Do circular clipping in normalized space

gm/circularclips.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 "SkCanvas.h"
 #include "SkPath.h"
@@ skipping 31 matching lines @@
             SkRegion::kUnion_Op,
             SkRegion::kXOR_Op,
             SkRegion::kReverseDifference_Op,
             SkRegion::kReplace_Op,
         };
 
         SkRect rect = SkRect::MakeLTRB(fX1 - fR, fY - fR, fX2 + fR, fY + fR);
 
         SkPaint fillPaint;
 
+        // Giant background circular clips (AA, non-inverted, replace/isect)
+        fillPaint.setColor(0x80808080);
+        canvas->save();
+        canvas->scale(10, 10);
+        canvas->translate(-((fX1 + fX2)/2 - fR), -(fY - 2*fR/3));
+        canvas->clipPath(fCircle1, SkRegion::kReplace_Op, true);
+        canvas->clipPath(fCircle2, SkRegion::kIntersect_Op, true);
+
+        canvas->drawRect(rect, fillPaint);
+
+        canvas->restore();
+      
+        fillPaint.setColor(0xFF000000);
+
         for (size_t i = 0; i < 4; i++) {
             fCircle1.toggleInverseFillType();
             if (i % 2 == 0) {
                 fCircle2.toggleInverseFillType();
             }
 
             canvas->save();
             for (size_t op = 0; op < SK_ARRAY_COUNT(ops); op++) {
                 canvas->save();
 
@@ skipping 10 matching lines @@
         }
     }
 
 private:
     typedef skiagm::GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 DEF_GM( return new CircularClipsGM; )