Add base types for path ops

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 "SkPathOpsPoint.h"
+#include "SkTDArray.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;
+
+    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]; }
+
+    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 findMaxCurvature(double tValues[]) const;
+    bool isLinear(int startIndex, int endIndex) const;
+    bool monotonicInY() 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]);
+    bool serpentine() const;
+    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, SkTDArray<double>* ts) const;
+    SkDQuad toQuad() const;
+    SkDPoint xyAtT(double t) const;
+};
+
+#endif