R/gs.r

In jefferis/paperutils: Support preparation of journal articles from LyX/pdflatex output

#' Compress a PDF using ghostscript
#'
#' When pdfout is missing it defaults to <input>_gso.pdf
#'
#' This seems to work well for pdflatex output
#' @param pdfin,pdfout Input and Output PDFs
#' @param firstpage,lastpage Page range (defaults to firstpage = 1, lastpage =
#'   last in PDF)
#' @param pdflevel Minimum compatible PDF version of output file
#' @param gsopts Further options for ghostscript
#' @param Force When FALSE, only update file for newer input
#' @return character vector with path to pdfout
#' @importFrom nat.utils RunCmdForNewerInput
#' @author jefferis
#' @export
#' @examples
#' \dontrun{
#' gscompress('statistics.pdf',gsopts='-dSubsetFonts=true -dEmbedAllFonts=true')
#' }
gscompress<-function(pdfin,pdfout,firstpage,lastpage,pdflevel="1.5",gsopts="",Force=TRUE){
  if(is.numeric(pdflevel)) pdflevel=as.character(pdflevel)
  pdfin=normalizePath(pdfin)
  if(missing(pdfout)) pdfout=sub("\\.pdf$","_gso.pdf",pdfin)
  else pdfout=normalizePath(pdfout, mustWork = FALSE)
  # save a copy of output file path
  real_out=pdfout
  if(pdfin==pdfout){
    pdfout=tempfile(basename(pdfout),tmpdir=dirname(pdfout),fileext='.pdf')
    on.exit(file.rename(pdfout,real_out))
  }
  
  basic_cmd=sprintf(paste('gs -sDEVICE=pdfwrite -dCompatibilityLevel=%s -dNOPAUSE',
          ' -dQUIET -dBATCH -dAutoRotatePages="/None"',gsopts),pdflevel)
  if(!missing(firstpage))
    basic_cmd=paste(basic_cmd,' -dFirstPage=',firstpage,sep="")
  if(!missing(lastpage))
    basic_cmd=paste(basic_cmd,' -dLastPage=',lastpage,sep="")
  
  cmd=paste(basic_cmd,sprintf('-sOutputFile=%s %s',shQuote(pdfout),shQuote(pdfin)))
  cat(cmd,"\n")
  RunCmdForNewerInput(cmd,pdfin,pdfout,Force=Force)
  return(real_out)
}