QML virtual keyboard + TextEdit

[nick85]

Hi all,

I'm attempting to build a virtual keyboard in my QML application (Qt 4.8.5 and QML 1.1).
What I really need is to simulate key events when pressing a key buttons of virtual keyboard.

I searched online for some solutions but I don't find a clear one.
The solution most listed seems to be to create a custom c++ class (with an Invokable method) that should simulate the key press and release event.

Surprisingly I did not find any example about it so I tried to build it but, into sendEvent call (bool QCoreApplication::sendEvent ( QObject * receiver, QEvent * event ) [static]), I don't know what set as receiver... or better I don't know how to pass the QML TextEdit "instance" as receiver.

How to do it?
Or otherwise there is another way to do it?


Part of my class code:

void KeyEmitter::simulateKey(QString keyName)
{
    // getting selected keycode
    Qt::Key keycode = _getKeyCodeFromName(keyName);
    if ( keycode == Qt::Key_unknown )
    {
#ifdef DEBUG_ENABLED
        qDebug() << "Cannot resolve keycode associated to " << keyName;
#endif
        return;
    }
 
    QObject * receiver = NULL; // ???
 
    if (keyName.length() == 1 && keyName[0].unicode() >= 'A' && keyName[0].unicode() <= 'Z')
    {
        QKeyEvent keyPressEvent(QEvent::KeyPress, keycode, Qt::ShiftModifier, keyName);
        QApplication::sendEvent(receiver, &keyPressEvent);
 
        QKeyEvent keyReleaseEvent(QEvent::KeyRelease, keycode, Qt::ShiftModifier, keyName);
        QApplication::sendEvent(receiver, &keyReleaseEvent);
    }
    else
    {
        QKeyEvent keyPressEvent(QEvent::KeyPress, keycode, Qt::NoModifier, keyName);
        QApplication::sendEvent(receiver, &keyPressEvent);
 
        QKeyEvent keyReleaseEvent(QEvent::KeyRelease, keycode, Qt::NoModifier, keyName);
        QApplication::sendEvent(receiver, &keyReleaseEvent);
    }
 
#ifdef DEBUG_ENABLED
    qDebug() << "Simulated key " <<  qPrintable(keyName);
#endif
}

void KeyEmitter::simulateKey(QString keyName)
{
    // getting selected keycode
    Qt::Key keycode = _getKeyCodeFromName(keyName);
    if ( keycode == Qt::Key_unknown )
    {
#ifdef DEBUG_ENABLED
        qDebug() << "Cannot resolve keycode associated to " << keyName;
#endif
        return;
    }

    QObject * receiver = NULL; // ???

    if (keyName.length() == 1 && keyName[0].unicode() >= 'A' && keyName[0].unicode() <= 'Z')
    {
        QKeyEvent keyPressEvent(QEvent::KeyPress, keycode, Qt::ShiftModifier, keyName);
        QApplication::sendEvent(receiver, &keyPressEvent);

        QKeyEvent keyReleaseEvent(QEvent::KeyRelease, keycode, Qt::ShiftModifier, keyName);
        QApplication::sendEvent(receiver, &keyReleaseEvent);
    }
    else
    {
        QKeyEvent keyPressEvent(QEvent::KeyPress, keycode, Qt::NoModifier, keyName);
        QApplication::sendEvent(receiver, &keyPressEvent);

        QKeyEvent keyReleaseEvent(QEvent::KeyRelease, keycode, Qt::NoModifier, keyName);
        QApplication::sendEvent(receiver, &keyReleaseEvent);
    }

#ifdef DEBUG_ENABLED
    qDebug() << "Simulated key " <<  qPrintable(keyName);
#endif
}

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Thanks in advance


UPDATE

I found a similar issue with mouse event in this post : http://stackoverflow.com/questions/7...-clicks-in-qml

I tried to pass the viewer as receiver in my application and it works!

Summarizing....
Into main:

int main(int argc, char *argv[])
{
    [...]
    QmlApplicationViewer viewer;
    [...]
    QScopedPointer<KeyEmitter> keyEmitter(new KeyEmitter(&viewer));
    viewer.rootContext()->setContextProperty("keyEmitter", keyEmitter.data());
    [...]
}

int main(int argc, char *argv[])
{
    [...]
    QmlApplicationViewer viewer;
    [...]
    QScopedPointer<KeyEmitter> keyEmitter(new KeyEmitter(&viewer));
    viewer.rootContext()->setContextProperty("keyEmitter", keyEmitter.data());
    [...]
}

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Into KeyEmitter class:

class KeyEmitter : public QObject
{
    Q_OBJECT
 
public:
 
    KeyEmitter*(QObject * receiver*, QObject * parent = NULL);  // Added passing of receiver
 
    Q_INVOKABLE void simulateKey(QString keyName);
    [...]
 
private:
 
    QObject * _receiver;
    [...]
};

class KeyEmitter : public QObject
{
    Q_OBJECT

public:

    KeyEmitter*(QObject * receiver*, QObject * parent = NULL);  // Added passing of receiver

    Q_INVOKABLE void simulateKey(QString keyName);
    [...]

private:

    QObject * _receiver;
    [...]
};

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into QML:

IconButton              // is an implementation of a "standard" button
    {
        id:  abutton
        text:  "a"
        onClicked:  keyEmitter.simulateKey(text)
    }

IconButton              // is an implementation of a "standard" button
    {
        id:  abutton
        text:  "a"
        onClicked:  keyEmitter.simulateKey(text)
    }

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[shtdown]

Hi,

thanks for posting your solution after you got it working I've got a few difficulties with my KeyEmitter class. Have you still got access to your code and could post the whole class code?

Thank you in advance