
maximum data point provided in that group. Data series without a
"group" property belong to the default group.
min => $num
max => $num
Defines the minimum and maximum value for the default group. If
not provided the minimum and maximum is calculated from the data
points belonging to this group. Chart types that plot relative
values make the default minimum 0 so the relative size of the
data points stay the same after scaling.
The data points are scaled so that they are plotted relative to
the ($min .. $max) range. For example if the ($min .. $max)
range is (5 .. 10) then a data point value of 7.5 is plotted in
the middle of the chart area.
group => { $name => { min => $min, max => $max }, ...},
Define parameters for named data series groups. Currently you
can only set up the minimum and maximum values used for scaling
the data points.
encoding => "t"
encoding => "s"
encoding => "e"
Select what kind of data encoding you want to be used. They
differ in the resolution they provide and in their readability
and verbosity. Resolution matters if you generate big charts.
Verbosity matters as some web client might refuse to dereference
URLs that are too long.
The "t" encoding is the most readable and verbose. It might
consume up to 5 bytes per data point. It provide a resolution of
1/1000.
The "s" encoding is the most compact; only consuming 1 byte per
data point. It provide a resolution of 1/62.
The "e" encoding provides the most resolution and it consumes 2
bytes per data point. It provide a resolution of 1/4096.
The default encoding is currently "t"; but expect this to
change. The default ought to be automatically selected based on
the resolution of the chart and the number of data points
provided.
color => $color
color => [$color1, $color2, ...]
Sets the colors to use for charting the data series. The
canonical form for $color is hexstrings either of "RRGGBB" or
"RRGGBBAA" form. When you use this interface you might also use
"RGB" form as well as some comon names like "red", "blue",
"green", "white", "black",... which are expanded to the
canonical form in the URI.
title => $str
title => { text => $str, color => $color, fontsize => $fontsize }
Sets the title for the chart; optionally changing the color and
fontsize used for the title.
margin => $num
margin => [ $left, $right, $top, $bottom ]
Sets the chart margins in pixels. If a single number is provided
then all the margins are set to this number of pixels.
SEE ALSO
URI
COPYRIGHT AND LICENSE
Copyright 2009 Gisle Aas.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.