Distance field fixes for Android

src/gpu/effects/GrDistanceFieldTextureEffect.cpp

 /*
  * 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)) {}
+        , fTextureSize(SkISize::Make(-1,-1)) {}
 
     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));
+        const GrDistanceFieldTextureEffect& dfTexEffect =
+                                              drawEffect.castEffect<GrDistanceFieldTextureEffect>();
 
         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");
+        builder->fsCodeAppendf("\tvec2 uv = %s;\n", fsCoordName.c_str());
+        builder->fsCodeAppendf("\tvec2 st = uv*%s;\n", textureSizeUniName);
+        builder->fsCodeAppend("\tfloat afwidth;\n");
+        if (dfTexEffect.isUniformScale()) {
+            // 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("\tafwidth = 0.7071*dFdx(st.x);\n");
+        } else {
+            builder->fsCodeAppend("\tvec2 Jdx = dFdx(st);\n");
+            builder->fsCodeAppend("\tvec2 Jdy = dFdy(st);\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("\tvec2 uv_grad;\n");
+            if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
+                // this is to compensate for the Adreno, which likes to drop tiles on division by 0
+                builder->fsCodeAppend("\tfloat uv_len2 = dot(uv, uv);\n");
+                builder->fsCodeAppend("\tif (uv_len2 < 0.0001) {\n");
+                builder->fsCodeAppend("\t\tuv_grad = vec2(0.7071, 0.7071);\n");
+                builder->fsCodeAppend("\t} else {\n");
+                builder->fsCodeAppend("\t\tuv_grad = uv*inversesqrt(uv_len2);\n");
+                builder->fsCodeAppend("\t}\n");
+            } else {
+                builder->fsCodeAppend("\tuv_grad = normalize(uv);\n");
+            }
+            builder->fsCodeAppend("\tvec2 grad = vec2(uv_grad.x*Jdx.x + uv_grad.y*Jdy.x,\n");
+            builder->fsCodeAppend("\t                 uv_grad.x*Jdx.y + uv_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("\tafwidth = 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 =
+
+        GrTexture* texture = drawEffect.effect()->get()->texture(0);
+        if (texture->width() != fTextureSize.width() ||
+            texture->height() != fTextureSize.height()) {
+            fTextureSize = SkISize::Make(texture->width(), texture->height());
+            uman.set2f(fTextureSizeUni,
+                       SkIntToScalar(fTextureSize.width()),
+                       SkIntToScalar(fTextureSize.height()));
+        }
+    }
+
+    static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
+        const GrDistanceFieldTextureEffect& dfTexEffect =
                                               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());
-        }
+
+        return dfTexEffect.isUniformScale() ? 0x1 : 0x0;
     }
 
 private:
     GrGLUniformManager::UniformHandle fTextureSizeUni;
-    SkSize                            fTextureSize;
+    SkISize                           fTextureSize;
 
     typedef GrGLVertexEffect INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrDistanceFieldTextureEffect::GrDistanceFieldTextureEffect(GrTexture* texture,
                                                            const GrTextureParams& params,
-                                                           const SkISize& size)
+                                                           bool uniformScale)
     : fTextureAccess(texture, params)
-    , fSize(SkSize::Make(SkIntToScalar(size.width()), SkIntToScalar(size.height()))) {
+    , fUniformScale(uniformScale) {
     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,
@@ skipping 24 matching lines @@
         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);
+    return GrDistanceFieldTextureEffect::Create(textures[texIdx], params, random->nextBool());
 }