fix(modeling): correct label line attachments not being recognized

* remove rounding where it does not matter
* work around some precision errors in logic
* adjust test cases (to higher precision)

Closes #669

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

@@ -2,7 +2,8 @@
 
 var sqrt = Math.sqrt,
     min = Math.min,
-    max = Math.max;
+    max = Math.max,
+    abs = Math.abs;
 
 /**
  * Calculate the square (power to two) of a number.
@@ -136,12 +137,6 @@ module.exports.getAttachment = getAttachment;
  */
 function getCircleSegmentIntersections(s1, s2, cc, cr) {
 
-  // silently round values
-  s1 = roundPoint(s1);
-  s2 = roundPoint(s2);
-  cc = roundPoint(cc);
-  cr = min(getDistance(s1, cc), getDistance(s2, cc));
-
   var baX = s2.x - s1.x;
   var baY = s2.y - s1.y;
   var caX = cc.x - s1.x;
@@ -155,6 +150,12 @@ function getCircleSegmentIntersections(s1, s2, cc, cr) {
   var q = c / a;
 
   var disc = pBy2 * pBy2 - q;
+
+  // round disc to 10 digits to work around
+  // negative, very close to zero results (-4e-15)
+  // being produced in some environments
+  disc = round(disc, 10);
+
   if (disc < 0) {
     return [];
   }
@@ -165,8 +166,8 @@ function getCircleSegmentIntersections(s1, s2, cc, cr) {
   var abScalingFactor2 = -pBy2 - tmpSqrt;
 
   var i1 = {
-    x: round(s1.x - baX * abScalingFactor1),
-    y: round(s1.y - baY * abScalingFactor1)
+    x: s1.x - baX * abScalingFactor1,
+    y: s1.y - baY * abScalingFactor1
   };
 
   if (disc === 0) { // abScalingFactor1 == abScalingFactor2
@@ -174,10 +175,11 @@ function getCircleSegmentIntersections(s1, s2, cc, cr) {
   }
 
   var i2 = {
-    x: round(s1.x - baX * abScalingFactor2),
-    y: round(s1.y - baY * abScalingFactor2)
+    x: s1.x - baX * abScalingFactor2,
+    y: s1.y - baY * abScalingFactor2
   };
 
+  // return only points on line segment
   return [ i1, i2 ].filter(function(p) {
     return isPointInSegment(p, s1, s2);
   });
@@ -192,7 +194,14 @@ function isPointInSegment(p, segmentStart, segmentEnd) {
 }
 
 function fenced(n, rangeStart, rangeEnd) {
-  return min(rangeStart, rangeEnd) <= n && n <= max(rangeStart, rangeEnd);
+
+  // use matching threshold to work around
+  // precisison errors in intersection computation
+
+  return (
+    n >= min(rangeStart, rangeEnd) - EQUAL_THRESHOLD &&
+    n <= max(rangeStart, rangeEnd) + EQUAL_THRESHOLD
+  );
 }
 
 /**
@@ -211,23 +220,32 @@ function mid(p1, p2) {
   };
 }
 
-function round(n) {
-  return Math.round(n * 1000) / 1000;
+/**
+ * Round number to precision
+ *
+ * @param {Number} number
+ * @param {Integer} [precision=1]
+ *
+ * @return {Number}
+ */
+function round(number, precision) {
+
+  if (typeof precision === 'undefined') {
+    return Math.round(number);
+  }
+
+  var factor = Math.pow(10, precision);
+  var tempNumber = number * factor;
+  var roundedTempNumber = Math.round(tempNumber);
+  return roundedTempNumber / factor;
 }
 
-function roundPoint(p) {
-  return {
-    x: round(p.x),
-    y: round(p.y)
-  };
-}
-
-var EQUAL_THRESHOLD = 0.2;
+var EQUAL_THRESHOLD = 0.1;
 
 function pointsEqual(p1, p2) {
 
   return (
-    Math.abs(p1.x - p2.x) <= EQUAL_THRESHOLD &&
-    Math.abs(p1.y - p2.y) <= EQUAL_THRESHOLD
+    abs(p1.x - p2.x) <= EQUAL_THRESHOLD &&
+    abs(p1.y - p2.y) <= EQUAL_THRESHOLD
   );
 }

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

@@ -232,14 +232,13 @@ describe('modeling/behavior/util - LineAttachmentUtil#getAttachment', function()
       var attachment = getAttachment({ x: 35.197169, y: 5.399375 }, floatingPointLine);
 
       // then
-      // expext values to be rounded to 3 decimal places
-      expect(attachment).to.eql({
-        type: 'bendpoint',
-        position: { x: 30.793, y: 10.463 },
-        bendpointIndex: 1,
-        segmentIndex: 0
-      });
+      expect(attachment.type).to.equal('bendpoint');
+      expect(attachment.segmentIndex).to.equal(1);
+      expect(attachment.bendpointIndex).to.equal(1);
 
+      // expect values to be roughly equal
+      expect(attachment.position.x).to.be.within(30.793 - EPSILON, 30.793 + EPSILON);
+      expect(attachment.position.y).to.be.within(10.463 - EPSILON, 10.463 + EPSILON);
     });
 
   });