[MapQuery] adding layer changes extent

[Steven M. Ottens]

  It turns out to be quite a sticky situation. The 
olMap.zoomToMaxExtent() can only be called once there is a baselayer. As 
such you cannot call it from the Map object, since the Map object can be 
created without layers eg:
var map = $('#map').mapQuery().data('mapQuery');
map.layers({
        type:'osm'
});

After some experimenting and discussion on #openlayers I think the way 
to go is to add a fake baselayer by creation of the Map object. This has 
some impact though. For instance the openlayers overviewmap uses the 
baselayer if no layer is defined. However this can be solved in the 
mapquery widget I think. Using this approach all tests work, all 
examples work (except for the overview widget, since I haven't fixed 
that one yet)

Steven

On 6/21/2011 5:22 PM, Justin Penka wrote:
> I would agree that it is not desirable to have the zoomToMaxExtent
> function contained directly inside each layer object. I certainly do see
> a need for the ability to set a zoom to max extent on the creation of
> the map/or layer manager object, but a click event should not fire the
> zoomToMaxExtent unless otherwise specified (ie zoomToMaxExtent button).
>
> I am not exactly sure in what case I would use it, but we could replace
> the zoomToMaxExtent with a function that zooms to the extent of the
> specified layer. Something like:
>
> this.map.olMap.zoomToExtent(layerName.getDataExtent());
>
> Although this does bring up the question: Is this a function that should
> exist in the layer object at all? To me it seems that it is more logical
> to make this a function of the map object but that's just my 2 cents.
>
> -Justin
>
>
> -----Original Message-----
> From: mapquery-bounces at lists.osgeo.org
> [mailto:mapquery-bounces at lists.osgeo.org] On Behalf Of Steven M. Ottens
> Sent: Tuesday, June 21, 2011 9:41 AM
> To: mapquery at lists.osgeo.org
> Subject: [MapQuery] adding layer changes extent
>
>    Hi all,
>
> I noticed when working on the new mqLayerManager widget that this:
>       $("p").click(function() {
>           jQuery('#map').data("mapQuery").layers({
>               type:'bing',        //create a bing maps layer
>               view:'satellite',    //use the bing satellite (aerial)
> layer, instead of bing road (default)
>
> key:'ArAGGPJ16xm0RXRbw27PvYc9Tfuj1k1dUr_gfA5j8QBD6yAYMlsAtF6YkVyiiLGn'
>               });
>           });
>
> changes the extent of the map. This is obviously not desirable. The
> problem here is the layer option zoomToMaxExtent: true. Disabling this
> fixes the problem, however most of the examples will not show a map,
> since they require zoomToMaxExtent set on the layer.
>
> So with some more digging I found that mapquery does this in the Layer
> object:
> if (options.zoomToMaxExtent) {
>           this.map.olMap.zoomToMaxExtent();
>       }
>
> I don't think this should be in the layer object. It does not make sense
>
> that a layer zooms to the maxextent of the map. it might be that there
> is a function where you can zoom to the maxextent of the layer, but
> that's something different and def. not olMap.zoomToMaxExtent();
>
> I'd like to propose to remove the zoomToMaxExtent option from the Layer
> object and somehow make sure that the map zooms to maxExtent when
> created (unless otherwise specified)
>
> any thoughts?
> Steven
>
>
>
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