R/geom-map.R

In ggpattern: 'ggplot2' Pattern Geoms

#' @include geom-polygon.R
NULL

#' @rdname geom-docs
#' @export
geom_map_pattern <- function(mapping = NULL, data = NULL,
                             stat = "identity",
                             ...,
                             map,
                             na.rm = FALSE,
                             show.legend = NA,
                             inherit.aes = TRUE) {
  # Get map input into correct form
  stopifnot(is.data.frame(map))
  if (!is.null(map$lat)) map$y <- map$lat
  if (!is.null(map$long)) map$x <- map$long
  if (!is.null(map$region)) map$id <- map$region
  if (!all(c("x", "y", "id") %in% names(map))) {
    cli::cli_abort("{.arg map} must have the columns {.col x}, {.col y}, and {.col id}.")
  }

  layer(
    data = data,
    mapping = mapping,
    stat = stat,
    geom = GeomMapPattern,
    position = PositionIdentity,
    show.legend = show.legend,
    inherit.aes = inherit.aes,
    params = list2(
      map = map,
      na.rm = na.rm,
      ...
    )
  )
}

#' @rdname ggpattern-ggproto
#' @format NULL
#' @usage NULL
#' @export
GeomMapPattern <- ggproto("GeomMapPattern", GeomPolygonPattern,
  draw_panel = function(data, panel_params, coord, lineend = "butt",
                        linejoin = "round", linemitre = 10, map) {
    # Only use matching data and map ids
    common <- intersect(data$map_id, map$id)
    data   <- data[data$map_id %in% common, , drop = FALSE]
    map    <- map[map$id %in% common, , drop = FALSE]

    # Munch, then set up id variable for polygonGrob -
    # must be sequential integers
    coords <- coord_munch(coord, map, panel_params, is_closed = TRUE)
    coords$group <- coords$group %||% coords$id
    grob_id <- match(coords$group, unique0(coords$group))

    # Align data with map
    data_rows <- match(coords$id[!duplicated(grob_id)], data$map_id)
    data      <- data[data_rows, , drop = FALSE]

    polygons <- split(coords, coords$group)
    boundary_dfs <- lapply(polygons, function(polygon) {
      create_polygon_df(
        x = polygon$x,
        y = polygon$y
      )
    })

    pattern_grobs <- create_pattern_grobs(data, boundary_dfs)

    col <- data$colour
    fill <- fill_alpha(data$fill, data$alpha)
    lwd <- data$linewidth * .pt

    polygon_grob_fn <- function(col, fill, lwd) {
      polygonGrob(
        x = coords$x,
        y = coords$y,
        default.units = "native",
        id = grob_id,
        gp = gpar(col = col,
                  fill = fill,
                  lwd = lwd,
                  lineend = lineend,
                  linejoin = linejoin,
                  linemitre = linemitre
        )
      )
    }

    grobTree(
      polygon_grob_fn(NA, fill, 0),
      pattern_grobs,
      polygon_grob_fn(col, NA, lwd)
    )
  },

  required_aes = c("map_id")
)