path ops -- rewrite angle sort

src/pathops/SkPathOpsQuad.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPathOpsQuad_DEFINED
 #define SkPathOpsQuad_DEFINED
 
 #include "SkPathOpsPoint.h"
 
 struct SkDQuadPair {
     const SkDQuad& first() const { return (const SkDQuad&) pts[0]; }
     const SkDQuad& second() const { return (const SkDQuad&) pts[2]; }
     SkDPoint pts[5];
 };
 
 struct SkDQuad {
     SkDPoint fPts[3];
 
+    SkDQuad flip() const {
+        SkDQuad result = {{fPts[2], fPts[1], fPts[0]}};
+        return result;
+    }
+
     void set(const SkPoint pts[3]) {
         fPts[0] = pts[0];
         fPts[1] = pts[1];
         fPts[2] = pts[2];
     }
 
     const SkDPoint& operator[](int n) const { SkASSERT(n >= 0 && n < 3); return fPts[n]; }
     SkDPoint& operator[](int n) { SkASSERT(n >= 0 && n < 3); return fPts[n]; }
 
     static int AddValidTs(double s[], int realRoots, double* t);
+    void align(int endIndex, SkDPoint* dstPt) const;
     SkDQuadPair chopAt(double t) const;
     SkDVector dxdyAtT(double t) const;
     static int FindExtrema(double a, double b, double c, double tValue[1]);
     bool isLinear(int startIndex, int endIndex) const;
     bool monotonicInY() const;
     double nearestT(const SkDPoint&) const;
     bool pointInHull(const SkDPoint&) const;
     static int RootsReal(double A, double B, double C, double t[2]);
     static int RootsValidT(const double A, const double B, const double C, double s[2]);
     static void SetABC(const double* quad, double* a, double* b, double* c);
@@ skipping 11 matching lines @@
         return quad.subDivide(a, c, t1, t2);
     }
     SkDCubic toCubic() const;
     SkDPoint top(double startT, double endT) const;
     SkDPoint xyAtT(double t) const;
 private:
 //  static double Tangent(const double* quadratic, double t);  // uncalled
 };
 
 #endif