[Rd] How to get R to compile with PNG support

From: Karl-Dieter Crisman <kcrisman_at_gmail.com>
Date: Mon, 18 Apr 2011 11:48:40 -0400


Dear R devel list,

Good morning; I'm with the Sage (http://www.sagemath.org) project.
(Some of you might have seen my talk on this at last summer's useR
conference).

We have some rudimentary support for using R graphics in various cases, which has proved useful to many of our users who want to go back and forth between R and other capabilities within Sage. Unfortunately, the way we originally implemented this was using the png and plot functions in R itself, which perhaps isn't the best
(i.e., everyone uses ggplot now? but I digress).

That means that when people download a binary of ours, or compile their own, whether R's plot and png functions work depends heavily on the rather obscure (to users) issue of exactly what headers are present on the compiling machine.

Unfortunately, it is *very* unclear what actually needs to be present!  There are innumerable places where this has come up for us, but http://trac.sagemath.org/sage_trac/ticket/8868 and http://ask.sagemath.org/question/192/compiling-r-with-png-support are two of the current places where people have compiled information.

The FAQ says, "Unless you do not want to view graphs on-screen you need ‘X11’ installed, including its headers and client libraries. For recent Fedora distributions it means (at least) ‘libX11’, ‘libX11-devel’, ‘libXt’ and ‘libXt-devel’. On Debian we recommend the meta-package ‘xorg-dev’. If you really do not want these you will need to explicitly configure R without X11, using --with-x=no."

Well, we don't actually need to view graphs on-screen, but we do need to be able to generate them and save them (as pngs, for instance) to the correct directory in Sage for viewing. But we have people who've tried to do this in Ubuntu, with libpng and xorg-dev installed, and the file /usr/include/X11/Xwindows.h exists, but all to no avail. There are almost as many solutions people have found as there are computers out there, it seems - slight hyperbole, but that's what it feels like.

We've posted more than once (I think) to the r-help list, but have gotten no useful feedback. Is there *anywhere* that the *exact* requirements R has for having

capabilities("png")
  png
FALSE come out TRUE are documented?

Then, not only could we be smarter in how we compile R (currently somewhat naively searching for /usr/include/X11/Xwindows.h to determine whether we'll try for png support), but we would be able to tell users something very precise to do (e.g., apt-get foo) if they currently have R without PNG support in Sage. Again, I emphasize that apparently getting xorg-dev doesn't always do the trick.

We do realize that for most people wanting to use just R, it's best to download a binary, which will behave nicely; Sage's "batteries included" philosophy means that we are asking for more specialized info from upstream, and for that I apologize in advance. I also apologize if I said something silly above, because I don't actually know what all these files are - I've just looked into enough support requests to have a decent idea of what's required. We are trying not to have to parse the makefile to figure all this out, and possibly making some mistake there as well.

Thank you SO much for any help with this, Karl-Dieter Crisman
for the Sage team



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