The includes of the system map out the dependencies of the system, which files depend on which, which subsystem depends on which. When working with a system, it's always useful to map out the dependencies before hand.

The software he's created the images for include WordPress, phpBB, and a few frameworks - Symfony, Zend Framework and CakePHP. He used the Inclued and Graphviz software to make the charts.

I wrote this xslt stylesheet to visualize the parse tree of a PHP source code. The stylesheet can actually convert any XML tree to graph in the dot format interpreted by Graphviz.

His code is a simple seven line script that outputs a nice, clean tree structure image of how the process flows. He includes links to all of the source and files he used to create the tree image.

We've had PHP Graphviz support in PEAR for quite a while but only by passing graph description files to graphviz binaries running in seperate processes and by collection their output files later.

Now it is possible to create graphs by adding nodes, edges and node and edge attributes to a graph within PHP itself.

He's even created a trac site for deonstration and downloading of this new bit of functionality. There's also some documentation in a simple manual on the trac pages as well.