zoom_to_feature_at_startup lizmap zooms to center of mapextends

[3liz]

zoom_to_feature_at_startup lizmap zooms to center of mapextends

[geomoes]

Even tough I don't understand, why the script did not work in my environment under Lizmap 3.3.3, I finally managed it to upgrade to 3.4.0.
Now the script works like expected.
It would be good to habe two enhancemends:

• avoid, that the whole project (generally at an larger scale) is beeing rendered before switching to the selected feature
• add the posibility to highlight the feature

[Gustry]

This script has been developed by @mdouchin, maybe you have idea?

[geomoes]

I changed now the project projection to EPSG:2169 (Luxembourg), updated the extend in the layer properties from the map canvas (showing the whole country) and did the same in the Lizmap-Plugin. The overlay-layers are in EPSG:2169 and the baselayers in EPSG:3857. In Lizmap all layers are displayed correct. When I activate the zoom_to_feature_at_startup script, I end up about 100km south-west from the feature. So defenitely outside the bounding box of the initial extend. I admit, that the title isn't correct anymore since the map doesn't zoom anymore to the center of the mapextend, but somewhere else (565137/6263080 in EPSG:2169 or 5,07663/48,93052 in EPSG:4326).
(using QGIS 4.14-1 on macos, Lizmap 3.3).

I checked the values returned by the script. Everything is OK until I come to
lizMap.zoomToFeature(featureType, fid, 'zoom');
since this returns 'undefined'.

One other strange thing is that
lizMap.map.getProjection();
gives me EPSG:900913, which is a synonym of EPSG:3857. Although my whole project is in EPSG:2169. Could that be an issue do to a missing EPSG-definition for 2169 in proj4?

[geomoes]

I've tried the script now with a new Lizmap project, that has only two layers. A PostGIS layer and an WMS baselayer. Both are in EPSG:3857 and the project projection is also set to EPSG:3857.
The layers display fine in Lizmap.
When I call the layer:
https://map.xxxx.xx/lizmap/index.php/view/map/?repository=hfnlm&project=lm_test#fid:v_btk_s_3857_51c2ab28_ba0f_488d_aba5_c54f0578f1cc.518
the map opens and stays at the initial view. No zooming.

The lizmap-log shows the following entry:

warning	2020-08-28 10:50:34	[2]	file_get_contents(http://map.xxxx.xx/cgi-bin/qgis_mapserv.fcgi?
service=WMS&request=GetCapabilitiesAtlas&map=/var/www/lizmap-web-client-3.3.3/lizmap/install/hfn_lm/lm_test.qgs): 
failed to open stream: HTTP request failed! HTTP/1.1 501 Not Implemented
	/var/www/lizmap-web-client-3.3.3/lizmap/modules/lizmap/classes/lizmapProxy.class.php	240

2020-08-28 10:50:34	95.90.255.241	error	("gid" = 518)

Any idea?

[johnzet39]

Same problem. And if I run lizMap.zoomToFeature(featureType, fid, 'zoom'); from browser console, it works correctly.

[geomoes]

OK, for me it works as well in the console even without issues concerning the projection.
I was a bit confused, since my project is set up in EPSG:2169 (Luxembourg), the layer (v_parzellen) I try to adress is also in EPSG:2169, but lizmap.getProjection() returns EPSG:900913 which corresponds to EPSG:3857.
When I use lizMap.zoomToFeature('v_parzellen', 518, 'zoom'); in the browser console I get exactly what I want. The map zooms to the feature with the id=518 on the layer v_parzellen. So at least I'm shure that it is not an issue with the projection.
I don't understand, why this doesn't work with the script? I tried to declare first var featureType = ''; to be shure it will be a string, but this doesn't change anything.

[johnzet39]

I tried to replacing the line of code

// Zoom to feature
//lizMap.zoomToFeature(featuretype.toString(), fid.toString(), 'zoom');

by

// Zoom to feature
setTimeout(() => {
  lizMap.zoomToFeature(featuretype, fid, 'zoom');
},2000);

and script works as we want. I don't know why, but maybe this will help to suggest some thoughts. If I set 1 second timeout, it don't work.

[johnzet39]

By the way, this only works for me if I have enabled atlas for the layer in plugin Lizmap. Although it is not required to execute a line in the browser console.

[geomoes]

OK, I've tested that the way you described. For me it works when

• enabling the atlas functionality for my layer (never took that in consideration)
• I had to increase the timeout to 3000 to get it work reliably.
  For me it seems to be an issue with the state of the DOM (at least concerning the timeout), that the script must be executed when the DOM is fully loaded.

[johnzet39]

//file map.js
function zoomToFeature( featureType, fid, zoomAction ){
      zoomAction = typeof zoomAction !== 'undefined' ?  zoomAction : 'zoom';
      
      var layerConfig = config.layers[featureType];
      var featureId = featureType + '.' + fid;

      var proj = new OpenLayers.Projection(config.layers[featureType].crs);
      if( config.layers[featureType].featureCrs )
          proj = new OpenLayers.Projection(config.layers[featureType].featureCrs);
      getLayerFeature(featureType, fid, function(feat) {
          zoomToOlFeature( feat, proj, zoomAction );
      });
}

So, if you don't use a timer then the variable proj = new OpenLayers.Projection(lizMap.config.layers[featureType].featureCrs) in function "zoomToFeature" (file map.js) does not have time to receive data (?) after loading map. And then in function "localZoomToOlFeature" an incorrect transform occurs.
Unfortunately, I dont understand yet why config.layers[featureType].crs and layers[featureType].featureCrs can/should be different. And does the layers[featureType].featureCrs always have to be 'EPSG:4326'. (If anyone can explain in a nutshell, I would appreciate it).
At the moment I am compelled to extract this function into the file of plugin and hard-assign the value to var proj = new OpenLayers.Projection('EPSG:4326');. I think the timer method is unreliable and inconvenient.

Sorry if I am not clear, english and javascript are my not native languages :).

[geomoes]

Well both aren't my native languages too.
I've tried to wrap the whole function (from the original script) in an

$(window).load(function(){
....
});  

to avoid, that code is executed before all elements of the DOM are loaded. But this didn't work neither.
Your setTimeout works in conjunction with the atlas functionality, but as You said it's unreliable and inconvenient.

After all, my initial intention was to just address a feature at a given layer, highlight it and zoom to it (that what the atlas does) just I want it by calling lizmap and passing the layer and the id in the GET parameters. So zoom_to_feature_at_startup would be ideal if it would work. I'll look at the atlas.js, maybe I'll find a way to fiddle out a way to archieve this.