Fix PathItem#isCrossing() to not return overlaps

Closes #1409

src/path/PathItem.Boolean.js

@@ -97,6 +97,17 @@ PathItem.inject(new function() {
         return result;
     }
 
+    function filterIntersection(inter) {
+        // TODO: Change isCrossing() to also handle overlaps (hasOverlap())
+        // that are actually involved in a crossing! For this we need proper
+        // overlap range detection / merging first... But as we call
+        // #resolveCrossings() first in boolean operations, removing all
+        // self-touching areas in paths, this works for the known use cases.
+        // The ideal implementation would deal with it in a way outlined in:
+        // https://github.com/paperjs/paper.js/issues/874#issuecomment-168332391
+        return inter.hasOverlap() || inter.isCrossing();
+    }
+
     function traceBoolean(path1, path2, operation, options) {
         // Only support subtract and intersect operations when computing stroke
         // based boolean operations (options.split = true).
@@ -121,8 +132,8 @@ PathItem.inject(new function() {
             _path2.reverse();
         // Split curves at crossings on both paths. Note that for self-
         // intersection, path2 is null and getIntersections() handles it.
-        var crossings = divideLocations(
+        var crossings = divideLocations(CurveLocation.expand(
-                CurveLocation.expand(_path1.getCrossings(_path2))),
+                _path1.getIntersections(_path2, filterIntersection))),
             paths1 = getPaths(_path1),
             paths2 = _path2 && getPaths(_path2),
             segments = [],
@@ -182,7 +193,7 @@ PathItem.inject(new function() {
     function splitBoolean(path1, path2, operation) {
         var _path1 = preparePath(path1),
             _path2 = preparePath(path2),
-            crossings = _path1.getCrossings(_path2),
+            crossings = _path1.getIntersections(_path2, filterIntersection),
             subtract = operation === 'subtract',
             divide = operation === 'divide',
             added = {},

src/path/PathItem.js

@@ -351,14 +351,7 @@ var PathItem = Item.extend(/** @lends PathItem# */{
      */
     getCrossings: function(path) {
         return this.getIntersections(path, function(inter) {
-            // TODO: Only return overlaps that are actually crossings! For this
+            return inter.isCrossing();
-            // we need proper overlap range detection / merging first...
-            // But as we call #resolveCrossings() first in boolean operations,
-            // removing all self-touching areas in paths, this currently works
-            // as it should in the known use cases.
-            // The ideal implementation would deal with it in a way outlined in:
-            // https://github.com/paperjs/paper.js/issues/874#issuecomment-168332391
-            return inter.hasOverlap() || inter.isCrossing();
         });
     },
 

test/tests/Path_Intersections.js

@@ -380,3 +380,23 @@ test('#1262', function() {
         { point: { x: 567.05562, y: 634.62043 }, time: 1 }
     ]);
 });
+
+test('#1409', function() {
+    var path1 = new Path({
+        segments: [[20, 20], [20, 80], [80, 80], [80, 20]],
+        closed: true
+    });
+    var path2 = new Path({
+        segments: [[80, 20], [80, 80], [140, 80], [140, 20]],
+        closed: true
+    });
+    testIntersections(path1.getCrossings(path2), []);
+
+    var rect1  = new Path.Rectangle(new Point(100, 100), new Size(100, 100));
+    var rect2 = rect1.clone();
+    testIntersections(rect1.getCrossings(rect2), []);
+
+    var circ1 = new Path.Circle(new Point(300,300), 40);
+    var circ2 = circ1.clone();
+    testIntersections(circ1.getCrossings(circ2), []);
+});