first cut at HQ GPU scaling; refactored existing bicubic scaler

src/gpu/effects/GrBicubicEffect.cpp

Index: src/gpu/effects/GrBicubicEffect.cpp
diff --git a/src/gpu/effects/GrBicubicEffect.cpp b/src/gpu/effects/GrBicubicEffect.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..9a38f678604bbe04baf2c2b530334b11d1a23d45
--- /dev/null
+++ b/src/gpu/effects/GrBicubicEffect.cpp
@@ -0,0 +1,175 @@
+#include "GrBicubicEffect.h"
+
+#define DS(x) SkDoubleToScalar(x)
+
+const SkScalar GrBicubicEffect::gMitchellCoefficients[16] = {
+    DS( 1.0 / 18.0), DS(-9.0 / 18.0), DS( 15.0 / 18.0), DS( -7.0 / 18.0),
+    DS(16.0 / 18.0), DS( 0.0 / 18.0), DS(-36.0 / 18.0), DS( 21.0 / 18.0),
+    DS( 1.0 / 18.0), DS( 9.0 / 18.0), DS( 27.0 / 18.0), DS(-21.0 / 18.0),
+    DS( 0.0 / 18.0), DS( 0.0 / 18.0), DS( -6.0 / 18.0), DS(  7.0 / 18.0),
+};
+
+
+class GrGLBicubicEffect : public GrGLEffect {
+public:
+    GrGLBicubicEffect(const GrBackendEffectFactory& factory,
+                      const GrDrawEffect&);
+    virtual void emitCode(GrGLShaderBuilder*,
+                          const GrDrawEffect&,
+                          EffectKey,
+                          const char* outputColor,
+                          const char* inputColor,
+                          const TextureSamplerArray&) SK_OVERRIDE;
+
+    static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);
+
+    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
+
+private:
+    typedef GrGLUniformManager::UniformHandle        UniformHandle;
+
+    UniformHandle       fCoefficientsUni;
+    UniformHandle       fImageIncrementUni;
+
+    GrGLEffectMatrix    fEffectMatrix;
+
+    typedef GrGLEffect INHERITED;
+};
+
+GrGLBicubicEffect::GrGLBicubicEffect(const GrBackendEffectFactory& factory,
+                                     const GrDrawEffect& drawEffect)
+    : INHERITED(factory)
+    , fEffectMatrix(drawEffect.castEffect<GrBicubicEffect>().coordsType()) {
+}
+
+void GrGLBicubicEffect::emitCode(GrGLShaderBuilder* builder,
+                                 const GrDrawEffect&,
+                                 EffectKey key,
+                                 const char* outputColor,
+                                 const char* inputColor,
+                                 const TextureSamplerArray& samplers) {
+    SkString coords;
+    fEffectMatrix.emitCodeMakeFSCoords2D(builder, key, &coords);
+    fCoefficientsUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
+                                           kMat44f_GrSLType, "Coefficients");
+    fImageIncrementUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
+                                             kVec2f_GrSLType, "ImageIncrement");
+
+    const char* imgInc = builder->getUniformCStr(fImageIncrementUni);
+    const char* coeff = builder->getUniformCStr(fCoefficientsUni);
+
+    SkString cubicBlendName;
+
+    static const GrGLShaderVar gCubicBlendArgs[] = {
+        GrGLShaderVar("coefficients",  kMat44f_GrSLType),
+        GrGLShaderVar("t",             kFloat_GrSLType),
+        GrGLShaderVar("c0",            kVec4f_GrSLType),
+        GrGLShaderVar("c1",            kVec4f_GrSLType),
+        GrGLShaderVar("c2",            kVec4f_GrSLType),
+        GrGLShaderVar("c3",            kVec4f_GrSLType),
+    };
+    builder->fsEmitFunction(kVec4f_GrSLType,
+                            "cubicBlend",
+                            SK_ARRAY_COUNT(gCubicBlendArgs),
+                            gCubicBlendArgs,
+                            "\tvec4 ts = vec4(1.0, t, t * t, t * t * t);\n"
+                            "\tvec4 c = coefficients * ts;\n"
+                            "\treturn c.x * c0 + c.y * c1 + c.z * c2 + c.w * c3;\n",
+                            &cubicBlendName);
+    builder->fsCodeAppendf("\tvec2 coord = %s - %s * vec2(0.5, 0.5);\n", coords.c_str(), imgInc);
+    builder->fsCodeAppendf("\tvec2 f = fract(coord / %s);\n", imgInc);
+    for (int y = 0; y < 4; ++y) {
+        for (int x = 0; x < 4; ++x) {
