The example call graph on the right shows the main class of phpCallGraph itself and the internal dependencies among its methods. It is also possible to visualize calls to internal functions of PHP and to some extend call dependencies among different classes. Have a look at the example call graphs to get an impression.
The core of the call graph generator forms an object-oriented PHP5 library, which may also be integrated in other projects. It leverages the InstantSVC CodeAnalyzer and DOT. On top of it, a commandline application allows easy creation of call graphs in various formats, e.g. text, png, jpg or svg. phpCallGraph is free software licensed under GPLv3.
I'm developing phpCallGraph just for fun in my spare time and I'm always eger on getting feedback or feature requests. Especially, let me know if you are analyzing any free software, since I collect example call graphs. If you would like to work with the code or test some own visualization ideas, feel free to join the project. I'm happy to give anyone, who is interested, access to the SVN Repository. Just drop me a mail to fakko at users dot sf dot net.
Greetings from Berlin,
Falko