I extracted this file from Qt's source code if anyone needs a Shortcut key sequence edit (here: http://qt.gitorious.org/qt-solutions/qt-solutions/raw/2174f117fe67c9e6be21c52003a436e866755fc3:qtpropertybrowser/src/qtpropertybrowserutils.cpp and http://qt.gitorious.org/qt-solutions/qt-solutions/source/2174f117fe67c9e6be21c52003a436e866755fc3:qtpro…

qtkeysequenceedit.cpp

/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Solutions component.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
**     of its contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qtkeysequenceedit.h"

#include <QEvent>
#include <QMenu>
#include <QContextMenuEvent>
#include <QStyleOption>
#include <QPainter>
#include <QStyle>


QtKeySequenceEdit::QtKeySequenceEdit(QWidget *parent)
    : QWidget(parent), m_num(0), m_lineEdit(new QLineEdit(this))
{
    QHBoxLayout *layout = new QHBoxLayout(this);
    layout->addWidget(m_lineEdit);
    layout->setMargin(0);
    m_lineEdit->installEventFilter(this);
    m_lineEdit->setReadOnly(true);
    m_lineEdit->setFocusProxy(this);
    setFocusPolicy(m_lineEdit->focusPolicy());
    setAttribute(Qt::WA_InputMethodEnabled);
}

bool QtKeySequenceEdit::eventFilter(QObject *o, QEvent *e)
{
    if (o == m_lineEdit && e->type() == QEvent::ContextMenu) {
        QContextMenuEvent *c = static_cast<QContextMenuEvent *>(e);
        QMenu *menu = m_lineEdit->createStandardContextMenu();
        const QList<QAction *> actions = menu->actions();
        QListIterator<QAction *> itAction(actions);
        while (itAction.hasNext()) {
            QAction *action = itAction.next();
            action->setShortcut(QKeySequence());
            QString actionString = action->text();
            const int pos = actionString.lastIndexOf(QLatin1Char('\t'));
            if (pos > 0)
                actionString.remove(pos, actionString.length() - pos);
            action->setText(actionString);
        }
        QAction *actionBefore = 0;
        if (actions.count() > 0)
            actionBefore = actions[0];
        QAction *clearAction = new QAction(tr("Clear Shortcut"), menu);
        menu->insertAction(actionBefore, clearAction);
        menu->insertSeparator(actionBefore);
        clearAction->setEnabled(!m_keySequence.isEmpty());
        connect(clearAction, SIGNAL(triggered()), this, SLOT(slotClearShortcut()));
        menu->exec(c->globalPos());
        delete menu;
        e->accept();
        return true;
    }

    return QWidget::eventFilter(o, e);
}

void QtKeySequenceEdit::slotClearShortcut()
{
    if (m_keySequence.isEmpty())
        return;
    setKeySequence(QKeySequence());
    emit keySequenceChanged(m_keySequence);
}

void QtKeySequenceEdit::handleKeyEvent(QKeyEvent *e)
{
    int nextKey = e->key();
    if (nextKey == Qt::Key_Control || nextKey == Qt::Key_Shift ||
            nextKey == Qt::Key_Meta || nextKey == Qt::Key_Alt ||
            nextKey == Qt::Key_Super_L || nextKey == Qt::Key_AltGr)
        return;

    nextKey |= translateModifiers(e->modifiers(), e->text());
    int k0 = m_keySequence[0];
    int k1 = m_keySequence[1];
    int k2 = m_keySequence[2];
    int k3 = m_keySequence[3];
    switch (m_num) {
        case 0: k0 = nextKey; k1 = 0; k2 = 0; k3 = 0; break;
        case 1: k1 = nextKey; k2 = 0; k3 = 0; break;
        case 2: k2 = nextKey; k3 = 0; break;
        case 3: k3 = nextKey; break;
        default: break;
    }
    ++m_num;
    if (m_num > 3)
        m_num = 0;
    m_keySequence = QKeySequence(k0, k1, k2, k3);
    m_lineEdit->setText(m_keySequence.toString(QKeySequence::NativeText));
    e->accept();
    emit keySequenceChanged(m_keySequence);
}

void QtKeySequenceEdit::setKeySequence(const QKeySequence &sequence)
{
    if (sequence == m_keySequence)
        return;
    m_num = 0;
    m_keySequence = sequence;
    m_lineEdit->setText(m_keySequence.toString(QKeySequence::NativeText));
}

QKeySequence QtKeySequenceEdit::keySequence() const
{
    return m_keySequence;
}

int QtKeySequenceEdit::translateModifiers(Qt::KeyboardModifiers state, const QString &text) const
{
    int result = 0;
    if ((state & Qt::ShiftModifier) && (text.size() == 0 || !text.at(0).isPrint() || text.at(0).isLetter() || text.at(0).isSpace()))
        result |= Qt::SHIFT;
    if (state & Qt::ControlModifier)
        result |= Qt::CTRL;
    if (state & Qt::MetaModifier)
        result |= Qt::META;
    if (state & Qt::AltModifier)
        result |= Qt::ALT;
    return result;
}

void QtKeySequenceEdit::focusInEvent(QFocusEvent *e)
{
    m_lineEdit->event(e);
    m_lineEdit->selectAll();
    QWidget::focusInEvent(e);
}

void QtKeySequenceEdit::focusOutEvent(QFocusEvent *e)
{
    m_num = 0;
    m_lineEdit->event(e);
    QWidget::focusOutEvent(e);
}

void QtKeySequenceEdit::keyPressEvent(QKeyEvent *e)
{
    handleKeyEvent(e);
    e->accept();
}

void QtKeySequenceEdit::keyReleaseEvent(QKeyEvent *e)
{
    m_lineEdit->event(e);
}

void QtKeySequenceEdit::paintEvent(QPaintEvent *)
{
    QStyleOption opt;
    opt.init(this);
    QPainter p(this);
    style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
}

bool QtKeySequenceEdit::event(QEvent *e)
{
    if (e->type() == QEvent::Shortcut ||
            e->type() == QEvent::ShortcutOverride  ||
            e->type() == QEvent::KeyRelease) {
        e->accept();
        return true;
    }
    return QWidget::event(e);
}

qtkeysequenceedit.h

/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Solutions component.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
**     of its contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QTKEYSEQUENCEEDIT_H
#define QTKEYSEQUENCEEDIT_H

#include <QWidget>
#include <QLineEdit>

#include <QHBoxLayout>

class QtKeySequenceEdit : public QWidget
{
    Q_OBJECT
public:
    QtKeySequenceEdit(QWidget *parent = 0);

    QKeySequence keySequence() const;
    bool eventFilter(QObject *o, QEvent *e);
public Q_SLOTS:
    void setKeySequence(const QKeySequence &sequence);
Q_SIGNALS:
    void keySequenceChanged(const QKeySequence &sequence);
protected:
    void focusInEvent(QFocusEvent *e);
    void focusOutEvent(QFocusEvent *e);
    void keyPressEvent(QKeyEvent *e);
    void keyReleaseEvent(QKeyEvent *e);
    void paintEvent(QPaintEvent *);
    bool event(QEvent *e);
private slots:
    void slotClearShortcut();
private:
    void handleKeyEvent(QKeyEvent *e);
    int translateModifiers(Qt::KeyboardModifiers state, const QString &text) const;

    int m_num;
    QKeySequence m_keySequence;
    QLineEdit *m_lineEdit;
};

#endif // QTKEYSEQUENCEEDIT_H