Production quality fast image up/downsampler

gm/downsamplebitmap.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 "gm.h"
 #include "SkGradientShader.h"
 
@@ skipping 57 matching lines @@
             paint.setFlags( paint.getFlags() | SkPaint::kHighQualityFilterBitmap_Flag );
 
             canvas->save();
             canvas->translate( (SkScalar) curX, 0.f );
             canvas->drawBitmapMatrix( fBM, matrix, &paint );
             canvas->restore();
 
             curWidth = (int) (fBM.width() * curScale + 2);
             curX += curWidth;
             curScale *= 0.75f;
-        } while (curX < 4*fBM.width());
+        } while (curWidth >= 2 && curX < 4*fBM.width());
     }
 
 private:
     typedef skiagm::GM INHERITED;
 };
 
 class DownsampleBitmapTextGM: public DownsampleBitmapGM {
   public:
       DownsampleBitmapTextGM(float textSize)
       : fTextSize(textSize)
@@ skipping 103 matching lines @@
       }
   private:
       typedef DownsampleBitmapGM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 DEF_GM( return new DownsampleBitmapTextGM(72); )
 DEF_GM( return new DownsampleBitmapCheckerboardGM(512,256); )
 DEF_GM( return new DownsampleBitmapImageGM("mandrill_512.png"); )