+            SkString coord;
+            coord.printf("coord + %s * vec2(%d, %d)", imgInc, x - 1, y - 1);
+            builder->fsCodeAppendf("\tvec4 s%d%d = ", x, y);
+            builder->fsAppendTextureLookup(samplers[0], coord.c_str());
+            builder->fsCodeAppend(";\n");
+        }
+        builder->fsCodeAppendf("\tvec4 s%d = %s(%s, f.x, s0%d, s1%d, s2%d, s3%d);\n", y, cubicBlendName.c_str(), coeff, y, y, y, y);
+    }
+    builder->fsCodeAppendf("\t%s = %s(%s, f.y, s0, s1, s2, s3);\n", outputColor, cubicBlendName.c_str(), coeff);
+}
+
+GrGLEffect::EffectKey GrGLBicubicEffect::GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
+    const GrBicubicEffect& bicubic = drawEffect.castEffect<GrBicubicEffect>();
+    EffectKey matrixKey = GrGLEffectMatrix::GenKey(bicubic.getMatrix(),
+                                                   drawEffect,
+                                                   bicubic.coordsType(),
+                                                   bicubic.texture(0));
+    return matrixKey;
+}
+
+void GrGLBicubicEffect::setData(const GrGLUniformManager& uman,
+                                const GrDrawEffect& drawEffect) {
+    const GrBicubicEffect& effect = drawEffect.castEffect<GrBicubicEffect>();
+    GrTexture& texture = *effect.texture(0);
+    float imageIncrement[2];
+    imageIncrement[0] = 1.0f / texture.width();
+    imageIncrement[1] = 1.0f / texture.height();
+    uman.set2fv(fImageIncrementUni, 0, 1, imageIncrement);
+    uman.setMatrix4f(fCoefficientsUni, effect.coefficients());
+    fEffectMatrix.setData(uman,
+                          effect.getMatrix(),
+                          drawEffect,
+                          effect.texture(0));
+}
+
+GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
+                                 const SkScalar coefficients[16])
+  : INHERITED(texture, MakeDivByTextureWHMatrix(texture)) {
+    for (int y = 0; y < 4; y++) {
+        for (int x = 0; x < 4; x++) {
+            // Convert from row-major scalars to column-major floats.
+            fCoefficients[x * 4 + y] = SkScalarToFloat(coefficients[y * 4 + x]);
+        }
+    }
+}
+
+GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
+                                 const SkScalar coefficients[16],
+                                 const SkMatrix &matrix,
+                                 const GrTextureParams &params,
+                                 CoordsType coordsType)
+  : INHERITED(texture, MakeDivByTextureWHMatrix(texture), params, coordsType) {
+    for (int y = 0; y < 4; y++) {
+        for (int x = 0; x < 4; x++) {
+            // Convert from row-major scalars to column-major floats.
+            fCoefficients[x * 4 + y] = SkScalarToFloat(coefficients[y * 4 + x]);
+        }
+    }
+}
+
+GrBicubicEffect::~GrBicubicEffect() {
+}
+
+const GrBackendEffectFactory& GrBicubicEffect::getFactory() const {
+    return GrTBackendEffectFactory<GrBicubicEffect>::getInstance();
+}
+
+bool GrBicubicEffect::onIsEqual(const GrEffect& sBase) const {
+    const GrBicubicEffect& s = CastEffect<GrBicubicEffect>(sBase);
+    return this->texture(0) == s.texture(0) &&
+           !memcmp(fCoefficients, s.coefficients(), 16);
+}
+
+void GrBicubicEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
+    // FIXME:  Perhaps we can do better.
+    *validFlags = 0;
+    return;
+}
+
+GR_DEFINE_EFFECT_TEST(GrBicubicEffect);
+
+GrEffectRef* GrBicubicEffect::TestCreate(SkMWCRandom* random,
+                                         GrContext* context,
+                                         const GrDrawTargetCaps&,
+                                         GrTexture* textures[]) {
+    int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
+                                      GrEffectUnitTest::kAlphaTextureIdx;
+    SkScalar coefficients[16];
+    for (int i = 0; i < 16; i++) {
+        coefficients[i] = random->nextSScalar1();
+    }
+    return GrBicubicEffect::Create(textures[texIdx], coefficients);
+}