R/annotation-raster.R

In ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics

#' @include geom-.R
#' @include geom-raster.R
NULL

#' Annotation: high-performance rectangular tiling
#'
#' This is a special version of [geom_raster()] optimised for static
#' annotations that are the same in every panel. These annotations will not
#' affect scales (i.e. the x and y axes will not grow to cover the range
#' of the raster, and the raster must already have its own colours). This
#' is useful for adding bitmap images.
#'
#' @param raster raster object to display, may be an `array` or a `nativeRaster`
#' @param xmin,xmax x location (in data coordinates) giving horizontal
#'   location of raster
#' @param ymin,ymax y location (in data coordinates) giving vertical
#'   location of raster
#' @param interpolate If `TRUE` interpolate linearly, if `FALSE`
#'   (the default) don't interpolate.
#' @export
#' @examples
#' # Generate data
#' rainbow <- matrix(hcl(seq(0, 360, length.out = 50 * 50), 80, 70), nrow = 50)
#' ggplot(mtcars, aes(mpg, wt)) +
#'   geom_point() +
#'   annotation_raster(rainbow, 15, 20, 3, 4)
#' # To fill up whole plot
#' ggplot(mtcars, aes(mpg, wt)) +
#'   annotation_raster(rainbow, -Inf, Inf, -Inf, Inf) +
#'   geom_point()
#'
#' rainbow2 <- matrix(hcl(seq(0, 360, length.out = 10), 80, 70), nrow = 1)
#' ggplot(mtcars, aes(mpg, wt)) +
#'   annotation_raster(rainbow2, -Inf, Inf, -Inf, Inf) +
#'   geom_point()
#' rainbow2 <- matrix(hcl(seq(0, 360, length.out = 10), 80, 70), nrow = 1)
#' ggplot(mtcars, aes(mpg, wt)) +
#'   annotation_raster(rainbow2, -Inf, Inf, -Inf, Inf, interpolate = TRUE) +
#'   geom_point()
annotation_raster <- function(raster, xmin, xmax, ymin, ymax,
                              interpolate = FALSE) {
  if (!inherits(raster, 'nativeRaster'))
    raster <- grDevices::as.raster(raster)

  layer(
    data = dummy_data(),
    mapping = NULL,
    stat = StatIdentity,
    position = PositionIdentity,
    geom = GeomRasterAnn,
    inherit.aes = FALSE,
    params = list(
      raster = raster,
      xmin = xmin,
      xmax = xmax,
      ymin = ymin,
      ymax = ymax,
      interpolate = interpolate
    )
  )

}

#' @rdname ggplot2-ggproto
#' @format NULL
#' @usage NULL
#' @export
GeomRasterAnn <- ggproto("GeomRasterAnn", Geom,
  extra_params = "",
  handle_na = function(data, params) {
    data
  },

  draw_panel = function(data, panel_params, coord, raster, xmin, xmax,
                        ymin, ymax, interpolate = FALSE) {
    if (!inherits(coord, "CoordCartesian")) {
      cli::cli_abort("{.fn annotation_raster} only works with {.fn coord_cartesian}.")
    }
    corners <- data_frame0(
      x = c(xmin, xmax),
      y = c(ymin, ymax),
      .size = 2
    )
    data <- coord$transform(corners, panel_params)

    x_rng <- range(data$x, na.rm = TRUE)
    y_rng <- range(data$y, na.rm = TRUE)

    rasterGrob(raster, x_rng[1], y_rng[1],
      diff(x_rng), diff(y_rng), default.units = "native",
      just = c("left","bottom"), interpolate = interpolate)
  }
)