Getting started with deckglgeoarrow

`deckglgeoarrow` provides functions to quickly add layers to a `mapgl::maplibregl()` map.

### Layers

Currently, the following `add*Layer` functions are available:

- `addGeoarrowScatterplotLayer` - points
- `addGeoarrowPathLayer` - lines
- `addGeoarrowPolygonLayer` - polygons

All layers accept one of three data related inputs:

- `data` - an R object from packages `wk`, `sf`, `geos` or `terra`
- `file` - a local file path to a `geoarrow` or `geoparquet` file
- `url` - a remote URL pointing to a `geoarrow` or `geoparquet` file

In addition, mainly for developers, `nanoarrow_array_streams` are also supported.

### Styles

For style customisation, all (Deck.gl) layers have two types of properties:

- `render_options` — constant properties across a layer (use function `renderOptions()`)
- `data_accessors` — properties that can vary across rows (use function `dataAccessors()`)

Additionally, `popup`(s) and `tooltip`(s) can be defined in various ways:

- `TRUE` - all attributes of a feature will be displayed
- `NULL`/`FALSE` - no popup/tooltip will be shown
- a character vector of `column names` - only the specified attribute columns will be shown

Similar to the style cusomisation mentioned above, `popups` and `tooltips` can be customised using `popup_options` via function `popupOptions()` and `tooltip_options` via function `tooltipOptions()`

### Example

Putting this together, here’s example showing 1k points using `addGeoarrowScatterplotLayer`

    library(mapgl)
    library(deckglgeoarrow)
    library(wk)

    style_openfreemap = 'https://tiles.openfreemap.org/styles/liberty'

    n = 1e3

    pts = data.frame(
      id = 1:n
      , geometry = xy(
        x = runif(n, -180, 180)
        , y = runif(n, -90, 90)
        , crs = 4326
      )
    )

    pts$radius = sample.int(15, nrow(pts), replace = TRUE)
    pts$fillColor = sample(hcl.colors(n, alpha = sample(seq(0, 1, length.out = n))))
    pts$lineWidth = sample.int(5, nrow(pts), replace = TRUE)
    pts$lineColor = sample(
      hcl.colors(n, alpha = sample(seq(0, 1, length.out = n)), palette = "inferno")
    )

    maplibre(style = style_openfreemap) |>
      addGeoArrowScatterplotLayer(
        data = pts
        , layer_id = "scatter"
        , geom_column_name = "geometry"
        , render_options = renderOptions(
          beforeId = "water"
        )
        , data_accessors = dataAccessors(
          getRadius = "radius"
          , getFillColor = "fillColor"
          , getLineWidth = "lineWidth"
          , getLineColor = "lineColor"
        )
        , popup = TRUE
        , popup_options = popupOptions(
          anchor = "bottom-right"
        )
        , tooltip = "id"
        , tooltip_options = tooltipOptions(
          anchor = "top-left"
          , closeOnMove = TRUE
        )
      ) |>
      add_navigation_control(visualize_pitch = TRUE) |>
      set_view(c(0, 0), 2) |>
      add_globe_control() |>
      add_layers_control(
        layers = list("Scatter Layer" = generateDeckglLayerId(
          layer_id = "scatter", beforeId = "water")
        )
      )

More examples can be found here.