support terra rasters

DESCRIPTION

@@ -16,7 +16,9 @@ Imports:
   geojsonsf,
   sf,
   rlang,
-  htmltools
+  htmltools,
+  grDevices,
+  terra
 Suggests: 
   shiny,
   mapboxapi,

R/sources.R

@@ -145,11 +145,57 @@ add_raster_dem_source <- function(map, id, url, tileSize = 512, maxzoom = NULL)
 #' @param map A map object created by the `mapboxgl` or `maplibre` function.
 #' @param id A unique ID for the source.
 #' @param url A URL pointing to the image source.
-#' @param coordinates A list of coordinates specifying the image corners in clockwise order: top left, top right, bottom right, bottom left.
+#' @param data A `SpatRaster` object from the `terra` package or a `RasterLayer` object.
+#' @param coordinates A list of coordinates specifying the image corners in clockwise order: top left, top right, bottom right, bottom left.  For `SpatRaster` or `RasterLayer` objects, this will be extracted for you.
+#' @param colors A vector of colors to use for the raster image.
 #'
 #' @return The modified map object with the new source added.
 #' @export
-add_image_source <- function(map, id, url, coordinates) {
+add_image_source <- function(map, id, url = NULL, data = NULL, coordinates = NULL, colors = NULL) {
+
+  if (!is.null(data)) {
+    if (inherits(data, "RasterLayer")) {
+      data <- terra::rast(data)
+    }
+
+    # Prepare color mapping
+    if (is.null(colors)) {
+      colors <- colorRampPalette(c("#440154", "#3B528B", "#21908C", "#5DC863", "#FDE725"))(256)
+    } else if (length(colors) < 256) {
+      colors <- colorRampPalette(colors)(256)
+    }
+
+    data <- data / max(values(data), na.rm = TRUE) * 255
+    data <- round(data)
+    coltb <- data.frame(value = 0:255, col = colors)
+
+
+    # Create color table
+    coltab(data) <- coltb
+
+    # Handle NA values
+    data[is.na(data[])] <- 255
+
+    png_path <- tempfile(fileext = ".png")
+    terra::writeRaster(data, png_path, overwrite = TRUE, NAflag = 255, datatype = "INT1U")
+    url <- base64enc::dataURI(file = png_path, mime = "image/png")
+
+    # Compute coordinates if not provided
+    if (is.null(coordinates)) {
+      ext <- ext(data)
+      coordinates <- list(
+        unname(c(ext[1], ext[4])),  # top-left
+        unname(c(ext[2], ext[4])),  # top-right
+        unname(c(ext[2], ext[3])),  # bottom-right
+        unname(c(ext[1], ext[3]))   # bottom-left
+      )
+    }
+  }
+
+  if (is.null(url)) {
+    stop("Either 'url' or 'data' must be provided.")
+  }
+
   source <- list(
     id = id,
     type = "image",