single-pixel-buffer: new protocol

This protocol allows creating single-pixel buffers. It can be useful to avoid having to allocate a real buffer just to fill it with the same pixel value. Some use-cases include drawing background surfaces or toplevel decorations.

Signed-off-by: Simon Ser contact@emersion.fr

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• Reviewer: @daniels
• 3 ACKs:
  • @emersion for wlroots
  • @daniels for Weston
  • @jadahl for Mutter
• 3 implementations:
  • wlroots: wlroots/wlroots!3428 (merged)
  • Mutter: https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2246
  • Weston: weston!769 (merged)
  • swaybg: https://github.com/swaywm/swaybg/pull/43
  • mpv: https://github.com/mpv-player/mpv/pull/10265
  • gstreamer: gstreamer/gstreamer!2662 (merged)