On 2009-07-16 07:52+0200 Werner Smekal wrote:

> Hi,
>>
>> In the case of the wxGC driver, from looking at the driver source and
>> the plot output, I think the reason it works is that it does not do
>> any text clipping.  The output from the wxwidgets driver with a
>> non-zero orientation seems to be the same as the xcairo output with
>> text clipping disabled.  I am not familiar with the wxwidgets driver
>> though, so I may be misunderstanding this somewhat.
>
> That's correct - I didn't implement the text clipping so far.
>>
>> As a somewhat related side-note, I see different output for example 1
>> with wxwidgets versus xcairo.  For plots 1 and 2, xcairo has the point
>> markers directly lined up with the plotted lines, whereas in the
>> wxwidgets output the points are slightly offset from the line.  This
>> is on Fedora 11 64bit, Cairo 1.8.6 and wxGTK 2.8.10.  I have attached
>> the output from each to illustrate.  This is likely an entirely
>> separate issue from this thread's topic though, if it is a PLplot
>> issue at all.
>
> It's a font issue. For some fonts it's problematic to correctly align
> the symbols. Since this happens if you use the freetype library also
> (only for some fonts, e.g. Arial in Windows) I believe there is not a
> general solution to that. Since there is at least one parameter which
> you can choose at will (fontsize multiplicator) this is very likely.

Hi Werner:

I also confirm the font offset issue mentioned by Hez.

I do agree font offsets are not done correctly for anything based on
plfreetype such as the gd devices or the AGG wxwidget mode.  However, my
understanding is the wxGC mode of wxwidgets is independent of plfreetype.
Furthermore, through independent semi-empirical corrections our font offsets
are correct for our qt and cairo devices (at least on my machine where I
made the final adjustment to the semiempirical corrections).  I don't
particularly like the semi-empirical adjustments and certainly don't
understand their necessity, but they do appear to work on all platforms (or
at least nobody has complained).

The cairo stack is based on libfreetype (and lots of other libraries) so
this libfreetype use (but not plfreetype's use of libfreetype) appears to
have the font offsets done correctly.  So there is hope for wxGC (assuming
it depends on freetype but not plfreetype) in this regard although wxGC font
offsets are far from correct at the moment and undoubtedly need
semi-empirical adjustments like that used for the qt and cairo device
drivers.

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).
__________________________

Linux-powered Science
__________________________

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