NAME
    Apache::GD::Graph - Generate Graphs in an Apache handler.

SYNOPSIS
    In httpd.conf:

            <Location /chart>
            SetHandler      perl-script
            PerlHandler     +Apache::GD::Graph
            # These are optional.
            #PerlSetVar     Expires         30      # days default.
            #PerlSetVar     CacheSize       5242880 # 5 megs default.
            #PerlSetVar     ImageType       png     # Default.
            # The default image type that graphs should be.
            # png is default, gif requires <= GD 1.19.
            # Any type supported by the installed version of GD will work.
            #
            # The next specifies the quality of generated JPEG images, best not to
            # specify this one and let GD figure it out.
            #PerlSetVar     JpegQuality     75 # 0 to 100
            # TTFFontPath tells GD::Text where to look for true type fonts. The
            # example here is the default value used.
            #PerlSetVar     TTFFontPath     /usr/ttfonts:/var/ttfonts:/usr/X11R6/lib/X11/fonts/ttf/:/usr/X11R6/lib/X11/fonts/truetype/:/usr/share/fonts/truetype
            </Location>

    Then send requests to:

            http://www.server.com/chart?type=lines&x_labels=[1st,2nd,3rd,4th,5th]&
            data1=[1,2,3,4,5]&data2=[6,7,8,9,10]&dclrs=[blue,yellow,green]>

    Options can also be sent as x-www-form-urlencoded data (ie., a
    form). This works better for large data sets, and allows simple
    charting forms to be set up. IE, for example, does not allow query
    strings larger than a kilobyte. Parameters in the query string take
    precedence over a form if specified.

INSTALLATION
    Like any other CPAN module, if you are not familiar with CPAN
    modules, see:
    http://www.cpan.org/doc/manual/html/pod/perlmodinstall.html

    MAKE SURE TO RESTART YOUR APACHE SERVER using `apachectl graceful'
    after upgrading this or any other Apache Perl module.

DESCRIPTION
    The primary purpose of this module is to allow a very easy to use,
    lightweight and fast charting capability for static pages, dynamic
    pages and CGI scripts, with the chart creation process abstracted
    and placed on any server.

    For example, embedding a pie chart can be as simple as:

            <img src="http://www.some-server.com/chart?type=pie&
            x_labels=[greed,pride,wrath]&data1=[10,50,20]&dclrs=[green,purple,red]"
            alt="pie chart of a few deadly sins">
            <!-- Note that all of the above options are optional except for data1!  -->

    And it gets cached both server side, and along any proxies to the
    client, and on the client's browser cache. Not to mention, chart
    generation is very fast.

    Of course, more complex things will be better done directly in your
    own Perl handlers, but this module allows a non-Perl environment to
    have access to the capabilities of GD::Graph.

    Another solution is to use ASP scripting with Microsoft Excel, which
    of course requires a Windows NT server and I have no idea how easy
    this is to do, or how fast.

    There are also many other ways to connect programs with charting
    capabilities, such as GNUPlot, or rrdtool to a web server. These may
    or may not be faster/more featureful etc.

TIPS
    Most more complicated things depend on knowing the GD::Graph
    interface.

    Firstly, make sure you are not using any spaces! If you want to pass
    a space in a parameter in a URL-encoded string, use `%20', in a form
    use a `+'.

    Make sure to use `cache=0' or `PerlSetVar CacheSize 0' when
    debugging, otherwise you will spend hours being very confused.

FONTS
    GD::Graph has some options that take a font description, such as
    title_font, legend_font, etc. (these map to the appropriate set_FOO
    methods in GD::Graph, see that manpage). See the TTFFontPath
    variable under SYNOPSIS for how to set the search path for fonts.
    MAKE SURE your fonts are readable by the user the Apache server runs
    under, this is usually "www-data" or "nobody". Otherwise your fonts
    will mysteriously fail with no notice.

    Sizes can be specified by using a list with the name and size. For
    example, if arial.ttf can be found somewhere in your TTFFontPath,
    you can do:

            ...title_font=(arial.ttf,20)

    To get a title using font Arial, in 20 points.

    Note that GD::Text does not parse out the names of fonts and such,
    you have to give it an actual filename, in the right case. So if
    using the Microsoft Windows core fonts, Arial Bold would be
    `arialbd.ttf'. Here's an example:

            http://server/chart?data1=[1,2,3,4,5]&title_font=(arialbd.ttf,20)&title=Just%20A%20Line

IMAGES
    You can place a logo in any corner of the graph using the `logo',
    `logo_resize' and `logo_position' options. See the GD::Graph
    manpage. If you just want a background image that is resized to fit
    your graph, see the `background_image' option herein.

TEXT/CAPTIONS
    The following GD::Graph options control placing text on the graph:
    title, x_label and y_label. the GD::Graph manpage for those and
    related options. In addition, this modules allows you to use the
    captionN option(s), to draw arbitrary strings on the graph. See
    below.

IMPLEMENTATION
    This module is implemented as a simple Apache mod_perl handler that
    generates and returns a png format graph (using Martien Verbruggen's
    GD::Graph module) based on the arguments passed in via a query
    string. It responds with the content-type "image/png" (or whatever
    is set via `PerlSetVar ImageType'), and sends a Expires: header of
    30 days (or whatever is set via `PerlSetVar Expires', or expires in
    the query string, in days) ahead.

