Is it safe to use QFont / QFontMetrics in a NON-GUI thread ?

[freeDNA]

for example:

@
class A : public QObject
{
Q_OBJECT
// ... //
signals:
void oneEntryFound(QString, int);

public slots:
void loadContent();
};

void A::loadContent()
{
QFont f("Segoe UI", 9);
QFontMetrics fm(f);

QuaZip zipFile(m_sFilePath);
bool bOK = zipFile.goToFirstFile();

while (bOK) {
     QString fn = zipFile.getCurrentFileName();
     emit oneEntryFound(fn, fm.width(fn));
     bOK = zipFile.goToNextFile();
}

}
@

and somewhere

@
void MyWidget::openZip(const QString& fn)
{
if (m_pA) m_pA->deleteLater();

 m_pA = new A(fn);
 m_pA->moveToThread(&m_Thread);

 connect(this, &MyWidget::blah, m_pA, &A::loadContent);
 connect(m_pA, &A::oneEntryFound, 
        [this] (QString fn, int w) { m_cW = qMax(m_cW, w); } 
        );

 emit blah();

}
@

Thanks in advance.

[euchkatzl]

Looking into the Qt docs will explain that QFont and QFontMetrics are reentrant:
http://doc-snapshot.qt-project.org/qt5-5.4/threads-reentrancy.html#reentrant

I think as long as you don't modify your QFont/QFontMetrics object from another threads this is okay.