In mode = "view", could tm_credits use leaflet::addTiles()

[olivroy]

I sometimes use (in v3)

library(tmap) # tmap v3.3.4
data(World, package = "tmap")
tmap_mode("view")
my_map <- tm_shape(World) +
  tm_polygons(title = "the title of my map", col = "area") +
  tm_basemap("OpenStreetMap") + tm_layout("title of my map") 

my_map

my_map |> 
  tmap_leaflet() |> 
  leaflet::addTiles(attributions = "Last update in October 2023")

Could this be equivalent as

my_map <- tm_shape(World) +
  tm_polygons(title = "the title of my map", col = "area") +
  tm_basemap("OpenStreetMap") + tm_layout("title of my map")  +
  tm_credits("Last update in October 2023")

Thanks

Apologies if this already exists in v4. I just wanted to type it quickly.

[mtennekes]

Good point, this should be done in v4.

In R-leaflet, the attributions are collected via the addTiles and addWMSTiles calls, and are placed in the HTML as follows:

<div class="leaflet-bottom leaflet-right">
  <div class="leaflet-control-attribution leaflet-control">
    <a href="https://leafletjs.com" title="A JS library for interactive maps">Leaflet</a> | Attribution A | Attribution B
  </div>
</div>

So in tmap we could collect all the tm_credits text, concatenate to credits_text, and pass it on via a dummy tile layer:

addTiles(urlTemplate = "", attribution = credits_text)

However, ideally, I would like to have more control of this attribution text via a function like addAttribution or setAttribution. @tim-salabim do you know if a function like this exists somewhere?

[tim-salabim]

Nope, no idea

[mtennekes]

Implemented, but I'd like your opinions about the defaults @olivroy and @Nowosad

Without tm_credits, the original attribution text appears (depends on the used tile layers):

tm_shape(world) + tm_polygons()

With tm_credits defined, the attribution text is replaced with the specified text:

tm_shape(world) + tm_polygons() + tm_credits("My attribution text")

Without arguments:

tm_shape(world) + tm_polygons() + tm_credits()

Two issues/questions:

1. What if the user would like to append (instead of replace) the attribution text? So instead of "Leaflet | My attribution text", the user would like to have "Leaflet | Tiles @ Esri - Esri, DeLorme, NAVTEQ, My attribution text" ?
2. Basemaps are also supported in plot mode. So if we keep the default attributions in view mode, to be consistent across modes, we also need a credits in plot mode, whenever tm_basemaps are added. Yes or no?

[olivroy]

This is great, thanks for implementing! I like the defaults you implemented.

What if the user would like to append (instead of replace) the attribution text? So instead of "Leaflet | My attribution text", the user would like to have "Leaflet | Tiles @ Esri - Esri, DeLorme, NAVTEQ, My attribution text" ?

I don't have strong feelings, maybe wait for FR and keep it simple for now? Maybe with an append argument to tm_credits()?

Basemaps are also supported in plot mode. So if we keep the default attributions in view mode, to be consistent across modes, we also need a credits in plot mode, whenever tm_basemaps are added. Yes or no?

The original credits are not essential to the map imo, but I wouldn't know the legal / copyright implications. I'd rather not see them by default on static maps with basemaps, but no strong feelings