Add mixed samples support to XPs

src/gpu/GrXferProcessor.cpp

Index: src/gpu/GrXferProcessor.cpp
diff --git a/src/gpu/GrXferProcessor.cpp b/src/gpu/GrXferProcessor.cpp
index e771f643c7fbfaa46f8348cd2846e6b1e1e29a9a..31ab60661186a2a6dc6f5463f3465138e2487b28 100644
--- a/src/gpu/GrXferProcessor.cpp
+++ b/src/gpu/GrXferProcessor.cpp
@@ -6,17 +6,25 @@
  */
 
 #include "GrXferProcessor.h"
+#include "GrPipelineBuilder.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 GrPipelineBuilder& builder,
+                                 const DstTexture* dstTexture,
+                                 bool willReadDstColor)
     : fWillReadDstColor(willReadDstColor)
+    , fDstReadUsesMixedSamples(willReadDstColor && builder.hasMixedSamples())
     , fReadsCoverage(true)
     , fDstTextureOffset() {
     if (dstTexture && dstTexture->texture()) {
+        SkASSERT(willReadDstColor);
         fDstTexture.reset(dstTexture->texture());
         fDstTextureOffset = dstTexture->offset();
         this->addTextureAccess(&fDstTexture);
@@ -41,12 +49,31 @@ GrXferProcessor::OptFlags GrXferProcessor::getOptimizations(const GrProcOptInfo&
     return flags;
 }
 
+bool GrXferProcessor::hasSecondaryOutput() const {
+    if (!this->willReadDstColor()) {
+        return this->onHasSecondaryOutput();
+    }
+    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 (this->getDstTexture() &&
         kTopLeft_GrSurfaceOrigin == this->getDstTexture()->origin()) {
         key |= 0x2;
     }
+    if (this->dstReadUsesMixedSamples()) {
+        key |= 0x4;
+    }
     b->add32(key);
     this->onGetGLProcessorKey(caps, b);
 }
@@ -160,12 +187,13 @@ SkString GrXferProcessor::BlendInfo::dump() const {
 
 ///////////////////////////////////////////////////////////////////////////////
 
-GrXferProcessor* GrXPFactory::createXferProcessor(const GrProcOptInfo& colorPOI,
+GrXferProcessor* GrXPFactory::createXferProcessor(const GrPipelineBuilder& builder,
+                                                  const GrProcOptInfo& colorPOI,
                                                   const GrProcOptInfo& coveragePOI,
                                                   const DstTexture* dstTexture,
                                                   const GrCaps& caps) const {
 #ifdef SK_DEBUG
-    if (this->willReadDstColor(caps, colorPOI, coveragePOI)) {
+    if (this->willReadDstColor(caps, builder, colorPOI, coveragePOI)) {
         if (!caps.shaderCaps()->dstReadInShaderSupport()) {
             SkASSERT(dstTexture && dstTexture->texture());
         } else {
@@ -174,12 +202,15 @@ GrXferProcessor* GrXPFactory::createXferProcessor(const GrProcOptInfo& colorPOI,
     } else {
         SkASSERT(!dstTexture || !dstTexture->texture()); 
     }
+    SkASSERT(!builder.hasMixedSamples() || caps.shaderCaps()->dualSourceBlendingSupport());
 #endif
-    return this->onCreateXferProcessor(caps, colorPOI, coveragePOI, dstTexture);
+    return this->onCreateXferProcessor(caps, builder, colorPOI, coveragePOI, 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 GrPipelineBuilder& builder,
+                                     const GrProcOptInfo& colorPOI,
+                                     const GrProcOptInfo& coveragePOI) const {
+    return (this->willReadDstColor(caps, builder, colorPOI, coveragePOI) &&
+            !caps.shaderCaps()->dstReadInShaderSupport());
 }