use conics for arcTo

src/core/SkGeometry.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 SkGeometry_DEFINED
@@ skipping 208 matching lines @@
 
 /** Given 2 unit vectors and a rotation direction, fill out the specified
     array of points with quadratic segments. Return is the number of points
     written to, which will be { 0, 3, 5, 7, ... kSkBuildQuadArcStorage }
 
     matrix, if not null, is appled to the points before they are returned.
 */
 int SkBuildQuadArc(const SkVector& unitStart, const SkVector& unitStop,
                    SkRotationDirection, const SkMatrix*, SkPoint quadPoints[]);
 
-// experimental
 struct SkConic {
     SkConic() {}
     SkConic(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2, SkScalar w) {
         fPts[0] = p0;
         fPts[1] = p1;
         fPts[2] = p2;
         fW = w;
     }
     SkConic(const SkPoint pts[3], SkScalar w) {
         memcpy(fPts, pts, sizeof(fPts));
         fW = w;
     }
 
     SkPoint  fPts[3];
     SkScalar fW;
 
     void set(const SkPoint pts[3], SkScalar w) {
         memcpy(fPts, pts, 3 * sizeof(SkPoint));
         fW = w;
     }
 
+    void set(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2, SkScalar w) {
+        fPts[0] = p0;
+        fPts[1] = p1;
+        fPts[2] = p2;
+        fW = w;
+    }
+
     /**
      *  Given a t-value [0...1] return its position and/or tangent.
      *  If pos is not null, return its position at the t-value.
      *  If tangent is not null, return its tangent at the t-value. NOTE the
      *  tangent value's length is arbitrary, and only its direction should
      *  be used.
      */
     void evalAt(SkScalar t, SkPoint* pos, SkVector* tangent = NULL) const;
     void chopAt(SkScalar t, SkConic dst[2]) const;
     void chop(SkConic dst[2]) const;
@@ skipping 24 matching lines @@
     /** Find the parameter value where the conic takes on its maximum curvature.
      *
      *  @param t   output scalar for max curvature.  Will be unchanged if
      *             max curvature outside 0..1 range.
      *
      *  @return  true if max curvature found inside 0..1 range, false otherwise
      */
     bool findMaxCurvature(SkScalar* t) const;
 
     static SkScalar TransformW(const SkPoint[3], SkScalar w, const SkMatrix&);
+
+    enum {
+        kMaxConicsForArc = 5
+    };
+    static int BuildUnitArc(const SkVector& start, const SkVector& stop, SkRotationDirection,
+                            const SkMatrix*, SkConic conics[kMaxConicsForArc]);
 };
 
 #include "SkTemplates.h"
 
 /**
  *  Help class to allocate storage for approximating a conic with N quads.
  */
 class SkAutoConicToQuads {
 public:
     SkAutoConicToQuads() : fQuadCount(0) {}
@@ skipping 30 matching lines @@
 private:
     enum {
         kQuadCount = 8, // should handle most conics
         kPointCount = 1 + 2 * kQuadCount,
     };
     SkAutoSTMalloc<kPointCount, SkPoint> fStorage;
     int fQuadCount; // #quads for current usage
 };
 
 #endif