fix bugs found by computing flat clips in 800K skps

src/pathops/SkIntersections.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 SkIntersections_DEFINE
 #define SkIntersections_DEFINE
 
 #include "SkPathOpsCubic.h"
 #include "SkPathOpsLine.h"
 #include "SkPathOpsPoint.h"
 #include "SkPathOpsQuad.h"
 
 class SkIntersections {
 public:
     SkIntersections()
         : fSwap(0)
 #ifdef SK_DEBUG
         , fDepth(0)
 #endif
     {
         sk_bzero(fPt, sizeof(fPt));
+        sk_bzero(fPt2, sizeof(fPt2));
         sk_bzero(fT, sizeof(fT));
         sk_bzero(fIsCoincident, sizeof(fIsCoincident));
+        sk_bzero(fNearlySame, sizeof(fNearlySame));
         reset();
         fMax = 0;  // require that the caller set the max
     }
 
     class TArray {
     public:
         explicit TArray(const double ts[9]) : fTArray(ts) {}
         double operator[](int n) const {
             return fTArray[n];
         }
         const double* fTArray;
     };
     TArray operator[](int n) const { return TArray(fT[n]); }
 
-    void set(const SkIntersections& i) {
-        memcpy(fPt, i.fPt, sizeof(fPt));
-        memcpy(fT, i.fT, sizeof(fT));
-        memcpy(fIsCoincident, i.fIsCoincident, sizeof(fIsCoincident));
-        fUsed = i.fUsed;
-        fMax = i.fMax;
-        fSwap = i.fSwap;
-        SkDEBUGCODE(fDepth = i.fDepth);
-    }
-
     void allowNear(bool nearAllowed) {
         fAllowNear = nearAllowed;
     }
 
     int cubic(const SkPoint a[4]) {
         SkDCubic cubic;
         cubic.set(a);
         fMax = 1;  // self intersect
         return intersect(cubic);
     }
@@ skipping 73 matching lines @@
     }
 
     int lineLine(const SkPoint a[2], const SkPoint b[2]) {
         SkDLine aLine, bLine;
         aLine.set(a);
         bLine.set(b);
         fMax = 2;
         return intersect(aLine, bLine);
     }
 
+    bool nearlySame(int index) const {
+        SkASSERT(index == 0 || index == 1);
+        return fNearlySame[index];
+    }
+
     const SkDPoint& pt(int index) const {
         return fPt[index];
     }
 
+    const SkDPoint& pt2(int index) const {
+        return fPt2[index];
+    }
+
     int quadHorizontal(const SkPoint a[3], SkScalar left, SkScalar right, SkScalar y,
                        bool flipped) {
         SkDQuad quad;
         quad.set(a);
         fMax = 2;
         return horizontal(quad, left, right, y, flipped);
     }
 
     int quadVertical(const SkPoint a[3], SkScalar top, SkScalar bottom, SkScalar x, bool flipped) {
         SkDQuad quad;
@@ skipping 13 matching lines @@
 
     int quadQuad(const SkPoint a[3], const SkPoint b[3]) {
         SkDQuad aQuad;
         aQuad.set(a);
         SkDQuad bQuad;
         bQuad.set(b);
         fMax = 4;
         return intersect(aQuad, bQuad);
     }
 
-    // leaves flip, swap, max alone
+    // leaves swap, max alone
     void reset() {
         fAllowNear = true;
         fUsed = 0;
     }
 
+    void set(bool swap, int tIndex, double t) {
+        fT[(int) swap][tIndex] = t;
+    }
+
     void setMax(int max) {
         fMax = max;
     }
 
     void swap() {
         fSwap ^= true;
     }
 
     void swapPts();
 
     bool swapped() const {
         return fSwap;
     }
 
     int used() const {
         return fUsed;
     }
 
     void downDepth() {
         SkASSERT(--fDepth >= 0);
     }
 
     void upDepth() {
         SkASSERT(++fDepth < 16);
     }
 
     void append(const SkIntersections& );
     void cleanUpCoincidence();
     int coincidentUsed() const;
+    void cubicInsert(double one, double two, const SkDPoint& pt, const SkDCubic& c1,
+                     const SkDCubic& c2);
     int cubicRay(const SkPoint pts[4], const SkDLine& line);
     void flip();
     int horizontal(const SkDLine&, double y);
     int horizontal(const SkDLine&, double left, double right, double y, bool flipped);
     int horizontal(const SkDQuad&, double left, double right, double y, bool flipped);
     int horizontal(const SkDQuad&, double left, double right, double y, double tRange[2]);
     int horizontal(const SkDCubic&, double y, double tRange[3]);
     int horizontal(const SkDCubic&, double left, double right, double y, bool flipped);
     int horizontal(const SkDCubic&, double left, double right, double y, double tRange[3]);
     // FIXME : does not respect swap
     int insert(double one, double two, const SkDPoint& pt);
-    void insertNear(double one, double two, const SkDPoint& pt);
+    void insertNear(double one, double two, const SkDPoint& pt1, const SkDPoint& pt2);
     // start if index == 0 : end if index == 1
     void insertCoincident(double one, double two, const SkDPoint& pt);
     int intersect(const SkDLine&, const SkDLine&);
     int intersect(const SkDQuad&, const SkDLine&);
     int intersect(const SkDQuad&, const SkDQuad&);
     int intersect(const SkDCubic&);  // return true if cubic self-intersects
     int intersect(const SkDCubic&, const SkDLine&);
     int intersect(const SkDCubic&, const SkDQuad&);
     int intersect(const SkDCubic&, const SkDCubic&);
     int intersectRay(const SkDLine&, const SkDLine&);
@@ skipping 23 matching lines @@
     }
 
 private:
     bool cubicCheckCoincidence(const SkDCubic& c1, const SkDCubic& c2);
     bool cubicExactEnd(const SkDCubic& cubic1, bool start, const SkDCubic& cubic2);
     void cubicNearEnd(const SkDCubic& cubic1, bool start, const SkDCubic& cubic2, const SkDRect& );
     void cleanUpParallelLines(bool parallel);
     void computePoints(const SkDLine& line, int used);
 
     SkDPoint fPt[9];  // FIXME: since scans store points as SkPoint, this should also
+    SkDPoint fPt2[9];  // used by nearly same to store alternate intersection point
     double fT[2][9];
     uint16_t fIsCoincident[2];  // bit set for each curve's coincident T
+    bool fNearlySame[2];  // true if end points nearly match
     unsigned char fUsed;
     unsigned char fMax;
     bool fAllowNear;
     bool fSwap;
 #ifdef SK_DEBUG
     int fDepth;
 #endif
 };
 
 extern int (SkIntersections::*CurveRay[])(const SkPoint[], const SkDLine& );
 extern int (SkIntersections::*CurveVertical[])(const SkPoint[], SkScalar top, SkScalar bottom,
             SkScalar x, bool flipped);
 
 #endif