I'm embedding Processing in another environment and want seamless communication with that environment. To achieve this, I want to provide a new predefined variable along the lines of mouseX and mouseY. Let's call this variable 'context', which will provide info about the containing environment. And I'd also like to add more event handlers along the lines of mousePressed() to trigger operations in the sketch when events happen in the containing environment.

Ok, hopefully my goals are clear. I created a subclass of PApplet, let's call it ContextAwarePApplet that provides the featueres I want. I can then export a Processing sketch, and modify the resulting java code to extend from ContextAwarePApplet and then add any logic to use my context features.

This all seems fairly straightforward. Now the real problem is I would like to use my context variable and event handlers in the original Processing sketch code, convert it to Java, automatically modify it to extend from ContextAwarePApplet and any other needed changes, then compile it.

In the processing IDE, I can't export my sketch if I reference the context variable because it doesn't exist in PApplet. It seems like the conversion to Java might work because the error I get is:
processing.app.debug.RunnerException: unexpected token: null
which sounds like it's happening during Runtime of the sketch.

I'm going to start digging into Processing internals to figure out what's going on during export and see if I can hook in somewhere to make this all work end-to-end.

But I was wondering if someone can point me in the right direction to jump-start this project. Maybe point me to another Processing project that does something similar? Or just tell me what classes in the Processing source I will need to work with?

Thanks for any help,
Adam

Indeed, the question belongs more to Integration section, but a moderator will eventually move it, if needed.

I too was thinking about making a library, it is much easier and reliable than altering Processing's source code: see how some libraries, like Video, implement callbacks like movieEvent(). Although no need to make a full fledged library in a separate jar, it can be just some code in your main application.

For example, you import one of your main application classes in your sketch, say ProcessingHandler. You create a method called buttonPressed() in your sketch, and pass this to the ProcessingHandler class which will be able to call your buttonPressed routine each time it is needed.