Reimplement fix for tdf#156629 and tdf#156630

Reimplement fix in commit 926c5246b6694d469a6caed5d7ea4c3a68648468
in an attempt to reduce the fix's performance hit. Instead of
invoking EnsureBitmapData() and converting the SkImage to a
memory buffer, any pending scaling on alpha masks is handled by
creating a new, scaled SkImage.

Note that in commit 926c5246b6694d469a6caed5d7ea4c3a68648468,
EnsureBitmapData() was invoked which converted the SkImage to a
memory buffer. That in turn would make Invert() a noop which
fixed the related bug where an image has been opened and, before
it has been printed or run in a slideshow, the alpha mask would
unexpectedly be inverted. So keep this immutable behavior without
calling EnsureBitmapData() by adding a new mutability flag.

Change-Id: I99dc272b40c53664ea49333402a6a637b1548a5f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/155850
Tested-by: Jenkins
Reviewed-by: Patrick Luby <plubius@neooffice.org>

0 files changed, 0 insertions, 0 deletions