clear bitmap in texture domain gm

gm/texturedomaineffect.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.
  */
 
 // This test only works with the GPU backend.
 
@@ skipping 28 matching lines @@
     }
 
     virtual uint32_t onGetFlags() const SK_OVERRIDE {
         // This is a GPU-specific GM.
         return kGPUOnly_Flag;
     }
 
     virtual void onOnceBeforeDraw() SK_OVERRIDE {
         fBmp.allocN32Pixels(100, 100);
         SkCanvas canvas(fBmp);
+        canvas.clear(0x00000000);
         SkPaint paint;
 
         SkColor colors1[] = { SK_ColorCYAN, SK_ColorLTGRAY, SK_ColorGRAY };
         paint.setShader(SkGradientShader::CreateSweep(65.f, 75.f, colors1,
                                                       NULL, SK_ARRAY_COUNT(colors1)))->unref();
         canvas.drawOval(SkRect::MakeXYWH(-5.f, -5.f,
                                          fBmp.width() + 10.f, fBmp.height() + 10.f), paint);
 
         SkColor colors2[] = { SK_ColorMAGENTA, SK_ColorLTGRAY, SK_ColorYELLOW };
         paint.setShader(SkGradientShader::CreateSweep(45.f, 55.f, colors2, NULL,
@@ skipping 90 matching lines @@
 private:
     SkBitmap fBmp;
 
     typedef GM INHERITED;
 };
 
 DEF_GM( return SkNEW(TextureDomainEffect); )
 }
 
 #endif