Add constant color GrFP.

include/gpu/GrInvariantOutput.h

Index: include/gpu/GrInvariantOutput.h
diff --git a/include/gpu/GrInvariantOutput.h b/include/gpu/GrInvariantOutput.h
index 4977333de4e80779432c0eb20289ad5065f47ae3..b70793ddca9b50ba261a162d7133fbf373dc86ea 100644
--- a/include/gpu/GrInvariantOutput.h
+++ b/include/gpu/GrInvariantOutput.h
@@ -116,10 +116,80 @@ public:
                                          SkMulDiv255Round(GrColorUnpackG(fColor), alpha),
                                          SkMulDiv255Round(GrColorUnpackB(fColor), alpha),
                                          SkMulDiv255Round(GrColorUnpackA(fColor), alpha));
+                // We don't need to change fIsSingleComponent in this case
             }
         }
     }
 
+    void mulByKnownFourComponents(GrColor color) {
+        GrColor a = GrColorUnpackA(color);
+        if (a == GrColorUnpackR(color) &&
+            a == GrColorUnpackG(color) &&
+            a == GrColorUnpackB(color)) {
+            this->mulByKnownSingleComponent(a);
+        } else if (0 == color) {

[egdaniel, 2015/03/04 20:22:34]

we definitely don't need the 0 check here since it would get caught above

[bsalomon, 2015/03/31 19:33:42]

Done.

+            this->internalSetToTransparentBlack();
+        } else {
+            if (color != 0xffffffff) {
+                fColor = GrColorPackRGBA(
+                    SkMulDiv255Round(GrColorUnpackR(fColor), GrColorUnpackR(color)),
+                    SkMulDiv255Round(GrColorUnpackG(fColor), GrColorUnpackG(color)),
+                    SkMulDiv255Round(GrColorUnpackB(fColor), GrColorUnpackB(color)),
+                    SkMulDiv255Round(GrColorUnpackA(fColor), GrColorUnpackA(color)));
+                    if (kRGBA_GrColorComponentFlags == fValidFlags) {
+                        GrColor a = GrColorUnpackA(fColor);
+                        fIsSingleComponent = a == GrColorUnpackR(fColor) &&
+                                             a == GrColorUnpackG(fColor) &&
+                                             a == GrColorUnpackB(fColor);
+                    }
+            }
+        }
+    }
+
+    // Ignores the incoming color's RGB and muls its alpha by color.
+    void mulAlphaByKnownFourComponents(GrColor color) {
+        GrColor a = GrColorUnpackA(color);
+        if (a == GrColorUnpackR(color) &&
+            a == GrColorUnpackG(color) &&
+            a == GrColorUnpackB(color)) {
+            this->mulAlphaByKnownSingleComponent(a);
+        } else if (0 == color) {

[egdaniel, 2015/03/04 20:22:34]

same as above.

[bsalomon, 2015/03/31 19:33:42]

Done.

+            this->internalSetToTransparentBlack();
+        } else if (fValidFlags & kA_GrColorComponentFlag) {
+            GrColor alpha = GrColorUnpackA(fColor);
+            if (0 == alpha) {
+                this->internalSetToTransparentBlack();
+            } else {
+                fColor = GrColorPackRGBA(
+                    SkMulDiv255Round(alpha, GrColorUnpackR(color)),
+                    SkMulDiv255Round(alpha, GrColorUnpackG(color)),
+                    SkMulDiv255Round(alpha, GrColorUnpackB(color)),
+                    SkMulDiv255Round(alpha, GrColorUnpackA(color)));
+                fValidFlags = kRGBA_GrColorComponentFlags;
+            }
+        } else {
+            fValidFlags = 0;
+        }
+    }
+
+    // Ignores the incoming color's RGB and muls its alpha by the alpha param and sets all channels
+    // equal to that value.
+    void mulAlphaByKnownSingleComponent(uint8_t alpha) {
+        if (0 == alpha || 0 == this->hasZeroAlpha()) {
+            this->internalSetToTransparentBlack();
+        } else {
+            if (fValidFlags & kA_GrColorComponentFlag) {
+                GrColor a = GrColorUnpackA(fColor);
+                a = SkMulDiv255Round(alpha, a);
+                fColor = GrColorPackRGBA(a, a, a, a);
+                fValidFlags = kRGBA_GrColorComponentFlags;
+            } else {
+                fValidFlags = 0;
+            }
+            fIsSingleComponent = true;
+        }
+    }
+
     void invalidateComponents(uint8_t invalidateFlags, ReadInput readsInput) {
         fValidFlags &= ~invalidateFlags;
         fIsSingleComponent = false;