Add Arithmetic mode xp.

src/effects/SkArithmeticMode_gpu.h

Index: src/effects/SkArithmeticMode_gpu.h
diff --git a/src/effects/SkArithmeticMode_gpu.h b/src/effects/SkArithmeticMode_gpu.h
index 84b839d2cb8c88745dfe58042a470392385198bc..17116c29be328c7908b55e032773ae78dc2a7edf 100644
--- a/src/effects/SkArithmeticMode_gpu.h
+++ b/src/effects/SkArithmeticMode_gpu.h
@@ -13,8 +13,11 @@
 #include "GrCoordTransform.h"
 #include "GrFragmentProcessor.h"
 #include "GrTextureAccess.h"
+#include "GrTypes.h"
+#include "GrXferProcessor.h"
 
 class GrInvariantOutput;
+class GrProcOptInfo;
 class GrTexture;
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -38,8 +41,6 @@ public:
 
     GrGLFragmentProcessor* createGLInstance() const SK_OVERRIDE;
 
-    GrTexture* backgroundTexture() const { return fBackgroundAccess.getTexture(); }
-
     float k1() const { return fK1; }
     float k2() const { return fK2; }
     float k3() const { return fK3; }
@@ -63,5 +64,121 @@ private:
     typedef GrFragmentProcessor INHERITED;
 };
 
+///////////////////////////////////////////////////////////////////////////////
+// Xfer Processor
+///////////////////////////////////////////////////////////////////////////////
+
+class GrArithmeticXP : public GrXferProcessor {
+public:
+    static GrXferProcessor* Create(float k1, float k2, float k3, float k4, bool enforcePMColor) {
+        return SkNEW_ARGS(GrArithmeticXP, (k1, k2, k3, k4, enforcePMColor));
+    }
+
+    ~GrArithmeticXP() SK_OVERRIDE {};
+
+    const char* name() const SK_OVERRIDE { return "Arithmetic"; }
+
+    void getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const SK_OVERRIDE;
+
+    GrGLXferProcessor* createGLInstance() const SK_OVERRIDE;
+
+    bool hasSecondaryOutput() const SK_OVERRIDE { return false; }
+
+    GrXferProcessor::OptFlags getOptimizations(const GrProcOptInfo& colorPOI,
+                                               const GrProcOptInfo& coveragePOI,
+                                               bool doesStencilWrite,
+                                               GrColor* overrideColor,
+                                               const GrDrawTargetCaps& caps) SK_OVERRIDE;
+
+    void getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const SK_OVERRIDE {
+        blendInfo->fSrcBlend = kOne_GrBlendCoeff;
+        blendInfo->fDstBlend = kZero_GrBlendCoeff;
+        blendInfo->fBlendConstant = 0;
+    }
+
+    float k1() const { return fK1; }
+    float k2() const { return fK2; }
+    float k3() const { return fK3; }
+    float k4() const { return fK4; }
+    bool enforcePMColor() const { return fEnforcePMColor; }
+
+private:
+    GrArithmeticXP(float k1, float k2, float k3, float k4, bool enforcePMColor);
+
+    bool onIsEqual(const GrXferProcessor& xpBase) const SK_OVERRIDE {
+        const GrArithmeticXP& xp = xpBase.cast<GrArithmeticXP>();
+        if (fK1 != xp.fK1 ||
+            fK2 != xp.fK2 ||
+            fK3 != xp.fK3 ||
+            fK4 != xp.fK4 ||
+            fEnforcePMColor != xp.fEnforcePMColor) {
+            return false;
+        }
+        return true;
+    }
+
+    float                       fK1, fK2, fK3, fK4;
+    bool                        fEnforcePMColor;
+
+    typedef GrXferProcessor INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+class GrArithmeticXPFactory : public GrXPFactory {
+public:
+    static GrXPFactory* Create(float k1, float k2, float k3, float k4, bool enforcePMColor) {
+        return SkNEW_ARGS(GrArithmeticXPFactory, (k1, k2, k3, k4, enforcePMColor));
+    }
+
+    GrXferProcessor* createXferProcessor(const GrProcOptInfo& colorPOI,
+                                         const GrProcOptInfo& coveragePOI) const SK_OVERRIDE {
+        return GrArithmeticXP::Create(fK1, fK2, fK3, fK4, fEnforcePMColor);
+    }
+
+    bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const SK_OVERRIDE {
+        return true;
+    }
+
+    bool canApplyCoverage(const GrProcOptInfo& colorPOI,
+                          const GrProcOptInfo& coveragePOI) const SK_OVERRIDE {
+        return true;
+    }
+
+    bool canTweakAlphaForCoverage() const SK_OVERRIDE {
+        return false;
+    }
+
+    void getInvariantOutput(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
+                            GrXPFactory::InvariantOutput*) const SK_OVERRIDE;
+
+    bool willReadDst(const GrProcOptInfo& colorPOI,
+                     const GrProcOptInfo& coveragePOI) const SK_OVERRIDE {
+        return true;
+    }
+
+private:
+    GrArithmeticXPFactory(float k1, float k2, float k3, float k4, bool enforcePMColor); 
+
+    bool onIsEqual(const GrXPFactory& xpfBase) const SK_OVERRIDE {
+        const GrArithmeticXPFactory& xpf = xpfBase.cast<GrArithmeticXPFactory>();
+        if (fK1 != xpf.fK1 ||
+            fK2 != xpf.fK2 ||
+            fK3 != xpf.fK3 ||
+            fK4 != xpf.fK4 ||
+            fEnforcePMColor != xpf.fEnforcePMColor) {
+            return false;
+        }
+        return true;
+    }
+
+    GR_DECLARE_XP_FACTORY_TEST;
+
+    float                       fK1, fK2, fK3, fK4;
+    bool                        fEnforcePMColor;
+
+    typedef GrXPFactory INHERITED;
+};
+
 #endif
 #endif