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..d975b4b8517dc46b486f56ea142d452ceb9fb3e0 100644
--- a/include/gpu/GrProcessor.h
+++ b/include/gpu/GrProcessor.h
@@ -37,14 +37,44 @@ public:
 
     virtual ~GrProcessor();
 
+    struct InvarientOutput{

[bsalomon, 2014/09/30 00:41:01]

"Invariant" (gulp)

There might be some more useful helpers for modifying this here:

e.g.:

void mulByUnknownOpaqueColor() {
    if (this->isOpaque()) {
        fValidFlags = kA_GrCCF;
    } else {
        fValidFlags = 0;
    }
    fIsSingleComponent = false;
}

void mulByUnknownColor() {
    // really any mulBy should have this "if"
    if (kA_GrCC && 0 == GrColorUnpackAlpha(fColor)) {
        fValidFlags = kRGBA_GrCCF;
        fColor = 0;
        fIsSingleComponent = true;
    } else {
        fValidFlags = 0;
        fIsSingleComponent = false;
    }
}

void mulByUnknownAlpha() {
   // fIsSingleComponent stays the same
   fValidFlags = 0;
}

void mulByKnownColor(GrColor color)

(I didn't think these through all that thoroughly)

There are probably very few effects that wouldn't be able to share a common
implementation using helpers.

[egdaniel, 2014/10/02 14:58:33]

Fixed speeling
Will work on adding helpers in follow up cl(s)

+        GrColor color;
+        uint32_t validFlags;

[bsalomon, 2014/09/30 00:41:01]

fColor, fValidFlags, fIsSingleComponent

[egdaniel, 2014/10/02 14:58:33]

Done.

+        bool isSingleComponent;
+
+        bool hasOpaqueAlpha() const {

[bsalomon, 2014/09/30 00:41:01]

isOpaque?

[egdaniel, 2014/10/02 14:58:33]

Done.

+            return ((validFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(color));
+        }
+
+        bool hasOpaqueColor() const {
+            return (validFlags == kRGBA_GrColorComponentFlags &&

[bsalomon, 2014/09/30 00:41:01]

isSolidWhite?

[egdaniel, 2014/10/02 14:58:33]

Done.

+                    0xFFFFFFFF == GrColorUnpackA(color));
+        }
+
+        /**
+         * If isSingleComponent is true, then the flag values for r, g, b, and a must all be the
+         * same. If the flags are all set then all color components must be equal.
+         */
+        SkDEBUGCODE(void validate() const;)
+
+    private:
+        SkDEBUGCODE(bool colorComponentsAllEqual() const;)
+    };
+
     /**
-     * This function is used to perform optimizations. When called the color and validFlags params
+     * This function is used to perform optimizations. When called the invarientOuput param
      * 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.
+     * In invarientOutput the validFlags member is a bitfield of GrColorComponentFlags. The
+     * isSingleComponent member indicates whether the input will be 1 or 4 bytes. The function
+     * updates the members of invarientOutput to indicate known values of its output. A component
+     * of the color member only has meaning if the corresponding bit in validFlags is set.
      */
-    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const = 0;
+    void computeInvarientOutput(InvarientOutput* invarientOutput) const {

[bsalomon, 2014/09/30 00:41:01]

Because the param is inout it feels weird to call it the param invariantOutput. 
"inout"? ...

[egdaniel, 2014/10/02 14:58:33]

Done.

+        this->onComputeInvarientOutput(invarientOutput);
+#ifdef SK_DEBUG
+        invarientOutput->validate();
+#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,
@@ -158,6 +188,10 @@ private:
         getFactory()).*/
     virtual bool onIsEqual(const GrProcessor& other) const = 0;
 
+    /** 
+     * Subclass implements this to support getConstantColorComponents(...).
+     */
+    virtual void onComputeInvarientOutput(InvarientOutput* invarientOutput) const = 0;
     friend class GrGeometryProcessor; // to set fRequiresVertexShader and build fVertexAttribTypes.
 
     SkSTArray<4, const GrCoordTransform*, true>  fCoordTransforms;