add arcto patheffect

src/effects/SkArcToPathEffect.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkArcToPathEffect.h"
+#include "SkPath.h"
+#include "SkPoint.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
+
+SkArcToPathEffect::SkArcToPathEffect(SkScalar radius) : fRadius(radius) {}
+
+bool SkArcToPathEffect::filterPath(SkPath* dst, const SkPath& src,
+                                   SkStrokeRec*, const SkRect*) const {
+    SkPath::Iter    iter(src, false);
+    SkPath::Verb    verb;
+    SkPoint         pts[4];
+
+    SkPoint         lastCorner = { 0, 0 }; // avoid warning
+    SkPath::Verb    prevVerb = SkPath::kMove_Verb;
+
+    for (;;) {
+        switch (verb = iter.next(pts, false)) {
+            case SkPath::kMove_Verb:
+                if (SkPath::kLine_Verb == prevVerb) {
+                    dst->lineTo(lastCorner);
+                }
+                dst->moveTo(pts[0]);
+                break;
+            case SkPath::kLine_Verb:
+                if (prevVerb == SkPath::kLine_Verb) {
+                    dst->arcTo(pts[0], pts[1], fRadius);
+                }
+                lastCorner = pts[1];
+                break;
+            case SkPath::kQuad_Verb:
+                dst->quadTo(pts[1], pts[2]);
+                lastCorner = pts[2];
+                break;
+            case SkPath::kConic_Verb:
+                dst->conicTo(pts[1], pts[2], iter.conicWeight());
+                lastCorner = pts[2];
+                break;
+            case SkPath::kCubic_Verb:
+                dst->cubicTo(pts[1], pts[2], pts[3]);
+                lastCorner = pts[3];
+                break;
+            case SkPath::kClose_Verb:
+                dst->lineTo(lastCorner);
+                break;
+            case SkPath::kDone_Verb:
+                dst->lineTo(lastCorner);
+                goto DONE;
+        }
+        prevVerb = verb;
+    }
+DONE:
+    return true;
+}
+
+SkFlattenable* SkArcToPathEffect::CreateProc(SkReadBuffer& buffer) {
+    return SkArcToPathEffect::Create(buffer.readScalar());
+}
+
+void SkArcToPathEffect::flatten(SkWriteBuffer& buffer) const {
+    buffer.writeScalar(fRadius);
+}