    In addition, it keeps a server-side cache in the file system using
    DeWitt Clinton's File::Cache module, whose size can be specified via
    `PerlSetVar CacheSize' in bytes.

OPTIONS
    type    Type of graph to generate, can be lines, bars, points,
            linespoints, area, mixed, pie. For a description of these,
            see the GD::Graph(3) manpage. Can also be one of the 3d
            types if GD::Graph3d is installed, or anything else with
            prefix GD::Graph::.

    width   Width of graph in pixels, 400 by default.

    height  Height of graph in pixels, 300 by default.

    expires Date of Expires header from now, in days. Same as
            `PerlSetVar Expires'.

    image_type
            Same as `PerlSetVar ImageType'. "png" by default, but can be
            anything supported by GD.

            If not specified via this option or in the config file, the
            image type can also be deduced from a single value in the
            'Accept' header of the request.

    jpeg_quality
            Same as `PerlSetVar JpegQuality'. A number from 0 to 100
            that determines the jpeg quality and the size. If not set at
            all, the GD library will determine the optimal setting.
            Changing this value doesn't seem to do much as far as line
            graphs go, but YMMV.

    background_image
            Set an image as the background for the graph. You are
            responsible for choosing a sane image to go with your graph,
            the background should be either transparent or the same
            color you will use. This is the same as using the `logo'
            parameter with an image of the same size as the graph,
            except this option will resize the image if necessary,
            making it more convenient for this purpose. The file or URL
            can be of any type your copy of GD supports.

    captionN
            Draws a character string using a TrueType font at an
            arbitrary location. Takes an array of
            `($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string)' where
            $fgcolor is the foreground color, $fontname is the name of a
            TTF font see the FONTS entry elsewhere in this document ,
            $ptsize is the point size, $x and $y are the coordinates,
            and $string is the actual characters to draw.

            N is an integer from 1 onward, like for the dataN option.
            This lets you specify multiple strings to draw.

            This follows exactly the GD stringTTF method, see the GD
            manpage.

            Angle is in degrees, you will primarily use angle `0' for
            normal left-to-right text. $x and $y are pixel coordinates
            from the upper left corner. $fontname is the name of a
            true-type font that will be found in the font path (see
            FONTS). Example:

                    http://isis/chart?data1=[1,2,3,4,5]&caption1=(1,arial.ttf,9,0,30,30,Hello)

    cache   Boolean value which determines whether or not the image will
            get cached server-side (for client-side caching, use the
            "expires" parameter). It is true (1) by default. Setting
            `PerlSetVar CacheSize 0' in the config file will achieve the
            same affect as `cache=0' in the query string.

    to_file The graph will not be sent back, but instead saved to the
            file indicated on the server. Apache will need permission to
            write to that directory. The result will not be cached. This
            is basically the same as making an RPC call to a Perl
            process to make a graph and store it to a file.

    no_axes This sets x_labels to an empty lists and sets
            y_number_format to "", effectively disabling axes labels.

    For the following, look at the plot method in the GD::Graph(3)
    manpage.

    x_labels
            Labels used on the X axis, the first array given to the plot
            method of GD::Graph. If unspecified or undef, no labels will
            be drawn.

    dataN   Values to plot, where N is a number starting with 1. Can be
            given any number of times with N increasing.

    ALL OTHER OPTIONS are passed to the corresponding set_<option>
    method, or the set(<option hash>) method using the following rules
    for the values:

    undef   Becomes a real undef.

    [one,two,3]
            Becomes an array reference.

    (one,two,3)
            This becomes a list, you can pass lists to set_SOMETHING
            methods of GD::Graph, if there is no corresponding set_
            method, the list will be silently converted to an anonymous
            array and used in an ordinary option.

    {one,1,two,2}
            Becomes a hash reference.

    http://somewhere/file.png
            Is pulled into a file and the file name is passed to the
            respective option. (Can be any scheme besides http:// that
            LWP::Simple supports.)

    [undef,something,undef] or {key,undef}
            You can create an array or hash with undefs.

    ['foo',bar] or 'baz' or {'key','value'}
            Single and double quoted strings are supported, either as
            singleton values or inside arrays and hashes.

            DON'T USE SPACES, this is a common mistake. A space in a
            URL-encoded string is %20, or a + in a form.

            Nested structures are still not supported, maybe later.

AUTHOR
    Rafael Kitover (caelum@debian.org)

COPYRIGHT
    This program is Copyright (c) 2000,2001 by Rafael Kitover. This
    program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

ACKNOWLEDGEMENTS
    This module owes its existance, obviously, to the availability of
    the wonderful GD::Graph module from Martien Verbruggen
    <mgjv@comdyn.com.au>.

    Thanks to my employer, Gradience, Inc., for allowing me to work on
    projects as free software.

    Thanks to Vivek Khera, Scott Holdren and Drew Negentesh for the bug
    fixes.

BUGS
    Probably a few.

    We should probably just let people set up their own
    PerlFixupHandlers for errors, but this makes it more difficult to
    set up. At least, it should be an option.

TODO
    Boxed captions. Variable mapping of x-labels to data points. If
    possible, a comprehensive test suite. Make it faster?

SEE ALSO
    the perl manpage, the GD::Graph manpage, the GD manpage

