R/compress_images.R

In ardata-fr/cookimage: Tools for images

#' @export
#' @importFrom locatexec exec_available node_exec
#' @title Minify size your images
#' @description Minify size of images located in a directory
#' and output results in another folder.
#'
#' This function can only be used after executing the command
#' [compress_images_install()] which installs a set of "npm" packages
#' on your machine.
#' @param dir_input,dir_output input and output directories
#' @examples
#' # generate some png
#' from_dir <- tempfile()
#' dir.create(from_dir)
#'
#' png(file = file.path(
#'   from_dir, "file_1.png"), width = 8.3, height = 11.7,
#'   units = "in", res = 300)
#' barplot(1:10, col = 1:10)
#' dev.off()
#'
#' png(file = file.path(
#'   from_dir, "file_2.png"), width = 8.3, height = 11.7,
#'   units = "in", res = 300)
#' barplot(1:10, col = 11:20)
#' dev.off()
#'
#' library(locatexec)
#' if(exec_available("node") &&
#'    compress_images_available()){
#'
#'   # generate dest folder
#'   new_dir <- tempfile()
#'   dir.create(new_dir)
#'
#'   # run compression
#'   compress_images(from_dir, new_dir)
#'
#'   desc_folder <- function(dir){
#'     all_files <- list.files(
#'       path = dir, full.names = TRUE, recursive = TRUE)
#'     data.frame(
#'       basename = basename(all_files),
#'       size = file.info(all_files)$size)
#'   }
#'
#'   desc_folder(from_dir)
#'   desc_folder(new_dir)
#' }
compress_images <- function(dir_input, dir_output = NULL){

  if(!dir.exists(dir_input)){
    stop("dir_input does not exist")
  }
  dir_output <- paste0(absolute_path(dir_output), "/")
  dir_input <- absolute_path(dir_input)
  if(!dir.exists(dir_output)){
    stop(shQuote(dir_output), " does not exist")
  }

  compimg_dir <- working_directory()

  exec_available("node", error = TRUE)
  exec_available("npm", error = TRUE)

  if(!compress_images_available()){
    stop("'compress-images' is not in your user data directory,",
         " run `compress_images_install()` to install it")
  }

  old_warn <- getOption("warn")
  options(warn = -1)
  info <- try(
    system2(
      node_exec(),
      args = c(
        shQuote(file.path(compimg_dir, "index.js"), type = "cmd"),
        shQuote(paste0(dir_input, "/**/*.{jpg,JPG,jpeg,JPEG,png,svg,gif}"), type = "cmd"),
        shQuote(dir_output, type = "cmd")
        ),
      stderr = TRUE, stdout = TRUE), silent = TRUE)
  options(warn = old_warn)
  out <- !1 %in% attr(info, "status")
  if(!out) {
    stop(paste0(info, collapse = "\n"))
  }

  dir_output
}