NAME

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">


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_colo
r,$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 ([email protected])

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
<[email protected]>.

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