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.