Respecify SkCanvas::drawArc, consolidate conversion to SkPath, add GM for oddball drawArcs

include/core/SkCanvas.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCanvas_DEFINED
 #define SkCanvas_DEFINED
 
@@ skipping 719 matching lines @@
         or framed based on the Style in the paint.
         @param cx       The x-coordinate of the center of the cirle to be drawn
         @param cy       The y-coordinate of the center of the cirle to be drawn
         @param radius   The radius of the cirle to be drawn
         @param paint    The paint used to draw the circle
     */
     void drawCircle(SkScalar cx, SkScalar cy, SkScalar radius,
                     const SkPaint& paint);
 
     /** Draw the specified arc, which will be scaled to fit inside the
-        specified oval. If the sweep angle is >= 360, then the oval is drawn
-        completely. Note that this differs slightly from SkPath::arcTo, which
-        treats the sweep angle mod 360.
+        specified oval. Sweep angles are not treated as modulo 360 and thus can
+        exceed a full sweep of the oval. Note that this differs slightly from
+        SkPath::arcTo, which treats the sweep angle mod 360. If the oval is empty
+        or the sweep angle is zero nothing is drawn. If useCenter is true the oval
+        center is inserted into the implied path before the arc and the path is
+        closed back to the, center forming a wedge. Otherwise, the implied path
+        contains just the arc and is not closed.
         @param oval The bounds of oval used to define the shape of the arc.
         @param startAngle Starting angle (in degrees) where the arc begins
         @param sweepAngle Sweep angle (in degrees) measured clockwise.
-        @param useCenter true means include the center of the oval. For filling
-                         this will draw a wedge. False means just use the arc.
+        @param useCenter true means include the center of the oval.
         @param paint    The paint used to draw the arc
     */
     void drawArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle,
                  bool useCenter, const SkPaint& paint);
 
     /** Draw the specified round-rect using the specified paint. The round-rect
         will be filled or framed based on the Style in the paint.
         @param rect     The rectangular bounds of the roundRect to be drawn
         @param rx       The x-radius of the oval used to round the corners
         @param ry       The y-radius of the oval used to round the corners
@@ skipping 949 matching lines @@
 
 class SkCanvasClipVisitor {
 public:
     virtual ~SkCanvasClipVisitor();
     virtual void clipRect(const SkRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipRRect(const SkRRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) = 0;
 };
 
 #endif