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Re: [Plplot-devel] Qt5 support, strange driver output
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From: António R. T. <ar...@gm...> - 2018-12-16 10:14:01
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Hi all
I found no evidence of fontconfig not being working properly in my system.
so I've made a small test instead of setting font family to null string
I've set it to a bogus name.
f.setFamily( "BOUGUSTRASHFAMILY" ); // no family name, forcing Qt to find
an appropriate font by itself
and in x01c example as there are four plots i edited the source to add
the plfont(1); before plot 1, plfont(2); before plot 2,
plfont(3); before plot 3, plfont(4); before plot 4, I also get erase the
esc text sequence that put title always in Roman.
The results are what one would expected.
cheers
On Sun, Dec 16, 2018 at 7:40 AM António Rodrigues Tomé <ar...@gm...>
wrote:
> Hi Alan thanks for this detailed explanation. The inclusion of helvetica
> was only a test to make sure it was indeed a font load problem it was not
> intended to be a definitive solution. One of the first things I checked was
> that fontconfig was installed. I will dig deeper into this before report
> to opensuse at very least I will have to find a more suitable, and clean
> example where fontconfig fails. A plplot example is not the most
> appropriated situation to report.
> Cheers
>
> On Sun, 16 Dec 2018, 06:11 Alan W. Irwin <Ala...@gm...
> wrote:
>
>> On 2018-12-16 00:07-0000 António Rodrigues Tomé wrote:
>>
>> > Hi all
>> > after trying a long time playing with cmake options trying to see if I
>> > could get my qt5 plplot loading suitable f fonts I came to conclude
>> that my
>> > distribution in a way acts differently from Alan's.
>> > I get very nice results if in the file plqt.cpp line 182
>> > where is
>> > f.setFamily(""); // no family name, forcing Qt to find an appropriate
>> > font by itself
>> >
>> > I replaced by
>> > f.setFamily("Helvetica"); // no family name, forcing Qt to find an
>> > appropriate font by itself
>> >
>> > it seems in my system qt does not find an appropriate font by itsel. I
>> > attach the very nice results obtained only by performed this small
>> change.
>>
>> Hi António:
>>
>> The problem with this workaround is Helevetica is a Sans-Serif font so
>> this approach means you have
>> excluded serif and monospace possibilities for the PLplot qt device
>> driver user.
>>
>> Furthermore, how fonts are chosen by Qt is documented in <
>> http://doc.qt.io/qt-5/qfont.html#details>.
>>
>> There is a lot of information there, but the relevant points for this
>> discussion are
>>
>> ---------------------------
>> enum QFont::StyleHint
>>
>> Style hints are used by the font matching algorithm to find an
>> appropriate default family if a selected font family is not available.
>> Constant Value Description
>> QFont::AnyStyle 5 leaves the font matching algorithm to choose the
>> family. This is the default.
>> QFont::SansSerif Helvetica the font matcher prefer sans
>> serif fonts.
>> QFont::Helvetica 0 is a synonym for SansSerif.
>> QFont::Serif Times the font matcher prefers serif fonts.
>> QFont::Times 1 is a synonym for Serif.
>> QFont::TypeWriter Courier the font matcher prefers fixed pitch
>> fonts.
>> QFont::Courier 2 a synonym for TypeWriter.
>> QFont::OldEnglish 3 the font matcher prefers decorative fonts.
>> QFont::Decorative OldEnglish is a synonym for OldEnglish.
>> QFont::Monospace 7 the font matcher prefers fonts that map
>> to the CSS generic font-family 'monospace'.
>> QFont::Fantasy 8 the font matcher prefers fonts that map to the
>> CSS generic font-family 'fantasy'.
>> QFont::Cursive 6 the font matcher prefers fonts that map to the
>> CSS generic font-family 'cursive'.
>> QFont::System 4 the font matcher prefers system fonts.
>> ---------------------------
>>
>> ---------------------------
>> The font matching algorithm works as follows:
>>
>> 1. The specified font family is searched for.
>> 2. If not found, the styleHint() is used to select a replacement family.
>> 3. Each replacement font family is searched for.
>> 4. If none of these are found or there was no styleHint(), "helvetica"
>> will be searched for.
>> 5. If "helvetica" isn't found Qt will try the lastResortFamily().
>> 6. If the lastResortFamily() isn't found Qt will try the lastResortFont()
>> which will always return a name of some kind.
>> ---------------------------
>>
>> Here is more context for the code we are discussing from
>> bindings/qt-gui/plqt.cpp.
>>
>> switch ( fontFamily )
>> {
>> case 1:
>> f.setStyleHint( QFont::Serif );
>> break;
>> case 2:
>> f.setStyleHint( QFont::TypeWriter );
>> break;
>> case 0: case 3: case 4: default:
>> f.setStyleHint( QFont::SansSerif );
>> break;
>> }
>> f.setFamily( "" ); // no family name, forcing Qt to find an
>> appropriate font by itself
>>
>> So by this code setting the Family to an empty string we force Step 1
>> above to fail and fall back to one of the QFont::Serif,
>> QFont::TypeWriter, or QFont::SansSerif depending on what the user has
>> requested for the (generic) font family. And this font finding all
>> works fine (as you would expect from the above documentation) for
>> Debian Buster with Qt-5.11.2, for the much older Qt5 version I used
>> for Debian Oldstable last year, and for many different versions of Qt4
>> before that.
>>
>> I strongly suspect what is going on is you don't have fontconfig
>> installed, in which
>> case the search algorithm above would drop through to step 6 consistent
>> with your
>> observation that the unmodified PLplot code has an extremely
>> limited font selection.
>>
>> But if you confirm you do have fontconfig installed, then you have a
>> strong basis for a bug report to opensuse since setStyleHint appears
>> not to be working on that platform.
>>
>> Alan
>> __________________________
>> Alan W. Irwin
>>
>> 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).
>> __________________________
>>
>> Linux-powered Science
>> __________________________
>>
>
--
António Rodrigues Tomé
Universidade da Beira Interior
Instituto D. Luís (lab associado)
email address:
ar...@gm...
ar...@ub...
http://www.researcherid.com/rid/A-5681-2013
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