vcl/skia/salbmp.cxx | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
New commits:
commit 9b5a00d2281bebaac5fccfde17de6ca5134fc229
Author: Noel Grandin <noelgran...@collabora.co.uk>
AuthorDate: Fri Oct 27 10:29:20 2023 +0200
Commit: Noel Grandin <noel.gran...@collabora.co.uk>
CommitDate: Fri Oct 27 21:16:30 2023 +0200
fix erase logic in SkiaSalBmp::BlendWith
regression from
commit 81994cb2b8b32453a92bcb011830fcb884f22ff3
Author: Noel Grandin <noelgran...@gmail.com>
Date: Fri Apr 16 20:33:10 2021 +0200
Convert internal vcl bitmap formats transparency->alpha (II)
Change-Id: I5cefa51c96d412f43f73277b590fd861397eb1a3
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/158526
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.gran...@collabora.co.uk>
diff --git a/vcl/skia/salbmp.cxx b/vcl/skia/salbmp.cxx
index 0876efed92ed..44997798db8b 100644
--- a/vcl/skia/salbmp.cxx
+++ b/vcl/skia/salbmp.cxx
@@ -628,7 +628,11 @@ bool SkiaSalBitmap::AlphaBlendWith(const SalBitmap&
rSalBmp)
{
const sal_uInt16 nGrey1 = mEraseColor.GetRed();
const sal_uInt16 nGrey2 = otherBitmap->mEraseColor.GetRed();
- const sal_uInt8 nGrey = static_cast<sal_uInt8>(nGrey1 + nGrey2 -
nGrey1 * nGrey2 / 255);
+ // Awkward calculation because the original used transparency, and to
replicate
+ // the logic we need to translate into transparency, perform the
original logic,
+ // then translate back to alpha.
+ const sal_uInt8 nGrey = static_cast<sal_uInt8>(
+ 255 - ((255 - nGrey1) + (255 - nGrey2) - (255 - nGrey1) * (255 -
nGrey2) / 255));
mEraseColor = Color(nGrey, nGrey, nGrey);
DataChanged();
SAL_INFO("vcl.skia.trace",
