Adding a TTF font to QML via QFontDatabase fails

[EStudley]

Hello,

I am trying to add the Roboto font to my application without having it installed by the operating system. The TTF files were downloaded directly from Google Fonts.

Working correctly:

• The TTF files can be correctly installed by Windows and works in QML that way. (QML family/styleName is right)
• The TTF file is being correctly referenced from my QRC file; QFile(":/fonts/Roboto-Regular.ttf").exists() returns true.

Not working:

• QFontDatabase::addApplicationFont(":/fonts/Roboto-Regular.ttf") returns -1.
• QFontDatabase::addApplicationFontFromData(QFile(":/fonts/Roboto-Regular.ttf").readAll()) returns -1.
• The font does not appear in my QML.

Possibly something about the complexity of the TTF file from Google Fonts? Is there any specific metadata missing?

Thanks.

[EStudley]

When I call:

qDebug() << QFontDatabase::addApplicationFontFromData(QFile(":/fonts/Roboto-Regular.ttf").readAll());

The following is output:

QIODevice::read (QFile, ":/fonts/Roboto-Regular.ttf"): device not open
QFSFileEngine::open: No file name specified
-1

[Bonnie]

Hey, are you on Linux or something?
There's a note on the doc:

Note: Adding application fonts on Unix/X11 platforms without fontconfig is currently not supported.

So I think you need to install fontconfig on your system first.

As for the QFile error: it needs to be opened for read before you can perform read on it, just as what it told you.
But still, this function has the same note as above.

[EStudley]

I am not on Linux unfortunately; Windows 10.

I've discovered that explorer.exe has a constant file lock on any .ttf file on my computer instantly. I am assuming that's the cause of the failure to load.

[fcarney]

font lock issue

[fcarney]

I am interested in the solution to this. Can you make the font be part of a qrc and use it from there?

[Bonnie]

@EStudley
I've tested in my WIndows 10, download the ttf from google fonts and add it to qrc.

qDebug() << QFontDatabase::addApplicationFont(":/font/Roboto-Regular.ttf");

this returns 0.
So at least the code is not the problem.