Add support for (geojson) layers

[felix-ht]

Adding full support for feature layers for ios, android and web. Click detection for these layers are supported as well. Code generation takes care of creating most of the code. Thanks to @maximumbuster for getting this started

Limitations

• expressions are not implemented in a typesafe way - however i would argue that this has limited benefits anyhow
• geojson is also not implemented using taypesafe classes - this could be done in a future merge request
• currently only numbers can be used as feature id's (with onFeatureTapped ) if web support is required https://github.com/andrea689/mapbox-gl-dart restricts ids Feature id should not be num but dynamic andrea689/mapbox-gl-dart#14

Notes

This pull request is based on code from #272 & #326

[felix-ht]

Note that belowLayerId in addFill{Type} is currently ignored for the web version - this will be addressed with andrea689/mapbox-gl-dart#15

[AAverin]

Man, tell me you didn't type every single of those 10k lines and managed to auto-generate all the boilerplate somehow!
Great job.

[felix-ht]

@AAverin most of it is generated and 50% is the style.json file 😄

@tobrun it would be really great if you could take a look before this get's merged

[m0nac0]

@felix-ht It would be great if we could also support the clustering attributes for geojson sources (https://docs.mapbox.com/mapbox-gl-js/style-spec/sources/#geojson-cluster). That would finally enable clustering in this plugin, a quite frequently requested feature.

But I totally understand if you don't want to add even more changes to this PR, we can also just open an issue for that after this PR has landed.

[felix-ht]

@m0nac0 i took a look and adding clustering should be pretty straightforward after this. It's also useful for my own usecase.

We would have to add some new code gen to create the ClusterProperties object, and parse it one the native side. This is trivial for web but certainly somewhat harder for native.

However i would like to push this to a future PR so we can get this one merged sooner. The api would stay stable as we would simply add some named parameters to addGeojsonSource

Another thing i want to add in the future is the ability to only update a specific feature in a source without replacing the whole collection. But i would also push this to some other future PR.

On a side note: i finished integrating this PR/branch into my own code base - an everything seems to work fine across all platforms. (Including fairly complicated data driven styles)

[tobrun]

@felix-ht amazing work and also thanks for @maximumbuster for kicking this off.
This goes above and beyond on what I was hoping to see supported for this wrapper SDK.
I was only planning to include this with moving towards #140 and #566 and using existing code generators for android/ios

[lukemadera]

Thanks for this awesome support and work @felix-ht Question - you noted it worked across multiple platforms but I noticed the code for addGeoJsonSource throws an error for non web? Or does this work on iOS & Android too? https://github.com/flutter-mapbox-gl/maps/blob/master/mapbox_gl_platform_interface/lib/src/mapbox_gl_platform_interface.dart#L280

Also, can a source be removed? I'm getting an error on rebuild when the data changes due to adding the same geojson source twice (it is already on the map). Should be an easy fix of checking if it is there first, but I get an error The method 'getSource' isn't defined for the class 'MapboxMap?'. Similar with remove source, which is needed for deleting sources. Does this functionality exist or does it need to be added? Any reason addSource and removeSource aren't exposed / available?

[m0nac0]

@lukemadera Regarding your first question: the implementation for iOS and Android lives in https://github.com/flutter-mapbox-gl/maps/blob/master/mapbox_gl_platform_interface/lib/src/method_channel_mapbox_gl.dart (it mostly just calls the relevant platform channel methods).

addGeoJsonSource and removeSource are available, support for other types of sources is being worked on in #797. @felix-ht Please correct me if I'm wrong.

[lukemadera]

Thanks @m0nac0 ! I am using addGeoJsonSource but removeSource is not working for me - could you share or point me to an example of how to use it?

[m0nac0]

Sorry, I haven't used the new GeoJson sources myself.

[felix-ht]

@lukemadera if you have issues please create a new ticket - this is not the place for discussions. But as far as i know removeSource should work fine. (You have to remove any layer attached to the source first)

[lukemadera]

As noted above @felix-ht I get an error: The method 'removeSource' isn't defined for the class 'MapboxMap?' Have you used removeSource? What property is it exposed on?

[felix-ht]

you have to use the MapboxMapController not the MapboxMap

[lukemadera]

Ah nice, progress! Thanks @felix-ht Getting an error though; I opened an issue: #850