[PATCH weston] compositor: automatically set opaque region for color formats

[Bill Spitzak]

Doesn't the compositor have access to what type the surfaces are? It can 
then know the surface is opaque and ignore the opaque region there. Then 
if the client changes back to a non-opaque surface the opaque region is 
unchanged and starts being used again.

I would expect this to be slightly more efficient because the compositor 
will also know that the opaque region is exactly equal to the surface area.

Pekka Paalanen wrote:
> Some color formats are naturally opaque: RGB, XRGB, YUV formats without
> A channel. For these, automatically set the opaque region to whole
> surface.
> 
> Note:
> If a client first sends a buffer with opaque color format, and then
> sends another buffer of the same size but with non-opaque color format,
> the opaque region in the server is no longer what the client expects
> based on protocol: it has been changed from what the client earlier
> specified into whole surface. Therefore this is a protocol change.