GM (and fix) for drawArc capping issue

gm/arcofzorro.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 "SkRandom.h"
+
+namespace skiagm {
+
+// This GM draws a lot of arcs in a 'Z' shape. It particularly exercises 
+// the 'drawArc' code near a singularly of its processing (i.e., near the
+// edge of one of its underlying quads).
+class ArcOfZorroGM : public GM {
+public:
+    ArcOfZorroGM() {
+        this->setBGColor(0xFFCCCCCC);
+    }
+
+protected:
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("arcofzorro");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return make_isize(1000, 1000);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        SkMWCRandom rand;
+
+        SkRect rect = SkRect::MakeXYWH(10, 10, 200, 200);
+
+        SkPaint p;
+
+        p.setStyle(SkPaint::kStroke_Style);
+        p.setStrokeWidth(35);
+        int xOffset = 0, yOffset = 0;
+        int direction = 0;
+
+        for (float arc = 134.0f; arc < 136.0f; arc += 0.01f) {
+            SkColor color = rand.nextU();
+            color |= 0xff000000;
+            p.setColor(color);
+
+            canvas->save();
+            canvas->translate(SkIntToScalar(xOffset), SkIntToScalar(yOffset));
+            canvas->drawArc(rect, 0, arc, false, p);
+            canvas->restore();
+
+            switch (direction) {
+            case 0:
+                xOffset += 10;
+                if (xOffset >= 700) {
+                    direction = 1;
+                }
+                break;
+            case 1:
+                xOffset -= 10;
+                yOffset += 10;
+                if (xOffset < 50) {
+                    direction = 2;
+                }
+                break;
+            case 2:
+                xOffset += 10;
+                break;
+            }
+        }
+
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return SkNEW(ArcOfZorroGM); )
+
+}