int main(int argc, char *argv[])
{
    qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));
    QApplication a(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/keyboard.qml")));

    MainWindow w;
    w.show();
    return a.exec();
}

It works for me, any opinion for better view please comment :)

You can find an example in this StackOverflow answer.

Instead of a QQmlApplicationEngine and a floating top-level window I would have used a non-layouted QQuickWidget to instantiate the InputPanel since you are using QWidgets.

You can replace the Binding object with a single line:

Component.onCompleted: keyboard.style.keyboardDesignMaximumHeight = 300

int main(int argc, char *argv[])
{
    qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));
    QApplication a(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/keyboard.qml")));

    MainWindow w;
    w.show();
    return a.exec();
}

It works for me, any opinion for better view please comment :)

int main(int argc, char *argv[])
{
    qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));
    QApplication a(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/keyboard.qml")));

    MainWindow w;
    w.show();
    return a.exec();
}

import QtQuick
import QtQuick.Window
import QtQuick.VirtualKeyboard
import QtQuick.VirtualKeyboard.Settings
import QtQuick.VirtualKeyboard.Styles

VirtualKeyboard {
    id: root

    KeyboardStyle {
        keyboardDesignMaximumHeight: 300
    }

    InputPanel {
        id: inputPanel
        width: parent.width
        anchors.bottom: parent.bottom
    }
}

Sounds like this issue: https://qt-project.atlassian.net/browse/QTBUG-128845

Yes I have same problem, but how could I solve the problem on this link, I could not understand.

Note: I used 6.11.1 and this topic about 6.11, I changed to 6.9.3 and I saw same size problem on keyboard.

@JKSH said in Resize VirtualKeyboard ing QWidget:

The official solution (available from Qt 6.11 onwards) is to customize the keyboard style and set the keyboardDesignMaximumHeight property: https://doc.qt.io/qt-6/qml-qtquick-virtualkeyboard-styles-keyboardstyle.html#keyboardDesignMaximumHeight-prop

Actually I do not know qml and I do not know how I use it.

Thanks for your reply @JKSH

it is so big and its size is half height of my screen

Sounds like this issue: https://qt-project.atlassian.net/browse/QTBUG-128845

The official solution (available from Qt 6.11 onwards) is to customize the keyboard style and set the keyboardDesignMaximumHeight property: https://doc.qt.io/qt-6/qml-qtquick-virtualkeyboard-styles-keyboardstyle.html#keyboardDesignMaximumHeight-prop

(Unfortunately, this API is quite unwieldy and not well documented: https://qt-project.atlassian.net/browse/QTBUG-144131 )