[OpenLayers-Users] wheel zooming: want to turn off re-centre of map at mouse location

[Michael Quentel]

In Navigation.js, it appears that the wheelChange function gets the
event x y, and not only zooms in or out, but also appears to re-centre
on the mouse event location.  Is this correct?  Please, need advice: I'd
like to turn off the map re-centreing on the mouse location when doing
mouse wheel zoom.  Not having success changing this.  Is Navigation.js
even where I should be trying to change this functionality?  

wheelChange function as it is now: 

    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 );
    },

I tried to change the above to read the following:

    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 zoomPoint = this.map.getCenter();
        //var newCenter = new OpenLayers.LonLat(
        //                    zoomPoint.lon + deltaX * newRes,
        //                    zoomPoint.lat + deltaY * newRes );
        var newCenter = zoomPoint;
        this.map.setCenter( newCenter, newZoom );
    },

That failed.  I also tried the following, which also failed:

    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 deltaX  = 1;
        var deltaY  = 1;
        var newRes  = this.map.baseLayer.resolutions[newZoom];
        //var zoomPoint = this.map.getLonLatFromPixel(evt.xy);
        var zoomPoint = this.map.getCenter();
        
        //debug
        console.info("zoomPoint.lat: ", zoomPoint.lat);
        console.info("zoomPoint.lon: ", zoomPoint.lon);
        
        
        var newCenter = new OpenLayers.LonLat(
                            zoomPoint.lon + deltaX * newRes,
                            zoomPoint.lat + deltaY * newRes );
        this.map.setCenter( newCenter, newZoom );
    },

The Firebug console.info calls did not even appear.  I'm not getting the
result I expected.  What would work?

Thank you.

Cheers,

Mike Quentel

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