Create Read-only Base class for GrDrawState that holds data members and getters

src/gpu/GrRODrawState.cpp

Index: src/gpu/GrRODrawState.cpp
diff --git a/src/gpu/GrRODrawState.cpp b/src/gpu/GrRODrawState.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..1460f57320e48e3c56d87278a96941936f66b333
--- /dev/null
+++ b/src/gpu/GrRODrawState.cpp
@@ -0,0 +1,167 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrRODrawState.h"
+#include "GrDrawTargetCaps.h"
+
+////////////////////////////////////////////////////////////////////////////////
+
+bool GrRODrawState::isEqual(const GrRODrawState& that) const {
+    bool usingVertexColors = this->hasColorVertexAttribute();
+    if (!usingVertexColors && this->fColor != that.fColor) {
+        return false;
+    }
+
+    if (this->fRenderTarget.get() != that.fRenderTarget.get() ||
+        this->fColorStages.count() != that.fColorStages.count() ||
+        this->fCoverageStages.count() != that.fCoverageStages.count() ||
+        !this->fViewMatrix.cheapEqualTo(that.fViewMatrix) ||
+        this->fSrcBlend != that.fSrcBlend ||
+        this->fDstBlend != that.fDstBlend ||
+        this->fBlendConstant != that.fBlendConstant ||
+        this->fFlagBits != that.fFlagBits ||
+        this->fVACount != that.fVACount ||
+        memcmp(this->fVAPtr, that.fVAPtr, this->fVACount * sizeof(GrVertexAttrib)) ||
+        this->fStencilSettings != that.fStencilSettings ||
+        this->fDrawFace != that.fDrawFace) {
+        return false;
+    }
+
+    bool usingVertexCoverage = this->hasCoverageVertexAttribute();
+    if (!usingVertexCoverage && this->fCoverage != that.fCoverage) {
+        return false;
+    }
+
+    bool explicitLocalCoords = this->hasLocalCoordAttribute();
+    for (int i = 0; i < this->numColorStages(); i++) {
+        if (!GrEffectStage::AreCompatible(this->getColorStage(i), that.getColorStage(i),
+                                          explicitLocalCoords)) {
+            return false;
+        }
+    }
+    for (int i = 0; i < this->numCoverageStages(); i++) {
+        if (!GrEffectStage::AreCompatible(this->getCoverageStage(i), that.getCoverageStage(i),
+                                          explicitLocalCoords)) {
+            return false;
+        }
+    }
+
+    SkASSERT(this->fVertexSize == that.fVertexSize);
+    SkASSERT(0 == memcmp(this->fFixedFunctionVertexAttribIndices,
+                            that.fFixedFunctionVertexAttribIndices,
+                            sizeof(this->fFixedFunctionVertexAttribIndices)));
+
+    return true;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+bool GrRODrawState::validateVertexAttribs() const {
+    // check consistency of effects and attributes
+    GrSLType slTypes[kMaxVertexAttribCnt];
+    for (int i = 0; i < kMaxVertexAttribCnt; ++i) {
+        slTypes[i] = static_cast<GrSLType>(-1);
+    }
+    int totalStages = this->numTotalStages();
+    for (int s = 0; s < totalStages; ++s) {
+        int covIdx = s - this->numColorStages();
+        const GrEffectStage& stage = covIdx < 0 ? this->getColorStage(s) :
+                                                  this->getCoverageStage(covIdx);
+        const GrEffect* effect = stage.getEffect();
+        SkASSERT(NULL != effect);
+        // make sure that any attribute indices have the correct binding type, that the attrib
+        // type and effect's shader lang type are compatible, and that attributes shared by
+        // multiple effects use the same shader lang type.
+        const int* attributeIndices = stage.getVertexAttribIndices();
+        int numAttributes = stage.getVertexAttribIndexCount();
+        for (int i = 0; i < numAttributes; ++i) {
+            int attribIndex = attributeIndices[i];
+            if (attribIndex >= fVACount ||
+                kEffect_GrVertexAttribBinding != fVAPtr[attribIndex].fBinding) {
+                return false;
+            }
+
+            GrSLType effectSLType = effect->vertexAttribType(i);
+            GrVertexAttribType attribType = fVAPtr[attribIndex].fType;
+            int slVecCount = GrSLTypeVectorCount(effectSLType);
+            int attribVecCount = GrVertexAttribTypeVectorCount(attribType);
+            if (slVecCount != attribVecCount ||
+                (static_cast<GrSLType>(-1) != slTypes[attribIndex] &&
+                    slTypes[attribIndex] != effectSLType)) {
+                return false;
+            }
+            slTypes[attribIndex] = effectSLType;
+        }
+    }
+
+    return true;
+}
+
+bool GrRODrawState::hasSolidCoverage() const {
+    // If we're drawing coverage directly then coverage is effectively treated as color.
+    if (this->isCoverageDrawing()) {
+        return true;
+    }
+
+    GrColor coverage;
+    uint32_t validComponentFlags;
+    // Initialize to an unknown starting coverage if per-vertex coverage is specified.
+    if (this->hasCoverageVertexAttribute()) {
+        validComponentFlags = 0;
+    } else {
+        coverage = fCoverage;
+        validComponentFlags = kRGBA_GrColorComponentFlags;
+    }
+
+    // Run through the coverage stages and see if the coverage will be all ones at the end.
+    for (int s = 0; s < this->numCoverageStages(); ++s) {
+        const GrEffect* effect = this->getCoverageStage(s).getEffect();
+        effect->getConstantColorComponents(&coverage, &validComponentFlags);
+    }
+    return (kRGBA_GrColorComponentFlags == validComponentFlags) && (0xffffffff == coverage);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+bool GrRODrawState::willEffectReadDstColor() const {
+    if (!this->isColorWriteDisabled()) {
+        for (int s = 0; s < this->numColorStages(); ++s) {
+            if (this->getColorStage(s).getEffect()->willReadDstColor()) {
+                return true;
+            }
+        }
+    }
+    for (int s = 0; s < this->numCoverageStages(); ++s) {
+        if (this->getCoverageStage(s).getEffect()->willReadDstColor()) {
+            return true;
+        }
+    }
+    return false;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// Some blend modes allow folding a fractional coverage value into the color's alpha channel, while
+// others will blend incorrectly.
+bool GrRODrawState::canTweakAlphaForCoverage() const {
+    /*
+     The fractional coverage is f.
+     The src and dst coeffs are Cs and Cd.
+     The dst and src colors are S and D.
+     We want the blend to compute: f*Cs*S + (f*Cd + (1-f))D. By tweaking the source color's alpha
+     we're replacing S with S'=fS. It's obvious that that first term will always be ok. The second
+     term can be rearranged as [1-(1-Cd)f]D. By substituting in the various possibilities for Cd we
+     find that only 1, ISA, and ISC produce the correct destination when applied to S' and D.
+     Also, if we're directly rendering coverage (isCoverageDrawing) then coverage is treated as
+     color by definition.
+     */
+    return kOne_GrBlendCoeff == fDstBlend ||
+           kISA_GrBlendCoeff == fDstBlend ||
+           kISC_GrBlendCoeff == fDstBlend ||
+           this->isCoverageDrawing();
+}
+