R/icons.R

In Robinlovelace/photomapr: Create Maps from Geotagged Photos

#' Make a icons from original photos
#' 
#' @param f File path to photo(s).
#' @param geometry A geometry specification such as `"100x80"`, meaning 100 pixels wide, 80 pixels high.
#' See [magick::geometry()] for details.
#' @export
make_icon = function(f, geometry = "400x300") {
  magick::image_scale(
    image = magick::image_read(f),
    geometry = geometry
  )
}

#' Generate a list of icon images
#' @inheritParams make_icon
#' @export
make_icons = function(f, geometry = "400x300") {
  lapply(f, make_icon, geometry = geometry)
}

#' Save icons of photos
#' @param dir_out Directory where files should be saved, `tempdir()` by default
#' @param format Output format. See [magick::image_write()] for details
#' @param overwrite Should previous files be overwritten? `TRUE` by default
#' @param ... Other arguments to pass to [magick::image_write()] 
#' @inheritParams make_icon
#' @export
photo_iconize = function(f, geometry = "400x300", dir_out = tempdir(), format = "png", overwrite = TRUE, ...) {
  f_icon = paste0(gsub(pattern = ".jpg", replacement = "", x = f), "_icon.", format)
  i_list = make_icons(f, geometry = geometry)
  purrr::map2(i_list, f_icon, magick::image_write, format = format, ...)
  file.copy(f_icon, dir_out, overwrite = overwrite)
  file.remove(f_icon)
  list.files(dir_out, "icon", full.names = TRUE)
}

#' Compress photos
#' 
#' Warning: **overwrites photos**
#' @param width The width of the results; aspect ratio will remain unchanged
#' @param ... Other arguments to pass to [magick::image_write()] 
#' @param quality Number from 0 to 100 representing the quality of .jpg images
#' @inheritParams photo_iconize
#' @inheritParams make_icon
#' @export
photo_compress_width = function(f,
                          width = 800,
                          quality = 70,
                          ...) {
  message("Warning: this will overwrite photos. Are you sure?")
  res = utils::menu(choices = c("Yes", "No"))
  if(res != 1) {
    stop("Maybe run this function on backed-up photos in a different directory.")
  }
  for(i in f) {
    im = magick::image_read(i)
    i_smaller = magick::image_scale(
      image = im,
      geometry = magick::geometry_size_pixels(width = width)
      )
    magick::image_write(i_smaller, i, quality = quality)
  }
}