GPU Gradients

src/effects/gradients/SkGradientShaderPriv.h

Index: src/effects/gradients/SkGradientShaderPriv.h
diff --git a/src/effects/gradients/SkGradientShaderPriv.h b/src/effects/gradients/SkGradientShaderPriv.h
index 31cc9f26171c6184b4535004ea1388d2de024bc4..9c534bc9a32764cb18be7bec8f13e30ddedfc5db 100644
--- a/src/effects/gradients/SkGradientShaderPriv.h
+++ b/src/effects/gradients/SkGradientShaderPriv.h
@@ -250,6 +250,19 @@ public:
     const SkMatrix& getMatrix() const { return fMatrix;}
 
     virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
+    
+    enum ColorType{
+        kTwo_ColorType,
+        kThree_ColorType,
+        kTexture_ColorType
+    };
+
+    inline int getNumColors() const { return fNumColors; };

[bsalomon, 2013/08/13 21:07:52]

Do we need fNumColors or can we just store ColorType directly? It seems like the
enum is a bit less misleading... it accurately describes the way color lookup is
implemented while fNumColors is only related to the number of colors (and the t
values...)

+    inline ColorType getColorType() const {
+        if (2 == fNumColors) {return kTwo_ColorType;}
+        else if (3 == fNumColors) {return kThree_ColorType;}
+        else {return kTexture_ColorType;}
+    }
 
 protected:
 
@@ -276,6 +289,7 @@ private:
     int fRow;
     SkMatrix fMatrix;
     bool fIsOpaque;
+    int fNumColors;
 
     typedef GrEffect INHERITED;
 
@@ -299,13 +313,25 @@ protected:
     enum {
         kMatrixKeyBitCnt = GrGLEffectMatrix::kKeyBits,
         kMatrixKeyMask = (1 << kMatrixKeyBitCnt) - 1,
+
+        kTwoColorKey = 2 << kMatrixKeyBitCnt,
+        kThreeColorKey = 3 << kMatrixKeyBitCnt,
+        kColorKeyMask = kThreeColorKey

[bsalomon, 2013/08/13 21:07:52]

maybe kTwoColorKey | kThreeColorKey... I realize that's identical currently, but
it seems like better documentation of  the intent of kColorKeyMask.

[dierk, 2013/08/14 21:33:15]

Done.

     };
 
+    inline GrGradientEffect::ColorType getColorType(EffectKey key){

[bsalomon, 2013/08/13 21:07:52]

static?

[dierk, 2013/08/14 21:33:15]

Done.

+        if (kTwoColorKey == (key & kColorKeyMask)) {
+            return GrGradientEffect::kTwo_ColorType;
+        } else if (kThreeColorKey == (key & kColorKeyMask)) {
+            return GrGradientEffect::kThree_ColorType;
+        } else {return GrGradientEffect::kTexture_ColorType;}
+    }
+    
     /**
      * Subclasses must call this. It will return a value restricted to the lower kMatrixKeyBitCnt
      * bits.
      */
-    static EffectKey GenMatrixKey(const GrDrawEffect&);
+    static EffectKey GenBaseGradientKey(const GrDrawEffect&);
 
     /**
      * Inserts code to implement the GrGradientEffect's matrix. This should be called before a
@@ -323,22 +349,27 @@ protected:
 
     // Emits the uniform used as the y-coord to texture samples in derived classes. Subclasses
     // should call this method from their emitCode().
-    void emitYCoordUniform(GrGLShaderBuilder* builder);
+    void emitUniforms(GrGLShaderBuilder* builder, EffectKey key);
+
 
-    // emit code that gets a fragment's color from an expression for t; for now this always uses the
-    // texture, but for simpler cases we'll be able to lerp. Subclasses should call this method from
-    // their emitCode().
-    void emitColorLookup(GrGLShaderBuilder* builder,
-                         const char* gradientTValue,
-                         const char* outputColor,
-                         const char* inputColor,
-                         const GrGLShaderBuilder::TextureSampler&);
+    // emit code that gets a fragment's color from an expression for t; Has branches for 3 separate
+    // control flows inside -- 2 color gradients, 3 color symmetric gradients (both using
+    // native GLSL mix), and 4+ color gradients that use the traditional texture lookup.
+    void emitColor(GrGLShaderBuilder* builder,
+                   const char* gradientTValue,
+                   EffectKey key,
+                   const char* outputColor,
+                   const char* inputColor,
+                   const GrGLShaderBuilder::TextureSamplerArray& samplers);
 
 private:
     static const GrEffect::CoordsType kCoordsType = GrEffect::kLocal_CoordsType;
 
     SkScalar fCachedYCoord;
     GrGLUniformManager::UniformHandle fFSYUni;
+    GrGLUniformManager::UniformHandle fColorStartUni;
+    GrGLUniformManager::UniformHandle fColorMidUni;
+    GrGLUniformManager::UniformHandle fColorEndUni;
     GrGLEffectMatrix fEffectMatrix;
 
     typedef GrGLEffect INHERITED;