R/f_extract_images.R

In pbixr: Access Data and Metadata from 'Microsoft' 'Power BI' Documents

#' @title Get an Image File from the Collection of Files Compressed in a '.pbix'
#' @description The collection of files compressed in a '.pbix' is searched for
#' images. An image is written to a temporary file. The path of the
#' temporary file and associated properties are returned.
#' @author Don Diproto
#' @param input_file_pbix Path of the input '.pbix'.
#' @param image_reg Pattern used to search for an image file stored in
#' a collection of files compressed in '.pbix' (e.g., "[.]png|[.]jpg").
#' @return A list: [[1]] a temporary location for an image, [[2]] the
#' name, length (kb) and date associated with an image.
#' @export
#' @seealso Uses: \code{\link{f_get_pbix_info}},
#' \code{\link{f_get_pbix_fir}}.
#' @examples
#' \dontrun{
#' # Get dummy data ------------------------------------------------------------
#' # Create a temporary directory
#' temp_dir <- file.path(tempdir(),"functionTest")
#' if(!dir.exists(temp_dir)) {
#' 	dir.create(temp_dir)
#' }
#' sample_file_name <- "OR_sample_func.pbix"
#' pathFileSample <- file.path(temp_dir, sample_file_name)
#'
#' # See if dummy data already exists in temporary directory
#' parent_temp_dir <- dirname(temp_dir)
#' existing_file <- list.files(parent_temp_dir,
#' pattern = sample_file_name, recursive = TRUE, full.names = TRUE)
#'
#' # Download the sample .pbix if it doesn't exist
#' if (length(existing_file) == 0) {
#'    url_pt1 <- "https://github.com/KoenVerbeeck/PowerBI-Course/blob/"
#'    url_pt2 <- "master/pbix/TopMovies.pbix?raw=true"
#'    url <- paste0(url_pt1, url_pt2)
#'    req <- download.file(url, destfile = pathFileSample, mode = "wb")
#' } else {
#'    pathFileSample <- existing_file[1]
#' }
#' # Do stuff ------------------------------------------------------------------
#'
#' image_reg <- "[.]png|[.]jpg"
#' # Run the function
#' test <- f_extract_images(pathFileSample, image_reg)
#' # Plot the image
#' im <- imager::load.image(test[[1]])
#' plot(im)
#'   }
f_extract_images <- function(input_file_pbix, image_reg) {
  # Collection of files compressed in .pbix are identified.
  get_pbix_info <- f_get_pbix_info(input_file_pbix)
  # A search for images is performed
  image_index <- grep(image_reg, get_pbix_info$Name)
  if (length(image_index) == 0) {
    # If an image does not exist
    output <- list(NULL, NULL)
  } else {
    # If an image exists
    image_info <- get_pbix_info[image_index, ]
    image_extension <- gsub(".*[.]", "", image_info$Name)

    # Write image to temporary file
    file_images <- c()
    for (image_i in seq_len(nrow(image_info))) {
      buffer <- f_get_pbix_fir(input_file_pbix, image_info$Name[image_i])
      temp_file <- tempfile()

      zz <- file(temp_file, "wb")
      writeBin(buffer, zz)
      close(zz)

      new_temp_file <- paste0(temp_file, ".", image_extension[image_i])
      file.rename(temp_file, new_temp_file)
      temp_file <- new_temp_file
      file_images[image_i] <- temp_file
    }

    output <- list(file_images, image_info)
  }
  return(output)
}