Virtual keyboard or onscreen keyboard for QtWidgets applications?

Question

I'm going to deploy the qtvirtualkeyboard in my widget-based application like so:

#include <QtWidgets>

int main(int argc, char *argv[]) {
    qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));
    QApplication app(argc, argv);
    QMainWindow window;
    QLineEdit input(&window);
    input.move(250, 250);
    window.show();
    return app.exec();
}

But the only issue is that the virtual keyboard input panel hides the underlying widgets and cover them!

How should I achieve this?

Is there any document or solution for widgets-based applications?

Beware that Qt Virtual Keyboard is available under GNU General Public License, version 3 (and not under LGPL for other modules) -- see [here](https://doc.qt.io/qt-5/qtvirtualkeyboard-index.html#licenses-and-attributions). You might need a commercial license...Good luck! — vlp, Jul 23 '19 at 16:18

Vahagn Avagyan · Answer 1 · 2019-07-23T11:05:11.083

2

you just need to add this line in main.cpp

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

and will work Virtual Keyboard in Qtwidgets))

edited Jul 23 '19 at 11:05

answered Jul 23 '19 at 10:58

Vahagn Avagyan

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4
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Thank you, but I did this already and the only issue is that the keyboard in some cases hides the widgets behind it and act as an overlay! here is a demo: https://i.stack.imgur.com/rBET7.gif – IMAN4K Jul 23 '19 at 13:18
1

Yes, I solved this question manually, you need to catch the event, and when you open the virtual keyboard, rearrange the window so that they were visible, – Vahagn Avagyan Jul 23 '19 at 13:38
use QStackedWidget – Vahagn Avagyan Jul 23 '19 at 13:40
But as far as I know qtvirtualkeyboard is implemented in QML so where is the keyboard widget to use inside QStackedWidget or to catch event? regards. – IMAN4K Jul 23 '19 at 18:45
Any idea about this? – IMAN4K Jul 25 '19 at 07:16
@IMAN4K QT alone cannot fix your interface, you need to do it manually, – Vahagn Avagyan Jul 25 '19 at 07:34
if you do not open to full screen, then this will already be 2 problem , – Vahagn Avagyan Jul 25 '19 at 07:36
I will open my MainWindow in fullscreen but how could I fix this manually? can you help us in more detail. Regards – IMAN4K Jul 25 '19 at 08:04

score 1 · Accepted Answer · answered Jul 30 '19 at 10:56

Finally got the solution!

You just need to call QGuiApplication::inputMethod() to get the application-wide Qt input method and then call QInputMethod::keyboardRectangle() and QInputMethod::isVisible() to get input method properties then remain a calculation based on your widget position and keyboard coordinate, here is a full-working sample to share:

lineedit.h:

class LineEdit :public QLineEdit {
    Q_OBJECT

public:
    LineEdit(QWidget *parent = nullptr);
    LineEdit(const QString&, QWidget *parent = nullptr);

protected:
    bool event(QEvent*) override;

private:
    bool _moved = false;
    int _lastDiff = 0;
};

lineedit.cpp:

LineEdit::LineEdit(QWidget *parent) :QLineEdit(parent) {
    setAttribute(Qt::WA_InputMethodEnabled, true);
    setInputMethodHints(inputMethodHints() | Qt::InputMethodHint::ImhDigitsOnly);
}

LineEdit::LineEdit(const QString& txt, QWidget *parent) : QLineEdit(txt, parent) {
    setAttribute(Qt::WA_InputMethodEnabled, true);
    setInputMethodHints(inputMethodHints() | Qt::InputMethodHint::ImhDigitsOnly);
}

bool LineEdit::event(QEvent* e) {
    const auto keyboard_rect = QGuiApplication::inputMethod()->keyboardRectangle();
    const auto keyboard_visible = QGuiApplication::inputMethod()->isVisible();
    const auto global_y = QWidget::mapToGlobal(rect().topLeft()).y() + height();
    const auto k_global_y = keyboard_rect.topLeft().y();
    const auto diff = k_global_y - global_y;
    const auto need_to_move = diff < 0;

    /* move main widget */
    if (keyboard_visible && !_moved && need_to_move) {
        _moved = true;
        _lastDiff = diff;
        const auto g = parentWidget()->frameGeometry();
        parentWidget()->move(g.x(), g.y() - qAbs(_lastDiff));
    }
    /* roll back */
    if (!keyboard_visible && _moved) {
        _moved = false;
        const auto g = parentWidget()->frameGeometry();
        parentWidget()->move(g.x(), g.y() + qAbs(_lastDiff));
    }
    return QLineEdit::event(e);
}

main.cpp:

#include <QtWidgets>

#define W 1024
#define H 768

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

    QMainWindow window(nullptr, Qt::FramelessWindowHint);

    LineEdit lineedit1(&window);
    lineedit1.move(100, 450);

    LineEdit lineedit2(&window);
    lineedit2.move(100, 100);

    window.resize(W, H);
    window.show();
    return app.exec();
}

results:

Virtual keyboard or onscreen keyboard for QtWidgets applications?

2 Answers2

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