Re: [Plplot-devel] GTK/extcairo example?

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

On 2009-04-21 08:46+0930 Jonathan Woithe wrote:

> There are many other examples and demos in the plplot distribution which
> show off plplot in all its glory.  Do we really need to complicate these
> "output driver" demos with code which essentially duplicates what's already
> in other examples?

One purpose of the examples is to test PLplot capabilities. I am concerned
that extXdrawable_demo.c only exercises 7 PLplot commands (counting plsdev,
plsetopt, plinit, and plend) so there might be hidden issues in the way this
output driver is implemented which are not encountered because PLplot
capabilities are exercised so little.  The current extXdrawable_demo.c does
exercise some 2D PLplot capability and also some limited 2D PLplot text
capability. So at least we know those capabilites work. However, I would
like to see it test more PLplot capabilities to increase the testing power
of this external X drawable demo.

I acknowledge I am paranoid about testing, but that paranoia got an energy
boost today when I noticed the missing text in the ext-cairo-test results.
:-)

Whoever volunteers to enhance extXdrawable_demo.c (assuming we get such a
volunteer) might as well make the result interesting looking as well to
serve yet another purpose of the examples which is to show off the glory of
PLplot.  Note, for GUI applications like this there is no practical purpose
served by making the result identical to any other example, and, although
not necessary, I would encourage the volunteer to do something entirely
different here to add a bit more interest.

> [out of order] For someone who just wants to see
> how to use these specific features, they then need to trawl through all this
> extra generic plplot code to get to the stuff they want (assuming that they
> don't completely overlook the bits they need).

Good point which could/should be addressed by carefully segregating the
PLplot commands (e.g., using a separate routine) from the rest of the demo
source and documentating that segration within the code.

I would now like to change to the related topic of ext-cairo-test.c. If we
get a volunteer to enhance that code (once the text bug is solved for
extcairo), then I would strongly encourage that volunteer to simply copy one
of the more complicated standard C examples (say example 9).  The reason for
this difference with the suggested enhancement of extXdrawable_demo.c is
ext-cairo-test.c produces a PostScript file result. That allows us to
compare PostScript file results directly to make sure everything is working
as intended (at least for the PLplot API subset exercised by the standard
example that is copied).

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); PLplot scientific plotting software
package (plplot.org); 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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