working on initial winding for cubics

src/pathops/SkPathOpsConic.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkIntersections.h"
 #include "SkLineParameters.h"
 #include "SkPathOpsConic.h"
 #include "SkPathOpsCubic.h"
@@ skipping 64 matching lines @@
 
 SkDPoint SkDConic::ptAtT(double t) const {
     double denominator = conic_eval_denominator(fWeight, t);
     SkDPoint result = {
         conic_eval_numerator(&fPts[0].fX, fWeight, t) / denominator,
         conic_eval_numerator(&fPts[0].fY, fWeight, t) / denominator
     };
     return result;
 }
 
-SkDPoint SkDConic::top(double startT, double endT) const {
-    SkDConic sub = subDivide(startT, endT);
-    SkDPoint topPt = sub[0];
-    if (topPt.fY > sub[2].fY || (topPt.fY == sub[2].fY && topPt.fX > sub[2].fX)) {
-        topPt = sub[2];
-    }
-    if (!between(sub[0].fY, sub[1].fY, sub[2].fY)) {
-        double extremeT;
-        if (FindExtrema(&sub[0].fY, sub.fWeight, &extremeT)) {
-            extremeT = startT + (endT - startT) * extremeT;
-            SkDPoint test = ptAtT(extremeT);
-            if (topPt.fY > test.fY || (topPt.fY == test.fY && topPt.fX > test.fX)) {
-                topPt = test;
-            }
-        }
-    }
-    return topPt;
-}
-
 /* see quad subdivide for rationale */
 SkDConic SkDConic::subDivide(double t1, double t2) const {
     double ax = conic_eval_numerator(&fPts[0].fX, fWeight, t1);
     double ay = conic_eval_numerator(&fPts[0].fY, fWeight, t1);
     double az = conic_eval_denominator(fWeight, t1);
     double midT = (t1 + t2) / 2;
     double dx = conic_eval_numerator(&fPts[0].fX, fWeight, midT);
     double dy = conic_eval_numerator(&fPts[0].fY, fWeight, midT);
     double dz = conic_eval_denominator(fWeight, midT);
     double cx = conic_eval_numerator(&fPts[0].fX, fWeight, t2);
     double cy = conic_eval_numerator(&fPts[0].fY, fWeight, t2);
     double cz = conic_eval_denominator(fWeight, t2);
     double bx = 2 * dx - (ax + cx) / 2;
     double by = 2 * dy - (ay + cy) / 2;
     double bz = 2 * dz - (az + cz) / 2;
     double dt = t2 - t1;
     double dt_1 = 1 - dt;
     SkScalar w = SkDoubleToScalar((1 + dt * (fWeight - 1))
             / sqrt(dt * dt + 2 * dt * dt_1 * fWeight + dt_1 * dt_1));
     SkDConic dst = {{{{ax / az, ay / az}, {bx / bz, by / bz}, {cx / cz, cy / cz}}}, w };
     return dst;
 }
 
 SkDPoint SkDConic::subDivide(const SkDPoint& a, const SkDPoint& c, double t1, double t2,
         SkScalar* weight) const {
     SkDConic chopped = this->subDivide(t1, t2);
     *weight = chopped.fWeight;
     return chopped[1];
 }
+
+SkDPoint SkDConic::top(double startT, double endT, double* topT) const {
+    SkDConic sub = subDivide(startT, endT);
+    SkDPoint topPt = sub[0];
+    *topT = startT;
+    if (topPt.fY > sub[2].fY || (topPt.fY == sub[2].fY && topPt.fX > sub[2].fX)) {
+        *topT = endT;
+        topPt = sub[2];
+    }
+    if (!between(sub[0].fY, sub[1].fY, sub[2].fY)) {
+        double extremeT;
+        if (FindExtrema(&sub[0].fY, sub.fWeight, &extremeT)) {
+            extremeT = startT + (endT - startT) * extremeT;
+            SkDPoint test = ptAtT(extremeT);
+            if (topPt.fY > test.fY || (topPt.fY == test.fY && topPt.fX > test.fX)) {
+                *topT = extremeT;
+                topPt = test;
+            }
+        }
+    }
+    return topPt;
+}