R/graph2bitmap.R

In export: Streamlined Export of Graphs and Data Tables

#' Save currently active R graph to bitmap format
#' 
#' Save the currently active R graph or a graph passed as an object or function 
#' to bitmap format with sensible defaults
#' 
#' 
#' @importFrom grDevices dev.size
#' @importFrom grDevices png
#' @importFrom grDevices tiff
#' @importFrom grDevices jpeg
#' @aliases graph2bitmap graph2png graph2tif graph2jpg
#' @param x given \code{ggplot2} plot or \code{lattice} plot object to export; if
#' set to \code{NULL} the currently active R graph will be exported; not
#' supported for base R plots.
#' @param file name of output file. Any extension is ignored and added
#' according to the requested output type. If file already exists it is overwritten.
#' @param fun plot passed on as a function used to create it; useful especially
#' for base R plots.
#' @param type desired output type - \code{PNG}, \code{TIF} or \code{JPG} are currently supported.
#' \code{PNG} is the preferred format, as it is a lossless format, and compresses better
#' than \code{TIF}.
#' @param aspectr desired width to height aspect ratio. If set to \code{NULL}, the
#' aspect ratio of the graphics device is used. Can also be combined with one
#' value for either the desired width or height of the graph.
#' @param width desired width in inches; can be combined with a desired
#' aspect ratio aspectr.
#' @param height desired height in inches; can be combined with a desired
#' aspect ratio aspectr.
#' @param dpi desired output in dpi; defaults to 600 dpi.
#' @param scaling scale width & height by a certain percentage.
#' @param font desired font to use for labels in PNG and TIFF output; defaults to 
#' \code{"Arial"} on Windows systems and to \code{"Helvetica"} on other systems.
#' @param bg desired background colour, e.g. \code{"white"} or \code{"transparent"}.
#' @param cairo logical, specifying whether or not to use \code{Cairographics} for export.
#' @param tiffcompression compression to use for \code{TIF} files.
#' @param jpegquality quality of \code{JPEG} compression.
#' @param \dots any other options are passed on to \code{grDevices}' \code{\link{png}}, 
#' \code{\link{tiff}}, or \code{\link{jpeg}} function (according to the supplied \code{type}).
#' @return No return value
#' @author Tom Wenseleers
#' @example examples/graph2bitmap.R
#' @seealso \code{\link{graph2office}}, \code{\link{graph2vector}}, \code{\link{graph2svg}}, \code{\link{graph2pdf}},
#' \code{\link{graph2eps}}
#' @export
#' 
graph2bitmap = function(x = NULL, file = "Rplot", fun = NULL, 
                        type = c("PNG","JPG","TIF"), aspectr = NULL, 
                        width = NULL, height = NULL, dpi = 300,  scaling = 100, 
                        font = ifelse(Sys.info()["sysname"] == "Windows", "Arial","Helvetica")[[1]], 
                        bg = "white", cairo = TRUE, 
                        tiffcompression = c("lzw","rle","jpeg","zip","lzw+p","zip+p"), 
                        jpegquality = 99, ...) {
  # Get initial graphical state
  dev.init <- dev.list()
  
  # Format arguments 
  type <- toupper(type)
  type <- match.arg(type, c("PNG", "JPG", "TIF"))
  if (type == "JPG") type <- "JPEG"
  if (type == "TIFF") type <- "TIF"
  tiffcompression <- match.arg(tiffcompression)
  ext <- paste0(".", tolower(type))
  file <- sub("^(.*)[.].*", "\\1", file)  # remove extension if given
  file <- paste0(file, ext)  # add extension
  obj <- x
  if (is.null(obj) & is.null(fun)) p = captureplot() else p = obj
  if (inherits(p,"list")) 
    stop("base R plots cannot be passed as objects, use ggplot2 or lattice plots instead")
  myplot = if (is.null(fun)) function(pl = p) print(pl) else fun
  
  # Get graphical device information 
  if(!identical(options()$device, FALSE)){
    plotsize = dev.size()
  } else {
    plotsize = c(7,5) # default device size: 10 inch x 10 inch
  }
  
  w <- plotsize[[1]]
  h <- plotsize[[2]]
  plotaspectr <- plotsize[[1]] / plotsize[[2]]
  if ( !is.null(aspectr) & is.null(height) & is.null(width)) { 
    plotaspectr <- aspectr
    if (plotaspectr >= 1) { h <- w / plotaspectr } else { w <- h * plotaspectr } 
  }
  if ((is.null(height))&(!is.null(width))) { w = width; h = w / plotaspectr }
  if ((is.null(width))&(!is.null(height))) { h = height; w = h / plotaspectr } 
  # if width and height is given override other scaling params
  if ((!is.null(width))&(!is.null(height))) { w = width; h = height }  
  w = w*scaling/100; h = h*scaling/100;
 
  if (type == "PNG") {
    png( filename = file, 
        type = ifelse(cairo,"cairo-png","windows"),
        units = "in", 
        width = w, 
        height = h, 
        family = font,
        res = dpi,
        bg = bg, ...)
    myplot()
    dev.reset(dev.init)
  }
  
  if (type == "TIF") {
    tiff( filename = file, 
         type = ifelse(cairo,"cairo","windows"),
         compression = tiffcompression,
         units = "in", 
         width = w, 
         height = h, 
         family = font, 
         res = dpi,
         bg = bg, ...)
    myplot()
    dev.reset(dev.init)
  }
  
  if (type == "JPEG") { 
    jpeg(filename = file, 
         quality = jpegquality,
         units = "in", 
         width = w, 
         height = h, 
         res = dpi,
         bg = bg, ...)
    myplot()
    dev.reset(dev.init)
  }  
  message(paste0("Exported graph as ",file))
}

#' @describeIn graph2bitmap 
#' Save currently active R graph to png file
#' @export
graph2png = function(...) graph2bitmap(type = "PNG", ...)

#' @describeIn graph2bitmap 
#' Save currently active R graph to TIF file
#' @export
graph2tif = function(...) graph2bitmap(type = "TIF", ...)

#' @describeIn graph2bitmap 
#' Save currently active R graph to JPEG file
#' @export
graph2jpg = function(...) graph2bitmap(type = "JPG", ...)