pathops coincidence and security rewrite

src/pathops/SkDCubicLineIntersection.cpp

 /*
  * Copyright 2012 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 "SkPathOpsCubic.h"
+#include "SkPathOpsCurve.h"
 #include "SkPathOpsLine.h"
 
 /*
 Find the interection of a line and cubic by solving for valid t values.
 
 Analogous to line-quadratic intersection, solve line-cubic intersection by
 representing the cubic as:
   x = a(1-t)^3 + 2b(1-t)^2t + c(1-t)t^2 + dt^3
   y = e(1-t)^3 + 2f(1-t)^2t + g(1-t)t^2 + ht^3
 and the line as:
@@ skipping 265 matching lines @@
             double cubicT = (double) (cIndex >> 1);
             if (fIntersections->hasT(cubicT)) {
                 continue;
             }
             double lineT = fLine.nearPoint(fCubic[cIndex], nullptr);
             if (lineT < 0) {
                 continue;
             }
             fIntersections->insert(cubicT, lineT, fCubic[cIndex]);
         }
+        addLineNearEndPoints();
+    }
+
+    void addLineNearEndPoints() {
+        for (int lIndex = 0; lIndex < 2; ++lIndex) {
+            double lineT = (double) lIndex;
+            if (fIntersections->hasOppT(lineT)) {
+                continue;
+            }
+            double cubicT = ((SkDCurve*) &fCubic)->nearPoint(SkPath::kCubic_Verb,
+                fLine[lIndex], fLine[!lIndex]);
+            if (cubicT < 0) {
+                continue;
+            }
+            fIntersections->insert(cubicT, lineT, fLine[lIndex]);
+        }
     }
 
     void addExactHorizontalEndPoints(double left, double right, double y) {
         for (int cIndex = 0; cIndex < 4; cIndex += 3) {
             double lineT = SkDLine::ExactPointH(fCubic[cIndex], left, right, y);
             if (lineT < 0) {
                 continue;
             }
             double cubicT = (double) (cIndex >> 1);
             fIntersections->insert(cubicT, lineT, fCubic[cIndex]);
         }
     }
 
     void addNearHorizontalEndPoints(double left, double right, double y) {
         for (int cIndex = 0; cIndex < 4; cIndex += 3) {
             double cubicT = (double) (cIndex >> 1);
             if (fIntersections->hasT(cubicT)) {
                 continue;
             }
             double lineT = SkDLine::NearPointH(fCubic[cIndex], left, right, y);
             if (lineT < 0) {
                 continue;
             }
             fIntersections->insert(cubicT, lineT, fCubic[cIndex]);
         }
-        // FIXME: see if line end is nearly on cubic
+        addLineNearEndPoints();

[herb_g, 2016/07/18 15:13:39]

this->

[caryclark, 2016/07/18 15:55:49]

Done.

     }
 
     void addExactVerticalEndPoints(double top, double bottom, double x) {
         for (int cIndex = 0; cIndex < 4; cIndex += 3) {
             double lineT = SkDLine::ExactPointV(fCubic[cIndex], top, bottom, x);
             if (lineT < 0) {
                 continue;
             }
             double cubicT = (double) (cIndex >> 1);
             fIntersections->insert(cubicT, lineT, fCubic[cIndex]);
         }
     }
 
     void addNearVerticalEndPoints(double top, double bottom, double x) {
         for (int cIndex = 0; cIndex < 4; cIndex += 3) {
             double cubicT = (double) (cIndex >> 1);
             if (fIntersections->hasT(cubicT)) {
                 continue;
             }
             double lineT = SkDLine::NearPointV(fCubic[cIndex], top, bottom, x);
             if (lineT < 0) {
                 continue;
             }
             fIntersections->insert(cubicT, lineT, fCubic[cIndex]);
         }
-        // FIXME: see if line end is nearly on cubic
+        addLineNearEndPoints();
     }
 
     double findLineT(double t) {
         SkDPoint xy = fCubic.ptAtT(t);
         double dx = fLine[1].fX - fLine[0].fX;
         double dy = fLine[1].fY - fLine[0].fY;
         if (fabs(dx) > fabs(dy)) {
             return (xy.fX - fLine[0].fX) / dx;
         }
         return (xy.fY - fLine[0].fY) / dy;
@@ skipping 72 matching lines @@
 
 // SkDCubic accessors to Intersection utilities
 
 int SkDCubic::horizontalIntersect(double yIntercept, double roots[3]) const {
     return LineCubicIntersections::HorizontalIntersect(*this, yIntercept, roots);
 }
 
 int SkDCubic::verticalIntersect(double xIntercept, double roots[3]) const {
     return LineCubicIntersections::VerticalIntersect(*this, xIntercept, roots);
 }