Add method Polyline.closestLayerPoint

Also fix method L.LineUtil.simplify for empty geometry

spec/runner.html

@@ -41,6 +41,7 @@
 
 		<!-- /layer -->
 		<script type="text/javascript" src="suites/layer/TileLayerSpec.js"></script>
+		<script type="text/javascript" src="suites/layer/vector/PolylineGeometrySpec.js"></script>
 		
 		<!-- /map -->
 		<script type="text/javascript" src="suites/map/MapSpec.js"></script>

spec/suites/SpecHelper.js

@@ -3,3 +3,26 @@ function noSpecs() {
 		expect('specs').toBe();
 	});
 }
+
+if (!Array.prototype.map) {
+  Array.prototype.map = function(fun /*, thisp */) {
+    "use strict";
+
+    if (this === void 0 || this === null)
+      throw new TypeError();
+
+    var t = Object(this);
+    var len = t.length >>> 0;
+    if (typeof fun !== "function")
+      throw new TypeError();
+
+    var res = new Array(len);
+    var thisp = arguments[1];
+    for (var i = 0; i < len; i++) {
+      if (i in t)
+        res[i] = fun.call(thisp, t[i], i, t);
+    }
+
+    return res;
+  };
+}

spec/suites/layer/vector/PolylineGeometrySpec.js

@@ -0,0 +1,35 @@
+describe('PolylineGeometry', function() {
+	
+	var c = document.createElement('div');
+	c.style.width = '400px';
+	c.style.height = '400px';
+	var map = new L.Map(c);
+	map.setView(new L.LatLng(55.8, 37.6), 6);
+	
+	describe("#distanceTo", function() {
+		it("should calculate correct distances to points", function() {
+			var p1 = map.latLngToLayerPoint(new L.LatLng(55.8, 37.6));
+			var p2 = map.latLngToLayerPoint(new L.LatLng(57.123076977278, 44.861962891635));
+			var latlngs = [[56.485503424111, 35.545556640339], [55.972522915346, 36.116845702918], [55.502459116923, 34.930322265253], [55.31534617509, 38.973291015816]]
+			.map(function(ll) {
+				return new L.LatLng(ll[0], ll[1]);
+			});
+			var polyline = new L.Polyline([], {
+				'noClip': true
+			});
+			map.addLayer(polyline);
+			
+			expect(polyline.closestLayerPoint(p1)).toEqual(null);
+			
+			polyline.setLatLngs(latlngs);
+			var point = polyline.closestLayerPoint(p1);
+			expect(point).not.toEqual(null);
+			expect(point.distance).not.toEqual(Infinity);
+			expect(point.distance).not.toEqual(NaN);
+			
+			var point2 = polyline.closestLayerPoint(p2);
+			
+			expect(point.distance).toBeLessThan(point2.distance);
+		});
+	});
+});

src/geometry/LineUtil.js

@@ -9,7 +9,7 @@ L.LineUtil = {
 	 * Improves rendering performance dramatically by lessening the number of points to draw.
 	 */
 	simplify: function(/*Point[]*/ points, /*Number*/ tolerance) {
-		if (!tolerance) return points.slice();
+		if (!tolerance || !points.length) return points.slice();
 		
 		// stage 1: vertex reduction
 		points = this.reducePoints(points, tolerance);
@@ -25,6 +25,12 @@ L.LineUtil = {
 		return Math.sqrt(this._sqPointToSegmentDist(p, p1, p2));
 	},
 	
+	closestPointOnSegment: function(/*Point*/ p, /*Point*/ p1, /*Point*/ p2) {
+		var point = this._sqClosestPointOnSegment(p, p1, p2);
+		point.distance = Math.sqrt(point._sqDist);
+		return point;
+	},
+	
 	// Douglas-Peucker simplification, see http://en.wikipedia.org/wiki/Douglas-Peucker_algorithm
 	simplifyDP: function(points, tol) {
 		var maxDist2 = 0,
@@ -140,8 +146,10 @@ L.LineUtil = {
 		return dx * dx + dy * dy;
 	},
 	
-	// square distance from point to a segment
-	_sqPointToSegmentDist: function(p, p1, p2) {
+	/**
+	 * @return L.Point point on segment with attribute _sqDist - square distance to segment
+	 */	
+	_sqClosestPointOnSegment: function(p, p1, p2) {
 		var x2 = p2.x - p1.x,
 			y2 = p2.y - p1.y;
 		
@@ -150,10 +158,18 @@ L.LineUtil = {
 		var dot = (p.x - p1.x) * x2 + (p.y - p1.y) * y2,
 			t = dot / this._sqDist(p1, p2);
 		
-		if (t < 0) return this._sqDist(p, p1);
-		if (t > 1) return this._sqDist(p, p2);
+		var apoint = p1;
+		if (t > 1) {
+			apoint = p2;
+		} else if (t > 0) {
+			apoint = new L.Point(p1.x + x2 * t, p1.y + y2 * t);
+		}
+		apoint._sqDist = this._sqDist(p, apoint);
+		return apoint;
+	},
 	
-		var proj = new L.Point(p1.x + x2 * t, p1.y + y2 * t);
-		return this._sqDist(p, proj);
+	// distance from a point to a segment between two points
+	_sqPointToSegmentDist: function(p, p1, p2) {
+		return this._sqClosestPointOnSegment(p, p1, p2)._sqDist;
 	}
 };

src/layer/vector/Polyline.js

@@ -51,6 +51,25 @@ L.Polyline = L.Path.extend({
 		return removed;
 	},
 	
+	closestLayerPoint: function(p) {
+		var minDistance = Infinity, parts = this._parts, p1, p2, minPoint = null;
+
+		for (var j = 0, jLen = parts.length; j < jLen; j++) {
+			var points = parts[j];
+			for (var i = 1, len = points.length; i < len; i++) {
+				p1 = points[i-1];
+				p2 = points[i];
+				var point = L.LineUtil._sqClosestPointOnSegment(p, p1, p2);
+				if (point._sqDist < minDistance) {
+					minDistance = point._sqDist;
+					minPoint = point;
+				}
+			}			
+		}
+		if (minPoint) minPoint.distance = Math.sqrt(minDistance);
+		return minPoint;
+	},
+
 	_getPathPartStr: function(points) {
 		var round = L.Path.VML;