Create helper functions to use in computeInvariantOutput calls

include/gpu/GrProcessor.h

Index: include/gpu/GrProcessor.h
diff --git a/include/gpu/GrProcessor.h b/include/gpu/GrProcessor.h
index c1755a895472a9973315de9bc575fc90fb928eca..c8ea02084a1026b45ac8a8aa48d477a559294221 100644
--- a/include/gpu/GrProcessor.h
+++ b/include/gpu/GrProcessor.h
@@ -44,6 +44,45 @@ public:
 
         InvariantOutput() : fColor(0), fValidFlags(0), fIsSingleComponent(false) {}
 
+        void mulByUnknownOpaqueColor() {
+            if (this->isOpaque()) {
+                fValidFlags = kA_GrColorComponentFlag;
+                fIsSingleComponent = false;
+            } else {
+                // Since the current state is not opaque we no longer care if the color being
+                // multiplied is opaque.
+                this->mulByUnknownColor(); 
+            }
+        }
+
+        void mulByUnknownColor() {
+            if (this->hasZeroAlpha()) {
+                this->transparentBlackOutput();
+            } else {
+                this->unknownOutput();
+            }
+        }
+
+        void mulByUnknownAlpha() {
+            if (this->hasZeroAlpha()) {
+                this->transparentBlackOutput();
+            } else {
+                // We don't need to change fIsSingleComponent in this case
+                fValidFlags = 0;
+            }
+        }
+
+        void transparentBlackOutput() {

[bsalomon, 2014/10/10 19:48:16]

setToTransparentBlack() ?

[egdaniel, 2014/10/13 16:44:57]

Done.

+            fValidFlags = kRGBA_GrColorComponentFlags;
+            fColor = 0;
+            fIsSingleComponent = true;
+        }
+
+        void unknownOutput() {

[bsalomon, 2014/10/10 19:48:16]

setUnknownOutput?

(just trying to avoid confusion about whether these are setters or queries)

[egdaniel, 2014/10/13 16:44:57]

Done.

+            fValidFlags = 0;
+            fIsSingleComponent = false;
+        }
+
         bool isOpaque() const {
             return ((fValidFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(fColor));
         }
@@ -59,8 +98,11 @@ public:
         SkDEBUGCODE(void validate() const;)
 
     private:
-        SkDEBUGCODE(bool colorComponentsAllEqual() const;)
+        bool hasZeroAlpha() const {
+            return ((fValidFlags & kA_GrColorComponentFlag) && 0 == GrColorUnpackA(fColor));
+        }
 
+        SkDEBUGCODE(bool colorComponentsAllEqual() const;)
         /**
          * If alpha is valid, check that any valid R,G,B values are <= A
          */