# This is imperative, especially the local = FALSE.
# We need to ensure that gdk_pixbuf_new() is available
# to the pixbuf loader libraries (for jpeg, gif, xpm, etc.)
# which are dynamically loaded by the Gtk libraries (specifically GtkHTML).
# However, these loader libraries are not linked against libgdk_pixbuf
# and so expect to find the symbols from that library in the host
# application. This doesn't happen in R unless we explicitly put
# the symbols there using dyn.load(, local = FALSE).
# The configuration of the RGtk package (or specifically the GtkHTML part
# of it) needs to find libgdk_pixbuf on the system and put that into the
# R code.
#
# It would be better to do this downloading, reading and writing to the GtkHTMLStream
# using connections and avoiding the file system.

dyn.load("/usr/lib/libgdk_pixbuf.so", local = FALSE)

htmlLoadImage <-
function(w, url, stream, ...)
{
        # see if there is a protocol in the URL separated from the
        # file name by a `:'
       x <- strsplit(url, ":")[[1]]
       if(length(x) > 1 && x[1] != "file") {
            # so there is a protocol
          tmp <- tempfile()
          if(download.file(url, destfile = tmp)) {
            stop(paste("Cannot download URL", url))
          }
          url <- tmp
       } else {
         if(x[1] == "file")
           url <- x[2]
         if(length(grep("^/", url)) == 0) {
           dir <- dirname(w$GetBase())
           if(nchar(dir))
             url <- paste(dir, url, sep=.Platform$file.sep)
           print(url)
         }
       }

       .Call("R_readFileToHTMLStream", as.character(url), stream, TRUE, PACKAGE="RGtk")
} 

 # From the RGtkViewers package.
 x <- viewHtml("")
 x$html$AddCallback("url_requested", htmlLoadImage)
 x$load("test2.html")