Enable hover options for vector sources in MapLibre

[walkerke]

Now that we have pmtiles support in MapLibre, #36 is relevant (the second part of the issue) as I only enabled hover options for tiles coming from Mapbox.

I tried swapping in the code directly from mapboxgl.js to maplibregl.js and it didn't work out of the box, so I'll need to look into this further.

[cboettig]

@walkerke can you expand upon what is missing here? Your tooltip hovers seem to work just fine?

library(mapgl)
pmtiles <- "https://data.source.coop/cboettig/us-boundaries/mappinginequality.pmtiles"


m <-
  maplibre(center=c(-72.9, 41.3), zoom=10, height="400") |>
  add_vector_source("mappinginequality_source",
                    url = paste0("pmtiles://", pmtiles)
  ) |>
  add_fill_layer(
    id = "mappinginequality_layer",
    source = "mappinginequality_source",
    source_layer = "mappinginequality",
    tooltip = "grade",
    filter = list("==", list("get", "city"), "New Haven"),
    fill_color = list("get", "fill")
  )

m

of course with any remote source your clever approach of creating a new html-styled column on-the-fly is not as viable, so it might be nice to have another option for multi-column and styled tooltip / mouse-over effects?

[walkerke]

here's an example using Mapbox:

https://walker-data.com/mapboxapi/articles/dynamic-maps.html#styling-vector-tiles-with-mapbox-gl-js-and-mapgl

It's the hover_options argument that isn't working in MapLibre for vector sources, as it needs to target a source layer which it isn't currently doing.

Also - I agree about improving the popup / tooltip generation!

[walkerke]

@cboettig dynamic tooltips are now possible! We do this by implementing the concat expression in Mapbox / MapLibre with a new concat() function:

library(mapgl)

maplibre(bounds = nc) |>
  add_source("nc", nc) |>
  add_fill_layer(
    id = "test",
    source = "nc",
    fill_color = "blue",
    popup = concat("Name: ", get_column("NAME"))
  )

[cboettig]

🎉 this is brilliant, thanks!