[Discuss] Desktop Managers

[Alan W. Irwin]

On 2014-08-02 22:41-0700 John Blomfield wrote:

> On 08/02/2014 05:46 PM, Alan W. Irwin wrote:
>> By the way, it appears from that review that KDE5 is already available
>> for opensuse.  So do you plan to give it a try as well? 
> I've only seen Unstable versions of the KDE 5 Framework and Qt5 available so 
> far on OpenSuse in order to "ease the transition" to KDE 5 desktop, so I 
> don't plan to try it yet. Nor have I investigated Qt5 to see how much impact 
> that upgrade will have on Qt4 applications. That is, will wholesale re-writes 
> of the applications be required or will it apply to new apps only? My guess 
> is that a move from KDE4 to KDE5 is probably a year away, perhaps on version 
> OpenSuse 14. The latest OpenSuse is currently 13.1 and there are likely to be 
> a 13.2 and 13.3 out first.

Hi John:

It sounds like OpenSuse is rightly being quite conservative about the
transition to KDE5.

With regards to the differences between Qt4 and Qt5, PLplot has a "qt"
device driver that depends on the Qt4 suite of libraries.  The
advertised differences between Qt4 and Qt5 are sufficiently small,
that we were encouraged to switch from linking our qt device code from
Qt4 to Qt5 without any qt device driver code changes.  That
essentially worked. However, the CMake methods you use to discover the
Qt5 headers and libraries are now completely changed with some of the
functionality now Qt5's responsibility rather than being solely done
by CMake alone.  The result is a much smoother build experience for
applications or libraries that depend on Qt5, but I also had to
substantially change the PLplot CMake-based build to use these new
CMake methods that are required for the Qt5 case.

However, once the build against Qt5 worked, it turned out we did not
much like the qt device driver results we got for that case.  The
problem is that for Qt5.2.1 and Qt5.3.1 there appear to be text
alignment issues so all the text in our qt device driver plots needs
to be substantially shifted in the vertical direction to line up with
the rest of the plot but with the sign and magnitude of that shift
changing between Qt5.2.1 and Qt5.3.1. A quick check of the Qt5 bug
tracker revealed large numbers of unresolved bug reports related to
text alignment issues which are presumably being worked on because of
the text alignment changes between 5.2.1 and 5.3.1.  So we will keep
trying new versions of Qt5 from time to time to see if and when these
text alignment bugs get fixed sufficiently to satisfy PLplot's needs.
Until that happens linking our qt device driver against Qt5 will only
be an experimental build option with PLplot, and by default our users
will build the qt device driver against Qt4 (and continue to get
outstanding results for that case).

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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