Add support for reading the dst pixel value in an effect. Use in a new effect for the kDarken xfer …

src/gpu/gl/GrGpuGL_program.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGpuGL.h"
 
 #include "GrEffect.h"
@@ skipping 140 matching lines @@
             SkScalarToFloat(m[SkMatrix::kMPersp2])
         };
         GL_CALL(MatrixMode(GR_GL_PROJECTION));
         GL_CALL(LoadMatrixf(mv));
         fHWPathStencilMatrixState.fViewMatrix = vm;
         fHWPathStencilMatrixState.fRenderTargetSize = size;
         fHWPathStencilMatrixState.fRenderTargetOrigin = rt->origin();
     }
 }
 
-bool GrGpuGL::flushGraphicsState(DrawType type) {
+bool GrGpuGL::flushGraphicsState(DrawType type, const GrDeviceCoordTexture* dstCopy) {
     const GrDrawState& drawState = this->getDrawState();
 
     // GrGpu::setupClipAndFlushState should have already checked this and bailed if not true.
     GrAssert(NULL != drawState.getRenderTarget());
 
     if (kStencilPath_DrawType == type) {
         this->flushPathStencilMatrix();
     } else {
         this->flushMiscFixedFunctionState();
 
         GrBlendCoeff srcCoeff;
         GrBlendCoeff dstCoeff;
         GrDrawState::BlendOptFlags blendOpts = drawState.getBlendOpts(false, &srcCoeff, &dstCoeff);
         if (GrDrawState::kSkipDraw_BlendOptFlag & blendOpts) {
             return false;
         }
 
         const GrEffectStage* stages[GrDrawState::kNumStages];
         for (int i = 0; i < GrDrawState::kNumStages; ++i) {
             stages[i] = drawState.isStageEnabled(i) ? &drawState.getStage(i) : NULL;
         }
         GrGLProgramDesc desc;
         GrGLProgramDesc::Build(this->getDrawState(),
                                kDrawPoints_DrawType == type,
                                blendOpts,
                                srcCoeff,
                                dstCoeff,
                                this,
+                               dstCopy,
                                &desc);
 
         fCurrentProgram.reset(fProgramCache->getProgram(desc, stages));
         if (NULL == fCurrentProgram.get()) {
             GrAssert(!"Failed to create program!");
             return false;
         }
         fCurrentProgram.get()->ref();
 
         GrGLuint programID = fCurrentProgram->programID();
@@ skipping 10 matching lines @@
         if (blendOpts & GrDrawState::kEmitTransBlack_BlendOptFlag) {
             color = 0;
             coverage = 0;
         } else if (blendOpts & GrDrawState::kEmitCoverage_BlendOptFlag) {
             color = 0xffffffff;
             coverage = drawState.getCoverage();
         } else {
             color = drawState.getColor();
             coverage = drawState.getCoverage();
         }
-        fCurrentProgram->setData(this, color, coverage, &fSharedGLProgramState);
+        fCurrentProgram->setData(this, color, coverage, dstCopy, &fSharedGLProgramState);
     }
     this->flushStencil(type);
     this->flushScissor();
     this->flushAAState(type);
 
     GrIRect* devRect = NULL;
     GrIRect devClipBounds;
     if (drawState.isClipState()) {
         this->getClip()->getConservativeBounds(drawState.getRenderTarget(), &devClipBounds);
         devRect = &devClipBounds;
@@ skipping 74 matching lines @@
                          GrGLAttribTypeToLayout(attribType).fCount,
                          GrGLAttribTypeToLayout(attribType).fType,
                          GrGLAttribTypeToLayout(attribType).fNormalized,
                          stride,
                          reinterpret_cast<GrGLvoid*>(
                          vertexOffsetInBytes + vertexAttrib->fOffset));
     }
 
     attribState->disableUnusedAttribArrays(this, usedAttribArraysMask);
 }