Measuring text width in Qt

You can use QFontMetrics class - see the width() method which can give you the width of a given QString.

QFont myFont(fontName, fontSize);;
QString str("I wonder how wide this is?");

QFontMetrics fm(myFont);
int width=fm.width(str);

In the paintEvent

QString text("text");
QFontMetrics fm = painter.fontMetrics();
int width = fm.width(text);

Since Qt 5.11 you must use horizontalAdvance() method of QFontMetrics class instead of width(). width() is now obselete.

QFont myFont(fontName, fontSize);;
QString str("I wonder how wide this is?");

QFontMetrics fm(myFont);
int width=fm.horizontalAdvance(str);

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