Add string art GM and sample.

gm/stringart.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"
+
+// Reproduces https://code.google.com/p/chromium/issues/detail?id=279014
+
+static const int kWidth = 640;
+static const int kHeight = 480;
+static const SkScalar kAngle = 0.305f;
+
+// Renders a string art shape.
+// The particular shape rendered can be controlled by adjusting kAngle, from 0 to 1
+
+class StringArtGM : public skiagm::GM {
+public:
+    StringArtGM() {}
+
+protected:
+    virtual SkString onShortName() {
+        return SkString("stringart");
+    }
+
+    virtual SkISize onISize() {
+        return SkISize::Make(kWidth, kHeight);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) {
+        SkScalar angle = kAngle*SK_ScalarPI + SkScalarHalf(SK_ScalarPI);
+        SkScalar size = SkMin32(kWidth, kHeight);
+        SkPoint center = SkPoint::Make(SkScalarHalf(kWidth), SkScalarHalf(kHeight));
+        SkScalar length = 5;
+        SkScalar step = angle;
+
+        SkPath path;
+        path.moveTo(center);
+
+        while (length < (SkScalarHalf(size) - 10.f))
+        {
+            SkPoint rp = SkPoint::Make(length*SkScalarCos(step) + center.fX,
+                                       length*SkScalarSin(step) + center.fY);
+            path.lineTo(rp);
+            length += SkScalarDiv(angle, SkScalarHalf(SK_ScalarPI));
+            step += angle;
+        }
+        path.close();
+
+        SkPaint paint;
+        paint.setAntiAlias(true);
+        paint.setStyle(SkPaint::kStroke_Style);
+        paint.setColor(0xFF007700);
+
+        canvas->drawPath(path, paint);
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+DEF_GM( return new StringArtGM; )