Add svg path arcto

include/core/SkPath.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 SkPath_DEFINED
 #define SkPath_DEFINED
 
@@ skipping 481 matching lines @@
      */
     void arcTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar radius);
 
     /** Append a line and arc to the current path. This is the same as the
         PostScript call "arct".
     */
     void arcTo(const SkPoint p1, const SkPoint p2, SkScalar radius) {
         this->arcTo(p1.fX, p1.fY, p2.fX, p2.fY, radius);
     }
 
-    /** Close the current contour. If the current point is not equal to the
-        first point of the contour, a line segment is automatically added.
-    */
-    void close();
+    enum ArcSize {
+        /** the smaller of the two possible SVG arcs. */
+        kSmall_ArcSize,
+        /** the larger of the two possible SVG arcs. */
+        kLarge_ArcSize,
+    };
 
     enum Direction {
         /** clockwise direction for adding closed contours */
         kCW_Direction,
         /** counter-clockwise direction for adding closed contours */
         kCCW_Direction,
     };
 
     /**
+     *  Append an elliptical arc from the current point in the format used by SVG.
+     *  The center of the ellipse is computed to satisfy the constraints below.
+     *
+     *  @param rx,ry The radii in the x and y directions respectively.
+     *  @param xAxisRotate The angle in degrees relative to the x-axis.
+     *  @param largeArc Determines whether the smallest or largest arc possible
+     *         is drawn.
+     *  @param sweep Determines if the arc should be swept in an anti-clockwise or
+     *         clockwise direction. Note that this enum value is opposite the SVG
+     *         arc sweep value.
+     *  @param x,y The destination coordinates.
+     */
+    void arcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc,
+               Direction sweep, SkScalar x, SkScalar y);
+
+    void arcTo(const SkPoint r, SkScalar xAxisRotate, ArcSize largeArc, Direction sweep,
+               const SkPoint xy) {
+        this->arcTo(r.fX, r.fY, xAxisRotate, largeArc, sweep, xy.fX, xy.fY);
+    }
+
+    /** Same as arcTo format used by SVG, but the destination coordinate is relative to the
+     *  last point on this contour. If there is no previous point, then a
+     *  moveTo(0,0) is inserted automatically.
+     *
+     *  @param rx,ry The radii in the x and y directions respectively.
+     *  @param xAxisRotate The angle in degrees relative to the x-axis.
+     *  @param largeArc Determines whether the smallest or largest arc possible
+     *         is drawn.
+     *  @param sweep Determines if the arc should be swept in an anti-clockwise or
+     *         clockwise direction. Note that this enum value is opposite the SVG
+     *         arc sweep value.
+     *  @param dx,dy The destination coordinates relative to the last point.
+     */
+    void rArcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc,
+                Direction sweep, SkScalar dx, SkScalar dy);
+
+    /** Close the current contour. If the current point is not equal to the
+        first point of the contour, a line segment is automatically added.
+    */
+    void close();
+
+    /**
      *  Returns whether or not a fill type is inverted
      *
      *  kWinding_FillType        -> false
      *  kEvenOdd_FillType        -> false
      *  kInverseWinding_FillType -> true
      *  kInverseEvenOdd_FillType -> true
      */
     static bool IsInverseFillType(FillType fill) {
         static_assert(0 == kWinding_FillType, "fill_type_mismatch");
         static_assert(1 == kEvenOdd_FillType, "fill_type_mismatch");
@@ skipping 574 matching lines @@
 
     friend class SkAutoPathBoundsUpdate;
     friend class SkAutoDisableOvalCheck;
     friend class SkAutoDisableDirectionCheck;
     friend class SkBench_AddPathTest; // perf test reversePathTo
     friend class PathTest_Private; // unit test reversePathTo
     friend class ForceIsRRect_Private; // unit test isRRect
 };
 
 #endif