Trigger feature related events with feature information and layer related events with layer information. Also adding events.on and events.un convenience methods. r=crschmidt (closes #1343)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@6149 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer.js

@@ -37,9 +37,26 @@ OpenLayers.Layer = OpenLayers.Class({
      */
     opacity: null,
 
-    /** 
+    /**
      * Constant: EVENT_TYPES
-     * {Array(String)} Supported application event types
+     * {Array(String)} Supported application event types.  Register a listener
+     *     for a particular event with the following syntax:
+     * (code)
+     * layer.events.register(type, obj, listener);
+     * (end)
+     *
+     * Listeners will be called with a reference to an event object.  The
+     *     properties of this event depends on exactly what happened.
+     *
+     * All event objects have at least the following properties:
+     *  - *object* {Object} A reference to layer.events.object.
+     *  - *element* {DOMElement} A reference to layer.events.element.
+     *
+     * Supported map event types:
+     *  - *loadstart* Triggered when layer loading starts.
+     *  - *loadend* Triggered when layer loading ends.
+     *  - *loadcancel* Triggered when layer loading is canceled.
+     *  - *visibilitychanged* Triggered when layer visibility is changed.
      */
     EVENT_TYPES: ["loadstart", "loadend", "loadcancel", "visibilitychanged"],
         
@@ -327,7 +344,10 @@ OpenLayers.Layer = OpenLayers.Class({
         if (newName != this.name) {
             this.name = newName;
             if (this.map != null) {
-                this.map.events.triggerEvent("changelayer");
+                this.map.events.triggerEvent("changelayer", {
+                    layer: this,
+                    property: "name"
+                });
             }
         }
     },    
@@ -530,7 +550,10 @@ OpenLayers.Layer = OpenLayers.Class({
             this.display(visibility);
             this.redraw();
             if (this.map != null) {
-                this.map.events.triggerEvent("changelayer");
+                this.map.events.triggerEvent("changelayer", {
+                    layer: this,
+                    property: "visibility"
+                });
             }
             this.events.triggerEvent("visibilitychanged");
         }
@@ -576,7 +599,9 @@ OpenLayers.Layer = OpenLayers.Class({
         if (isBaseLayer != this.isBaseLayer) {
             this.isBaseLayer = isBaseLayer;
             if (this.map != null) {
-                this.map.events.triggerEvent("changebaselayer");
+                this.map.events.triggerEvent("changebaselayer", {
+                    layer: this
+                });
             }
         }
     },