[Users] Programmatically changing the base map projection

I've had similar problems and I've solved it by adding an event listener to the map's baselayerchange event. you would put mapOptionsEtrs properties on the Etrs base layer rather than on the map. Map options are most ignored and overwritten by base layer options. here is my baselayerchange event handler, which is called with the map as scope. function onBaseLayerChange(evtObj){ var mapProj, baseProj, map, newBase, reproject, map = this, newBase = evtObj.layer, mapProj = (map.projection && map.projection instanceof OpenLayers.Projection) ? map.projection : new OpenLayers.Projection(map.projection), baseProj = newBase.projection, reproject = !(baseProj.equals(mapProj)), if (reproject) { var center, maxExt, //calc proper reporojected center center = map.getCenter().transform(mapProj, baseProj), //calc correct reprojected extents maxExt = newBase.maxExtent, //set map projection, extent, & center of map to proper values map.projection = baseProj, map.maxExtent = maxExt, map.setCenter(center), } } Matt Priour Kestrel Computer Consulting From: Hugo Sent: Monday, June 20, 2011 12:45 PM To: Subject: [Users] Programmatically changing the base map projection Dear Geoext users, I'm trying to develop a functionality that will allow the user to change the base map projection. The initial map is using the spherical mercator projection so that OSM and Google/Yahoo/Bing layers can be displayed. Because the users will need to edit features at specific scales (1:25.000, 1:10.000) i need to develop a function that will change the projection from spherical mercator to ETRS PTM06 (EPSG:3763). I think i'm almost there but somehow, after reprojection the base map i get my map full extent much higher in latitude (so, more to the north) and much smaller in longitude (more to the west). My steps are: 1. Remove all OSM/Google/Yahoo/Bing layers from the map. 2. Add new options to the map 3. Merge new options (projection) to a blank layer and set it as basellayer 4. Loop the remaining layers and add new options. The relevant part of the code is below: //Map options var mapOptions = { maxExtent: bBox, maxResolution: 305.74811309814453, minResolution: 0.29858214169740677, resolutions: mapResolutions, units: 'm', projection: baseMercator, displayProjection: wgs, restrictedExtent: bBox, panMethod: OpenLayers.Easing.Quad.easeOut, numZoomLevels: 20, controls: [] }, var mapOptionsEtrs = { maxExtent: bBoxEtrs, maxResolution: 282.2220698223045, minResolution: 0.35277758727788067, resolutions: mapResolutionsEtrs, units: 'm', projection: etrs, displayProjection: etrs, restrictedExtent: bBoxEtrs, panMethod: OpenLayers.Easing.Quad.easeOut, numZoomLevels: 10, }, //Reprojection logic var radioValue = Ext.getCmp('srsradiogroup').getValue().getGroupValue(), var mapProj = map.getProjection(), var baseCart = treePanel.getNodeById('basecartography'), if (radioValue != mapProj && radioValue == 'EPSG:3763') { baseCart.cascade(function () { var childNodes = this.childNodes, for (i = 0, i <, childNodes.length, i++) { switch (childNodes[i].text) { case 'OpenStreetMap': childNodes[i].disable(), map.removeLayer(osm), break, case 'Google Streets': childNodes[i].disable(), map.removeLayer(gstreets), break, // and so on... } } }), map.setOptions(mapOptionsEtrs), map.layerContainerOrigin.transform(baseMercator, etrs), blankLayer.addOptions({ projection: etrs }), map.setBaseLayer(blankLayer), for (i = 0, i <, mapPanel.map.layers.length, i++) { var className = mapPanel.map.layers[i].CLASS_NAME, if (className == 'OpenLayers.Layer.WMS') { mapPanel.map.layers[i].addOptions({ srs: etrs }), } else if (className == 'OpenLayers.Layer.Vector') { mapPanel.map.layers[i].projection = etrs, } else { //here i will control other types of layers like tilecache } } } Checking the map and layers projection through firebug, it seems everything is correct. I've also tried to get the initial extent of the map, reproject it and zoom to it after the reprojection but the it still goes to the same place. What might be the issues here?? Am i doing something completely wrong? Cheers, Hugo -- Hugo Martins LabNT - ISEGI UNL Campus de Campolide 1070-312 Lisboa N 38°43'56.84', W 9°9'35.74' -------------------------------------------------------------------------------- _______________________________________________ Users mailing list Source.

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