New option for arithmetic mode

src/effects/SkArithmeticMode.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkArithmeticMode.h"
 #include "SkColorPriv.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkString.h"
 #include "SkUnPreMultiply.h"
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "GrCoordTransform.h"
 #include "gl/GrGLEffect.h"
 #include "GrTBackendEffectFactory.h"
 #endif
 
 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 validatePMColor) {
+        return SkNEW_ARGS(SkArithmeticMode_scalar, (k1, k2, k3, k4, validatePMColor));
     }
 
     virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
                         const SkAlpha aa[]) const SK_OVERRIDE;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkArithmeticMode_scalar)
 
 #if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect, GrTexture* background) const SK_OVERRIDE;
 #endif
 
 private:
-    SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4) {
+    SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4, bool validatePMColor) {
         fK[0] = k1;
         fK[1] = k2;
         fK[2] = k3;
         fK[3] = k4;
+        fValidatePMColor = validatePMColor;
     }
 
     SkArithmeticMode_scalar(SkReadBuffer& buffer) : INHERITED(buffer) {
         fK[0] = buffer.readScalar();
         fK[1] = buffer.readScalar();
         fK[2] = buffer.readScalar();
         fK[3] = buffer.readScalar();
+        fValidatePMColor = buffer.readBool();
     }
 
     virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE {
         INHERITED::flatten(buffer);
         buffer.writeScalar(fK[0]);
         buffer.writeScalar(fK[1]);
         buffer.writeScalar(fK[2]);
         buffer.writeScalar(fK[3]);
+        buffer.writeBool(fValidatePMColor);
     }
     SkScalar fK[4];
+    bool fValidatePMColor;
 
     typedef SkXfermode INHERITED;
 };
 
 static int pinToByte(int value) {
     if (value < 0) {
         value = 0;
     } else if (value > 255) {
         value = 255;
     }
@@ skipping 66 matching lines @@
                     }
 
                     a = arith(k1, k2, k3, k4, sa, da);
                     r = arith(k1, k2, k3, k4, sr, dr);
                     g = arith(k1, k2, k3, k4, sg, dg);
                     b = arith(k1, k2, k3, k4, sb, db);
                 }
             } 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 (fValidatePMColor) {
+                    r = SkMin32(r, a);
+                    g = SkMin32(g, a);
+                    b = SkMin32(b, a);
+                }
             }
 
             // apply antialias coverage if necessary
             if (aaCoverage && 0xFF != aaCoverage[i]) {
                 int scale = aaCoverage[i] + (aaCoverage[i] >> 7);
                 a = blend(a, SkGetPackedA32(sc), scale);
                 r = blend(r, SkGetPackedR32(sc), scale);
                 g = blend(g, SkGetPackedG32(sc), scale);
                 b = blend(b, SkGetPackedB32(sc), scale);
             }
 
             // turn the result back into premul
             if (gUseUnpremul && (0xFF != a)) {
                 int scale = a + (a >> 7);
                 r = SkAlphaMul(r, scale);
                 g = SkAlphaMul(g, scale);
                 b = SkAlphaMul(b, scale);
             }
-            dst[i] = SkPackARGB32(a, r, g, b);
+            dst[i] = SkPackARGB32NoCheck(a, r, g, b);

[sugoi1, 2014/03/27 19:07:36]

Is this ok or should I still call SkPackARGB32() when we have fValidatePMColor
set to true?

[Stephen White, 2014/03/27 19:38:16]

Hmm, that's a good point. I guess just to make sure nobody removes the SkMin32()
lines above, doing SkPackARGB32() conditionally on the flag makes sense.

[sugoi1, 2014/04/01 13:42:10]

Done.

         }
     }
 }
 
 #ifndef SK_IGNORE_TO_STRING
 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(fValidatePMColor ? 1 : 0);
 }
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 static bool fitsInBits(SkScalar x, int bits) {
     return SkScalarAbs(x) < (1 << (bits - 1));
 }
 
 #if 0 // UNUSED
 static int32_t toDot8(SkScalar x) {
     return (int32_t)(x * 256);
 }
 #endif
 
 SkXfermode* SkArithmeticMode::Create(SkScalar k1, SkScalar k2,
-                                     SkScalar k3, SkScalar k4) {
+                                     SkScalar k3, SkScalar k4,
+                                     bool validatePMColor) {
     if (fitsInBits(k1, 8) && fitsInBits(k2, 16) &&
         fitsInBits(k2, 16) && fitsInBits(k2, 24)) {
 
 #if 0 // UNUSED
         int32_t i1 = toDot8(k1);
         int32_t i2 = toDot8(k2);
         int32_t i3 = toDot8(k3);
         int32_t i4 = toDot8(k4);
         if (i1) {
             return SkNEW_ARGS(SkArithmeticMode_quad, (i1, i2, i3, i4));
         }
         if (0 == i2) {
             return SkNEW_ARGS(SkArithmeticMode_dst, (i3, i4));
         }
         if (0 == i3) {
             return SkNEW_ARGS(SkArithmeticMode_src, (i2, i4));
         }
         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, validatePMColor);
 }
 
