R/download_images.R

In nfox29/photosearcher: Photo Searcher

#' Download images
#'
#' Downloads images based on their Flickr ID. Uses the flickr.photos.getSizes
#' API method from the Flickr API to test whether you have permission to
#' download an image. See
#' \url{https://www.flickr.com/services/api/flickr.photos.getSizes.html} for
#' more information on the API method. If permission is available the image is
#' downloaded and saved as a .jpeg in a given save directory.
#'
#' Please be aware that download times will vary depending on number of
#' photographs, size of photographs, internet speed and other factors.
#' Downloading a large amount of photographs may take some time.
#'
#'When running the function you need an API key saved as
#'photosearcher_key.sysdata in your working directory. If this is the first
#'function you run you will be prompted to create and enter your API key. The
#'API key will then be saved as photosearcher_key.sysdata in your working
#'directory and is used for all function.
#'
#' @param photo_id numeric or character vector. id of photo to download, can be
#'   single id, list or column for photo_search outputs
#' @param save_dir character. name of directory for photos to be saved in.
#' @param max_image_height numeric. maximum number of pixels for images height
#' @param max_image_width numeric. maximum number of pixels for images width
#' @param overwrite_file logical. Whether to overwritten existing files. if
#'   TRUE, files will be overwritten and you will be warned in the output.
#'   Default is FALSE.
#' @param quiet logical. If TRUE, suppress status messages (if any), and the
#'   progress bar.
#'
#' @return character. A vector of the images attempted to be downloaded and
#'   whether they were. If an image was not downloaded, information on why is
#'   provided. Images will be saved to \code{save_dir}.
#'
#' @family Get data for known photograph
#'
#' @export
#'
#' @examples
#' \dontrun{
#' download_images(photo_id = 48704764812, save_dir = ".")
#'
#' download_images(photo_id = 48704764812, max_image_height = 1200,
#' max_image_width = 1200, save_dir = ".") }

download_images <- function(photo_id,
                            save_dir = NULL,
                            max_image_height = NULL,
                            max_image_width = NULL,
                            overwrite_file = FALSE,
                            quiet = FALSE) {

  # this checks for the presence of a key, if no key it prompts the user to
  # create one, it then checks the validity of the key
  api_key <- create_and_check_key()

  # check directory
  if (!dir.exists(save_dir)) {

    stop("Please supply a save directory")

  }

  downloadable <- dplyr::bind_rows(
    lapply(photo_id, function(x) download_image_single(
      x,
      save_dir,
      api_key,
      max_image_height,
      max_image_width,
      overwrite_file,
      quiet)))


  return(downloadable)
}


#' @noRd
download_image_single <- function(photo_id,
                                  save_dir,
                                  api_key,
                                  max_image_height,
                                  max_image_width,
                                  overwrite_file,
                                  quiet) {
  downloaded <- NULL

  z <- paste("https://api.flickr.com/services/rest/",
             "?method=flickr.photos.getSizes&api_key=",
             api_key,
             "&photo_id=",
             photo_id,
             sep = "")

  photo_xml <- search_url(z)

  warn <- data.frame(xml2::xml_attrs(xml2::xml_children(photo_xml)))

  if (warn[2, ] == "Photo not found"){

    out <- data.frame(id = photo_id,
                      downloaded = "No: photo not found",
                      stringsAsFactors = FALSE)

  } else {

  if (!is.null(photo_xml)) {

    download_atts <- xml2::xml_find_all(photo_xml,
                                        "//sizes",
                                        ns = xml2::xml_ns(photo_xml))

    tmp_df <- dplyr::bind_rows(
      lapply(xml2::xml_attrs(download_atts),
             function(x) data.frame(as.list(x), stringsAsFactors = FALSE)))


      if ((tmp_df$candownload) == 1) {

        photo_url <- xml2::xml_find_all(photo_xml,
                                        "//size",
                                        ns = xml2::xml_ns(photo_xml))

        tmp_df <- dplyr::bind_rows(lapply(
          xml2::xml_attrs(photo_url),
          function(x) data.frame(as.list(x), stringsAsFactors = FALSE)))

        # choose image size (height)
        if (!is.null(max_image_height)) {
          tmp_df <- tmp_df[!(as.numeric(tmp_df$height) >
                               as.numeric(max_image_height)), ]
        }

        # choose image size (width)
        if (!is.null(max_image_width)) {
          tmp_df <- tmp_df[!(as.numeric(tmp_df$width) >
                               as.numeric(max_image_width)), ]
        }

        if (nrow(tmp_df) > 0){

          # download biggest possible image
          to_download <- tmp_df$source[nrow(tmp_df)]

          check_file <- gsub(".*/", "", to_download)

          check_file2 <- (paste(".\\",save_dir, "\\", check_file, sep = ""))

          if (file.exists(check_file2)){

            if (isFALSE(overwrite_file)){

              out <- data.frame(id = photo_id,
                                downloaded = "No: file already existed",
                                stringsAsFactors = FALSE)

            } else {

              utils::download.file(
                url = to_download,
                destfile = file.path(save_dir, basename(to_download)),
                mode = "wb",
                quiet = quiet)

              out <- data.frame(id = photo_id,
                                downloaded = "Yes: file overwritten",
                                stringsAsFactors = FALSE)

            }


          } else {

            utils::download.file(
              url = to_download,
              destfile = file.path(save_dir, basename(to_download)),
              mode = "wb",
              quiet = quiet)

            out <- data.frame(id = photo_id,
                              downloaded = "Yes: downloaded",
                              stringsAsFactors = FALSE)

            }

        } else {

          out <- data.frame(id = photo_id,
                            downloaded = "No: no photos meeting size criteria",
                            stringsAsFactors = FALSE)

        }


      } else {

      out <- data.frame(id = photo_id,
                        downloaded = "No: no download permission",
                        stringsAsFactors = FALSE)
      }
   }

  }

  return(out)

}