Add Coverage Drawing XP

src/gpu/effects/GrCoverageSetOpXP.h

Index: src/gpu/effects/GrCoverageSetOpXP.h
diff --git a/src/gpu/effects/GrCoverageSetOpXP.h b/src/gpu/effects/GrCoverageSetOpXP.h
new file mode 100644
index 0000000000000000000000000000000000000000..eb1f81d0f90d55995882f23831f10bd70fae5176
--- /dev/null
+++ b/src/gpu/effects/GrCoverageSetOpXP.h
@@ -0,0 +1,109 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrCoverageSetOpXP_DEFINED
+#define GrCoverageSetOpXP_DEFINED
+
+#include "GrTypes.h"
+#include "GrXferProcessor.h"
+#include "SkRegion.h"
+
+class GrInvariantOutput;
+class GrProcOptInfo;
+
+/**
+ * This Xfer Processor is used to blend the coverage together with the Dst given a specific set

[bsalomon, 2014/12/16 17:35:56]

"This xfer processor directly blends the src coverage with the dst using a set
operator. It is useful for rendering coverage masks using CSG. It can optionally
invert the src coverage before applying the set operator." ?

[egdaniel, 2014/12/17 21:12:37]

Done.

+ * operation. This XP will never use the output of the color stages. It is also legal to have the XP
+ * use the inverse coverage (1 - cov) as the Src to the blend instead of simply using coverage.
+ */
+class GrCoverageSetOpXP : public GrXferProcessor {
+public:
+    static GrXferProcessor* Create(SkRegion::Op regionOp, bool invertCoverage) {
+        return SkNEW_ARGS(GrCoverageSetOpXP, (regionOp, invertCoverage));
+    }
+
+    virtual ~GrCoverageSetOpXP();
+
+    virtual const char* name() const { return "Coverage Set Op"; }
+
+    void getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const SK_OVERRIDE;
+
+    GrGLXferProcessor* createGLInstance() const SK_OVERRIDE;
+
+    bool hasSecondaryOutput() const SK_OVERRIDE { return false; }
+
+    GrXferProcessor::OptFlags getOptimizations(const GrProcOptInfo& colorPOI,
+                                               const GrProcOptInfo& coveragePOI,
+                                               bool colorWriteDisabled,
+                                               bool doesStencilWrite,
+                                               GrColor* color,
+                                               const GrDrawTargetCaps& caps) SK_OVERRIDE;
+
+    void getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const SK_OVERRIDE;
+
+    bool invertCoverage() const { return fInvertCoverage; }
+
+private:
+    GrCoverageSetOpXP(SkRegion::Op regionOp, bool fInvertCoverage);
+
+    bool onIsEqual(const GrXferProcessor& xpBase) const SK_OVERRIDE {
+        const GrCoverageSetOpXP& xp = xpBase.cast<GrCoverageSetOpXP>();
+        return (fRegionOp == xp.fRegionOp &&
+                fInvertCoverage == xp.fInvertCoverage);
+    }
+
+    SkRegion::Op fRegionOp;
+    bool         fInvertCoverage;
+
+    typedef GrXferProcessor INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+class GrCoverageSetOpXPFactory : public GrXPFactory {
+public:
+    static GrXPFactory* Create(SkRegion::Op regionOp, bool invertCoverage = false);
+
+    GrXferProcessor* createXferProcessor(const GrProcOptInfo& colorPOI,
+                                         const GrProcOptInfo& coveragePOI) const SK_OVERRIDE;
+
+    bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const SK_OVERRIDE {
+        return false;

[bsalomon, 2014/12/16 17:35:56]

seems like it does, right? It uses the color variants of the blend coeffs, seems
like it'd just work.

[egdaniel, 2014/12/17 21:12:37]

Done.

+    }
+
+    bool canApplyCoverage(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
+                          bool colorWriteDisabled) const SK_OVERRIDE {
+        return true;
+    }
+
+    bool willBlendWithDst(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
+                          bool colorWriteDisabled) const SK_OVERRIDE;
+
+    bool canTweakAlphaForCoverage() const SK_OVERRIDE { return false; }

[bsalomon, 2014/12/16 17:35:56]

can't wait to kill this guy

[egdaniel, 2014/12/17 21:12:37]

you are not alone...

+
+    bool getOpaqueAndKnownColor(const GrProcOptInfo& colorPOI,
+                                const GrProcOptInfo& coveragePOI,
+                                GrColor* solidColor,
+                                uint32_t* solidColorKnownComponents) const SK_OVERRIDE;
+
+private:
+    GrCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage);
+
+    bool onIsEqual(const GrXPFactory& xpfBase) const SK_OVERRIDE {
+        const GrCoverageSetOpXPFactory& xpf = xpfBase.cast<GrCoverageSetOpXPFactory>();
+        return fRegionOp == xpf.fRegionOp;
+    }
+
+    GR_DECLARE_XP_FACTORY_TEST;
+
+    SkRegion::Op fRegionOp;
+    bool         fInvertCoverage;
+
+    typedef GrXPFactory INHERITED;
+};
+#endif
+