protocol: Add wl_surface.damage_buffer
wl_surface.damage uses surface local co-ordinates. Buffer scale and buffer transforms came along, and EGL surfaces have no understanding of them. Theoretically, clients pass damage rectangles - in Y-inverted surface co-ordinates) to EGLSwapBuffersWithDamage, and the EGL implementation passed them on to wayland. However, for this to work the EGL implementation must be able to flip those rectangles into the space the compositor is expecting, but it's unable to do so because it doesn't know the height of the transformed buffer. So, currently, EGLSwapBuffersWithDamage is unusable and EGLSwapBuffers has to pass (0,0) - (INT32_MAX, INT32_MAX) damage to function. wl_surface.damage_buffer allows damage to be registered on a surface in buffer co-ordinates, avoiding this problem. Credit where it's due, these ideas are not entirely my own: Over a year ago the idea of changing damage co-ordinates to buffer co-ordinates was suggested (by Jason Ekstrand), and it was at least partially rejected and abandoned. At the time it was also suggested (by Pekka Paalanen) that adding a new wl_surface.damage_buffer request was another option. This will eventually resolve: https://bugs.freedesktop.org/show_bug.cgi?id=78190 by making the problem irrelevant. Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk> Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> Signed-off-by: Derek Foreman <derekf@osg.samsung.com> Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
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