Qt6: QFontDatabase does not addApplicationFont

achak

I cannot addApplicationFont. It allways returns -1.
I tried simple example at: https://github.com/eyllanesc/stackoverflow/tree/master/questions/55585443. The code is:

#include <QtWidgets>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QWidget w;
    QVBoxLayout *lay = new QVBoxLayout{&w};
    QComboBox combo;
    QLabel label{"Stack Overflow"};
    lay->addWidget(&combo);
    lay->addWidget(&label);
    QObject::connect(&combo, &QComboBox::currentTextChanged, [&label](const QString & name){
        label.setFont(QFont(name));
    });
    QDir directory(":/Roboto");
    for(const QFileInfo & info:  directory.entryInfoList()){
        int id = QFontDatabase::addApplicationFont(info.absoluteFilePath());
        if(id != -1){
            QStringList font_families = QFontDatabase::applicationFontFamilies(id);
            if(!font_families.isEmpty())
                combo.addItem(font_families.first());
        }
    }
    w.show();
    return a.exec();
}

My QT version is 6. Most of found tutorials, recomendations and answers are about older versions.

Thanks

SGaist

Hi,

Does it work if you use Qt 5 ?

achak

I use Qt Creator 5.0.0 based on Qt 5.15.2. QT version is 6.1.3

jsulm

@achak I think @SGaist wanted that you test with Qt5 to see whether it works with that version.

achak

@jsulm I have big project used QT6. The fonts feature is last part of it. I can check the example on Qt 5 but this does not help me with my project :(

Christian Ehrlicher

@achak said in Qt6: QFontDatabase does not addApplicationFont:

can check the example on Qt 5 but this does not help me with my project

But it would solve the question if it's a regression or not.

achak

@Christian-Ehrlicher What is simplest way for check old version.

jsulm

@achak Install Qt 5.15.2 and build your app using it.

achak

@jsulm said in Qt6: QFontDatabase does not addApplicationFont:

@achak Install Qt 5.15.2 and build your app using it.

Unfortunatelly, by our policy I cannot install another version QT.
The QT 5.15 is unsupported from 69/5/2021. If the sample works on 5.15, how it will support the issue?

jsulm

@achak As @Christian-Ehrlicher wrote: checking whether or not it works with Qt5 is just to see whether there is a regression in Qt6. Means: if it works in Qt5 but not in Qt6 then something was broken in Qt6.

kkoehne

In addition, you might want to enable the qt.qpa.fonts category and see whether it prints any helpful debug messages on why your fons are not loaded: https://doc.qt.io/qt-6/qloggingcategory.html#configuring-categories

achak

@kkoehne said in Qt6: QFontDatabase does not addApplicationFont:

qt.qpa.fonts

Thanks!!
Following is output:

qt.qpa.fonts: systemDefaultFont QFont(Segoe UI,9,-1,5,400,0,0,0,0,0,0,0,0,0,0,1)
qt.qpa.fonts: QWindowsFontDatabase Clear type:  true gamma:  1.2
qt.qpa.fonts: systemDefaultFont QFont(Segoe UI,9,-1,5,400,0,0,0,0,0,0,0,0,0,0,1)
qt.qpa.fonts: "Segoe UI"
qt.qpa.fonts: "addFontToDatabase Segoe UI 0 TTF=1 TRUETYPE scalable=1 Size=65535 Style=0 Weight=400 stretch=100"
qt.qpa.fonts: "addFontToDatabase Segoe UI 0 TTF=1 TRUETYPE scalable=1 Size=65535 Style=0 Weight=700 stretch=100"
qt.qpa.fonts: "addFontToDatabase Segoe UI 0 TTF=1 TRUETYPE scalable=1 Size=65535 Style=1 Weight=700 stretch=100"
qt.qpa.fonts: "addFontToDatabase Segoe UI 0 TTF=1 TRUETYPE scalable=1 Size=65535 Style=1 Weight=400 stretch=100"
qt.qpa.fonts: createEngine "Segoe UI" 9 pt hintingPreference= QFont::PreferDefaultHinting color= false 96 dpi useDirectWrite= false
qt.qpa.fonts: QWindowsFontEngine "Segoe UI" -12
qt.qpa.fonts: fontEngine FONTDEF QFontDef(Family="Segoe UI", pointsize=9, pixelsize=12, styleHint=5, weight=400, stretch=100, hintingPreference=0) 0x2ce0360 0x0

kkoehne

Hi, unfortunately the output isn't as informative as I have hoped :(

I just gave https://github.com/eyllanesc/stackoverflow/tree/master/questions/55585443 a test drive; the example works for me with Qt 6.2.2, both with MSVC and MinGW.

Can you try also with Qt 6.2.2?

achak

@kkoehne I trie on QT 6.2.2. I installed 6.2.3 on clear machine ( no QT 5 before) - the font did not set.

achak

Last days I tried the example on vers 6.2. 6.2.2 and 6.2.3 on differnt machines. The ties was on both Debug and Releas. Alltime is same issue :(

liteyear

I got this working in 6.2.3 recently. At first I was tripped up by the qrc path. Note that if you have something like:

qml.files = $$files(*.qml)
qml.prefix = /qml
fonts.files = $$files(fonts/*)
fonts.prefix = / # will automatically get directory name "fonts" as prefix
RESOURCES += qml fonts

in your .pro file, then Qt will expect to find qml files in the top-level directory, but their qrc path will have a "/qml" prefix. On the other hand it will expect to find ttf files in the fonts subdirectory, and still need to be accessed using a "/fonts" prefix.

So with the /pro above, this works for me in main.cpp:

QFontDatabase::addApplicationFont(":/fonts/Arial.ttf");
QFontDatabase::addApplicationFont(":/fonts/Arial Italic.ttf");
QFontDatabase::addApplicationFont(":/fonts/Arial Bold.ttf");
QFontDatabase::addApplicationFont(":/fonts/Arial Bold Italic.ttf");

returning 0, 1, 2 and 3 respectively.

Also remember to clean your build before re-building, because the qrc resource files might be pre-built by qmake.

PS. I'm not recommending anyone distribute Arial with your app. Do you own legal research.

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Qt6: QFontDatabase does not addApplicationFont