Implement color filter as GrGLEffect

src/gpu/GrDrawState.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrDrawState_DEFINED
 #define GrDrawState_DEFINED
 
@@ skipping 248 matching lines @@
      *  Sets the color to be used for the next draw to be
      *  (r,g,b,a) = (alpha, alpha, alpha, alpha).
      *
      *  @param alpha The alpha value to set as the color.
      */
     void setAlpha(uint8_t a) {
         this->setColor((a << 24) | (a << 16) | (a << 8) | a);
     }
 
     /**
-     * Add a color filter that can be represented by a color and a mode. Applied
-     * after color-computing effect stages.
-     */
-    void setColorFilter(GrColor c, SkXfermode::Mode mode) {
-        fCommon.fColorFilterColor = c;
-        fCommon.fColorFilterMode = mode;
-    }
-
-    GrColor getColorFilterColor() const { return fCommon.fColorFilterColor; }
-    SkXfermode::Mode getColorFilterMode() const { return fCommon.fColorFilterMode; }
-
-    /**
      * Constructor sets the color to be 'color' which is undone by the destructor.
      */
     class AutoColorRestore : public ::SkNoncopyable {
     public:
         AutoColorRestore() : fDrawState(NULL), fOldColor(0) {}
 
         AutoColorRestore(GrDrawState* drawState, GrColor color) {
             fDrawState = NULL;
             this->set(drawState, color);
         }
@@ skipping 62 matching lines @@
     /// The input color to the first color-stage is either the constant color or interpolated
     /// per-vertex colors. The input to the first coverage stage is either a constant coverage
     /// (usually full-coverage) or interpolated per-vertex coverage.
     ///
     /// See the documentation of kCoverageDrawing_StateBit for information about disabling the
     /// the color / coverage distinction.
     ////
 
     const GrEffectRef* addColorEffect(const GrEffectRef* effect, int attr0 = -1, int attr1 = -1) {
         SkASSERT(NULL != effect);
+        if (!(*effect)->willUseInputColor()) {

[bsalomon, 2013/10/02 16:37:59]

I don't think this is safe because of AutoRestoreEffects(). We either need to
address that, or just keep the effects around and ignore them when we turn this
draw state into a program (skip effects before an effect that ignores its
input).

Also, I think we would want similar logic in addCoverageEffect().

[Kimmo Kinnunen, 2013/10/04 06:21:18]

Done. Not sure the new naming is the best possible, though.

+            fColorStages.reset();
+        }
         SkNEW_APPEND_TO_TARRAY(&fColorStages, GrEffectStage, (effect, attr0, attr1));
         return effect;
     }
 
     const GrEffectRef* addCoverageEffect(const GrEffectRef* effect, int attr0 = -1, int attr1 = -1) {
         SkASSERT(NULL != effect);
         SkNEW_APPEND_TO_TARRAY(&fCoverageStages, GrEffectStage, (effect, attr0, attr1));
         return effect;
     }
 
@@ skipping 535 matching lines @@
             fCommon.fViewMatrix.reset();
         } else {
             fCommon.fViewMatrix = *initialViewMatrix;
         }
         fCommon.fSrcBlend = kOne_GrBlendCoeff;
         fCommon.fDstBlend = kZero_GrBlendCoeff;
         fCommon.fBlendConstant = 0x0;
         fCommon.fFlagBits = 0x0;
         fCommon.fStencilSettings.setDisabled();
         fCommon.fCoverage = 0xffffffff;
-        fCommon.fColorFilterMode = SkXfermode::kDst_Mode;
-        fCommon.fColorFilterColor = 0x0;
         fCommon.fDrawFace = kBoth_DrawFace;
     }
 
     /** Fields that are identical in GrDrawState and GrDrawState::DeferredState. */
     struct CommonState {
         // These fields are roughly sorted by decreasing likelihood of being different in op==
         GrColor               fColor;
         SkMatrix              fViewMatrix;
         GrBlendCoeff          fSrcBlend;
         GrBlendCoeff          fDstBlend;
         GrColor               fBlendConstant;
         uint32_t              fFlagBits;
         const GrVertexAttrib* fVAPtr;
         int                   fVACount;
         GrStencilSettings     fStencilSettings;
         GrColor               fCoverage;
-        SkXfermode::Mode      fColorFilterMode;
-        GrColor               fColorFilterColor;
         DrawFace              fDrawFace;
 
         // This is simply a different representation of info in fVertexAttribs and thus does
         // not need to be compared in op==.
         int fFixedFunctionVertexAttribIndices[kGrFixedFunctionVertexAttribBindingCnt];
 
         bool operator== (const CommonState& other) const {
             bool result = fColor == other.fColor &&
                           fViewMatrix.cheapEqualTo(other.fViewMatrix) &&
                           fSrcBlend == other.fSrcBlend &&
                           fDstBlend == other.fDstBlend &&
                           fBlendConstant == other.fBlendConstant &&
                           fFlagBits == other.fFlagBits &&
                           fVACount == other.fVACount &&
                           !memcmp(fVAPtr, other.fVAPtr, fVACount * sizeof(GrVertexAttrib)) &&
                           fStencilSettings == other.fStencilSettings &&
                           fCoverage == other.fCoverage &&
-                          fColorFilterMode == other.fColorFilterMode &&
-                          fColorFilterColor == other.fColorFilterColor &&
                           fDrawFace == other.fDrawFace;
             SkASSERT(!result || 0 == memcmp(fFixedFunctionVertexAttribIndices,
                                             other.fFixedFunctionVertexAttribIndices,
                                             sizeof(fFixedFunctionVertexAttribIndices)));
             return result;
         }
         bool operator!= (const CommonState& other) const { return !(*this == other); }
     };
 
     /** GrDrawState uses GrEffectStages to hold stage state which holds a ref on GrEffectRef.
@@ skipping 109 matching lines @@
      *  @param count      the number of attributes being set, limited to kMaxVertexAttribCnt.
      */
     void setVertexAttribs(const GrVertexAttrib attribs[], int count);
 
     typedef SkRefCnt INHERITED;
 };
 
 GR_MAKE_BITFIELD_OPS(GrDrawState::BlendOptFlags);
 
 #endif