Re: [Plplot-devel] ocaml and antialiased gtk embedding (cairo)

[Alan W. I. <ir...@be...>]

On 2017-10-02 15:35-0000 Philippe STRAUSS via Plplot-devel wrote:

> Hello plplot devs,
> I'm an ocaml user using plplot in one of my pet project.The plcairo layer seems not usable anymore, what happened?

Hi Philippe:

Thanks very much for your interest in plcairo.

To answer your question above, I have reviewed the situation with git
blame and git log and the fundamental answer is the last two commits
by Hezekiah Carty before he took at least a temporary break from
developing PLplot in 2014 is he switched from the cairo to cairo2
OCaml module (commit 84d2a85) and followed up (commit e88308c) by
changing our OCaml documentation in presumably a compatible way with
that change.  Commit 84d2a85 was a substantial change, and here is the
associated commit message:

commit 84d2a859f31b69c1d440a7a61d5c57528de94355
Author: Hezekiah M. Carty <he...@0o...>
Date:   Thu Jul 3 14:46:13 2014 +0000

     Switch to a different OCaml Cairo binding ("cairo2" in opam)

     This is a more actively maintained binding to the Cairo library.  It is
     unfortunately not packaged for Debian at this time so interested users
     would need to install the library through opam.  opam is generally the
     recommended way to install and manage OCaml libraries (this cpan, pip, etc)
     so this isn't a particularly serious limitation.

     svn path=/trunk/; revision=13134

So the situation is I cannot test plcairo on our principal testing
platform (my Debian Jessie box), I am not even sure cairo2 will be
available once I upgrade that box to Debian Stretch, and despite Hez's
thought that opam might be the answer, I am reluctant to potentially
mess up my Debian installation with an opam installation on top of
that. Since we are stuck now and possibly in the forseeable future
with regard to testing plcairo and because Hez continues to be out of
touch, I ultimately decided to disable this capability (see commits
893625c and 84760038).  However, the net effect of those two changes
was extremely small so it should be absolutely straightforward to
resurrect plcairo again.  For example, you could do that
by reversing those two particular commits.

So given this background what do you recommend on the cairo versus
cairo2 question, and in particular do you know whether there is an
official Debian package that provides that cairo2 module?

Another possibility is I could go back to cairo from cairo2 by
reversing Hez's last two commits, but that would be a substantial
change so I would only do that if you recommend cairo over cairo2
these days.

Yet another possibility would be for PLplot to support an untested (by me)
cairo2 version plus a tested cairo version, but from the
size of commit 84d2a859f3 that would be a fair amount of work
to implement.

> I have some spare time to tackle the issue under guidance in case. I
use plplot embedded in a gtk windows from within ocaml like the
xgtk_interface example. I have ocaml cairo and cairo2 bindings.
regards.

Sounds good!  It appears by reversing my two small commits that you
might be in business with cairo2 right away, but regardless of that I
would appreciate the cairo/cairo2 advice I requested from you above,
and I would certainly be willing to help you with any CMake issues you
encounter and also apply your requested patches (if I have some
convenient way to test them).

Best wishes,

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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Linux-powered Science
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