Add constant color GrFP.

src/gpu/effects/GrColorProcessor.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/GrColorProcessor.h"
+#include "gl/GrGLProcessor.h"
+#include "gl/GrGLSL.h"
+#include "gl/builders/GrGLProgramBuilder.h"
+
+class GrGLColorProcessor : public GrGLFragmentProcessor {
+public:
+    GrGLColorProcessor() : fPrevColor(GrColor_ILLEGAL) {}
+
+    void emitCode(GrGLFPBuilder* builder,
+                  const GrFragmentProcessor& fp,
+                  const char* outputColor,
+                  const char* inputColor,
+                  const TransformedCoordsArray& coords,
+                  const TextureSamplerArray& samplers) SK_OVERRIDE {
+        GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+        const char* colorUni;
+        fColorUniform = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
+                                            kVec4f_GrSLType, kMedium_GrSLPrecision, "constantColor",
+                                            &colorUni);
+        switch (fp.cast<GrColorProcessor>().inputMode()) {
+            case GrColorProcessor::kIgnore_InputMode:
+                fsBuilder->codeAppendf("%s = %s;", outputColor, colorUni);
+                break;
+            case GrColorProcessor::kModulateRGBA_InputMode:
+                fsBuilder->codeAppendf("%s = %s * %s;", outputColor, inputColor, colorUni);
+                break;
+            case GrColorProcessor::kModulateA_InputMode:
+                fsBuilder->codeAppendf("%s = %s.a * %s;", outputColor, inputColor, colorUni);
+                break;
+        }
+    }
+
+    void setData(const GrGLProgramDataManager& pdm, const GrProcessor& processor) SK_OVERRIDE {
+        GrColor color = processor.cast<GrColorProcessor>().color();
+        // We use the value 0 as an uninit sentinel, so we will always upload that value even if it

[egdaniel, 2015/03/04 20:22:34]

update comment to say grcolor_illegal

[bsalomon, 2015/03/31 19:33:42]

Done.

+        // were to be used repeatedly.
+        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 GrColorProcessor::onComputeInvariantOutput(GrInvariantOutput* inout) const {
+    if (kIgnore_InputMode == fMode) {
+        inout->setToOther(kRGBA_GrColorComponentFlags, fColor, GrInvariantOutput::kWill_ReadInput);

[egdaniel, 2015/03/04 20:22:34]

do you think we should update setToOther to set fIsSingleComponent to true if
fColor is all equal and valid? Currently it always sets it to false. Currently
there is a debug code only function colorComponentsAllEqual that would check
this. Just need to move out of debug only. Other option would be to pass it in
as a param whether it is single component or not.

This thought is for if someone wanted a coverage stage that just set a constant
single component color.

[bsalomon, 2015/03/31 19:33:42]

Done.

+    } else {
+        GrColor r = GrColorUnpackR(fColor);
+        bool colorIsSingleChannel = r == GrColorUnpackG(fColor) && r == GrColorUnpackB(fColor) &&
+                                    r == GrColorUnpackA(fColor);
+        if (kIgnore_InputMode == fMode) {
+            if (colorIsSingleChannel) {
+                inout->mulByKnownSingleComponent(r);
+            } else {
+                inout->mulByKnownFourComponents(fColor);
+            }
+        } else {
+            if (colorIsSingleChannel) {
+                inout->mulAlphaByKnownSingleComponent(r);
+            } else {
+                inout->mulAlphaByKnownFourComponents(fColor);
+            }
+        }
+    }
+}
+
+void GrColorProcessor::getGLProcessorKey(const GrGLCaps&, GrProcessorKeyBuilder* b) const {
+    b->add32(fMode);
+}
+
+GrGLFragmentProcessor* GrColorProcessor::createGLInstance() const  {
+    return SkNEW(GrGLColorProcessor);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrColorProcessor);
+
+GrFragmentProcessor* GrColorProcessor::TestCreate(SkRandom* random,
+                                                  GrContext*,
+                                                  const GrDrawTargetCaps&,
+                                                  GrTexture*[]) {
+    GrColor color = random->nextU();
+    InputMode mode = static_cast<InputMode>(random->nextULessThan(kInputModeCnt));
+    return GrColorProcessor::Create(color, mode);
+}