Add geoJSON source and layer

[brichet]

This PR will add geoJSON sources and vector layers.

• Add a geoJSON file path as a source
• Validate the geoJSON format before adding the source
• Create a vector layer from the source (filled polygon and coordinate points for start)
• Tests

Discussion:

Do we want to save the data in the shared document ?

Currently the file path is saved as a source in the shared document, and the data are read when creating the source in the map tool.
The main advantage of saving the data is to be more easily reactive to changes in the data (no need to manually reload the file).
The main drawback is probably the size of the shared document if several geoJSON data are used. Also other kind of data (not geoJSON) might need a parser to be correctly included in the shared document. To avoid this, we could add some kind of "listener" on data file, and update the source in the map tool automatically.

Follow up

• add more options depending of the vector type (line width, circle radius...)
• add more vector types

[github-actions]

👈 Launch a Binder on branch brichet/jupytergis/geoJSON

[martinRenou]

Do we want to save the data in the shared document ?

I believe we'll have two cases:

• the geojson is backed by an external file
• the geojson is included in our jgis file

In the first case, your approach is good I think. We can also provide the ability to embed the JSON into our file, but we should probably not do it by default.

The second case will appear if the user tries to add a geojson from the Python API in the notebook, something like:

# in-memory JSON creation
geojson = {"features": [...]}

jgis_document.add_json_source(geojson)

[brichet]

This PR also updates the toolbar to display some categories.
It can be removed if it overloads the toolbar.

[martinRenou]

Looks great! I will give a review.

Just a comment from your screencast, it seems you could use "ui:widget": "color" in the UI Schema to use a color picker widget for the fill color

[martinRenou]

I think it looks great as-is. My comments can be resolved in follow-up PRs.

[martinRenou]

It can be removed if it overloads the toolbar.

I feel like it overloads the toolbar indeed. Also, from a UX point of view it would feel better to create the source and the layer at the same time in one click, similar to what we've done for custom raster sources.

[martinRenou]

ezgif-3-3aca4e2c99.mp4

[martinRenou]

I can help with the conflicts if needed

[brichet]

@martinRenou I added commits to use only one form to create both the GeoJSON source and the vector layer.

[martinRenou]

I preferred the GeoJSON icon you had here:

As your button is only for creating a vector layer out of a GeoJSON file/data.

[martinRenou]

Let's merge and iterate! Thanks a lot

[brichet]

I preferred the GeoJSON icon you had here:

As your button is only for creating a vector layer out of a GeoJSON file/data.

Currently it only supports geoJSON, but maybe we'll be able to handle several data types source with the same form/button.