Add mixed samples support to XPs

src/gpu/GrXferProcessor.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrXferProcessor.h"
+#include "GrPipelineBuilder.h"
 #include "GrProcOptInfo.h"
 #include "gl/GrGLCaps.h"
 
 GrXferProcessor::GrXferProcessor()
-    : fWillReadDstColor(false), fReadsCoverage(true), fDstTextureOffset() {
+    : fWillReadDstColor(false)
+    , fDstReadUsesMixedSamples(false)
+    , fReadsCoverage(true)
+    , fDstTextureOffset() {
 }
 
-GrXferProcessor::GrXferProcessor(const DstTexture* dstTexture, bool willReadDstColor)
+GrXferProcessor::GrXferProcessor(const DstTexture* dstTexture,
+                                 bool willReadDstColor,
+                                 bool hasMixedSamples)
     : fWillReadDstColor(willReadDstColor)
+    , fDstReadUsesMixedSamples(willReadDstColor && hasMixedSamples)
     , fReadsCoverage(true)
     , fDstTextureOffset() {
     if (dstTexture && dstTexture->texture()) {
         SkASSERT(willReadDstColor);
         fDstTexture.reset(dstTexture->texture());
         fDstTextureOffset = dstTexture->offset();
         this->addTextureAccess(&fDstTexture);
         this->setWillReadFragmentPosition();
     }
 }
@@ skipping 19 matching lines @@
     if (flags & GrXferProcessor::kIgnoreCoverage_OptFlag) {
         fReadsCoverage = false;
     }
     return flags;
 }
 
 bool GrXferProcessor::hasSecondaryOutput() const {
     if (!this->willReadDstColor()) {
         return this->onHasSecondaryOutput();
     }
-    return false;
+    return this->dstReadUsesMixedSamples();
 }
 
 void GrXferProcessor::getBlendInfo(BlendInfo* blendInfo) const {
     blendInfo->reset();
     if (!this->willReadDstColor()) {
         this->onGetBlendInfo(blendInfo);
+    } else if (this->dstReadUsesMixedSamples()) {
+        blendInfo->fDstBlend = kIS2A_GrBlendCoeff;
     }
 }
 
 void GrXferProcessor::getGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
     uint32_t key = this->willReadDstColor() ? 0x1 : 0x0;
     if (key) {
         if (const GrTexture* dstTexture = this->getDstTexture()) {
             key |= 0x2;
             if (kTopLeft_GrSurfaceOrigin == dstTexture->origin()) {
                 key |= 0x4;
             }
         }
         if (this->readsCoverage()) {
             key |= 0x8;
         }
+        if (this->dstReadUsesMixedSamples()) {
+            key |= 0x10;
+        }
     }
     b->add32(key);
     this->onGetGLProcessorKey(caps, b);
 }
 
 bool GrXferProcessor::willNeedXferBarrier(const GrRenderTarget* rt,
                                           const GrCaps& caps,
                                           GrXferBarrierType* outBarrierType) const {
     if (static_cast<const GrSurface*>(rt) == this->getDstTexture()) {
         // Texture barriers are required when a shader reads and renders to the same texture.
@@ skipping 96 matching lines @@
                fWriteColor, equation_string(fEquation), coeff_string(fSrcBlend),
                coeff_string(fDstBlend), fBlendConstant);
     return out;
 }
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrXferProcessor* GrXPFactory::createXferProcessor(const GrProcOptInfo& colorPOI,
                                                   const GrProcOptInfo& coveragePOI,
+                                                  bool hasMixedSamples,
                                                   const DstTexture* dstTexture,
                                                   const GrCaps& caps) const {
 #ifdef SK_DEBUG
-    if (this->willReadDstColor(caps, colorPOI, coveragePOI)) {
+    if (this->willReadDstColor(caps, colorPOI, coveragePOI, hasMixedSamples)) {
         if (!caps.shaderCaps()->dstReadInShaderSupport()) {
             SkASSERT(dstTexture && dstTexture->texture());
         } else {
             SkASSERT(!dstTexture || !dstTexture->texture()); 
         }
     } else {
         SkASSERT(!dstTexture || !dstTexture->texture()); 
     }
+    SkASSERT(!hasMixedSamples || caps.shaderCaps()->dualSourceBlendingSupport());
 #endif
-    return this->onCreateXferProcessor(caps, colorPOI, coveragePOI, dstTexture);
+    return this->onCreateXferProcessor(caps, colorPOI, coveragePOI, hasMixedSamples, dstTexture);
 }
 
-bool GrXPFactory::willNeedDstTexture(const GrCaps& caps, const GrProcOptInfo& colorPOI,
-                                    const GrProcOptInfo& coveragePOI) const {
-    return (this->willReadDstColor(caps, colorPOI, coveragePOI) 
-            && !caps.shaderCaps()->dstReadInShaderSupport());
+bool GrXPFactory::willNeedDstTexture(const GrCaps& caps,
+                                     const GrProcOptInfo& colorPOI,
+                                     const GrProcOptInfo& coveragePOI,
+                                     bool hasMixedSamples) const {
+    return (this->willReadDstColor(caps, colorPOI, coveragePOI, hasMixedSamples) &&
+            !caps.shaderCaps()->dstReadInShaderSupport());
 }