Posted by Sven Gothel on Jun 29, 2023; 3:17am
URL: https://forum.jogamp.org/GlueGen-Proudly-Beating-Panama-tp4042711p4042718.html

First JavaCallback working draft pushed w/ docs, see git logs and perhaps

- Updated JavaCallback
  https://jogamp.org/gluegen/doc/GlueGen_Mapping.html#java-callback-from-native-c-api-support

- Updated Overview, covering (hopefully) all big bullets - beating Panama ;-)
  https://jogamp.org/gluegen/doc/GlueGen_Mapping.html#overview

Discussion:

Now we have to thing about the practical 'resource mapping',
as mentioned in the remark (*TODO: Refine ownership + release*) in
https://jogamp.org/cgit/gluegen.git/commit/?id=6591f1fef419841660311bbb554aeda7b267c9a7

Here the ownership or mapping of java userParam -> our little native
glue struct-instance.

Questions:
- Some want ThreadLocal?
- Some want a special key like a context?
  - Example: glDebugMessageCallback(..)
- Just some other argument passed to Callback-SetFunc?
  - Example: OpenAL AL_SOFT_callback_buffer extension
- ... you get the idea.

Right now it is sort of global to the binding instance.

Proposal:
One idea is to produce a CallbackFuncTypeUsrKey class,
which gets all Callback-SetFunc arguments funneled via its ctor.
This class may use any of these arguments as its key criteria
plus also use other external criteria like Thread.currentThread().
(Not performance critical here, since Callback-SetFunc gets called rarely).

Key criteria implies implementing the equals() and hashCode() functions
based on said criteria.

Of course, we would produce this class by default and only use the userParam
as key -> no default change.

The user can configure using its own CallbackFuncTypeUsrKey class definition,
where only the ctor must be same, i.e. fed with all Callback-SetFunc arguments.
User would have all freedoms to implement the actual key for the mapping.