[OpenLayers-Users] Toggle visibility of baselayer

[Robert Buckley]

Hi,

In my app I am automatically changing the baselayer according to zoomlevel as follows...


 function mapEvent(event) {
                ZoomLev = map.getZoom();
                switch(ZoomLev){
                case 0:
                if(map.BaseLayer!=layer_5mil){map.setBaseLayer(layer_5mil);}
                   break;
                   
                case 1:
                if(map.BaseLayer!=layer_5mil){map.setBaseLayer(layer_5mil);}                
                   break;
                   
                case 2:
                if(map.BaseLayer!=layer_500){map.setBaseLayer(layer_500);} 
                   break; 
                   
                case 3:
                if(map.BaseLayer!=layer_500){map.setBaseLayer(layer_500);} 
                   break;
                   
                case 4:
                if(map.BaseLayer!=tk_100){map.setBaseLayer(tk_100);} 
                   break;
                   
                case 5:
                if(map.BaseLayer!=tk_100){map.setBaseLayer(tk_100);} 
                   break;
                   
                case 6:
                if(map.BaseLayer!=tk_50){map.setBaseLayer(tk_50);} 
                   break;        
                   
                case 7:
                if(map.BaseLayer!=tk_25){map.setBaseLayer(tk_25);} 
                   break;
                   
                case 8:
                if(map.BaseLayer!=tk_10){map.setBaseLayer(tk_10);} 
                   break;                                                                       
                }
               }
   

What I need to do now is toggle the visibility of the current basemap so the user can  turn off base layer...ie just have a white basemap.  I have tried various methods including using this...

 action = new GeoExt.Action({
       icon: 'images/tick.png',
        map: map,
        tooltip: {
            title: 'turn baselayer off'
        },
        handler: function () {
                 var map = Ext.getCmp("mapPanel");
                 mapPanel.map.setBaseLayer(emptymap);
        

        }
    });



but the map will not change to leer.


can anyone see what I could do?,

yours,

Rob
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