leafem: 'leaflet' Extensions for 'mapview'

# # Helper function, copied from mapview - v2.7.1
#
# ## the two crs we use
# wmcrs <- "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"
# llcrs <- "+proj=longlat +datum=WGS84 +no_defs"
#
# non_proj_warning <-
#   "supplied layer has no projection information and is shown without background map"
#
# wrong_proj_warning <-
#   paste0("projection of supplied layer is not leaflet conform.", "\n",
#          "  projecting to '", llcrs, "'")
#
# # Check and potentially adjust projection of objects to be rendered =======
# checkAdjustProjection <- function(x, method = "bilinear") {
#
#   x <- switch(class(x)[1],
#               "RasterLayer" = rasterCheckAdjustProjection(x, method),
#               "RasterStack" = rasterCheckAdjustProjection(x, method),
#               "RasterBrick" = rasterCheckAdjustProjection(x, method),
#               "SpatialPointsDataFrame" = spCheckAdjustProjection(x),
#               "SpatialPolygonsDataFrame" = spCheckAdjustProjection(x),
#               "SpatialLinesDataFrame" = spCheckAdjustProjection(x),
#               "SpatialPoints" = spCheckAdjustProjection(x),
#               "SpatialPolygons" = spCheckAdjustProjection(x),
#               "SpatialLines" = spCheckAdjustProjection(x),
#               "sf" = sfCheckAdjustProjection(x),
#               "XY" = sfCheckAdjustProjection(x),
#               "sfc_POINT" = sfCheckAdjustProjection(x),
#               "sfc_MULTIPOINT" = sfCheckAdjustProjection(x),
#               "sfc_LINESTRING" = sfCheckAdjustProjection(x),
#               "sfc_MULTILINESTRING" = sfCheckAdjustProjection(x),
#               "sfc_POLYGON" = sfCheckAdjustProjection(x),
#               "sfc_MULTIPOLYGON" = sfCheckAdjustProjection(x),
#               "sfc_GEOMETRY" = sfCheckAdjustProjection(x),
#               "sfc_GEOMETRYCOLLECTION" = sfCheckAdjustProjection(x))
#
#   return(x)
#
# }
#
# # Project Raster* objects for mapView =====================================
# rasterCheckAdjustProjection <- function(x, method) {
#
#   is.fact <- raster::is.factor(x)[1]
#
#   # if (is.na(raster::projection(x))) {
#   #   warning(non_proj_warning)
#   #   raster::extent(x) <- scaleExtent(x)
#   #   raster::projection(x) <- llcrs
#   if (is.fact) {
#     x <- raster::projectRaster(
#       x, raster::projectExtent(x, crs = sp::CRS(wmcrs)),
#       method = "ngb")
#     x <- raster::as.factor(x)
#   } else {
#     x <- raster::projectRaster(
#       x, raster::projectExtent(x, crs = sp::CRS(wmcrs)),
#       method = method)
#   }
#
#   return(x)
#
# }
#
#
# # Project stars* objects for mapView =====================================
# starsCheckAdjustProjection <- function(x, method) {
#
#   x <- sf::st_transform(
#     x,
#     crs = llcrs
#   )
#   return(x)
#
# }
#
#
# # Check and potentially adjust projection of sf objects ===================
# sfCheckAdjustProjection <- function(x) {
#
#   if (is.na(sf::st_crs(x))) {
#     return(x) # warning(non_proj_warning)
#   } else { #if (!validLongLat(sf::st_crs(x)$proj4string)) {
#     x <- sf::st_transform(x, llcrs)
#   }
#
#   return(x)
#
# }
#
#
# # Check and potentially adjust projection of Spatial* objects =============
# spCheckAdjustProjection <- function(x) {
#
#   # if (is.na(raster::projection(x))) {
#   #   warning(non_proj_warning)
#   #   if (class(x)[1] %in% c("SpatialPointsDataFrame", "SpatialPoints")) {
#   #     methods::slot(x, "coords") <- scaleCoordinates(coordinates(x)[, 1],
#   #                                                    coordinates(x)[, 2])
#   #   } else if (class(x)[1] %in% c("SpatialPolygonsDataFrame",
#   #                                 "SpatialPolygons")) {
#   #     x <- scalePolygonsCoordinates(x)
#   #   } else if (class(x)[1] %in% c("SpatialLinesDataFrame",
#   #                                 "SpatialLines")) {
#   #     x <- scaleLinesCoordinates(x)
#   #   }
#   #
#   #   raster::projection(x) <- llcrs
#
#   if (!identical(raster::projection(x), llcrs)) {
#     x <- sp::spTransform(x, CRSobj = llcrs)
#   }
#
#   return(x)
#
# }