Do circle anti-aliasing in normalized space to avoid precision issues with half-floats on Adreno.

gm/circles.cpp

 
 /*
  * Copyright 2012 Intel 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 "SkBlurDrawLooper.h"
 #include "SkBlurMask.h"
@@ skipping 139 matching lines @@
 
         {
         SkMatrix m;
         m.setRotate(SkIntToScalar(30));
         fMatrices.push_back(m);
         }
     }
 
     virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
         SkLCGRandom rand;
+        // Draw a giant AA circle as the background.
+        SkISize size = this->getISize();
+        SkScalar giantRadius = SkTMin(SkIntToScalar(size.fWidth),
+                                      SkIntToScalar(size.fHeight)) / 2.f;
+        SkPoint giantCenter = SkPoint::Make(SkIntToScalar(size.fWidth/2),
+                                            SkIntToScalar(size.fHeight/2));
+        SkPaint giantPaint;
+        giantPaint.setAntiAlias(true);
+        giantPaint.setColor(0x80808080);
+        canvas->drawCircle(giantCenter.fX, giantCenter.fY, giantRadius, giantPaint);
+        
         canvas->translate(20 * SK_Scalar1, 20 * SK_Scalar1);
         int i;
         for (i = 0; i < fPaints.count(); ++i) {
             canvas->save();
             // position the path, and make it at off-integer coords.
             canvas->translate(SK_Scalar1 * 200 * (i % 5) + SK_Scalar1 / 4,
                               SK_Scalar1 * 200 * (i / 5) + 3 * SK_Scalar1 / 4);
             SkColor color = rand.nextU();
             color |= 0xff000000;
             fPaints[i].setColor(color);
@@ skipping 32 matching lines @@
     SkTArray<SkPaint> fPaints;
     SkTArray<SkMatrix> fMatrices;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new CircleGM; }
 static GMRegistry reg(MyFactory);
 
 }