fix(modeling/layout): handle zero-length lines during adjustment

Closes #669

lib/features/modeling/behavior/util/LineAttachmentUtil.js

@@ -74,16 +74,16 @@ function getAttachment(point, line) {
     segmentEnd = line[idx + 1];
 
     if (pointsEqual(segmentStart, segmentEnd)) {
-      continue;
+      intersections = [ segmentStart ];
+    } else {
+      segmentStartDistance = getDistance(point, segmentStart);
+      segmentEndDistance = getDistance(point, segmentEnd);
+
+      minDistance = min(segmentStartDistance, segmentEndDistance);
+
+      intersections = getCircleSegmentIntersections(segmentStart, segmentEnd, point, minDistance);
     }
 
-    segmentStartDistance = getDistance(point, segmentStart);
-    segmentEndDistance = getDistance(point, segmentEnd);
-
-    minDistance = min(segmentStartDistance, segmentEndDistance);
-
-    intersections = getCircleSegmentIntersections(segmentStart, segmentEnd, point, minDistance);
-
     if (intersections.length < 1) {
       throw new Error('expected between [1, 2] circle -> line intersections');
     }
@@ -222,6 +222,12 @@ function roundPoint(p) {
   };
 }
 
+var EQUAL_THRESHOLD = 0.2;
+
 function pointsEqual(p1, p2) {
-  return p1.x === p2.x && p1.y === p2.y;
+
+  return (
+    Math.abs(p1.x - p2.x) <= EQUAL_THRESHOLD &&
+    Math.abs(p1.y - p2.y) <= EQUAL_THRESHOLD
+  );
 }

test/spec/features/modeling/behavior/util/LineAttachmentUtilSpec.js

@@ -4,6 +4,7 @@ var getAttachment = require('lib/features/modeling/behavior/util/LineAttachmentU
 
 var EPSILON = 0.1;
 
+
 describe('modeling/behavior/util - LineAttachmentUtil#getAttachment', function() {
 
   // test line
@@ -198,7 +199,7 @@ describe('modeling/behavior/util - LineAttachmentUtil#getAttachment', function()
     //     \
     //      *
     //
-    var otherLine = [
+    var floatingPointLine = [
       { x: 10.141592, y: 10.653589 },
       // -
       { x: 30.793238, y: 10.462643 },
@@ -212,7 +213,7 @@ describe('modeling/behavior/util - LineAttachmentUtil#getAttachment', function()
     it('float value segment', function() {
 
       // when
-      var attachment = getAttachment({ x: 20.197169, y: 5.399375 }, otherLine);
+      var attachment = getAttachment({ x: 20.197169, y: 5.399375 }, floatingPointLine);
 
       // then
       expect(attachment.type).to.equal('segment');
@@ -228,7 +229,7 @@ describe('modeling/behavior/util - LineAttachmentUtil#getAttachment', function()
     it('float value bendboint', function() {
 
       // when
-      var attachment = getAttachment({ x: 35.197169, y: 5.399375 }, otherLine);
+      var attachment = getAttachment({ x: 35.197169, y: 5.399375 }, floatingPointLine);
 
       // then
       // expext values to be rounded to 3 decimal places
@@ -243,4 +244,52 @@ describe('modeling/behavior/util - LineAttachmentUtil#getAttachment', function()
 
   });
 
+
+  describe('handle zero-length line', function() {
+
+    var zeroLengthLine = [
+      { x: 10, y: 10 },
+      // -
+      { x: 10, y: 10 }
+    ];
+
+
+    var zeroLengthFloatingPointLine = [
+      { x: 10.1, y: 10.12313 },
+      // -
+      { x: 10, y: 10.112 }
+    ];
+
+
+    it('should treat zero-length as bendpoint attach', function() {
+
+      // when
+      var attachment = getAttachment({ x: 15.1, y: 15.123 }, zeroLengthLine);
+
+      // then
+      expect(attachment).to.eql({
+        type: 'bendpoint',
+        position: { x: 10, y: 10 },
+        segmentIndex: 0,
+        bendpointIndex: 0
+      });
+    });
+
+
+    it('should treat approx zero-length as bendpoint attach', function() {
+
+      // when
+      var attachment = getAttachment({ x: 15.1, y: 15.123 }, zeroLengthFloatingPointLine);
+
+      // then
+      expect(attachment).to.eql({
+        type: 'bendpoint',
+        position: { x: 10.1, y: 10.12313 },
+        segmentIndex: 0,
+        bendpointIndex: 0
+      });
+    });
+
+  });
+
 });