Format: Added EncodedPolyline class

This class is able to convert an encoded polyline string into a LineString embedded in a Vector Feature. See https://developers.google.com/maps/documentation/utilities/polylinealgorithm for more information.
2012-12-26 18:25:04 +01:00
parent 4b2e80fa36
commit 63a9567858
4 changed files with 128 additions and 0 deletions
@@ -306,6 +306,7 @@
                "OpenLayers/Format/GML/v2.js",
                "OpenLayers/Format/GML/v3.js",
                "OpenLayers/Format/Atom.js",
+                "OpenLayers/Format/EncodedPolyline.js",
                "OpenLayers/Format/KML.js",
                "OpenLayers/Format/GeoRSS.js",
                "OpenLayers/Format/WFS.js",
@@ -0,0 +1,85 @@
+/* Copyright (c) 2006-2012 by OpenLayers Contributors (see authors.txt for
+ * full list of contributors). Published under the 2-clause BSD license.
+ * See license.txt in the OpenLayers distribution or repository for the
+ * full text of the license. */
+
+/**
+ * @requires OpenLayers/Format.js
+ * @requires OpenLayers/Feature/Vector.js
+ */
+
+/**
+ * Class: OpenLayers.Format.EncodedPolyline
+ * Class for reading and writing encoded polylines.  Create a new instance
+ * with the <OpenLayers.Format.EncodedPolyline> constructor.
+ *
+ * Inherits from:
+ *  - <OpenLayers.Format>
+ */
+OpenLayers.Format.EncodedPolyline = OpenLayers.Class(OpenLayers.Format, {
+
+    /**
+     * Constructor: OpenLayers.Format.EncodedPolyline
+     * Create a new parser for encoded polylines
+     *
+     * Parameters:
+     * options - {Object} An optional object whose properties will be set on
+     *           this instance
+     *
+     * Returns:
+     * {<OpenLayers.Format.EncodedPolyline>} A new encoded polylines parser.
+     */
+    initialize: function(options) {
+        OpenLayers.Format.prototype.initialize.apply(this, [options]);
+    },
+
+    /**
+     * Method: read
+     * Deserialize an encoded polyline string and return a vector feature.
+     *
+     * Parameters:
+     * encoded - {String} An encoded polyline string
+     *
+     * Returns:
+     * {<OpenLayers.Feature.Vector>} A vector feature with a linestring.
+     */
+    read: function(encoded) {
+        var points = new Array();
+
+        var lat = 0;
+        var lon = 0;
+
+        for (var i = 0; i < encoded.length;) {
+            var b;
+            var result = 0;
+            var shift = 0;
+
+            do {
+                b = encoded.charCodeAt(i++) - 63;
+                result |= (b & 0x1f) << shift;
+                shift += 5;
+            } while (b >= 0x20);
+
+            lat += ((result & 1) ? ~(result >> 1) : (result >> 1));
+
+            result = 0;
+            shift = 0;
+
+            do {
+                b = encoded.charCodeAt(i++) - 63;
+                result |= (b & 0x1f) << shift;
+                shift += 5;
+            } while (b >= 0x20);
+
+            lon += ((result & 1) ? ~(result >> 1) : (result >> 1));
+
+            points.push(new OpenLayers.Geometry.Point(lon * 1e-5, lat * 1e-5));
+        }
+
+        return new OpenLayers.Feature.Vector(
+            new OpenLayers.Geometry.LineString(points)
+        );
+    },
+
+    CLASS_NAME: "OpenLayers.Format.EncodedPolyline"
+});