New private movePyPx method to avoid going through all the unnecessary pixel-lonlat conversions. p=elemoine,me (closes #3062)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@11535 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/EventPane.js

@@ -211,6 +211,22 @@ OpenLayers.Layer.EventPane = OpenLayers.Class(OpenLayers.Layer, {
         OpenLayers.Layer.prototype.setZIndex.apply(this, arguments);
         this.pane.style.zIndex = parseInt(this.div.style.zIndex) + 1;
     },
+    
+    /**
+     * Method: moveByPx
+     * Move the layer based on pixel vector. To be implemented by subclasses.
+     *
+     * Parameters:
+     * dx - {Number} The x coord of the displacement vector.
+     * dy - {Number} The y coord of the displacement vector.
+     */
+    moveByPx: function(dx, dy) {
+        OpenLayers.Layer.prototype.moveByPx.apply(this, arguments);
+        
+        if (this.dragPanMapObject) {
+            this.dragPanMapObject(dx, -dy);
+        }
+    },
 
     /**
      * Method: moveTo