patch for #831 - simplify the notion of untiled (now an option on grid layers called 'singleTile') and implementing loading events for gridded/untiled layers. thanks tim and chris for reviewing this beast.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@3725 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Tile.js

@@ -21,6 +21,19 @@ OpenLayers.Tile = OpenLayers.Class.create();
 OpenLayers.Tile.prototype = {
     
     /** 
+     * Constant: EVENT_TYPES
+     * {Array(String)} Supported application event types
+     */
+    EVENT_TYPES: [ "loadstart", "loadend", "reload"],
+    
+    /**
+     * APIProperty: events
+     * {<OpenLayers.Events>} An events object that handles all 
+     *                       events on the tile.
+     */
+    events: null,
+
+    /**
      * Property: id 
      * {String} null
      */
@@ -66,6 +79,12 @@ OpenLayers.Tile.prototype = {
      */
     drawn: false,
 
+    /**
+     * Property: isLoading
+     * {Boolean} Is the tile loading?
+     */
+    isLoading: false,
+    
     /** TBD 3.0 -- remove 'url' from the list of parameters to the constructor.
      *             there is no need for the base tile class to have a url.
      * 
@@ -88,6 +107,8 @@ OpenLayers.Tile.prototype = {
 
         //give the tile a unique id based on its BBOX.
         this.id = OpenLayers.Util.createUniqueID("Tile_");
+        
+        this.events = new OpenLayers.Events(this, null, this.EVENT_TYPES);
     },
     
     /** 
@@ -99,6 +120,9 @@ OpenLayers.Tile.prototype = {
         this.bounds = null;
         this.size = null;
         this.position = null;
+        
+        this.events.destroy();
+        this.events = null;
     },
 
     /**