Change default basemap to avoid Carto API key

[gmatosferreira]

Following on #520 and the need for mapview to support the recently introduced Carto basemaps API key, I think that it does not make sense for the default basemap to be Carto anymore.

For reference, basemaps currently default to "CartoDB.Positron", "CartoDB.DarkMatter", "OpenStreetMap", "Esri.WorldImagery", "OpenTopoMap".

Since mapview is widely used in the R ecosystem, I think the default basemap should remain a completely open registration free provider.

Using the Leaflet official providers list, I think that Esri.WorldGrayCanvas is the most visually similar to the CartoDB.Positron.

Stadia.AlidadeSmoothDark seems a good alternative to CartoDB.DarkMatter.

I think this is a big change and should be coordinated by the authors, (@tim-salabim) so I will keep my contribution to opening the discussion and let it guide the changes to be implemented. 🙂

[gmatosferreira]

As an illustration to my suggested changes, here are the current and suggested basemaps:

Current	Suggested
CartoDB.Positron	Esri.WorldGrayCanvas
CartoDB.DarkMatter	Stadia.AlidadeSmoothDark

[tim-salabim]

I think thats a good idea!

@mtennekes @Nowosad what does tmap use as default these days? IINM it uses esri.greycanvas, right?

[gmatosferreira]

@tim-salabim I've been migrating my web apps to use the basemaps I suggested and I just figured out that Stadia.AlidadeSmoothDark requires registration for usages that are not local.

https://stadiamaps.com/pricing/

Maybe you should consider other alternative to the dark map. However, I can't find any totally open on the Leaflet providers list. ☹️

[tim-salabim]

I am also considering to add openfreemap as a base map provider, so we can use their positron/dark maps as replacement... This would either be a new package ({leaflet.openfreemap} maybe?) or be integrated into {leafem}. I currently prefer the latter.

See https://openfreemap.org/quick_start/ (section "Using Leaflet") for a guide on how this would work...

Thoughts?

[gmatosferreira]

Hey, @tim-salabim! That seems like a great alternative. 😃 The project seems mature and they provide layers that are pretty aligned with the simplified visuals of Carto. Additionally, it seems to be an European project (based in Hungary) and developed with an open source mindset.

It's a pity that they are not listed on Leaflet providers list, but I will take care of that today, opening the pull request to add them. 🙂

[gmatosferreira]

Hello, again, @tim-salabim!

I have took a deeper look into this and it looks like OpenFreeMap only works with vector tiles, which is not supported natively by Leaflet. 🥴

Printscreen from https://github.com/hyperknot/openfreemap/blob/main/README.md

[tim-salabim]

Yes, that's why we would need to ship maplibre-gl.js and leaflet-maplibre-gl.js with package {leafem} and add some functionality to add those vector tiles to the leaflet map. Not sure how much effort this will be, but I'll give it a try when I find time

[gmatosferreira]

Hello again, @tim-salabim! I have been thinking about this vector tiles problem and the seamless alternative approach proposed by Maplibre GL Leaflet. The fact that the API they provide keeps the interface similar to the Leaflet native L.tileLayer() method, made me wonder if we could just extend leaflet-extras/leaflet-providers to support vector tiles (something like L.tileLayer.provider('OpenFreeMap.Liberty').addTo(map)) leaving the usage of L.tileLayer() or L.maplibreGL() to its internal logic.

With this approach, the cascading changes on rstudio/leaflet.providers and a minor update on rstudio/leaflet to add the required MapLibre GL dependencies to the map HTML if it is of type vector, would enable mapview to support vector tiles without any code changes (would just need to update the dependencies to require the latest version of the previous).

I have prepared these changes and tested them locally, generating a simple map with vector and raster tiles using just the code below (with the updated rstudio/leaflet.providers and rstudio/leaflet installed), that you can check at: https://ushift.tecnico.ulisboa.pt/content/maps/github/mapview_vector_tiles.html

bus_lanes <- sf::st_read("https://github.com/U-Shift/busclar/releases/download/0.1/bus_lanes_osm_lisbon.gpkg", quiet = TRUE)
library(mapview)
options("mapviewBasemaps" = c("OpenFreeMap.Bright", "OpenFreeMap.Positron", "OpenFreeMap.Dark", "StadiaVector.AlidadeSmooth", "Esri.WorldGrayCanvas","Stadia.AlidadeSmoothDark","OpenStreetMap", "Esri.WorldImagery", "OpenTopoMap"))
mapview(bus_lanes)

What do you think of this approach? Regardless of your decision, I have opened the PR for leaflet-extras/leaflet-providers to support vector tiles, at leaflet-extras/leaflet-providers#706.

[tim-salabim]

Ok, let's see what the leaflet-providers guys say

[mtennekes]

@tim-salabim yes tmap uses esri world canvas as default, but very happy to which to ofm once leaflet support is there.