[OpenLayers-Users] Overlay Aligment changing on Pan

[Andreas Hocevar]

Hi,

your code has several errors regarding map projection. I attached a
modified version that works:

* the OpenLayers.Map constructor takes two arguments: the name of the
map and the options. You had 3 arguments. Instead of adding controls
and numZoomLevels as 3rd argument, you should include those in the
options.

* same for the layer definition of google_hy. The sphericalMercator:
true option was ignored because you added it as 3rd argument.

* map.setCenter: you cannot use the displayProjection here.
displayProjection is only for controls that work with coordinates
(e.g. MousePosition). So you have to transform the center coordinates
to the map projection.

* vector feature coordinates: unless you use Layer.GML or Layer.WFS,
you also have to provide your coordinates in the correct projection.

Regards,
Andreas.

On Wed, Jun 25, 2008 at 6:39 AM, czieler <carole.zieler at gmail.com> wrote:
>
> I wanted to post a link to a sample of this problem:
> http://webgirlunleashed.com/openlayers/test/test.html
>
> If you click and drag the map, or just pan, you'll notice that the 'car'
> feature is moved a few pixels each time you drag the map or pan.
>
> If anyone can give me any insight on what might be causing the
> problem...that would be great.  I'm using Firefox 2.0, but I've checked it
> on several versions as well as Firefox 3.0 and it occurs on all of them.
>
> czieler wrote:
>>
>> Has anyone had any issues where Overlay Alignment is slightly changed when
>> you pan the map?
>>
>> I have a Google Hybrid map as my base layer, and I then have a WFS layer
>> on top of this, as well as a Vector layer.  I'm zoomed in to level 19 (
>> although this happens at other zoom levels ), and when I pan the map, my
>> WFS and Vector layers seem to become slightly offset each time I pan ( so
>> it becomes progressively worse ).
>>
>> Edit:
>> I just thought to include sample code, as I thought that would be the
>> first question people would respond with:
>>
>> var options = {
>>       projection: new OpenLayers.Projection("EPSG:900913"),
>>       displayProjection: new OpenLayers.Projection("EPSG:4326"),
>>       units: "m",
>>       maxResolution: 156543.0339,
>>       maxExtent: new OpenLayers.Bounds(-20037508, -20037508,
>>                                        20037508, 20037508.34)
>> };
>> map = new OpenLayers.Map( 'map',{controls: [new
>> OpenLayers.Control.Navigation(), new OpenLayers.Control.PanZoomBar()],
>> numZoomLevels:30},options);
>>
>>
>> var google = new OpenLayers.Layer.Google( "Google", {"sphericalMercator":
>> true});
>> var google_hy = new OpenLayers.Layer.Google( "Google Hybrid" , {type:
>> G_HYBRID_MAP}, {"sphericalMercator": true});
>> var yahoo_hy = new OpenLayers.Layer.Yahoo( "Yahoo
>> Hybrid",{type:YAHOO_MAP_HYB}, {"sphericalMercator": true});
>> map.setCenter(new OpenLayers.LonLat(lat,lon), 19); // lat lon are passed
>> into this function
>>
>> wfs = new OpenLayers.Layer.WFS("MyWFSLayer", url, {maxfeatures: "200"},
>> {extractAttributes: true, displayInLayerSwitcher:
>> true,sphericalMercator:true}); // url is passed into this function
>> wfs.markers = new OpenLayers.Layer.Markers(""); // if I don't put this
>> here, I get a js error
>> wfs.setOpacity(0.9);
>> map.addLayer(wfs);
>>
>
> --
> View this message in context: http://www.nabble.com/Overlay-Aligment-changing-on-Pan-tp18099824p18104866.html
> Sent from the OpenLayers Users mailing list archive at Nabble.com.
>
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