cantata/support/keysequencewidget.cpp

/***************************************************************************
 *   Copyright (C) 2005-2015 by the Quassel Project                        *
 *   devel@quassel-irc.org                                                 *
 *                                                                         *
 *   This class has been inspired by KDE's KKeySequenceWidget and uses     *
 *   some code snippets of its implementation, part of kdelibs.            *
 *   The original file is                                                  *
 *       Copyright (C) 1998 Mark Donohoe <donohoe@kde.org>                 *
 *       Copyright (C) 2001 Ellis Whitehead <ellis@kde.org>                *
 *       Copyright (C) 2007 Andreas Hartmetz <ahartmetz@gmail.com>         *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.         *
 ***************************************************************************/

#include <QApplication>
#include <QDebug>
#include <QKeyEvent>
#include <QHBoxLayout>
#include <QIcon>
#include <QMessageBox>
#include <QToolButton>
#include <QStyle>

// This defines the unicode symbols for special keys (kCommandUnicode and friends)
#ifdef Q_OS_MAC
#  include <Carbon/Carbon.h>
#endif

#include "action.h"
#include "actioncollection.h"
#include "keysequencewidget.h"

KeySequenceButton::KeySequenceButton(KeySequenceWidget *d_, QWidget *parent)
    : QPushButton(parent),
    d(d_)
{
}


bool KeySequenceButton::event(QEvent *e)
{
    if (d->isRecording() && e->type() == QEvent::KeyPress) {
        keyPressEvent(static_cast<QKeyEvent *>(e));
        return true;
    }

    // The shortcut 'alt+c' ( or any other dialog local action shortcut )
    // ended the recording and triggered the action associated with the
    // action. In case of 'alt+c' ending the dialog.  It seems that those
    // ShortcutOverride events get sent even if grabKeyboard() is active.
    if (d->isRecording() && e->type() == QEvent::ShortcutOverride) {
        e->accept();
        return true;
    }

    return QPushButton::event(e);
}


void KeySequenceButton::keyPressEvent(QKeyEvent *e)
{
    int keyQt = e->key();
    if (keyQt == -1) {
        // Qt sometimes returns garbage keycodes, I observed -1, if it doesn't know a key.
        // We cannot do anything useful with those (several keys have -1, indistinguishable)
        // and QKeySequence.toString() will also yield a garbage string.
        QMessageBox::information(this,
            tr("The key you just pressed is not supported by Qt."),
            tr("Unsupported Key"));
        return d->cancelRecording();
    }

    uint newModifiers = e->modifiers() & (Qt::SHIFT | Qt::CTRL | Qt::ALT | Qt::META);

    //don't have the return or space key appear as first key of the sequence when they
    //were pressed to start editing - catch and them and imitate their effect
    if (!d->isRecording() && ((keyQt == Qt::Key_Return || keyQt == Qt::Key_Space))) {
        d->startRecording();
        d->_modifierKeys = newModifiers;
        d->updateShortcutDisplay();
        return;
    }

    // We get events even if recording isn't active.
    if (!d->isRecording())
        return QPushButton::keyPressEvent(e);

    e->accept();
    d->_modifierKeys = newModifiers;

    switch (keyQt) {
    case Qt::Key_AltGr: //or else we get unicode salad
        return;
    case Qt::Key_Shift:
    case Qt::Key_Control:
    case Qt::Key_Alt:
    case Qt::Key_Meta:
    case Qt::Key_Menu: //unused (yes, but why?)
        d->updateShortcutDisplay();
        break;

    default:
        if (!(d->_modifierKeys & ~Qt::SHIFT)) {
            // It's the first key and no modifier pressed. Check if this is
            // allowed
            if (!d->isOkWhenModifierless(keyQt))
                return;
        }

        // We now have a valid key press.
        if (keyQt) {
            if ((keyQt == Qt::Key_Backtab) && (d->_modifierKeys & Qt::SHIFT)) {
                keyQt = Qt::Key_Tab | d->_modifierKeys;
            }
            else if (d->isShiftAsModifierAllowed(keyQt)) {
                keyQt |= d->_modifierKeys;
            }
            else
                keyQt |= (d->_modifierKeys & ~Qt::SHIFT);

            d->_keySequence = QKeySequence(keyQt);
            d->doneRecording();
        }
    }
}


void KeySequenceButton::keyReleaseEvent(QKeyEvent *e)
{
    if (e->key() == -1) {
        // ignore garbage, see keyPressEvent()
        return;
    }

    if (!d->isRecording())
        return QPushButton::keyReleaseEvent(e);

    e->accept();

    uint newModifiers = e->modifiers() & (Qt::SHIFT | Qt::CTRL | Qt::ALT | Qt::META);

    // if a modifier that belongs to the shortcut was released...
    if ((newModifiers & d->_modifierKeys) < d->_modifierKeys) {
        d->_modifierKeys = newModifiers;
        d->updateShortcutDisplay();
    }
}


