[OpenLayers-Users] Help with setLatLng

[Christopher Schmidt]

On Mon, Oct 05, 2009 at 12:41:49PM -0400, Jesse Bushkar wrote:
> Hello all, this is my first post as I have only recently started using
> OpenLayers.  It is awesome to say the least.  I'm currently using OpenLayers
> integrated with Cloudmade so I hope that this question is being posted in
> the appropriate place and to the appropriate group.
> 
> I'm attempting to use the new HTML javascript functions getCurrentPosition
> and watchPosition to constantly update a marker (and the center) of a map.
> These two functions are great, and I've successfully tied them into the
> setCenter function so that the center of the map follows your position when
> using a geolocation-aware browser.  However, when I try to set a marker and
> then use the setLatLng function, I have no luck.  Below is the code.  It
> appears that setLatLng function breaks the rest, because whenever that line
> is there, the map does not re-center or re-zoom. 

Well, that's because there is no such function in OpenLayers.

However, something like marker.moveTo(this.map.getLayerPxFromLonLat(lonlat))
might work.

Where did you get that function name from?

-- Chris

> If I comment it out, it
> works fine but of course the marker doesn't adjust to the new coords.
> 
> 
> --
> success = function(position){
> 
> var epsg4326 = new OpenLayers.Projection("EPSG:4326");
> var epsg900913 = new OpenLayers.Projection("EPSG:900913");
>     var center = new OpenLayers.LonLat(position.coords.longitude,
> position.coords.latitude).transform(epsg4326, epsg900913);
>       var zoom = parseInt(map.center.zoom);
>     OL.maps[map.id].map.setCenter(center, zoom, false, false);
> var markers = new OpenLayers.Layer.Markers("Markers");
>         OL.maps[map.id].map.addLayer(markers);
> var marker = new OpenLayers.Marker(center);
>                 markers.addMarker(marker);
> }
> 
>  fail = function(){
>       alert("Your browser does not support Geolocation");
>     var center = new OpenLayers.LonLat(map.center.lon, map.center.lat);
>       var zoom = parseInt(map.center.zoom);
>     OL.maps[map.id].map.setCenter(center, zoom, false, false);
> }
> 
> updateLocation = function(position){ // Fires everytime your location change
> positions
>                                 var epsg4326 = new
> OpenLayers.Projection("EPSG:4326");
>                                 var epsg900913 = new
> OpenLayers.Projection("EPSG:900913");
>                                 var newCenter = new
> OpenLayers.LonLat(position.coords.longitude,
> position.coords.latitude).transform(epsg4326, epsg900913);
>                            var zoom = parseInt(map.center.zoom);
>             marker.setLatLng(newCenter);
>             OL.maps[map.id].map.setCenter(newCenter, 18);
>             };
> 
> navigator.geolocation.getCurrentPosition(success, fail);
> 
> navigator.geolocation.watchPosition(updateLocation);
> 
> --
> 
> As you can see, there are three functions, then the two geolocation
> functions are called below them.  This code is admittedly ugly and
> incomplete since it is being taken from a much larger file, but I believe
> all the things necessary to troubleshoot the 'marker.setLatLng(newCenter);'
> line are present.
> 
> I'm thinking that the problem may stem from the local variables inside each
> function: ie. inside of updateLocation() there is no marker defined, but I'm
> not really sure what to do about that (or even if that is accurate).  My
> javascript is improving but still not up to snuff, so I'm probably (and
> hopefully) missing something very obvious here.
> 
> Thanks in advance for any help provided.  You can see the live file at
> www.savannahtraveler.com/maps

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-- 
Christopher Schmidt
MetaCarta