diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/gpu/effects/GrDistanceFieldTextureEffect.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/skia/trunk/src/gpu/effects/GrDistanceFieldTextureEffect.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,155 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrDistanceFieldTextureEffect.h"
+#include "gl/GrGLEffect.h"
+#include "gl/GrGLSL.h"
+#include "gl/GrGLTexture.h"
+#include "gl/GrGLVertexEffect.h"
+#include "GrTBackendEffectFactory.h"
+#include "GrTexture.h"
+
+// The distance field is constructed as unsigned char values, so that the zero value is at 128,
+// and the range is [-4, 4 - 1/255). Hence our multiplier is 8 - 1/32 and zero threshold is 128/255.
+#define MULTIPLIER "7.96875"
+#define THRESHOLD "0.50196078431"
+
+class GrGLDistanceFieldTextureEffect : public GrGLVertexEffect {
+public:
+    GrGLDistanceFieldTextureEffect(const GrBackendEffectFactory& factory,
+                                   const GrDrawEffect& drawEffect)
+        : INHERITED (factory)
+        , fTextureSize(SkSize::Make(-1.f,-1.f)) {}
+
+    virtual void emitCode(GrGLFullShaderBuilder* builder,
+                          const GrDrawEffect& drawEffect,
+                          EffectKey key,
+                          const char* outputColor,
+                          const char* inputColor,
+                          const TransformedCoordsArray&,
+                          const TextureSamplerArray& samplers) SK_OVERRIDE {
+        SkASSERT(1 == drawEffect.castEffect<GrDistanceFieldTextureEffect>().numVertexAttribs());
+
+        SkAssertResult(builder->enableFeature(GrGLShaderBuilder::kStandardDerivatives_GLSLFeature));
+
+        SkString fsCoordName;
+        const char* vsCoordName;
+        const char* fsCoordNamePtr;
+        builder->addVarying(kVec2f_GrSLType, "textureCoords", &vsCoordName, &fsCoordNamePtr);
+        fsCoordName = fsCoordNamePtr;
+
+        const char* attrName0 =
+            builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0])->c_str();
+        builder->vsCodeAppendf("\t%s = %s;\n", vsCoordName, attrName0);
+
+        const char* textureSizeUniName = NULL;
+        fTextureSizeUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
+                                              kVec2f_GrSLType, "TextureSize",
+                                              &textureSizeUniName);
+
+        builder->fsCodeAppend("\tvec4 texColor = ");
+        builder->fsAppendTextureLookup(samplers[0],
+                                       fsCoordName.c_str(),
+                                       kVec2f_GrSLType);
+        builder->fsCodeAppend(";\n");
+        builder->fsCodeAppend("\tfloat distance = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
+
+        // we adjust for the effect of the transformation on the distance by using
+        // the length of the gradient of the texture coordinates. We use st coordinates
+        // to ensure we're mapping 1:1 from texel space to pixel space.
+        builder->fsCodeAppendf("\tvec2 st = %s*%s;\n", fsCoordName.c_str(), textureSizeUniName);
+        builder->fsCodeAppend("\tvec2 Jdx = dFdx(st);\n");
+        builder->fsCodeAppend("\tvec2 Jdy = dFdy(st);\n");
+        builder->fsCodeAppend("\tvec2 st_grad = normalize(st);\n");
+        builder->fsCodeAppend("\tvec2 grad = vec2(st_grad.x*Jdx.x + st_grad.y*Jdy.x,\n");
+        builder->fsCodeAppend("\t                 st_grad.x*Jdx.y + st_grad.y*Jdy.y);\n");
+
+        // this gives us a smooth step across approximately one fragment
+        // (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
+        builder->fsCodeAppend("\tfloat afwidth = 0.7071*length(grad);\n");
+        builder->fsCodeAppend("\tfloat val = smoothstep(-afwidth, afwidth, distance);\n");
+
+        builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
+                                   (GrGLSLExpr4(inputColor) * GrGLSLExpr1("val")).c_str());
+    }
+
+    virtual void setData(const GrGLUniformManager& uman,
+                         const GrDrawEffect& drawEffect) SK_OVERRIDE {
+        SkASSERT(fTextureSizeUni.isValid());
+        const GrDistanceFieldTextureEffect& distanceFieldEffect =
+                                              drawEffect.castEffect<GrDistanceFieldTextureEffect>();
+        if (distanceFieldEffect.getSize().width() != fTextureSize.width() ||
+            distanceFieldEffect.getSize().height() != fTextureSize.height()) {
+            fTextureSize = distanceFieldEffect.getSize();
+            uman.set2f(fTextureSizeUni,
+                       distanceFieldEffect.getSize().width(),
+                       distanceFieldEffect.getSize().height());
+        }
+    }
+
+private:
+    GrGLUniformManager::UniformHandle fTextureSizeUni;
+    SkSize                            fTextureSize;
+
+    typedef GrGLVertexEffect INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+GrDistanceFieldTextureEffect::GrDistanceFieldTextureEffect(GrTexture* texture,
+                                                           const GrTextureParams& params,
+                                                           const SkISize& size)
+    : fTextureAccess(texture, params)
+    , fSize(SkSize::Make(SkIntToScalar(size.width()), SkIntToScalar(size.height()))) {
+    this->addTextureAccess(&fTextureAccess);
+    this->addVertexAttrib(kVec2f_GrSLType);
+}
+
+bool GrDistanceFieldTextureEffect::onIsEqual(const GrEffect& other) const {
+    const GrDistanceFieldTextureEffect& cte = CastEffect<GrDistanceFieldTextureEffect>(other);
+    return fTextureAccess == cte.fTextureAccess;
+}
+
+void GrDistanceFieldTextureEffect::getConstantColorComponents(GrColor* color,
+                                                             uint32_t* validFlags) const {
+    if ((*validFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(*color) &&
+        GrPixelConfigIsOpaque(this->texture(0)->config())) {
+        *validFlags = kA_GrColorComponentFlag;
+    } else {
+        *validFlags = 0;
+    }
+}
+
+const GrBackendEffectFactory& GrDistanceFieldTextureEffect::getFactory() const {
+    return GrTBackendEffectFactory<GrDistanceFieldTextureEffect>::getInstance();
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+GR_DEFINE_EFFECT_TEST(GrDistanceFieldTextureEffect);
+
+GrEffectRef* GrDistanceFieldTextureEffect::TestCreate(SkRandom* random,
+                                                     GrContext*,
+                                                     const GrDrawTargetCaps&,
+                                                     GrTexture* textures[]) {
+    int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
+                                      GrEffectUnitTest::kAlphaTextureIdx;
+    static const SkShader::TileMode kTileModes[] = {
+        SkShader::kClamp_TileMode,
+        SkShader::kRepeat_TileMode,
+        SkShader::kMirror_TileMode,
+    };
+    SkShader::TileMode tileModes[] = {
+        kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))],
+        kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))],
+    };
+    GrTextureParams params(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
+                                                           GrTextureParams::kNone_FilterMode);
+    SkISize size = SkISize::Make(1024, 2048);
+
+    return GrDistanceFieldTextureEffect::Create(textures[texIdx], params, size);
+}