PR for #38 permalink

[justb4]

This is a minimal permalink implementation, it is configuration-driven. Using a new permalink config object, example:

  "permalink": {
    "location": "hash",                  # how to specify in address bar hash(#) default or query(?)
    "projection": "EPSG:4326",   # projection for permalink coords (default: map projection)
    "paramPrefix": "",                   # prefix for permalink parameters (default: empty str)
    "history": true,                        # should history be kept and shown in browser history (default: false)
    "precision": 6                          # for numbers: center, zoom, extent
  },

Defaults apply, so "permalink": {} is also valid.

• Encoding: using c (center), z (zoom) , r (rotation) with optional prefixes e.g. map_c=.
• Example: http://localhost:8081/#z=1.9867&c=2.306,39.5258&r=0
• Non-map related params, e.g. appCtx= are preserved
• optional history popstate capture
• optional parameter prefixes: map_z=1.9867&map_c=2.306,39.5258&map_r=0
• optional projection in permalink, e.g. use WGS84 i.s.o. OSM Merc coords
• Implementation in new class src/components/ol/PermalinkController.js as ordinary class
• Allow for overriding in Map.vue/PermalinkController.js app-specific subclasses via Factory Method.
• prepared for URL sharing (PermalinkController.getParamStr ()) method
• prepared for IFrame Embed sharing (PermalinkController.getEmbedHTML ()) method
• allow map extent URL parameter i.s.o. center+zoom (configurable)
• allow layers (lids?) to be encoded (challenge: layers are loaded async)
• Unit Tests

[justb4]

All planned permalink features now implemented. Need to revisit layer handling when #113 is merged (async layer creation).

[justb4]

So this was already there, only unit tests are lacking. The ShareButton component (#128) builds on this PR.

[justb4]

Should be good to go.

[chrismayer]

Does every layer has a property url? Not sure about that

[chrismayer]

Looks good to me, thanks @justb4. One little question above and one general question:

Will it be easily possible to apply another permalink structure? I have a public application called Shareloc, which provides shareable links for OpenLayers maps. In the future I might want to upgrade Shareloc to Wegue. The permalink in this PR looks a bit different from the one used with Shareloc (e.g. https://apps.meggsimum.de/shareloc/share.html?zoom=7&X=8.541570112005266&Y=50.5918788090799&bgLayer=osm.base). So I would need to map / modify the parameter keys and maybe add more. Would this easily possible with the approach in this PR? TIA!

[justb4]

Not directly, though there is some abstraction already via the config: paramPrefix which is reflected in the permalink param names and their encoding/decoding. This was somewhat similar as in GeoExt.

A next step would be to make all param-names configurable with sensible default. Not too difficult as parameter naming is just in a few places (2). Only bgLayer is a bit specific in the Shareloc approach. In the current approach there is just layers as some Layers are already background-type (isBaseLayer).

[chrismayer]

Not directly, though there is some abstraction already via the config: paramPrefix which is reflected in the permalink param names and their encoding/decoding. This was somewhat similar as in GeoExt.

A next step would be to make all param-names configurable with sensible default. Not too difficult as parameter naming is just in a few places (2). Only bgLayer is a bit specific in the Shareloc approach. In the current approach there is just layers as some Layers are already background-type (isBaseLayer).

Thanks for clarification.

[chrismayer]

I just tested the Permlink behaviour and found something unexpected. If a layer gets activated it is not added to the permalink. Steps to reporduce:

• Open http://localhost:8081/?appCtx=projected
• Activate WMS - Natura 2000 Areas - PDOK layer with the LayerList tool.
• Check the URL it still remains as before.:

[justb4]

Confirmed. As soon as you alter the Map View (pan, zoom) the Layer is added. Almost sure the problem is that changing active Layers does not trigger moveend from the OL Map (to which PermalinkController listens). Investigating. May need to listen to other generic Event, change?

[chrismayer]

It is not intended that activating a layer triggers moveend on the map. I think listening to change:visible on the map's LayerGroup should be the correct event. Derivable by map.getLayerGroup().

[justb4]

Yes, aware by now. Approach now (before seeing comment above) is to listen to two additional events: 'change:visible' for each Layer and 'change:length' for the Map's Layer Collection. The latter is needed whenever Wegue support dynamic Layer addition. Also added tests and this approach works. Tried listening to change:visible for Map's LayerGroup but this had no effect. But I was not familiar with LayerGroup.

I will push the changes for now and make it WIP for review.

[chrismayer]

Thanks for your ongoing work @justb4 ! LGTM, I'll merge now.