Merge pull request #4268 from jonataswalker/get-overlay-by-id

Add method for retrieving ol.Overlay by id

src/ol/map.js

@@ -342,6 +342,13 @@ ol.Map = function(options) {
    */
   this.overlays_ = optionsInternal.overlays;
 
+  /**
+   * A lookup of overlays by id.
+   * @private
+   * @type {Object.<string, ol.Overlay>}
+   */
+  this.overlayIdIndex_ = {};
+
   /**
    * @type {ol.renderer.Map}
    * @private
@@ -460,21 +467,14 @@ ol.Map = function(options) {
         event.element.setMap(null);
       }, false, this);
 
-  this.overlays_.forEach(
-      /**
-       * @param {ol.Overlay} overlay Overlay.
-       * @this {ol.Map}
-       */
-      function(overlay) {
-        overlay.setMap(this);
-      }, this);
+  this.overlays_.forEach(this.addOverlayInternal_, this);
 
   goog.events.listen(this.overlays_, ol.CollectionEventType.ADD,
       /**
        * @param {ol.CollectionEvent} event Collection event.
        */
       function(event) {
-        event.element.setMap(this);
+        this.addOverlayInternal_(/** @type {ol.Overlay} */ (event.element));
       }, false, this);
 
   goog.events.listen(this.overlays_, ol.CollectionEventType.REMOVE,
@@ -482,6 +482,10 @@ ol.Map = function(options) {
        * @param {ol.CollectionEvent} event Collection event.
        */
       function(event) {
+        var id = event.element.getId();
+        if (id !== undefined) {
+          delete this.overlayIdIndex_[id.toString()];
+        }
         event.element.setMap(null);
       }, false, this);
 
@@ -539,6 +543,20 @@ ol.Map.prototype.addOverlay = function(overlay) {
 };
 
 
+/**
+ * This deals with map's overlay collection changes.
+ * @param {ol.Overlay} overlay Overlay.
+ * @private
+ */
+ol.Map.prototype.addOverlayInternal_ = function(overlay) {
+  var id = overlay.getId();
+  if (id !== undefined) {
+    this.overlayIdIndex_[id.toString()] = overlay;
+  }
+  overlay.setMap(this);
+};
+
+
 /**
  * Add functions to be called before rendering. This can be used for attaching
  * animations before updating the map's view.  The {@link ol.animation}
@@ -767,6 +785,20 @@ ol.Map.prototype.getOverlays = function() {
 };
 
 
+/**
+ * Get an overlay by its identifier (the value returned by overlay.getId()).
+ * Note that the index treats string and numeric identifiers as the same. So
+ * `map.getOverlayById(2)` will return an overlay with id `'2'` or `2`.
+ * @param {string|number} id Overlay identifier.
+ * @return {ol.Overlay} Overlay.
+ * @api
+ */
+ol.Map.prototype.getOverlayById = function(id) {
+  var overlay = this.overlayIdIndex_[id.toString()];
+  return overlay !== undefined ? overlay : null;
+};
+
+
 /**
  * Get the map interactions. Modifying this collection changes the interactions
  * associated with the map.

src/ol/overlay.js

@@ -73,6 +73,12 @@ ol.Overlay = function(options) {
 
   goog.base(this);
 
+  /**
+   * @private
+   * @type {number|string|undefined}
+   */
+  this.id_ = options.id;
+
   /**
    * @private
    * @type {boolean}
@@ -187,6 +193,16 @@ ol.Overlay.prototype.getElement = function() {
 };
 
 
+/**
+ * Get the overlay identifier which is set on constructor.
+ * @return {number|string|undefined} Id.
+ * @api
+ */
+ol.Overlay.prototype.getId = function() {
+  return this.id_;
+};
+
+
 /**
  * Get the map associated with this overlay.
  * @return {ol.Map|undefined} The map that the overlay is part of.