How to use QCoreApplication::postEvent to inject synthetic input events

c++ qt qcoreapplication
trenki picture trenki · Jan 4, 2012 · Viewed 17.2k times · Source

I'm injecting Keyboard and Mouse events which are comming over the network into my Qt Application and use QCoreApplication::postEvent for this. The mouse coordinates are absolute screen pixel coordinates.

QMouseEvent *event = new QMouseEvent(type, QPoint(x, y), mouse_button, mouse_buttons,
    Qt::NoModifier);
QCoreApplication::postEvent(g_qtdraw.main.widget, event);

Initially I had just one widget (referenced by g_qtdraw.main.widget) so I simply used that one as the receiver argument for postEvent. Now my application has more than one widget and the above code does not do what I want any longer.

A second widget is shown in fullscreen mode and I know that all mouse events have to go to this window but with the above code they are still routed to the main widget.

How do I choose the correct widget as the receiver (the one under the mouse x,y coords)? Is there a standard way, so that Qt chooses the right widget or do I have to track this myself?

Answer

Dusty Campbell picture Dusty Campbell · Jan 5, 2012

Can you use QApplication::widgetAt() to find the correct widget at the position and then post to that?

QPoint pos(x, y);
QMouseEvent *event = new QMouseEvent(type, pos, mouse_button, mouse_buttons,  Qt::NoModifier);
QWidget *receiver = QApplication::widgetAt(pos);
QCoreApplication::postEvent(receiver, event);

I wouldn't expect that you would have to do this for the key events though. They should be sent to the focused widget (QApplication::focusWidget()).

Unfortunately, I haven't tested any of this.

Related questions

Suppress warning "QApplication was not created in main() thread"

I've created a Qt-based network library for use with applications that are not running a Qt event loop, and which are not necessarily otherwise Qt applications. This was made possible by creating a QCoreApplication instance in a thread per the …

Read More
Please instantiate the QApplication object first

I have a static class and want it to have static QSettings. But with my initialization I get a warning: QSettings* MySQLConnection::settings = new QSettings(QApplication::applicationDirPath() + "/config.ini", QSettings::IniFormat); QCoreApplication::applicationDirPath: Please instantiate the QApplication object first As …

Read More
How to convert int to QString?

Is there a QString function which takes an int and outputs it as a QString?

Read More