Check that coverage FPs are compatible with alpha as coverage

Change-Id: Ic3b6a02248d571e82f6729827c199d358fb75114
Reviewed-on: https://skia-review.googlesource.com/8508
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>

6 files changed, 23 insertions, 4 deletions

diff --git a/src/effects/SkRRectsGaussianEdgeMaskFilter.cpp b/src/effects/SkRRectsGaussianEdgeMaskFilter.cpp
index 7635759ca2..b3967ecabb 100644
--- a/src/effects/SkRRectsGaussianEdgeMaskFilter.cpp
+++ b/src/effects/SkRRectsGaussianEdgeMaskFilter.cpp
@@ -206,7 +206,10 @@ public:
     };
 
     RRectsGaussianEdgeFP(const SkRRect& first, const SkRRect& second, SkScalar radius)
-            : INHERITED(kNone_OptimizationFlags), fFirst(first), fSecond(second), fRadius(radius) {
+            : INHERITED(kCompatibleWithCoverageAsAlpha_OptimizationFlag)
+            , fFirst(first)
+            , fSecond(second)
+            , fRadius(radius) {
         this->initClassID<RRectsGaussianEdgeFP>();
 
         fFirstMode = ComputeMode(fFirst);
diff --git a/src/gpu/GrProcOptInfo.h b/src/gpu/GrProcOptInfo.h
index 1a8578980d..ac3cb36966 100644
--- a/src/gpu/GrProcOptInfo.h
+++ b/src/gpu/GrProcOptInfo.h
@@ -26,6 +26,7 @@ public:
 
     GrProcOptInfo(const GrPipelineInput& input) : GrProcOptInfo() {
         fIsLCDCoverage = input.isLCDCoverage();
+        fAllProcessorsCompatibleWithCoverageAsAlpha = !input.isLCDCoverage();
         fIsOpaque = input.isOpaque();
         GrColor color;
         if (input.isConstant(&color)) {
@@ -37,6 +38,7 @@ public:
     void resetToLCDCoverage() {
         *this = GrProcOptInfo();
         fIsLCDCoverage = true;
+        fAllProcessorsCompatibleWithCoverageAsAlpha = false;
     }
 
     void reset(const GrPipelineInput& input) { *this = GrProcOptInfo(input); }
diff --git a/src/gpu/GrRenderTargetOpList.cpp b/src/gpu/GrRenderTargetOpList.cpp
index 69ba279434..b7dd37a922 100644
--- a/src/gpu/GrRenderTargetOpList.cpp
+++ b/src/gpu/GrRenderTargetOpList.cpp
@@ -315,6 +315,14 @@ void GrRenderTargetOpList::addDrawOp(const GrPipelineBuilder& pipelineBuilder,
     if (const GrFragmentProcessor* clipFP = appliedClip.clipCoverageFragmentProcessor()) {
         args.fAnalysis.fCoveragePOI.analyzeProcessors(&clipFP, 1);
     }
+#ifdef SK_DEBUG
+    // Other than tests that exercise atypical behavior we expect all coverage FPs to be compatible
+    // with the coverage-as-alpha optimization.
+    if (!args.fAnalysis.fCoveragePOI.allProcessorsCompatibleWithCoverageAsAlpha() &&
+        !args.fAnalysis.fCoveragePOI.isLCDCoverage()) {
+        GrCapsDebugf(this->caps(), "Coverage FP is not compatible with coverage as alpha.\n");
+    }
+#endif
 
     if (!renderTargetContext->accessRenderTarget()) {
         return;
diff --git a/src/gpu/effects/GrConvexPolyEffect.cpp b/src/gpu/effects/GrConvexPolyEffect.cpp
index 0248beb9ce..838dff8e3a 100644
--- a/src/gpu/effects/GrConvexPolyEffect.cpp
+++ b/src/gpu/effects/GrConvexPolyEffect.cpp
@@ -253,8 +253,12 @@ sk_sp<GrFragmentProcessor> GrConvexPolyEffect::Make(GrPrimitiveEdgeType type, co
             return GrConstColorProcessor::Make(GrColor4f::OpaqueWhite(),
                                                GrConstColorProcessor::kModulateRGBA_InputMode);
         }
+        // This could use kIgnore instead of kModulateRGBA but it would trigger a debug print
+        // about a coverage processor not being compatible with the alpha-as-coverage optimization.
+        // We don't really care about this unlikely case so we just use kModulateRGBA to suppress
+        // the print.
         return GrConstColorProcessor::Make(GrColor4f::TransparentBlack(),
-                                           GrConstColorProcessor::kIgnore_InputMode);
+                                           GrConstColorProcessor::kModulateRGBA_InputMode);
     }
 
     SkVector t;
diff --git a/src/gpu/effects/GrCustomXfermode.cpp b/src/gpu/effects/GrCustomXfermode.cpp
index d7330691ae..36936f8db1 100644
--- a/src/gpu/effects/GrCustomXfermode.cpp
+++ b/src/gpu/effects/GrCustomXfermode.cpp
@@ -300,7 +300,8 @@ GrXferProcessor::OptFlags CustomXP::onGetOptimizations(const GrPipelineAnalysis&
      */
 
     OptFlags flags = kNone_OptFlags;
-    if (analysis.fColorPOI.allProcessorsCompatibleWithCoverageAsAlpha()) {
+    if (analysis.fColorPOI.allProcessorsCompatibleWithCoverageAsAlpha() &&
+        analysis.fCoveragePOI.allProcessorsCompatibleWithCoverageAsAlpha()) {
         flags |= kCanTweakAlphaForCoverage_OptFlag;
     }
     return flags;
diff --git a/src/gpu/effects/GrPorterDuffXferProcessor.cpp b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
index ead4ed6f3f..6b7d0ba025 100644
--- a/src/gpu/effects/GrPorterDuffXferProcessor.cpp
+++ b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
@@ -466,7 +466,8 @@ GrXferProcessor::OptFlags PorterDuffXferProcessor::onGetOptimizations(
             optFlags |= GrXferProcessor::kIgnoreColor_OptFlag;
         }
         if (analysis.fColorPOI.allProcessorsCompatibleWithCoverageAsAlpha() &&
-            fBlendFormula.canTweakAlphaForCoverage() && !analysis.fCoveragePOI.isLCDCoverage()) {
+            analysis.fCoveragePOI.allProcessorsCompatibleWithCoverageAsAlpha() &&
+            fBlendFormula.canTweakAlphaForCoverage()) {
             optFlags |= GrXferProcessor::kCanTweakAlphaForCoverage_OptFlag;
         }
     }