NAME

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

SYNOPSIS

In httpd.conf:

        #PerlModule Apache::compat # uncomment this in Apache2!

        <Location /chart>
        SetHandler      perl-script
        PerlHandler     +Apache::GD::Graph
        ## These are optional (defaults shown)
        ##                              In days:
        #PerlSetVar     Expires         30
        #
        ##                              In megs:
        #PerlSetVar     CacheSize       5242880
        #PerlSetVar     ImageType       png
        #PerlSetVar     JpegQuality     75 # 0 to 100
        #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 allows simple charting forms to be set up, also, Internet Explorer does not allow query strings larger than a kilobyte so in those cases a POSTED form must be used. 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">
        <!-- All 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).

The following fonts are built-in to GD, these strings will resolve into the appropriate fonts except when quoted:

gdSmallFont, gdLargeFont, gdMediumBoldFont, gdTinyFont, gdGiantFont

There is also a way to use your own True Type Fonts. 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.

Fonts can also be specified as a relative path to the DocumentRoot of the server, these must begin with "../". For example, if you have a directory "fonts" under DocumentRoot, then you might specify a font like so:

        ../fonts/arial.ttf

If DocumentRoot happens to be /var/www then the font that will be looked up is /var/www/fonts/arial.ttf.

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, matches are case-insensitive. 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

COLORS

All colors, including those specified for the captionN option, are specified using the colour names from GD::Graph::colour. They are, at time of writing:

white, lgray, gray, dgray, black, lblue, blue, dblue, gold, lyellow, yellow, dyellow, lgreen, green, dgreen, lred, red, dred, lpurple, purple, dpurple, lorange, orange, pink, dpink, marine, cyan, lbrown, dbrown.

IMAGES

You can place a logo in any corner of the graph using the logo, logo_resize and logo_position options. See GD::Graph. 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. GD::Graph 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 GD::Graph(3). 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,$string[,$box_color,$box_offset]) where $fgcolor is the foreground color, $fontname is the name of a TTF font see "FONTS" , $ptsize is the point size, $x and $y are the coordinates, and $string is the actual characters to draw.

$box_color and $box_offset are optional parameters, if set the caption will be drawn with a box around it in that color and that distance from the caption string. The default offset of 9 should work well in most cases.

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

Note: you cannot use builtin GD fonts like gdTinyFont for captions, you have to use a real TTF font.

This uses the GD stringTTF method, see GD. Colour names are indexed using the GD::Graph::colour builtins (see above), fonts are resolved by font path or relative to DocumentRoot, parameters are processed as per "DATA TYPES".

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 "FONTS". Example:

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

To draw the box around the caption as a dashed or dotted line use:

gd_set_style

This option sets the style for the special gdStyled color index. It's simply a list of colors that becomes the pattern for lines and such drawn with it. For example, to get a dashed red line:

        gd_set_style=(red,red,red,red,red,red,
        gdTransparent,gdTransparent,
        gdTransparent,gdTransparent);

The list can be arbitrarily long.

Note: at this time, the only place where you can use colors of this style is for the box around a caption. Just specify gdStyled as the color.

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 GD::Graph(3).

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:jj

DATA TYPES

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.)

../fonts/arial.ttf

Paths following this pattern will be interpreted as paths relative to DocumentRoot of the web server.

gdSmallFont, gdLargeFont, gdMediumBoldFont, gdTinyFont, gdGiantFont, gdStyled, gdBrushed, gdStyledBrushed, gdTransparent

These are reserved strings. If not quoted, they will be converted to the builtin GD constants of the same name. See GD for details.

[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.

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

Variable mapping of x-labels to data points. Better test suite.

SEE ALSO

perl, GD::Graph, GD::Graph::colour, GD

cpanm Apache::GD::Graph

perl -MCPAN -e shell
install Apache::GD::Graph