Convert animated unpremul images to premul during decode (#8698)

brianosman · web-flow · commit 098ada53988b · 2019-04-23T13:47:23.000-04:00
Skia allows drawing unpremul images, but filtering them can look bad. Internally Skia performs this transformation when creating SkImages from encoded data (so this already happens for MakeCrossContextFromEncoded), and for consistency/quality it should be done here, too. Fixes #28785
diff --git a/lib/ui/painting/codec.cc b/lib/ui/painting/codec.cc
@@ -401,7 +401,10 @@ sk_sp<SkImage> MultiFrameCodec::GetNextFrameImage(
                         : SkBitmap();
   const bool frameAlreadyCached = bitmap.getPixels();
   if (!frameAlreadyCached) {
-    const SkImageInfo info = codec_->getInfo().makeColorType(kN32_SkColorType);
+    SkImageInfo info = codec_->getInfo().makeColorType(kN32_SkColorType);
+    if (info.alphaType() == kUnpremul_SkAlphaType) {
+      info = info.makeAlphaType(kPremul_SkAlphaType);
+    }
     bitmap.allocPixels(info);
 
     SkCodec::Options options;
