Make skpaint->grpaint flow work for composing draws (verts and atlas)
One side effect is that the SkShader's (or implicit shader's) fragment processor is responsible for the transition from an unpremul paint color to a premul color.
Review URL: https://codereview.chromium.org/1348583002
diff --git a/include/gpu/GrFragmentProcessor.h b/include/gpu/GrFragmentProcessor.h
index 4b0e1e1..776e893 100644
--- a/include/gpu/GrFragmentProcessor.h
+++ b/include/gpu/GrFragmentProcessor.h
@@ -31,7 +31,21 @@
* 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*);
+ static const GrFragmentProcessor* MulOutputByInputAlpha(const GrFragmentProcessor*);
+
+ /**
+ * Similar to the above but it modulates the output r,g,b of the child processor by the input
+ * rgb and then multiplies all the components by the input alpha. This effectively modulates
+ * the child processor's premul color by a unpremul'ed input and produces a premul output
+ */
+ static const GrFragmentProcessor* MulOutputByInputUnpremulColor(const GrFragmentProcessor*);
+
+ /**
+ * Returns a parent fragment processor that adopts the passed fragment processor as a child. The
+ * parent will ignore its input color and instead feed the passed in color as input to the
+ * child.
+ */
+ static const GrFragmentProcessor* OverrideInput(const GrFragmentProcessor*, GrColor);
GrFragmentProcessor()
: INHERITED()