[OpenLayers-Users] how to synchronize 2 maps ?

[Gilles Bassière]

Hi list,

I have 2 OL maps in the same page and I would like them to be 
synchronized, say when an event occurred in any of the two maps, it 
should be handled by the two maps, so that both maps always show the 
same area. For example, I use map2's controls to zoom in and both maps 
zoom in.

I've been told that it should be possible with OL but I can't find any 
such thing in this list archives...

So far, my maps are initialized like this:

// Map options 
--------------------------------------------------------------
var url1 = ... ;
var url2 = ... ;
var optionsSet = {
   maxExtent: new OpenLayers.Bounds(590100, 2420300, 596600, 2428500),
   maxResolution: 12,
   numZoomLevels: 10,
   units: "m",
   tileSize: new OpenLayers.Size(256, 256),
   projection: "EPSG:27572",
   theme: "./compare/customOL.css",
   controls: []
}

// Map definition 
-----------------------------------------------------------
var map1 = new OpenLayers.Map($("map1"), optionsSet);
var map2 = new OpenLayers.Map($("map2"), optionsSet);

var background1 = new OpenLayers.Layer.WMS("Background", url1, {layers: 
"Background", format: "image/png"}, {isBaseLayer: true, reproject: false});
var background2 = new OpenLayers.Layer.WMS("Background", url2, {layers: 
"Background", format: "image/png"}, {isBaseLayer: true, reproject: false});

map1.addLayer(background1);
map2.addLayer(background2);

map1.addControl( new OpenLayers.Control.MousePosition() );
map1.addControl( new OpenLayers.Control.MouseDefaults() );
map1.addControl( new OpenLayers.Control.PanZoomBar() );

map2.addControl( new OpenLayers.Control.MousePosition() );
map2.addControl( new OpenLayers.Control.MouseDefaults() );
map2.addControl( new OpenLayers.Control.PanZoomBar() );



I tried to assign the same control objects to both maps:

myPanZoomBarControl = new OpenLayers.Control.PanZoomBar() ;
map1.addControl( myPanZoomBarControl );
map2.addControl( myPanZoomBarControl );

The previous doesn't work. The control appear only on the 1st map and 
control the 2nd map...
I also tried with the fallThrough property set to true but it doesn't 
have much effect.

Has someone already got 2 maps synchronized ? Does someone know whether 
it's possible ?

-- 
Gilles Bassiere
MAKINA CORPUS
30 rue des Jeuneurs
FR-75011 PARIS
http://www.makina-corpus.com