try to avoid skia alpha blending with fully opaque bitmaps

E.g. the document in tdf#140753 has a PNG which technically has
an alpha channel, but it's actually completely opaque. Doing this
avoids having the pixel data for the separate alpha bitmap, and
it also avoids the pointless (somewhat costly in the raster case)
alpha blending.

Change-Id: I0916962e5894a111002c667a2f98782765aacb1f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111893
Tested-by: Luboš Luňák <l.lunak@collabora.com>
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

0 files changed, 0 insertions, 0 deletions