Revert of pathops version two

src/pathops/SkDLineIntersection.cpp

Index: src/pathops/SkDLineIntersection.cpp
diff --git a/src/pathops/SkDLineIntersection.cpp b/src/pathops/SkDLineIntersection.cpp
index ed96b9c5d7997033d92f4e1c630c50e2814546e6..8fc673f2fb80e36558df1ae889a82863e6e05975 100644
--- a/src/pathops/SkDLineIntersection.cpp
+++ b/src/pathops/SkDLineIntersection.cpp
@@ -7,6 +7,45 @@
 #include "SkIntersections.h"
 #include "SkPathOpsLine.h"
 
+/* Determine the intersection point of two lines. This assumes the lines are not parallel,
+   and that that the lines are infinite.
+   From http://en.wikipedia.org/wiki/Line-line_intersection
+ */
+SkDPoint SkIntersections::Line(const SkDLine& a, const SkDLine& b) {
+    double axLen = a[1].fX - a[0].fX;
+    double ayLen = a[1].fY - a[0].fY;
+    double bxLen = b[1].fX - b[0].fX;
+    double byLen = b[1].fY - b[0].fY;
+    double denom = byLen * axLen - ayLen * bxLen;
+    SkASSERT(denom);
+    double term1 = a[1].fX * a[0].fY - a[1].fY * a[0].fX;
+    double term2 = b[1].fX * b[0].fY - b[1].fY * b[0].fX;
+    SkDPoint p;
+    p.fX = (term1 * bxLen - axLen * term2) / denom;
+    p.fY = (term1 * byLen - ayLen * term2) / denom;
+    return p;
+}
+
+int SkIntersections::cleanUpCoincidence() {
+    do {
+        int last = fUsed - 1;
+        for (int index = 0; index < last; ++index) {
+            if (fT[0][index] == fT[0][index + 1]) {
+                removeOne(index + (int) (fT[1][index] == 0 || fT[1][index] == 1));
+                goto tryAgain;
+            }
+        }
+        for (int index = 0; index < last; ++index) {
+            if (fT[1][index] == fT[1][index + 1]) {
+                removeOne(index + (int) (fT[0][index] == 0 || fT[0][index] == 1));
+                goto tryAgain;
+            }
+        }
+        return fUsed;
+tryAgain: ;
+    } while (true);
+}
+
 void SkIntersections::cleanUpParallelLines(bool parallel) {
     while (fUsed > 2) {
         removeOne(1);
@@ -18,9 +57,6 @@
             SkASSERT(startMatch || endMatch);
             removeOne(endMatch);
         }
-    }
-    if (fUsed == 2) {
-        fIsCoincident[0] = fIsCoincident[1] = 0x03;
     }
 }
 
@@ -45,6 +81,12 @@
     SkDVector ab0 = a[0] - b[0];
     double numerA = ab0.fY * bLen.fX - bLen.fY * ab0.fX;
     double numerB = ab0.fY * aLen.fX - aLen.fY * ab0.fX;
+#if 0
+    if (!between(0, numerA, denom) || !between(0, numerB, denom)) {
+        fUsed = 0;
+        return 0;
+    }
+#endif
     numerA /= denom;
     numerB /= denom;
     int used;
@@ -148,6 +190,7 @@
                     }
                     SkASSERT(a[iA] != b[nearer]);
                     SkASSERT(iA == (bNearA[nearer] > 0.5));
+                    fNearlySame[iA] = true;
                     insertNear(iA, nearer, a[iA], b[nearer]);
                     aNearB[iA] = -1;
                     bNearA[nearer] = -1;
@@ -190,6 +233,18 @@
 
 static double horizontal_intercept(const SkDLine& line, double y) {
      return SkPinT((y - line[0].fY) / (line[1].fY - line[0].fY));
+}
+
+int SkIntersections::horizontal(const SkDLine& line, double y) {
+    fMax = 2;
+    int horizontalType = horizontal_coincident(line, y);
+    if (horizontalType == 1) {
+        fT[0][0] = horizontal_intercept(line, y);
+    } else if (horizontalType == 2) {
+        fT[0][0] = 0;
+        fT[0][1] = 1;
+    }
+    return fUsed = horizontalType;
 }
 
 int SkIntersections::horizontal(const SkDLine& line, double left, double right,
@@ -268,6 +323,18 @@
     return SkPinT((x - line[0].fX) / (line[1].fX - line[0].fX));
 }
 
+int SkIntersections::vertical(const SkDLine& line, double x) {
+    fMax = 2;
+    int verticalType = vertical_coincident(line, x);
+    if (verticalType == 1) {
+        fT[0][0] = vertical_intercept(line, x);
+    } else if (verticalType == 2) {
+        fT[0][0] = 0;
+        fT[0][1] = 1;
+    }
+    return fUsed = verticalType;
+}
+
 int SkIntersections::vertical(const SkDLine& line, double top, double bottom,
                               double x, bool flipped) {
     fMax = 3;  // cleanup parallel lines will bring this back line
@@ -326,3 +393,14 @@
     return fUsed;
 }
 
+// from http://www.bryceboe.com/wordpress/wp-content/uploads/2006/10/intersect.py
+// 4 subs, 2 muls, 1 cmp
+static bool ccw(const SkDPoint& A, const SkDPoint& B, const SkDPoint& C) {
+    return (C.fY - A.fY) * (B.fX - A.fX) > (B.fY - A.fY) * (C.fX - A.fX);
+}
+
+// 16 subs, 8 muls, 6 cmps
+bool SkIntersections::Test(const SkDLine& a, const SkDLine& b) {
+    return ccw(a[0], b[0], b[1]) != ccw(a[1], b[0], b[1])
+            && ccw(a[0], a[1], b[0]) != ccw(a[0], a[1], b[1]);
+}