如何在 Windows 中仅为平板电脑模式启动 Qt 虚拟键盘

Question

I am making an application for Windows desktops and tablets. I need to launch Qt virtual keyboard in tablet mode.

I followed this example in Qt docs

I just put one line of code in my main.cpp to get Qt virtual keyboard working

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

But now virtual keyboard launches in desktop mode also, which is not needed. How do I restrict the Qt virtual keyboard for tablet mode only?

I am using Qt 5.9 and tried 5.12. Windows on-screen keyboard does not launch all the time when needed

Answer 1

For checking tablet mode you can use bool QWindowsWindowFunctions::isTabletMode() static function which is introduced in Qt 5.9. For enabling virtual keyboard in table mode and disabling in desktop mode you can periodically check it in a timer and show/hide InputPanel respectively:

InputPanel {
    id: inputPanel

    property bool enableKeyboard: false
    ...
    states: State {
        name: "visible"
        when: enableKeyboard && inputPanel.active
        PropertyChanges {
            target: inputPanel
            y: appContainer.height - inputPanel.height
        }
    }
    ...
}

enableKeyboard property is defined to activate/deactivate keyboard and it should be updated regularly using a Timer like:

Timer {
    onTriggered: enableKeyboard = utils.isTabletMode()
    running: true
    repeat: true
    interval: 1000
}

You should define isTabletMode function in a QObject based class like:

#include <QtPlatformHeaders/QWindowsWindowFunctions>
...
Q_INVOKABLE bool isTabletMode() {
     return QWindowsWindowFunctions::isTabletMode();
}

Do not forget to expose you class to qml by:

qmlengine->rootContext()->setContextProperty("utils", pointerToMyClass);