NAME
    URI::GoogleChart - Generate Google Chart URIs

SYNOPSIS
     use URI::GoogleChart;
     my $chart = URI::GoogleChart->new("lines", 300, 100,
         data => [45, 80, 55, 68],
         range_show => "left",
         range_round => 1,
     );

     # save chart to a file
     use LWP::Simple qw(getstore);
     getstore($chart, "chart.png");

     # or embed chart in an HTML file
     use HTML::Entities;
     my $enc_chart = encode_entities($chart);

     open(my $fh, ">", "chart.html") || die;
     print $fh qq(
         <h1>My Chart</h1>
         <p><img src="$enc_chart"></p>
     );
     close($fh) || die;

DESCRIPTION
    This module provide a constructor method for Google Chart URLs. When
    dereferenced Google will serve back PNG images of charts based on the
    provided parameters.

    The Google Chart service is described at
    <http://code.google.com/apis/chart/> and these pages also define the Web
    API in terms of the parameters these URLs take. This module make it
    easier to generate URLs 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
    URLs.

    The following constructor method is provided:

    $uri = URI::GoogleChart->new( $type, $width, $height, %opt )
        The constructor method's first 3 arguments are mandatory and they
        define the type of chart to generate and the dimension of the image
        in pixels. Additional 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 additional arguments in the form of key/value pairs can either
        be one of the "chXXX" parameters 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.
            In the most general form each series is defined by a hash with
            the "v" element being an array of data points (numbers) 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 provide an array of numbers
            instead of the series hash.

            As a short hand when you only have a single data series, you can
            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.

            Data series belong to ranges. A range is defined by a minimum
            and a maximum value. Data points are scaled so that they are
            plotted relative to the range they belong to. For example if the
            range is (5 .. 10) then a data point value of 7.5 is plotted in
            the middle of the chart area. Ranges are automatically
            calculated based on the data provided, but you can also force
            certain minimum and maximum values to apply.

            The following data series properties can be provided in addition
            to "v" described above:

            The "range" property can be used to group data series together
            that belong to the same range. The value of the "range" property
            is a range name. Data series without a "range" property belong
            to the default range.

        min => $num
        max => $num
            Defines the default minimum and maximum value for the default
            range. If not provided the minimum and maximum is calculated
            from the data points belonging to this range.

            The specified minimum or maximum are ignored if some of data
            values provided are outside this range.

            Chart types that plot relative values (like bar charts or venn
            diagrams) should use 0 as the minimum, as this make the relative
            size of the data points stay the same after scaling. Because of
            this the default default minimum for these charts is 0, so you
            don't actually need to specify it.

        range_round => $bool
            Extend the default range so that the min/max values are nice
            multiples of 1, 5, 10, 50, 100,... and such numbers. This gives
            the chart more "air" and look better if you display the range of
            values with "range_show".

        range_show => "left"
        range_show => "right"
        range_show => "top"
        range_show => "bottom"
            Makes the given axis show the range of values charted for the
            default range.

        range => { $name => \%opt, ...},
            Define parameters for named data series ranges. The range named
            "" is the default range.

            The option values that can be set are "min", "max", "round",
            "show". See the description of the corresponding entry for the
            default range above.

        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" (or "text") 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" (or "simple") encoding is the most compact; only
            consuming 1 byte per data point. It provide a resolution of
            1/62.

            The "e" (or "extended") encoding provides the most resolution
            and it consumes 2 bytes per data point. It provide a resolution
            of 1/4096.

            The default encoding is 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 URL.

            The built in colors are the 16 colors of the HTML specification
            (see <http://en.wikipedia.org/wiki/HTML_color_names>). If you
            want to use additional color names you can assign your mapping
            to the %URI::GoogleChart::COLOR_ALIAS hash before start creating
            charts. Example:

                local $URI::GoogleChart::COLOR_ALIAS{"gold"} = "FFD700";

        background => $color
            Sets the color for the chart background. See description for
            color above for how to specify color values. The color value
            "transparent" gives you a fully transparent background.

        title => $str
        title => [ $str, $color, $fontsize ]
            Sets the title for the chart; optionally changing the color and
            fontsize used for the title.

        label = $str
        label = [ $str, $str,... ]
            Labels the data (or data series) of the chart.

        rotate => $degrees
            Rotate the orientation of a pie chart (clockwise).

            The first slice starts at the right side of the pie (at 3
            o'clock). If you rotate the pie 90 degrees the first slice
            starts at the bottom. If you rotate -90 degrees (or 270) the
            first slices starts at the top of the pie.

        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
    <http://cpansearch.perl.org/src/GAAS/URI-GoogleChart-1.02/examples.html>

    <http://code.google.com/apis/chart/>

    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.

