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qt5keyboard-events
Mr. Developerdude
Mr. Developerdude

Reputation: 9668

How to fake keyboard event to widget in Qt5

I have made a custom virtual keyboard widget for my kiosk application, and now comes the time when I want it to produce fake keyboard events and feed them to an QLineEdit of choice.

I do the following:

// target is the QWidget to receive the events
// k is the Qt::Key (keycode) I want to send (Testing with an 'A')
Qt::Key k=Qt::Key_A;
if(0!=target){
    //According to docs this will be freed once posted
    QKeyEvent * press=new QKeyEvent(QKeyEvent::KeyPress, (int )k,0);
    QKeyEvent * release=new QKeyEvent(QKeyEvent::KeyRelease, (int )k,0);
    //Give the target focus just to be sure it is available for input
    target->setFocus();
    //Post the events (queue up and let the target consume them when the eventloop gets around to the target)
    QCoreApplication::postEvent ( target, press) ;
    QCoreApplication::postEvent ( target, release) ;
}

I see the target widget receive focus, but there are no letters typed into the input field like I would expect. What am I doing wrong? Which assumptions are wrong?

PS: I know that this could be solved by using existing virtual keyboards or at least using the platform interface as is done in this post. In our approach we have decided to build the kayboard into the application to obtain full control over the UX and keyboard design.

Thanks!

Upvotes: 1

Views: 1467

Answers (1)

Mr. Developerdude
Mr. Developerdude

Reputation: 9668

Since no-one stepped up, I will try to provide some closure.

It turns out that Qt5 comes with a library of testing facilities called testlib. It has all sorts of goodies to facilitate easy creation, management and running of unit tests for Qt application. Among these facilities there is a set of functions for sending fake events such as fake typing of text, mouse clicks etc. It is quite comprehensive and covers many use-cases. Since this is used internally by Qt developers to test Qt itself it is also production proven code.

I simply copied what I needed from there.

Upvotes: 2

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