Implement support for mixed sampled render targets

src/gpu/GrStencilAndCoverPathRenderer.cpp

Index: src/gpu/GrStencilAndCoverPathRenderer.cpp
diff --git a/src/gpu/GrStencilAndCoverPathRenderer.cpp b/src/gpu/GrStencilAndCoverPathRenderer.cpp
index aed1743af22216864a2aa2382a2ea724cc0c82a9..d1507ed6e552500613d13c21ae4dd21e5ad192f0 100644
--- a/src/gpu/GrStencilAndCoverPathRenderer.cpp
+++ b/src/gpu/GrStencilAndCoverPathRenderer.cpp
@@ -58,9 +58,30 @@ bool GrStencilAndCoverPathRenderer::canDrawPath(const GrDrawTarget* target,
                                                 const SkPath& path,
                                                 const SkStrokeRec& stroke,
                                                 bool antiAlias) const {
-    return !stroke.isHairlineStyle() &&
-           !antiAlias && // doesn't do per-path AA, relies on the target having MSAA
-           pipelineBuilder->getStencil().isDisabled();
+
+    if (stroke.isHairlineStyle()) {
+        return false;
+    }
+    if (!pipelineBuilder->getStencil().isDisabled()) {
+        return false;
+    }
+    if (antiAlias) {
+        // No Xfer processors that might do blending inside the shader.
+        // Coverage modulation for mixed samples is done *after* shading, so blending
+        // must occur in the ROP.
+        // TODO: Update Xfer processors to better support mixed samples.
+        if (GrRenderTarget::kStencil_SampleConfig ==
+            pipelineBuilder->getRenderTarget()->sampleConfig() &&
+            pipelineBuilder->willXPNeedDstCopy(*fGpu->caps(), GrProcOptInfo(), GrProcOptInfo())) {
+            return false;
+        }
+
+        return pipelineBuilder->getRenderTarget()->isMultisampled(
+                   GrRenderTarget::kStencil_BufferBit) &&
+               pipelineBuilder->canTweakAlphaForCoverage();
+    } else {
+        return true; // doesn't do per-path AA, relies on the target having MSAA
+    }
 }
 
 GrPathRenderer::StencilSupport
@@ -101,7 +122,6 @@ bool GrStencilAndCoverPathRenderer::onDrawPath(GrDrawTarget* target,
                                                const SkPath& path,
                                                const SkStrokeRec& stroke,
                                                bool antiAlias) {
-    SkASSERT(!antiAlias);
     SkASSERT(!stroke.isHairlineStyle());
 
     SkASSERT(pipelineBuilder->getStencil().isDisabled());
@@ -160,5 +180,10 @@ bool GrStencilAndCoverPathRenderer::onDrawPath(GrDrawTarget* target,
     }
 
     pipelineBuilder->stencil()->setDisabled();
+    if (antiAlias) {
+        SkASSERT(pipelineBuilder->getRenderTarget()->isMultisampled(
+                     GrRenderTarget::kStencil_BufferBit));
+        pipelineBuilder->enableState(GrPipelineBuilder::kHWAntialias_StateBit);

[Chris Dalton, 2015/04/17 22:05:12]

Sorry, I think I may have misled you about where to put this. We need to enable
kHWAntialias_StateBit *before* this function calls target->drawPath(). Can you
move this 'if' block to the top of the function?

+    }
     return true;
 }