Getting font metrics without a GUI (console mode)

Question

Let's say some images must be generated by the Qt console program and that font metrics are necessary by internal algorithms (they use the text width / height ) as input to calculate the position in which the picture should be). This program should work on Linux without any graphical interface (runlevel-3, basically a cluster without any display server).

Problem: QFontMetrics are only available when starting the Qt application in GUI mode.
Any workaround for getting string metrics without any display server?

Answer 1

Ok after additional comments, I think I understand your problem. Just do it like this:

include <QApplication> int main(int argv, char **args) { QApplication app(argv, args); QApplication::processEvents(); // this should allow `QApplication` to complete its initialization // do here whatever you need return 0; // or some other value to report errors } 

You can also try using QGuiApplication , this version does not require (does not use) widgets.

See also the example in the documentation on how to handle no cases of gui.

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This code works fine on my Ubnutu with Qt 5.3

 #include <QGuiApplication> #include <QFontMetrics> #include <QDebug> int main(int argc, char *argv[]) { QGuiApplication a(argc, argv); QFont font("Times", 10, QFont::Bold); qDebug() << font; QFontMetrics metrics(font); qDebug() << metrics.boundingRect("test"); return 0; } 

It also works with Qt 4.8 when using QApplication .

The project file was pretty simple

 QT += core TARGET = MetricsNoGui TEMPLATE = app SOURCES += main.cpp