avoid crash if DrawTransformedBitmap() would mean empty Skia bitmap
I can reproduce this sometimes with the document from tdf#136223.
Change-Id: Ie6e57f18936a5de7f99ab01932be229625b737c1
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/103596
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>
diff --git a/vcl/skia/gdiimpl.cxx b/vcl/skia/gdiimpl.cxx
index 0fff877..ade34a6 100644
--- a/vcl/skia/gdiimpl.cxx
+++ b/vcl/skia/gdiimpl.cxx
@@ -1484,6 +1484,8 @@ sk_sp<SkImage> SkiaSalGraphicsImpl::mergeCacheBitmaps(const SkiaSalBitmap& bitma
// GPU-accelerated drawing with SkShader should be fast enough to not need caching.
if (isGPU())
return image;
if (targetSize.IsEmpty())
return image;
if (alphaBitmap && alphaBitmap->IsFullyOpaqueAsAlpha())
alphaBitmap = nullptr; // the alpha can be ignored
// Probably not much point in caching of just doing a copy.
