Use correct gradient calculation for rotated distance fields.

src/gpu/batches/GrAADistanceFieldPathRenderer.cpp

 
 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrAADistanceFieldPathRenderer.h"
 
@@ skipping 172 matching lines @@
 
     void onPrepareDraws(Target* target) const override {
         int instanceCount = fGeoData.count();
 
         SkMatrix invert;
         if (this->usesLocalCoords() && !this->viewMatrix().invert(&invert)) {
             SkDebugf("Could not invert viewmatrix\n");
             return;
         }
 
+        const SkMatrix& ctm = this->viewMatrix();
         uint32_t flags = 0;
-        flags |= this->viewMatrix().isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
+        flags |= ctm.isScaleTranslate() ? kScaleOnly_DistanceFieldEffectFlag : 0;
+        flags |= ctm.isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
 
         GrTextureParams params(SkShader::kRepeat_TileMode, GrTextureParams::kBilerp_FilterMode);
 
         // Setup GrGeometryProcessor
         GrBatchAtlas* atlas = fAtlas;
         SkAutoTUnref<GrGeometryProcessor> dfProcessor(
                 GrDistanceFieldPathGeoProc::Create(this->color(),
                                                    this->viewMatrix(),
                                                    atlas->getTexture(),
                                                    params,
@@ skipping 438 matching lines @@
     geometry.fAntiAlias = random->nextBool();
     geometry.fGenID = random->nextU();
 
     return AADistanceFieldPathBatch::Create(geometry, viewMatrix,
                                             gTestStruct.fAtlas,
                                             &gTestStruct.fPathCache,
                                             &gTestStruct.fPathList);
 }
 
 #endif