cubicline intersection binary search

src/pathops/SkPathOpsCubic.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 SkPathOpsCubic_DEFINED
 #define SkPathOpsCubic_DEFINED
 
 #include "SkPath.h"
 #include "SkPathOpsPoint.h"
 #include "SkTArray.h"
 
 struct SkDCubicPair {
     const SkDCubic& first() const { return (const SkDCubic&) pts[0]; }
     const SkDCubic& second() const { return (const SkDCubic&) pts[3]; }
     SkDPoint pts[7];
 };
 
 struct SkDCubic {
-    SkDPoint fPts[4];
-
-    void set(const SkPoint pts[4]) {
-        fPts[0] = pts[0];
-        fPts[1] = pts[1];
-        fPts[2] = pts[2];
-        fPts[3] = pts[3];
-    }
-
-    static const int gPrecisionUnit;
+    enum SearchAxis {
+        kXAxis,
+        kYAxis
+    };
 
     const SkDPoint& operator[](int n) const { SkASSERT(n >= 0 && n < 4); return fPts[n]; }
     SkDPoint& operator[](int n) { SkASSERT(n >= 0 && n < 4); return fPts[n]; }
 
     void align(int endIndex, int ctrlIndex, SkDPoint* dstPt) const;
+    double binarySearch(double min, double max, double axisIntercept, SearchAxis xAxis) const;
     double calcPrecision() const;
     SkDCubicPair chopAt(double t) const;
     bool clockwise() const;
     static void Coefficients(const double* cubic, double* A, double* B, double* C, double* D);
     bool controlsContainedByEnds() const;
     SkDVector dxdyAtT(double t) const;
     bool endsAreExtremaInXOrY() const;
     static int FindExtrema(double a, double b, double c, double d, double tValue[2]);
-    int findInflections(double tValues[]) const;
+    int findInflections(double tValues[2]) const;
 
-    static int FindInflections(const SkPoint a[4], double tValues[]) {
+    static int FindInflections(const SkPoint a[4], double tValues[2]) {
         SkDCubic cubic;
         cubic.set(a);
         return cubic.findInflections(tValues);
     }
 
     int findMaxCurvature(double tValues[]) const;
     bool isLinear(int startIndex, int endIndex) const;
     bool monotonicInY() const;
     SkDPoint ptAtT(double t) const;
     static int RootsReal(double A, double B, double C, double D, double t[3]);
     static int RootsValidT(const double A, const double B, const double C, double D, double s[3]);
+
+    int searchRoots(double extremes[6], int extrema, double axisIntercept,
+                    SearchAxis xAxis, double* validRoots) const;
     bool serpentine() const;
+
+    void set(const SkPoint pts[4]) {
+        fPts[0] = pts[0];
+        fPts[1] = pts[1];
+        fPts[2] = pts[2];
+        fPts[3] = pts[3];
+    }
+
     SkDCubic subDivide(double t1, double t2) const;
 
     static SkDCubic SubDivide(const SkPoint a[4], double t1, double t2) {
         SkDCubic cubic;
         cubic.set(a);
         return cubic.subDivide(t1, t2);
     }
 
     void subDivide(const SkDPoint& a, const SkDPoint& d, double t1, double t2, SkDPoint p[2]) const;
 
     static void SubDivide(const SkPoint pts[4], const SkDPoint& a, const SkDPoint& d, double t1,
                           double t2, SkDPoint p[2]) {
         SkDCubic cubic;
         cubic.set(pts);
         cubic.subDivide(a, d, t1, t2, p);
     }
 
     SkDPoint top(double startT, double endT) const;
     void toQuadraticTs(double precision, SkTArray<double, true>* ts) const;
     SkDQuad toQuad() const;
 
     // utilities callable by the user from the debugger when the implementation code is linked in
     void dump() const;
     void dumpNumber() const;
+
+    static const int gPrecisionUnit;
+
+    SkDPoint fPts[4];
 };
 
 #endif