We know it at begin_frame() time, so if we pass it there instead of
end_frame(), we can use it then to make decisions about opacity.
For example, we could notice that the whole surface is opaque and choose
an RGBx format.
We don't do that yet, but now we could.
By using the inlining macro trick, we can work around deprecation
warnings from removing this function as a public API, which will happen
in the next commits.
... and pass the opaque region of the node.
We don't do anything with it yet, this is just the plumbing.
The original function still exists, it passes NULL which is the value
for no opaque region at all.
Make begin_frame() set a rendering colorstate and depth, and provide it
to the renderers via gdk_draw_context_get_depth() and
gdk_draw_context_get_color_state().
This allows the draw contexts to define their own values, so that ie the
Cairo and GL renderer can choose different settings for rendering (in
particular, GL can choose GL_SRGB and do the srgb conversion; while
Cairo relies on the renderer).
The term "hdr" is so overloaded, we shouldn't use them anywhere, except
from maybe describing all of this work in blog posts and other marketing
materials.
So do renames:
* hdr => high_depth
* request_hdr => prefers_high_depth
This more accurately describes what is going on.
We used to pass 2 regions to GdkDrawCotnext.end_frame() but code was
confusing what they meant. So we now don't do that anymore and only pass
the region that matters: The frame region.
This makes the previous gdk_draw_context_is_drawing() function public
under a new name.
I decided against the old name because we use the term "frame" for a
drawing operation, so I wanted to have this boolean flag reuse the term.
As they require a draw context and the draw context is already bound to
the surface, it makes much more sense and reduces abiguity by moving
these APIs to the draw context.
As a side effect, we simplify GdkSurface APIs to a point where
GdkSurface now does not concern itself with drawing anymore at all,
apart from being the object that creates draw contexts.
... instead of a gl context.
This requires some refactoring in the way we mark the shared context as
drawing: We now call begin_frame/end_frame() on it and ignore the call
on the main context.
Unfortunately we need to do this check in all vfuncs, which sucks. But I
haven't found a better way.
