check to see if CGImage already knows if we're opaque
Review URL: https://codereview.appspot.com/6838043
git-svn-id: http://skia.googlecode.com/svn/trunk@6340 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/ports/SkImageDecoder_CG.cpp b/src/ports/SkImageDecoder_CG.cpp
index ba7a89c..c1b63ea 100644
--- a/src/ports/SkImageDecoder_CG.cpp
+++ b/src/ports/SkImageDecoder_CG.cpp
@@ -87,8 +87,18 @@
CGContextDrawImage(cg, CGRectMake(0, 0, width, height), image);
CGContextRelease(cg);
- // since CGImage won't tell us if it is opaque, we have to compute it.
- bm->computeAndSetOpaquePredicate();
+ CGImageAlphaInfo info = CGImageGetAlphaInfo(image);
+ switch (info) {
+ case kCGImageAlphaNone:
+ case kCGImageAlphaNoneSkipLast:
+ case kCGImageAlphaNoneSkipFirst:
+ SkASSERT(SkBitmap::ComputeIsOpaque(*bm));
+ bm->setIsOpaque(true);
+ break;
+ default:
+ // we don't know if we're opaque or not, so compute it.
+ bm->computeAndSetOpaquePredicate();
+ }
bm->unlockPixels();
return true;
}