Support Processing libraries

[gaocegege]

ref https://forum.processing.org/two/discussion/comment/97845/#Comment_97845

And, before implementing new features in Processing, the mode should look (someday, in the future) at how renjin imports Java libraries -- no need to reinvent the wheel of plotting.

The experience of the Processing.py mode with Java-libraries-in-Jython seems to have been this: Some Processing(Java) libraries worked without needing changes. Others required minor changes. Others needed a full separate version of the library or would not work at all.

[jeremydouglass]

For reference, this is how library Processing.py / Jython handles importing native Processing(Java) libraries.

https://github.com/jdf/processing.py/blob/master/runtime/src/jycessing/LibraryImporter.java

It looks quite complex -- I believe because a lot seems to be about auto-discovering non-jar resources.

The renjin documentation starting point for import() seems to be Ch5, p27: Importing Java Classes Into R Code:

https://media.readthedocs.org/pdf/renjin/latest/renjin.pdf#page31

I wonder if some very widely used Processing libraries are already importable and already work out-of-the-box, without changes to the renjin import mechanism.

[jeremydouglass]

Per our discussion: an example of a popular 3rd-party Processing library:

• http://mrfeinberg.com/peasycam/
• https://github.com/jdf/peasycam

Built-in libraries to consider starting with for testing:

• https://processing.org/reference/libraries/video/index.html
• https://processing.org/reference/libraries/pdf/index.html
• https://processing.org/reference/libraries/serial/index.html

[gaocegege]

Now Processing.R supports libraries in PDE, for example, https://github.com/jdf/peasycam.

But it fails in Runner because of the libraries discovery in standalone sketch.

[jeremydouglass]

Initial library discovery work done in #133

[gaocegege]

The ad-hoc code has been fixed in #137

[gaocegege]

We need to test more libraries to test if the feature works well