Add flag for SkGpuSurface creation to enable distance fields.

src/gpu/GrDistanceFieldTextContext.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 "GrDistanceFieldTextContext.h"
 #include "GrAtlas.h"
 #include "GrDrawTarget.h"
@@ skipping 15 matching lines @@
 
 static const int kSmallDFFontSize = 32;
 static const int kSmallDFFontLimit = 32;
 static const int kMediumDFFontSize = 64;
 static const int kMediumDFFontLimit = 64;
 static const int kLargeDFFontSize = 128;
 
 SK_CONF_DECLARE(bool, c_DumpFontCache, "gpu.dumpFontCache", false,
                 "Dump the contents of the font cache before every purge.");
 
+GrDistanceFieldTextContext::GrDistanceFieldTextContext(GrContext* context,
+                                                       const SkDeviceProperties& properties,
+                                                       bool enable)
+                                                    : GrTextContext(context, properties) {
 #if SK_FORCE_DISTANCEFIELD_FONTS
-static const bool kForceDistanceFieldFonts = true;
+    fEnableDFRendering = true;
 #else
-static const bool kForceDistanceFieldFonts = false;
+    fEnableDFRendering = enable;
 #endif
-
-GrDistanceFieldTextContext::GrDistanceFieldTextContext(GrContext* context,
-                                                       const SkDeviceProperties& properties)
-                                                    : GrTextContext(context, properties) {
     fStrike = NULL;
 
     fCurrTexture = NULL;
     fCurrVertex = 0;
 
     fVertices = NULL;
     fMaxVertices = 0;
 }
 
 GrDistanceFieldTextContext::~GrDistanceFieldTextContext() {
     this->flushGlyphs();
 }
 
 bool GrDistanceFieldTextContext::canDraw(const SkPaint& paint) {
-    if (!kForceDistanceFieldFonts && !paint.isDistanceFieldTextTEMP()) {
+    if (!fEnableDFRendering && !paint.isDistanceFieldTextTEMP()) {
         return false;
     }
 
     // rasterizers and mask filters modify alpha, which doesn't
     // translate well to distance
     if (paint.getRasterizer() || paint.getMaskFilter() ||
         !fContext->getTextTarget()->caps()->shaderDerivativeSupport()) {
         return false;
     }
 
@@ skipping 425 matching lines @@
                                       SkScalarToFixed(y) - (glyph.fAdvanceY >> alignShift)
                                         + SK_FixedHalf, //d1g.fHalfSampleY,
                                       fontScaler);
             }
             pos += scalarsPerPosition;
         }
     }
 
     this->finish();
 }