 
 //////////////////////////////////////////////////////////////////////////////
 
 #if SK_SUPPORT_GPU
 
 class GrGLArithmeticEffect : public GrGLEffect {
 public:
     GrGLArithmeticEffect(const GrBackendEffectFactory&, const GrDrawEffect&);
     virtual ~GrGLArithmeticEffect();
 
     virtual void emitCode(GrGLShaderBuilder*,
                           const GrDrawEffect&,
                           EffectKey,
                           const char* outputColor,
                           const char* inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) SK_OVERRIDE;
 
     virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
 
 private:
     GrGLUniformManager::UniformHandle fKUni;
+    bool fValidatePMColor;
 
     typedef GrGLEffect INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 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 validatePMColor,
+                               GrTexture* background) {
+        AutoEffectUnref effect(SkNEW_ARGS(GrArithmeticEffect, (k1, k2, k3, k4, validatePMColor,
+                                                               background)));
         return CreateEffectRef(effect);
     }
 
     virtual ~GrArithmeticEffect();
 
     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
 
     typedef GrGLArithmeticEffect GLEffect;
     static const char* Name() { return "Arithmetic"; }
     GrTexture* backgroundTexture() const { return fBackgroundAccess.getTexture(); }
 
     virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
 
     float k1() const { return fK1; }
     float k2() const { return fK2; }
     float k3() const { return fK3; }
     float k4() const { return fK4; }
+    bool validatePMColor() const { return fValidatePMColor; }
 
 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 validatePMColor,
+                       GrTexture* background);
     float                       fK1, fK2, fK3, fK4;
+    bool                        fValidatePMColor;
     GrCoordTransform            fBackgroundTransform;
     GrTextureAccess             fBackgroundAccess;
 
     GR_DECLARE_EFFECT_TEST;
     typedef GrEffect INHERITED;
 
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrArithmeticEffect::GrArithmeticEffect(float k1, float k2, float k3, float k4,
-                                       GrTexture* background)
-  : fK1(k1), fK2(k2), fK3(k3), fK4(k4) {
+                                       bool validatePMColor, GrTexture* background)
+  : fK1(k1), fK2(k2), fK3(k3), fK4(k4), fValidatePMColor(validatePMColor) {
     if (background) {
         fBackgroundTransform.reset(kLocal_GrCoordSet, background);
         this->addCoordTransform(&fBackgroundTransform);
         fBackgroundAccess.reset(background);
         this->addTextureAccess(&fBackgroundAccess);
     } else {
         this->setWillReadDstColor();
     }
 }
 
 GrArithmeticEffect::~GrArithmeticEffect() {
 }
 
 bool GrArithmeticEffect::onIsEqual(const GrEffect& sBase) const {
     const GrArithmeticEffect& s = CastEffect<GrArithmeticEffect>(sBase);
     return fK1 == s.fK1 &&
            fK2 == s.fK2 &&
            fK3 == s.fK3 &&
            fK4 == s.fK4 &&
+           fValidatePMColor == s.fValidatePMColor &&
            backgroundTexture() == s.backgroundTexture();
 }
 
 const GrBackendEffectFactory& GrArithmeticEffect::getFactory() const {
     return GrTBackendEffectFactory<GrArithmeticEffect>::getInstance();
 }
 
 void GrArithmeticEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
     // TODO: optimize this
     *validFlags = 0;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrGLArithmeticEffect::GrGLArithmeticEffect(const GrBackendEffectFactory& factory,
                                            const GrDrawEffect& drawEffect)
-   : INHERITED(factory) {
+   : INHERITED(factory),
+     fValidatePMColor(true) {
 }
 
 GrGLArithmeticEffect::~GrGLArithmeticEffect() {
 }
 
 void GrGLArithmeticEffect::emitCode(GrGLShaderBuilder* builder,
                                     const GrDrawEffect& drawEffect,
                                     EffectKey key,
                                     const char* outputColor,
                                     const char* inputColor,
@@ skipping 28 matching lines @@
 
     builder->fsCodeAppendf("\t\tvec4 dst = %s;\n", dstColor);
     if (gUseUnpremul) {
         builder->fsCodeAppendf("\t\tdst.rgb = clamp(dst.rgb / dst.a, 0.0, 1.0);\n");
     }
 
     builder->fsCodeAppendf("\t\t%s = %s.x * src * dst + %s.y * src + %s.z * dst + %s.w;\n", outputColor, kUni, kUni, kUni, kUni);
     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 (fValidatePMColor) {
         builder->fsCodeAppendf("\t\t%s.rgb = min(%s.rgb, %s.a);\n", outputColor, outputColor, outputColor);
     }
 }
 
 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());
+    fValidatePMColor = arith.validatePMColor();
 }
 
 GrEffectRef* GrArithmeticEffect::TestCreate(SkRandom* rand,
                                             GrContext*,
                                             const GrDrawTargetCaps&,
                                             GrTexture*[]) {
     float k1 = rand->nextF();
     float k2 = rand->nextF();
     float k3 = rand->nextF();
     float k4 = rand->nextF();
+    bool validatePMColor = rand->nextBool();
 
-    AutoEffectUnref gEffect(SkNEW_ARGS(GrArithmeticEffect, (k1, k2, k3, k4, NULL)));
+    AutoEffectUnref gEffect(SkNEW_ARGS(GrArithmeticEffect,
+                                       (k1, k2, k3, k4, validatePMColor, NULL)));
     return CreateEffectRef(gEffect);
 }
 
 GR_DEFINE_EFFECT_TEST(GrArithmeticEffect);
 
 bool SkArithmeticMode_scalar::asNewEffect(GrEffectRef** effect, GrTexture* background) const {
     if (effect) {
         *effect = GrArithmeticEffect::Create(SkScalarToFloat(fK[0]),
                                              SkScalarToFloat(fK[1]),
                                              SkScalarToFloat(fK[2]),
                                              SkScalarToFloat(fK[3]),
+                                             fValidatePMColor,
                                              background);
     }
     return true;
 }
 
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkArithmeticMode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArithmeticMode_scalar)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END