[R] Plotting directly to memory?

[Duncan Murdoch]

Is there a way to open a graphics device that plots entirely to an array 
or raster in memory?  I'd prefer it to use base graphics, but grid would 
be fine if it makes a difference.

For an explicit example, I'd like to do the equivalent of this:

   filename <- tempfile(fileext = ".png")
   png(filename)
   plot(1:10, 1:10)
   dev.off()

   library(png)
   img <- readPNG(filename)

   unlink(filename)


which puts the desired plot into the array `img`, but I'd like to do it 
without needing the `png` package or the temporary file.

A possibly slightly simpler request would be to do this only for 
plotting text, i.e. I'd like to rasterize some text into an array.

Duncan Murdoch