Re: New approach to generating charts in PSPP ? (John Darrington)

[Harry Thijssen]

Hi

It looks certainly better/more professional. 

For the down side point 2, I guess most people install a pre-build binary package. The people who build there own binary will most likely be able to handle this additional requirement.

Hav fun

From: John Darrington <address@hidden>

To: address@hidden
Subject: New approach to generating charts in PSPP ?
Message-ID: <20170802174516.GA15843@jocasta.intra>
Content-Type: text/plain; charset="us-ascii"

A number of users have been commenting for a while that PSPP's
charts are somewhat clunky.

Because of this, I've been looking for a while for graphing libraries
to help us.  There is of course gnuplot (which despite its name is not
GNU software), but that has some practical and some licensing issues.
Amoung others that I found is GseGrafix (which IS a GNU program).
This certainly doesn't have any licensing problems (it's GPLv3+). But
1. It needs gnome canvas which does not typically get installed on
modern GNU/Linux distros, and is incompatible with Gtk+3 anyway; and
2. It's not a library.

So I've forked it and replaced gnomeCanvas with cairo, and massaged it
a little to provide a callable API.  I've registered a project at
http://sv.gnu.org/p/gsegrafix-experimental and hacked the PSPP code to
use this library.

I'm attaching results of a simple graph with both the new an the old.

What do people think about replacing our existing charting code with
GseGrafix?

The advantages that I can see are:

 1. Less code in PSPP.

 2. Clean separation of the charting code.

 3. Better (in my opinion) graphics.

 4. 3D plots can be generated.

 5. If we can persuade GseGrafix upstream to accept our changes, then
    somebody else maintains it for us.

On the down side:

 1. GseGrafix currently lacks some types of chart (eg: BoxPlots,
     Piecharts)

 2. It's another library that users have to install.


What do people think?