qtvirtualkeyboard in QWidget App

MarKus12

My QWidget based -none QML- app has a mainwindow and several forms.
I use Qt5.15.8 and gcc or clang to compile it.
I googled now for 2 days and tried to understand the abstract documentation given.

QT_IM_MODULE is set

qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));

before creating

QApplication a(argc, argv);

I also did overwrite the focusInEvent of a created subclass myLineEdit
mylineedit.h:

#include <QLineEdit>
#include <QWidget>

class myLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    //myLineEdit();

    explicit myLineEdit(QWidget *parent = nullptr);

protected:
    void focusInEvent(QFocusEvent *);
    void focusOutEvent(QFocusEvent *);
};

with mylineedit.cpp:

myLineEdit::myLineEdit(QWidget *parent) : QLineEdit(parent)
{
}

void myLineEdit::focusInEvent(QFocusEvent *)
{
    qWarning() << "myLineEdit :FocusInEvent activates kbd";
    setAttribute(Qt::WA_InputMethodEnabled, true);
    QApplication::inputMethod()->show();
}

void myLineEdit::focusOutEvent(QFocusEvent *)
{
    qWarning() << "myLineEdit :FocusOutEvent hides kbd";
    QApplication::inputMethod()->hide();

}

Running the app for desktop it shows the vkbd.
Running the cross compiled app on target, it don't.
The basic example does run fine on the target.

I did try to integrate a .qml file in my app to make define an input panel, like documentation requested. So far i came up with:

import QtQuick 2.0
import QtQuick.VirtualKeyboard 2.1


Item {
   id: root
   InputPanel {
        id: inputPanel
        width: parent.width
        height: parent.height/3;
        y: Qt.inputMethod.visible ? parent.height - inputPanel.height : parent.height
        anchors.left: parent.left
        anchors.right: parent.right
    }
}

Currently i suspect that there might be an additional input.Method needed.
Does anybody can point me in the right direction. (QML curses would help, i know)

Thanks, appreciate it.

MarKus12

the whole idea of integrating a Qt Virtual keyboard in a QWidget might be not a great one.
I found QQuickWidget and QQuickView attempts which both deal with integrating qml code into
your QWidget application.

But I couldn't find a way to only use the qt virtual keyboard without rewriting the ui then.

Well at this point i don't understand the documentation under:
https://doc.qt.io/qt-5/qtvirtualkeyboard-index.html
where it says:

Supports both Qt Quick and Qt Widgets applications.

How is that feature meant?