Implement color filter as GrGLEffect

src/gpu/GrDrawState.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawState.h"
 #include "GrPaint.h"
 
@@ skipping 41 matching lines @@
 
     // Enable the clip bit
     this->enableState(GrDrawState::kClip_StateBit);
 
     this->setColor(paint.getColor());
     this->setCoverage4(paint.getCoverage());
     this->setState(GrDrawState::kDither_StateBit, paint.isDither());
     this->setState(GrDrawState::kHWAntialias_StateBit, paint.isAntiAlias());
 
     this->setBlendFunc(paint.getSrcBlendCoeff(), paint.getDstBlendCoeff());
-    this->setColorFilter(paint.getColorFilterColor(), paint.getColorFilterMode());
     this->setCoverage(paint.getCoverage());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 static size_t vertex_size(const GrVertexAttrib* attribs, int count) {
     // this works as long as we're 4 byte-aligned
 #ifdef SK_DEBUG
     uint32_t overlapCheck = 0;
 #endif
@@ skipping 139 matching lines @@
         validComponentFlags = kRGBA_GrColorComponentFlags;
         color = this->getColor();
     }
 
     // Run through the color stages
     for (int s = 0; s < fColorStages.count(); ++s) {
         const GrEffectRef* effect = fColorStages[s].getEffect();
         (*effect)->getConstantColorComponents(&color, &validComponentFlags);
     }
 
-    // Check if the color filter could introduce an alpha.
-    // We could skip the above work when this is true, but it is rare and the right fix is to make
-    // the color filter a GrEffect and implement getConstantColorComponents() for it.
-    if (SkXfermode::kDst_Mode != this->getColorFilterMode()) {
-        validComponentFlags = 0;
-    }
-
     // Check whether coverage is treated as color. If so we run through the coverage computation.
     if (this->isCoverageDrawing()) {
         GrColor coverageColor = this->getCoverage();
         GrColor oldColor = color;
         color = 0;
         for (int c = 0; c < 4; ++c) {
             if (validComponentFlags & (1 << c)) {
                 U8CPU a = (oldColor >> (c * 8)) & 0xff;
                 U8CPU b = (coverageColor >> (c * 8)) & 0xff;
                 color |= (SkMulDiv255Round(a, b) << (c * 8));
@@ skipping 236 matching lines @@
         fDrawState->fColorStages[s].saveCoordChange(&fSavedCoordChanges[i]);
         fDrawState->fColorStages[s].localCoordChange(coordChangeMatrix);
     }
 
     int numCoverageStages = fDrawState->numCoverageStages();
     for (int s = 0; s < numCoverageStages; ++s, ++i) {
         fDrawState->fCoverageStages[s].saveCoordChange(&fSavedCoordChanges[i]);
         fDrawState->fCoverageStages[s].localCoordChange(coordChangeMatrix);
     }
 }