Replace GrExtractAlphaFragmentProcessor with DstIn compose processor
Review URL: https://codereview.chromium.org/1347943003
diff --git a/include/gpu/GrFragmentProcessor.h b/include/gpu/GrFragmentProcessor.h
index a5e0d98..4b0e1e1 100644
--- a/include/gpu/GrFragmentProcessor.h
+++ b/include/gpu/GrFragmentProcessor.h
@@ -23,6 +23,16 @@
*/
class GrFragmentProcessor : public GrProcessor {
public:
+ /**
+ * In many instances (e.g. SkShader::asFragmentProcessor() implementations) it is desirable to
+ * only consider the input color's alpha. However, there is a competing desire to have reusable
+ * GrFragmentProcessor subclasses that can be used in other scenarios where the entire input
+ * color is considered. This function exists to filter the input color and pass it to a FP. It
+ * does so by returning a parent FP that multiplies the passed in FPs output by the parent's
+ * input alpha. The passed in FP will not receive an input color.
+ */
+ static const GrFragmentProcessor* MulOuputByInputAlpha(const GrFragmentProcessor*);
+
GrFragmentProcessor()
: INHERITED()
, fUsesLocalCoords(false)