path ops work in progress

src/pathops/SkPathOpsLine.cpp

Index: src/pathops/SkPathOpsLine.cpp
diff --git a/src/pathops/SkPathOpsLine.cpp b/src/pathops/SkPathOpsLine.cpp
index 48c042a7facbb7ecfe525669662bdf7649e1b17a..1b548fcd30b20e4f59729808239585a37095fb2c 100644
--- a/src/pathops/SkPathOpsLine.cpp
+++ b/src/pathops/SkPathOpsLine.cpp
@@ -78,9 +78,7 @@ double SkDLine::nearPoint(const SkDPoint& xy) const {
     }
     double t = numer / denom;
     SkDPoint realPt = ptAtT(t);
-    SkDVector distU = xy - realPt;
-    double distSq = distU.fX * distU.fX + distU.fY * distU.fY;
-    double dist = sqrt(distSq); // OPTIMIZATION: can we compare against distSq instead ?
+    double dist = realPt.distance(xy);   // OPTIMIZATION: can we compare against distSq instead ?
     // find the ordinal in the original line with the largest unsigned exponent
     double tiniest = SkTMin(SkTMin(SkTMin(fPts[0].fX, fPts[0].fY), fPts[1].fX), fPts[1].fY);
     double largest = SkTMax(SkTMax(SkTMax(fPts[0].fX, fPts[0].fY), fPts[1].fX), fPts[1].fY);
@@ -93,6 +91,35 @@ double SkDLine::nearPoint(const SkDPoint& xy) const {
     return t;
 }
 
+bool SkDLine::nearRay(const SkDPoint& xy) const {
+    // project a perpendicular ray from the point to the line; find the T on the line
+    SkDVector len = fPts[1] - fPts[0]; // the x/y magnitudes of the line
+    double denom = len.fX * len.fX + len.fY * len.fY;  // see DLine intersectRay
+    SkDVector ab0 = xy - fPts[0];
+    double numer = len.fX * ab0.fX + ab0.fY * len.fY;
+    double t = numer / denom;
+    SkDPoint realPt = ptAtT(t);
+    double dist = realPt.distance(xy);   // OPTIMIZATION: can we compare against distSq instead ?
+    // find the ordinal in the original line with the largest unsigned exponent
+    double tiniest = SkTMin(SkTMin(SkTMin(fPts[0].fX, fPts[0].fY), fPts[1].fX), fPts[1].fY);
+    double largest = SkTMax(SkTMax(SkTMax(fPts[0].fX, fPts[0].fY), fPts[1].fX), fPts[1].fY);
+    largest = SkTMax(largest, -tiniest);
+    return RoughlyEqualUlps(largest, largest + dist); // is the dist within ULPS tolerance?
+}
+
+// Returns true if a ray from (0,0) to (x1,y1) is coincident with a ray (0,0) to (x2,y2)
+// OPTIMIZE: a specialty routine could speed this up -- may not be called very often though
+bool SkDLine::NearRay(double x1, double y1, double x2, double y2) {
+    double denom1 = x1 * x1 + y1 * y1;
+    double denom2 = x2 * x2 + y2 * y2;
+    SkDLine line = {{{0, 0}, {x1, y1}}};
+    SkDPoint pt = {x2, y2};
+    if (denom2 > denom1) {
+        SkTSwap(line[1], pt);
+    }
+    return line.nearRay(pt);
+}
+
 double SkDLine::ExactPointH(const SkDPoint& xy, double left, double right, double y) {
     if (xy.fY == y) {
         if (xy.fX == left) {
@@ -106,7 +133,7 @@ double SkDLine::ExactPointH(const SkDPoint& xy, double left, double right, doubl
 }
 
 double SkDLine::NearPointH(const SkDPoint& xy, double left, double right, double y) {
-    if (!AlmostEqualUlps(xy.fY, y)) {
+    if (!AlmostBequalUlps(xy.fY, y)) {
         return -1;
     }
     if (!AlmostBetweenUlps(left, xy.fX, right)) {
@@ -115,6 +142,18 @@ double SkDLine::NearPointH(const SkDPoint& xy, double left, double right, double
     double t = (xy.fX - left) / (right - left);
     t = SkPinT(t);
     SkASSERT(between(0, t, 1));
+    double realPtX = (1 - t) * left + t * right;
+    SkDVector distU = {xy.fY - y, xy.fX - realPtX};
+    double distSq = distU.fX * distU.fX + distU.fY * distU.fY;
+    double dist = sqrt(distSq); // OPTIMIZATION: can we compare against distSq instead ?
+    double tiniest = SkTMin(SkTMin(y, left), right);
+    double largest = SkTMax(SkTMax(y, left), right);
+    largest = SkTMax(largest, -tiniest);
+    if (!AlmostEqualUlps(largest, largest + dist)) { // is the dist within ULPS tolerance?
+        return -1;
+    }
+    t = SkPinT(t);
+    SkASSERT(between(0, t, 1));
     return t;
 }
 
@@ -131,7 +170,7 @@ double SkDLine::ExactPointV(const SkDPoint& xy, double top, double bottom, doubl
 }
 
 double SkDLine::NearPointV(const SkDPoint& xy, double top, double bottom, double x) {
-    if (!AlmostEqualUlps(xy.fX, x)) {
+    if (!AlmostBequalUlps(xy.fX, x)) {
         return -1;
     }
     if (!AlmostBetweenUlps(top, xy.fY, bottom)) {
@@ -140,5 +179,27 @@ double SkDLine::NearPointV(const SkDPoint& xy, double top, double bottom, double
     double t = (xy.fY - top) / (bottom - top);
     t = SkPinT(t);
     SkASSERT(between(0, t, 1));
+    double realPtY = (1 - t) * top + t * bottom;
+    SkDVector distU = {xy.fX - x, xy.fY - realPtY};
+    double distSq = distU.fX * distU.fX + distU.fY * distU.fY;
+    double dist = sqrt(distSq); // OPTIMIZATION: can we compare against distSq instead ?
+    double tiniest = SkTMin(SkTMin(x, top), bottom);
+    double largest = SkTMax(SkTMax(x, top), bottom);
+    largest = SkTMax(largest, -tiniest);
+    if (!AlmostEqualUlps(largest, largest + dist)) { // is the dist within ULPS tolerance?
+        return -1;
+    }
+    t = SkPinT(t);
+    SkASSERT(between(0, t, 1));
     return t;
 }
+
+#ifdef SK_DEBUG
+void SkDLine::dump() {
+    SkDebugf("{{");
+    fPts[0].dump();
+    SkDebugf(", ");
+    fPts[1].dump();
+    SkDebugf("}}\n");
+}
+#endif