I wanted to use other layout engines besides dot(1), so I hacked Graphviz.php to allow a Unix-style interpreter specification for the other rendering engines in Graphviz. This is backwards compatible (since it is a legal dot comment) and avoids coming up with new syntax.
The interpreter spec must immediately follow the opening tag: "<graphviz>#!/sw/bin/neato" for example. I explicitly check for allowed rendering engines to avoid script injection security issues.
Extension at: http://www.Bytesmiths.com/InfoArk/Graphviz.php.gz
Annotated examples at: http://www.IslandSeeds.org/wiki/Test:Graphviz
Enjoy!
PS: It would be nice to have "out of band" communications with extensions, like <graphviz engine="neato">. It could simply bundle up everything it finds in the tag into an associative array. This would be very useful (for example) in text-wrapping, since so many extensions seem to generate images. (<graphviz style="float:right">, for example)
:::: The day Microsoft makes something that doesn't suck is probably the day they start making vacuum cleaners. -- Ernst Jan Plugge :::: Jan Steinman http://www.Bytesmiths.com/Item/98-4882-15