Fix attribution

[vgeorge]

This adds a custom_attribution property to the Map class and fix Maplibre CSS by adding an import. Contributes to:

• Import MapLibre CSS #436
• [BUG] Layer Attribution Option #545

To test, add the custom_attribution property to a Map instance as demonstrated in the API docs examples.

@kylebarron this is ready for review.

[kylebarron]

Does the attribution need to support hyperlinking too? I.e. do we need to define not just text but also the target URL?

[vgeorge]

@kylebarron the MapLibre attribution control renders html links if the attribution text contains an element. They are not appearing now because the Map container has z-index: -1, making the DeckGL canvas to be placed in front of the map controllers, blocking mouse events on it. In the recording below I disabled the z-index, but that caused the data layer to disappear. The z-index is not defined in Lonboard code, I would suggest we address this issue in separate because resolving the z-index conflict might require a more complex solution that ensures both the DeckGL canvas and MapLibre controllers are correctly rendered and interactive.

[kylebarron]

Right. I think this is again tied to #437. The "proper" way as of the latest deck.gl versions is to use MapboxOverlay, which has the pros and cons described in #437. I think when you use MapboxOverlay then the maplibre attribution control is clickable.

[vgeorge]

Apologies, I haven't looked into #437 in depth. I believe we can implement a custom attribution control, which would untie us from MapLibre. We would need a way to extract attribution from map styles JSON, but I think it is doable. Should we keep discussing this on #561?

[kylebarron]

This is also quite tied to the decision here: #437, of whether we should fully tie ourselves to Maplibre or not, or whether we should at least provide an option for ourselves in the future to have deck-only rendering without Maplibre

[vgeorge]

@kylebarron If you are concerned about having the parameter custom_attribution as part of the Map class API, I would say it doesn't tie us much to MapLibre, because all other major open-source mapping libraries (OpenLayers, Leaflet) accept HTML text in attribution controls. Additionally, if we need to use Deck.gl directly, it should be straightforward to implement an Attribution control that accepts HTML text.

[kylebarron]

Should we maybe mention that this custom_attribution string can be HTML? Or should we wait on that until the link is actually clickable with fixed z-index?

[vgeorge]

I believe we should mention it once it is supported properly. Let's keep tracking it on #561.