New option for arithmetic mode

src/effects/SkArithmeticMode.cpp

Index: src/effects/SkArithmeticMode.cpp
diff --git a/src/effects/SkArithmeticMode.cpp b/src/effects/SkArithmeticMode.cpp
index 034ea376743d614eb63360bc4ba25717459748e8..41cc2667416e34a572246874d80fc54bdbcfd8d2 100644
--- a/src/effects/SkArithmeticMode.cpp
+++ b/src/effects/SkArithmeticMode.cpp
@@ -22,8 +22,9 @@ static const bool gUseUnpremul = false;
 
 class SkArithmeticMode_scalar : public SkXfermode {
 public:
-    static SkArithmeticMode_scalar* Create(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4) {
-        return SkNEW_ARGS(SkArithmeticMode_scalar, (k1, k2, k3, k4));
+    static SkArithmeticMode_scalar* Create(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
+                                           bool enforcePMColor) {
+        return SkNEW_ARGS(SkArithmeticMode_scalar, (k1, k2, k3, k4, enforcePMColor));
     }
 
     virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
@@ -37,11 +38,12 @@ public:
 #endif
 
 private:
-    SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4) {
+    SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4, bool enforcePMColor) {
         fK[0] = k1;
         fK[1] = k2;
         fK[2] = k3;
         fK[3] = k4;
+        fEnforcePMColor = enforcePMColor;
     }
 
     SkArithmeticMode_scalar(SkReadBuffer& buffer) : INHERITED(buffer) {
@@ -49,6 +51,7 @@ private:
         fK[1] = buffer.readScalar();
         fK[2] = buffer.readScalar();
         fK[3] = buffer.readScalar();
+        fEnforcePMColor = buffer.readBool();
     }
 
     virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE {
@@ -57,8 +60,10 @@ private:
         buffer.writeScalar(fK[1]);
         buffer.writeScalar(fK[2]);
         buffer.writeScalar(fK[3]);
+        buffer.writeBool(fEnforcePMColor);
     }
     SkScalar fK[4];
+    bool fEnforcePMColor;
 
     typedef SkXfermode INHERITED;
 };
@@ -145,11 +150,13 @@ void SkArithmeticMode_scalar::xfer32(SkPMColor dst[], const SkPMColor src[],
             } else {
                 a = arith(k1, k2, k3, k4, SkGetPackedA32(sc), SkGetPackedA32(dc));
                 r = arith(k1, k2, k3, k4, SkGetPackedR32(sc), SkGetPackedR32(dc));
-                r = SkMin32(r, a);
                 g = arith(k1, k2, k3, k4, SkGetPackedG32(sc), SkGetPackedG32(dc));
-                g = SkMin32(g, a);
                 b = arith(k1, k2, k3, k4, SkGetPackedB32(sc), SkGetPackedB32(dc));
-                b = SkMin32(b, a);
+                if (fEnforcePMColor) {
+                    r = SkMin32(r, a);
+                    g = SkMin32(g, a);
+                    b = SkMin32(b, a);
+                }
             }
 
             // apply antialias coverage if necessary
@@ -168,7 +175,7 @@ void SkArithmeticMode_scalar::xfer32(SkPMColor dst[], const SkPMColor src[],
                 g = SkAlphaMul(g, scale);
                 b = SkAlphaMul(b, scale);
             }
-            dst[i] = SkPackARGB32(a, r, g, b);
+            dst[i] = fEnforcePMColor ? SkPackARGB32(a, r, g, b) : SkPackARGB32NoCheck(a, r, g, b);
         }
     }
 }
@@ -178,10 +185,9 @@ void SkArithmeticMode_scalar::toString(SkString* str) const {
     str->append("SkArithmeticMode_scalar: ");
     for (int i = 0; i < 4; ++i) {
         str->appendScalar(fK[i]);
-        if (i < 3) {
-            str->append(" ");
-        }
+        str->append(" ");
     }
+    str->appendS32(fEnforcePMColor ? 1 : 0);
 }
 #endif
 
@@ -198,7 +204,8 @@ static int32_t toDot8(SkScalar x) {
 #endif
 
 SkXfermode* SkArithmeticMode::Create(SkScalar k1, SkScalar k2,
-                                     SkScalar k3, SkScalar k4) {
+                                     SkScalar k3, SkScalar k4,
+                                     bool enforcePMColor) {
     if (fitsInBits(k1, 8) && fitsInBits(k2, 16) &&
         fitsInBits(k2, 16) && fitsInBits(k2, 24)) {
 
@@ -219,7 +226,7 @@ SkXfermode* SkArithmeticMode::Create(SkScalar k1, SkScalar k2,
         return SkNEW_ARGS(SkArithmeticMode_linear, (i2, i3, i4));
 #endif
     }
-    return SkArithmeticMode_scalar::Create(k1, k2, k3, k4);
+    return SkArithmeticMode_scalar::Create(k1, k2, k3, k4, enforcePMColor);
 }
 
