I want to debug event handling code and would like to convert QEvent::Type
enum's value to a human-readable string. QEvent
has a Q_GADGET
macro, so presumably there's a way of pulling that off?
Recent versions of Qt do the right thing when outputting events to the debug stream, so the below isn't neccessary. If you get an error similar to warning C4273: 'operator <<' : inconsistent dll linkage
, it means that your version of Qt already supports this without need for the code below.
The Q_GADGET
macro adds a QMetaObject staticMetaObject
member to the class. The static metaobject's definition is generated by moc, and it - in the case of QEvent
- contains the enumeration information.
Below is an example of how to leverage that to give a more reasonable QDebug
output of events.
#include <QEvent>
#include <QMetaEnum>
#include <QDebug>
/// Gives human-readable event type information.
QDebug operator<<(QDebug str, const QEvent * ev) {
static int eventEnumIndex = QEvent::staticMetaObject
.indexOfEnumerator("Type");
str << "QEvent";
if (ev) {
QString name = QEvent::staticMetaObject
.enumerator(eventEnumIndex).valueToKey(ev->type());
if (!name.isEmpty()) str << name; else str << ev->type();
} else {
str << (void*)ev;
}
return str.maybeSpace();
}
Use example:
void MyObject::event(QEvent* ev) {
qDebug() << "handling an event" << ev;
}