The cogl_is_* functions were showing up quite high on profiles due to
iterating through arrays of cogl handles.
This does away with all the handle arrays and implements a simple struct
inheritance scheme. All cogl objects now add a CoglHandleObject _parent;
member to their main structures. The base object includes 2 members a.t.m; a
ref_count, and a klass pointer. The klass in turn gives you a type and
virtual function for freeing objects of that type.
Each handle type has a _cogl_##handle_type##_get_type () function
automatically defined which returns a GQuark of the handle type, so now
implementing the cogl_is_* funcs is just a case of comparing with
obj->klass->type.
Another outcome of the re-work is that cogl_handle_{ref,unref} are also much
more efficient, and no longer need extending for each handle type added to
cogl. The cogl_##handle_type##_{ref,unref} functions are now deprecated and
are no longer used internally to Clutter or Cogl. Potentially we can remove
them completely before 1.0.
There is no need for a custom hsl to rgb converter since Clutter implements
this logic; originally it wasn't quite as optimal, but that has now been
fixed.
Using test-cogl-vertex-buffer as a test case which is CPU bound due to
hls -> rgb conversions this alternative algorithm looked to be ~10%
faster when tested on an X61s Lenovo.
The test is a sanity check that dynamic updating of vertex data via the cogl
vertex buffer api works and has reasonable performance. (though it can't be
considered a well designed benchmark since it wastes casual amounts of CPU
time simply choosing pretty colors.)
The code also aims to demonstrate one way of creating, updating and efficiently
drawing a quad mesh structure via the vertex buffer api which could be applied
to lots of different use cases.
