With Erik's approval on #341, I'm happy with this. This restores the

mousewheel functionality we had in earlier releases in a similar way, rewritten
for handlers. (The benefit of handlers in this case is that handlers are 
write-once, use many, so the next mousewheel thing we get will *also* be able 
to use this code.)


git-svn-id: http://svn.openlayers.org/trunk/openlayers@2877 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/Navigation.js

@@ -59,20 +59,33 @@ OpenLayers.Control.Navigation.prototype =
         return false;
     },
 
+    wheelChange: function(evt, deltaZ) {
+        var newZoom = this.map.getZoom() + deltaZ;
+        if (!this.map.isValidZoomLevel(newZoom)) return;
+
+        var size    = this.map.getSize();
+        var deltaX  = size.w/2 - evt.xy.x;
+        var deltaY  = evt.xy.y - size.h/2;
+        var newRes  = this.map.baseLayer.resolutions[newZoom];
+        var zoomPoint = this.map.getLonLatFromPixel(evt.xy);
+        var newCenter = new OpenLayers.LonLat(
+                            zoomPoint.lon + deltaX * newRes,
+                            zoomPoint.lat + deltaY * newRes );
+        this.map.setCenter( newCenter, newZoom );
+    },
+
     /** User spun scroll wheel up
      * 
      */
     wheelUp: function(evt) {
-        this.map.setCenter(this.map.getLonLatFromPixel(evt.xy),
-                           this.map.getZoom() + 1);
+        this.wheelChange(evt, 1);
     },
 
     /** User spun scroll wheel down
      * 
      */
     wheelDown: function(evt) {
-        this.map.setCenter(this.map.getLonLatFromPixel(evt.xy),
-                           this.map.getZoom() - 1);
+        this.wheelChange(evt, -1);
     },
     
     /** @final @type String */

lib/OpenLayers/Handler/MouseWheel.js

@@ -13,6 +13,14 @@ OpenLayers.Handler.MouseWheel.prototype = OpenLayers.Class.inherit( OpenLayers.H
     /** @type function **/
     wheelListener: null,
 
+    /** @type OpenLayers.Pixel
+     *  @private
+     * 
+     *  mousePosition is necessary because evt.clientX/Y is buggy in Moz on
+     *  wheel events, so we cache and use the value from the last mousemove.
+     **/
+    mousePosition: null,
+
     /**
      * @constructor
      *
@@ -68,8 +76,7 @@ OpenLayers.Handler.MouseWheel.prototype = OpenLayers.Class.inherit( OpenLayers.H
                 // add the mouse position to the event because mozilla has a bug
                 // with clientX and clientY (see https://bugzilla.mozilla.org/show_bug.cgi?id=352179)
                 // getLonLatFromViewPortPx(e) returns wrong values
-                // TODO FIXME FIXME this might not be the right way to port the 2.3 behavior
-                e.xy = this.map.events.getMousePosition(e);
+                e.xy = this.mousePosition;
                 if (delta < 0) {
                    this.callback("down", [e, delta]);
                 } else {
@@ -82,6 +89,10 @@ OpenLayers.Handler.MouseWheel.prototype = OpenLayers.Class.inherit( OpenLayers.H
         }
     },
 
+    mousemove: function (evt) {
+        this.mousePosition = evt.xy;
+    },
+
     activate: function (evt) {
         OpenLayers.Handler.prototype.activate.apply(this, arguments);
         //register mousewheel events specifically on the window and document