#774 - dragPan only calls setCenter if the map moves - thanks for the discussion and careful review Eric!

git-svn-id: http://svn.openlayers.org/trunk/openlayers@3902 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/DragPan.js

@@ -20,31 +20,53 @@ OpenLayers.Control.DragPan = OpenLayers.Class(OpenLayers.Control, {
      */
     type: OpenLayers.Control.TYPE_TOOL,
     
+    /**
+     * Property: panned
+     * {Boolean} The map moved.
+     */
+    panned: false,
+    
     /**
      * Method: draw
      * Creates a Drag handler, using <OpenLayers.Control.PanMap.panMap> and
      * <OpenLayers.Control.PanMap.panMapDone> as callbacks.
      */    
     draw: function() {
-        this.handler = new OpenLayers.Handler.Drag( this,
-                            {"move": this.panMap, "up": this.panMap} );
+        this.handler = new OpenLayers.Handler.Drag(this,
+                            {"move": this.panMap, "done": this.panMapDone});
     },
 
     /**
     * Method: panMap
     *
     * Parameters:
-    * xy - {<OpenLayers.Pixel>} Pixel of the up position
+    * xy - {<OpenLayers.Pixel>} Pixel of the mouse position
     */
-    panMap: function (xy) {
+    panMap: function(xy) {
+        this.panned = true;
         var deltaX = this.handler.last.x - xy.x;
         var deltaY = this.handler.last.y - xy.y;
         var size = this.map.getSize();
         var newXY = new OpenLayers.Pixel(size.w / 2 + deltaX,
                                          size.h / 2 + deltaY);
-        var newCenter = this.map.getLonLatFromViewPortPx( newXY ); 
+        var newCenter = this.map.getLonLatFromViewPortPx( newXY );
         this.map.setCenter(newCenter, null, this.handler.dragging);
     },
+    
+    /**
+     * Method: panMapDone
+     * Finish the panning operation.  Only call setCenter (through <panMap>)
+     *     if the map has actually been moved.
+     *
+     * Parameters:
+     * xy - {<OpenLayers.Pixel>} Pixel of the mouse position
+     */
+    panMapDone: function(xy) {
+        if(this.panned) {
+            this.panMap(xy);
+            this.panned = false;
+        }
+    },
 
     CLASS_NAME: "OpenLayers.Control.DragPan"
 });