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
__________________________
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