macOS Don't throw away backingstore buffers when backing properties change

Clients such as QtWidgets that do their own dirty tracking will assume
they can just flush in response to the expose event, without repainting
anything. Since we have no way at the moment to inform these clients that
the backingstore content might be invalid we can't just throw it away.

It turns out that to pick up changes in color spaces we can just tag
the existing buffers with the new color space, so we don't need to
throw it away. And for the older surface-backed mode we tag the color
space on flush, so we didn't need to invalidate anything in the first
place.

Fixes: QTBUG-80844
Task-number: QTBUG-77749
Change-Id: Icb1ceb178894bb43887cdf03fb855d2d614b5ab0
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

0 files changed, 0 insertions, 0 deletions