Add constant color GrFP.

src/gpu/effects/GrConstColorProcessor.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "effects/GrConstColorProcessor.h"
+#include "gl/GrGLProcessor.h"
+#include "gl/GrGLSL.h"
+#include "gl/builders/GrGLProgramBuilder.h"
+
+class GLConstColorProcessor : public GrGLFragmentProcessor {
+public:
+    GLConstColorProcessor() : fPrevColor(GrColor_ILLEGAL) {}
+
+    void emitCode(GrGLFPBuilder* builder,
+                  const GrFragmentProcessor& fp,
+                  const char* outputColor,
+                  const char* inputColor,
+                  const TransformedCoordsArray& coords,
+                  const TextureSamplerArray& samplers) override {
+        GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+        const char* colorUni;
+        fColorUniform = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
+                                            kVec4f_GrSLType, kMedium_GrSLPrecision, "constantColor",
+                                            &colorUni);
+        switch (fp.cast<GrConstColorProcessor>().inputMode()) {
+            case GrConstColorProcessor::kIgnore_InputMode:
+                fsBuilder->codeAppendf("%s = %s;", outputColor, colorUni);
+                break;
+            case GrConstColorProcessor::kModulateRGBA_InputMode:
+                fsBuilder->codeAppendf("%s = %s * %s;", outputColor, inputColor, colorUni);
+                break;
+            case GrConstColorProcessor::kModulateA_InputMode:
+                fsBuilder->codeAppendf("%s = %s.a * %s;", outputColor, inputColor, colorUni);
+                break;
+        }
+    }
+
+    void setData(const GrGLProgramDataManager& pdm, const GrProcessor& processor) override {
+        GrColor color = processor.cast<GrConstColorProcessor>().color();
+        // We use the "illegal" color value as an uninit sentinel. However, ut isn't inherently
+        // illegal to use this processor with unpremul colors. So we correctly handle the case
+        // when the "illegal" color is used but we will always upload it.
+        if (GrColor_ILLEGAL == color || fPrevColor != color) {
+            static const GrGLfloat scale = 1.f / 255.f;
+            GrGLfloat floatColor[4] = {
+                GrColorUnpackR(color) * scale,
+                GrColorUnpackG(color) * scale,
+                GrColorUnpackB(color) * scale,
+                GrColorUnpackA(color) * scale,
+            };
+            pdm.set4fv(fColorUniform, 1, floatColor);
+            fPrevColor = color;
+        }
+    }
+
+private:
+    GrGLProgramDataManager::UniformHandle fColorUniform;
+    GrColor                               fPrevColor;
+
+    typedef GrGLFragmentProcessor INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+void GrConstColorProcessor::onComputeInvariantOutput(GrInvariantOutput* inout) const {
+    if (kIgnore_InputMode == fMode) {
+        inout->setToOther(kRGBA_GrColorComponentFlags, fColor, GrInvariantOutput::kWill_ReadInput);
+    } else {
+        GrColor r = GrColorUnpackR(fColor);
+        bool colorIsSingleChannel = r == GrColorUnpackG(fColor) && r == GrColorUnpackB(fColor) &&
+                                    r == GrColorUnpackA(fColor);
+        if (kModulateRGBA_InputMode == fMode) {
+            if (colorIsSingleChannel) {
+                inout->mulByKnownSingleComponent(r);
+            } else {
+                inout->mulByKnownFourComponents(fColor);
+            }
+        } else {
+            if (colorIsSingleChannel) {
+                inout->mulAlphaByKnownSingleComponent(r);
+            } else {
+                inout->mulAlphaByKnownFourComponents(fColor);
+            }
+        }
+    }
+}
+
+void GrConstColorProcessor::getGLProcessorKey(const GrGLCaps&, GrProcessorKeyBuilder* b) const {
+    b->add32(fMode);
+}
+
+GrGLFragmentProcessor* GrConstColorProcessor::createGLInstance() const  {
+    return SkNEW(GLConstColorProcessor);
+}
+
+bool GrConstColorProcessor::onIsEqual(const GrFragmentProcessor& other) const {
+    const GrConstColorProcessor& that = other.cast<GrConstColorProcessor>();
+    return fMode == that.fMode && fColor == that.fColor;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrConstColorProcessor);
+
+GrFragmentProcessor* GrConstColorProcessor::TestCreate(SkRandom* random,
+                                                       GrContext*,
+                                                       const GrDrawTargetCaps&,
+                                                       GrTexture*[]) {
+    GrColor color;
+    int colorPicker = random->nextULessThan(3);
+    switch (colorPicker) {
+        case 0: {
+            uint32_t a = random->nextULessThan(0x100);
+            uint32_t r = random->nextULessThan(a+1);
+            uint32_t g = random->nextULessThan(a+1);
+            uint32_t b = random->nextULessThan(a+1);
+            color = GrColorPackRGBA(r, g, b, a);
+            break;
+        }
+        case 1:
+            color = 0;
+            break;
+        case 2:
+            color = random->nextULessThan(0x100);
+            color = color | (color << 8) | (color << 16) | (color << 24);
+            break;
+    }
+    InputMode mode = static_cast<InputMode>(random->nextULessThan(kInputModeCnt));
+    return GrConstColorProcessor::Create(color, mode);
+}