Add isSingleComponent bool to getConstantColorComponent

include/gpu/GrProcessor.h

Index: include/gpu/GrProcessor.h
diff --git a/include/gpu/GrProcessor.h b/include/gpu/GrProcessor.h
index 7053872bbe4a75d6e0039c0c646daf00af8043a9..3060b2bdf78bc25d07e1cba636c55ac5d8e82f36 100644
--- a/include/gpu/GrProcessor.h
+++ b/include/gpu/GrProcessor.h
@@ -40,11 +40,19 @@ public:
     /**
      * This function is used to perform optimizations. When called the color and validFlags params
      * indicate whether the input components to this effect in the FS will have known values.
-     * validFlags is a bitfield of GrColorComponentFlags. The function updates both params to
-     * indicate known values of its output. A component of the color param only has meaning if the
-     * corresponding bit in validFlags is set.
+     * validFlags is a bitfield of GrColorComponentFlags. The isSingleComponent param indicates
+     * whether the input will be 1 or 4 bytes. The function updates all params to indicate known
+     * values of its output. A component of the color param only has meaning if the corresponding
+     * bit in validFlags is set. If an effect sets isSingleComponent to true, then validFlags must
+     * be all 1's or all 0's. If it is all 1's then all color components must be equal.

[bsalomon, 2014/09/29 15:28:04]

all 1's isn't quit right (since this is a uint32_t).

"...then the flag value for r,g,b, and a must all be the same. If the flags are
set then ..."?

[egdaniel, 2014/09/29 15:50:20]

Done.

      */
-    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const = 0;
+    void getConstantColorComponents(GrColor* color, uint32_t* validFlags,
+                                    bool* isSingleComponent) const {
+        this->onGetConstantColorComponents(color, validFlags, isSingleComponent);
+#ifdef SK_DEBUG
+        this->validateComponents(*color, *validFlags, *isSingleComponent);
+#endif
+    }
 
     /** This object, besides creating back-end-specific helper objects, is used for run-time-type-
         identification. The factory should be an instance of templated class,
@@ -153,11 +161,19 @@ protected:
 private:
     SkDEBUGCODE(void assertEquality(const GrProcessor& other) const;)
 
+    SkDEBUGCODE(void validateComponents(GrColor color, uint32_t validFlags,
+                                        bool isSingleComponent) const;)
+
     /** Subclass implements this to support isEqual(). It will only be called if it is known that
         the two effects are of the same subclass (i.e. they return the same object from
         getFactory()).*/
     virtual bool onIsEqual(const GrProcessor& other) const = 0;
 
+    /** 
+     * Subclass implements this to support getConstantColorComponents(...).
+     */
+    virtual void onGetConstantColorComponents(GrColor* color, uint32_t* validFlags,
+                                              bool* isSingleComponent) const = 0;
     friend class GrGeometryProcessor; // to set fRequiresVertexShader and build fVertexAttribTypes.
 
     SkSTArray<4, const GrCoordTransform*, true>  fCoordTransforms;