 
@@ -242,8 +249,11 @@ public:
 
     virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
 
+    static EffectKey GenKey(const GrDrawEffect&, const GrGLCaps& caps);
+
 private:
     GrGLUniformManager::UniformHandle fKUni;
+    bool fEnforcePMColor;
 
     typedef GrGLEffect INHERITED;
 };
@@ -252,8 +262,10 @@ private:
 
 class GrArithmeticEffect : public GrEffect {
 public:
-    static GrEffectRef* Create(float k1, float k2, float k3, float k4, GrTexture* background) {
-        AutoEffectUnref effect(SkNEW_ARGS(GrArithmeticEffect, (k1, k2, k3, k4, background)));
+    static GrEffectRef* Create(float k1, float k2, float k3, float k4, bool enforcePMColor,
+                               GrTexture* background) {
+        AutoEffectUnref effect(SkNEW_ARGS(GrArithmeticEffect, (k1, k2, k3, k4, enforcePMColor,
+                                                               background)));
         return CreateEffectRef(effect);
     }
 
@@ -271,12 +283,15 @@ public:
     float k2() const { return fK2; }
     float k3() const { return fK3; }
     float k4() const { return fK4; }
+    bool enforcePMColor() const { return fEnforcePMColor; }
 
 private:
     virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
 
-    GrArithmeticEffect(float k1, float k2, float k3, float k4, GrTexture* background);
+    GrArithmeticEffect(float k1, float k2, float k3, float k4, bool enforcePMColor,
+                       GrTexture* background);
     float                       fK1, fK2, fK3, fK4;
+    bool                        fEnforcePMColor;
     GrCoordTransform            fBackgroundTransform;
     GrTextureAccess             fBackgroundAccess;
 
@@ -288,8 +303,8 @@ private:
 ///////////////////////////////////////////////////////////////////////////////
 
 GrArithmeticEffect::GrArithmeticEffect(float k1, float k2, float k3, float k4,
-                                       GrTexture* background)
-  : fK1(k1), fK2(k2), fK3(k3), fK4(k4) {
+                                       bool enforcePMColor, GrTexture* background)
+  : fK1(k1), fK2(k2), fK3(k3), fK4(k4), fEnforcePMColor(enforcePMColor) {
     if (background) {
         fBackgroundTransform.reset(kLocal_GrCoordSet, background);
         this->addCoordTransform(&fBackgroundTransform);
@@ -309,6 +324,7 @@ bool GrArithmeticEffect::onIsEqual(const GrEffect& sBase) const {
            fK2 == s.fK2 &&
            fK3 == s.fK3 &&
            fK4 == s.fK4 &&
+           fEnforcePMColor == s.fEnforcePMColor &&
            backgroundTexture() == s.backgroundTexture();
 }
 
@@ -325,7 +341,8 @@ void GrArithmeticEffect::getConstantColorComponents(GrColor* color, uint32_t* va
 
 GrGLArithmeticEffect::GrGLArithmeticEffect(const GrBackendEffectFactory& factory,
                                            const GrDrawEffect& drawEffect)
-   : INHERITED(factory) {
+   : INHERITED(factory),
+     fEnforcePMColor(true) {
 }
 
 GrGLArithmeticEffect::~GrGLArithmeticEffect() {
@@ -374,7 +391,7 @@ void GrGLArithmeticEffect::emitCode(GrGLShaderBuilder* builder,
     builder->fsCodeAppendf("\t\t%s = clamp(%s, 0.0, 1.0);\n", outputColor, outputColor);
     if (gUseUnpremul) {
         builder->fsCodeAppendf("\t\t%s.rgb *= %s.a;\n", outputColor, outputColor);
-    } else {
+    } else if (fEnforcePMColor) {
         builder->fsCodeAppendf("\t\t%s.rgb = min(%s.rgb, %s.a);\n", outputColor, outputColor, outputColor);
     }
 }
@@ -382,6 +399,17 @@ void GrGLArithmeticEffect::emitCode(GrGLShaderBuilder* builder,
 void GrGLArithmeticEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const GrArithmeticEffect& arith = drawEffect.castEffect<GrArithmeticEffect>();
     uman.set4f(fKUni, arith.k1(), arith.k2(), arith.k3(), arith.k4());
+    fEnforcePMColor = arith.enforcePMColor();
+}
+
+GrGLEffect::EffectKey GrGLArithmeticEffect::GenKey(const GrDrawEffect& drawEffect,
+                                                   const GrGLCaps&) {
+    const GrArithmeticEffect& arith = drawEffect.castEffect<GrArithmeticEffect>();
+    EffectKey key = arith.enforcePMColor() ? 1 : 0;
+    if (arith.backgroundTexture()) {
+        key |= 2;
+    }
+    return key;
 }
 
 GrEffectRef* GrArithmeticEffect::TestCreate(SkRandom* rand,
@@ -392,8 +420,10 @@ GrEffectRef* GrArithmeticEffect::TestCreate(SkRandom* rand,
     float k2 = rand->nextF();
     float k3 = rand->nextF();
     float k4 = rand->nextF();
+    bool enforcePMColor = rand->nextBool();
 
-    AutoEffectUnref gEffect(SkNEW_ARGS(GrArithmeticEffect, (k1, k2, k3, k4, NULL)));
+    AutoEffectUnref gEffect(SkNEW_ARGS(GrArithmeticEffect,
+                                       (k1, k2, k3, k4, enforcePMColor, NULL)));
     return CreateEffectRef(gEffect);
 }
 
@@ -405,6 +435,7 @@ bool SkArithmeticMode_scalar::asNewEffect(GrEffectRef** effect, GrTexture* backg
                                              SkScalarToFloat(fK[1]),
                                              SkScalarToFloat(fK[2]),
                                              SkScalarToFloat(fK[3]),
+                                             fEnforcePMColor,
                                              background);
     }
     return true;