Move distance field generation to the glyph cache

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"
+#include "SkDistanceFieldGen.h"
 
 class GrGLDistanceFieldTextureEffect : public GrGLVertexEffect {
 public:
     GrGLDistanceFieldTextureEffect(const GrBackendEffectFactory& factory,
                                    const GrDrawEffect& drawEffect)
         : INHERITED (factory)
         , fTextureSize(SkISize::Make(-1,-1)) {}
 
     virtual void emitCode(GrGLFullShaderBuilder* builder,
                           const GrDrawEffect& drawEffect,
@@ skipping 21 matching lines @@
         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");
+        builder->fsCodeAppend("\tfloat distance = " 
+                     SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\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 uv = %s;\n", fsCoordName.c_str());
         builder->fsCodeAppendf("\tvec2 st = uv*%s;\n", textureSizeUniName);
         builder->fsCodeAppend("\tfloat afwidth;\n");
         if (dfTexEffect.isSimilarity()) {
             // 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)
@@ skipping 160 matching lines @@
             builder->fsCodeAppend("\tvec2 Jdx = dFdx(st);\n");
             builder->fsCodeAppend("\tvec2 Jdy = dFdy(st);\n");
             builder->fsCodeAppendf("\tvec2 offset = %s.z*Jdx;\n", textureSizeUniName);
         }
 
         // green is distance to uv center
         builder->fsCodeAppend("\tvec4 texColor = ");
         builder->fsAppendTextureLookup(samplers[0], "uv", kVec2f_GrSLType);
         builder->fsCodeAppend(";\n");
         builder->fsCodeAppend("\tvec3 distance;\n");
-        builder->fsCodeAppend("\tdistance.y = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
+        builder->fsCodeAppend("\tdistance.y = " 
+                     SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\n");
         // red is distance to left offset
         builder->fsCodeAppend("\tvec2 uv_adjusted = uv - offset;\n");
         builder->fsCodeAppend("\ttexColor = ");
         builder->fsAppendTextureLookup(samplers[0], "uv_adjusted", kVec2f_GrSLType);
         builder->fsCodeAppend(";\n");
-        builder->fsCodeAppend("\tdistance.x = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
+        builder->fsCodeAppend("\tdistance.x = " 
+                     SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\n");
         // blue is distance to right offset
         builder->fsCodeAppend("\tuv_adjusted = uv + offset;\n");
         builder->fsCodeAppend("\ttexColor = ");
         builder->fsAppendTextureLookup(samplers[0], "uv_adjusted", kVec2f_GrSLType);
         builder->fsCodeAppend(";\n");
-        builder->fsCodeAppend("\tdistance.z = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
-
+        builder->fsCodeAppend("\tdistance.z = " 
+                     SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\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.
 
         // To be strictly correct, we should compute the anti-aliasing factor separately
         // for each color component. However, this is only important when using perspective
         // transformations, and even then using a single factor seems like a reasonable
         // trade-off between quality and speed.
         builder->fsCodeAppend("\tfloat afwidth;\n");
         if (dfTexEffect.isUniformScale()) {
@@ skipping 114 matching lines @@
     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);
 
     return GrDistanceFieldLCDTextureEffect::Create(textures[texIdx], params,
                                                    random->nextBool(), random->nextBool());
 }