Fix SDF gradient calculation for non-uniform xforms

gm/dftext.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "gm.h"
 #include "Resources.h"
 #include "SkCanvas.h"
 #include "SkStream.h"
@@ skipping 178 matching lines @@
 #else
         paint.setTextSize(SkIntToScalar(22));
 #endif
         for (size_t i = 0; i < SK_ARRAY_COUNT(fg); ++i) {
             paint.setColor(fg[i]);
 
             canvas->drawText(text, textLen, x, y, paint);
             y += paint.getFontMetrics(NULL);
         }
 
+        // check skew
+        {
+            paint.setLCDRenderText(false);
+            SkAutoCanvasRestore acr(canvas, true);
+            canvas->skew(0.0f, 0.151515f);
+            paint.setTextSize(32);
+            canvas->drawText(text, textLen, 745, 70, paint);
+        }
+        {
+            paint.setLCDRenderText(true);
+            SkAutoCanvasRestore acr(canvas, true);
+            canvas->skew(0.5f, 0.0f);
+            paint.setTextSize(32);
+            canvas->drawText(text, textLen, 580, 230, paint);
+        }
+
         // check color emoji
         paint.setTypeface(fTypeface);
         canvas->drawText(text, textLen, 670, 100, paint);
 
 #if SK_SUPPORT_GPU
         // render offscreen buffer
         if (surface) {
             SkAutoCanvasRestore acr(inputCanvas, true);
             // since we prepended this matrix already, we blit using identity
             inputCanvas->resetMatrix();
             SkImage* image = surface->newImageSnapshot();
             inputCanvas->drawImage(image, 0, 0, NULL);
             image->unref();
         }
 #endif
     }
 
 private:
     SkTypeface* fTypeface;
 
     typedef skiagm::GM INHERITED;
 };
 
 DEF_GM( return SkNEW(DFTextGM); )