/******************************************************************************/

KeySequenceWidget::KeySequenceWidget(QWidget *parent)
    : QWidget(parent),
    _shortcutsModel(nullptr),
    _isRecording(false),
    _modifierKeys(0)
{
    QHBoxLayout *layout = new QHBoxLayout(this);
    layout->setMargin(0);

    _keyButton = new KeySequenceButton(this, this);
    _keyButton->setFocusPolicy(Qt::StrongFocus);
    _keyButton->setToolTip(tr("Click on the button, then enter the shortcut like you would in the program.\nExample for Ctrl+a: hold the Ctrl key and press a."));
    layout->addWidget(_keyButton);

    _clearButton = new QToolButton(this);
    layout->addWidget(_clearButton);

    _clearButton->setIcon(style()->standardIcon(QStyle::SP_LineEditClearButton));

    setLayout(layout);

    connect(_keyButton, SIGNAL(clicked()), SLOT(startRecording()));
    connect(_keyButton, SIGNAL(clicked()), SIGNAL(clicked()));
    connect(_clearButton, SIGNAL(clicked()), SLOT(clear()));
    connect(_clearButton, SIGNAL(clicked()), SIGNAL(clicked()));
}


void KeySequenceWidget::setModel(ShortcutsModel *model)
{
    Q_ASSERT(!_shortcutsModel);
    _shortcutsModel = model;
}


bool KeySequenceWidget::isOkWhenModifierless(int keyQt) const
{
    //this whole function is a hack, but especially the first line of code
//    if (QKeySequence(keyQt).toString().length() == 1)
//        return false;

    switch (keyQt) {
    case Qt::Key_Return:
//    case Qt::Key_Space:
    case Qt::Key_Tab:
    case Qt::Key_Backtab: //does this ever happen?
    case Qt::Key_Backspace:
    case Qt::Key_Delete:
        return false;
    default:
        return true;
    }
}


bool KeySequenceWidget::isShiftAsModifierAllowed(int keyQt) const
{
    // Shift only works as a modifier with certain keys. It's not possible
    // to enter the SHIFT+5 key sequence for me because this is handled as
    // '%' by qt on my keyboard.
    // The working keys are all hardcoded here :-(
    if (keyQt >= Qt::Key_F1 && keyQt <= Qt::Key_F35)
        return true;

    if (QChar(keyQt).isLetter())
        return true;

    switch (keyQt) {
    case Qt::Key_Return:
    case Qt::Key_Space:
    case Qt::Key_Backspace:
    case Qt::Key_Escape:
    case Qt::Key_Print:
    case Qt::Key_ScrollLock:
    case Qt::Key_Pause:
    case Qt::Key_PageUp:
    case Qt::Key_PageDown:
    case Qt::Key_Insert:
    case Qt::Key_Delete:
    case Qt::Key_Home:
    case Qt::Key_End:
    case Qt::Key_Up:
    case Qt::Key_Down:
    case Qt::Key_Left:
    case Qt::Key_Right:
        return true;

    default:
        return false;
    }
}


void KeySequenceWidget::updateShortcutDisplay()
{
    QString s = _keySequence.toString(QKeySequence::NativeText);
    s.replace('&', QLatin1String("&&"));

    if (_isRecording) {
        if (_modifierKeys) {
#ifdef Q_OS_MAC
            if (_modifierKeys & Qt::META) s += QChar(kControlUnicode);
            if (_modifierKeys & Qt::ALT) s += QChar(kOptionUnicode);
            if (_modifierKeys & Qt::SHIFT) s += QChar(kShiftUnicode);
            if (_modifierKeys & Qt::CTRL) s += QChar(kCommandUnicode);
#else
            if (_modifierKeys & Qt::META) s += tr("Meta", "Meta key") + '+';
            if (_modifierKeys & Qt::CTRL) s += tr("Ctrl", "Ctrl key") + '+';
            if (_modifierKeys & Qt::ALT) s += tr("Alt", "Alt key") + '+';
            if (_modifierKeys & Qt::SHIFT) s += tr("Shift", "Shift key") + '+';
#endif
        }
        else {
            s = tr("Input", "What the user inputs now will be taken as the new shortcut");
        }
        // make it clear that input is still going on
        s.append(" ...");
    }

    if (s.isEmpty()) {
        s = tr("None", "No shortcut defined");
    }

    s.prepend(' ');
    s.append(' ');
    _keyButton->setText(s);
}


void KeySequenceWidget::startRecording()
{
    _modifierKeys = 0;
    _oldKeySequence = _keySequence;
    _keySequence = QKeySequence();
    _conflictingIndex = QModelIndex();
    _isRecording = true;
    _keyButton->grabKeyboard();

    if (!QWidget::keyboardGrabber()) {
        qWarning() << "Failed to grab the keyboard! Most likely qt's nograb option is active";
    }

    _keyButton->setDown(true);
    updateShortcutDisplay();
}


void KeySequenceWidget::doneRecording()
{
    bool wasRecording = _isRecording;
    _isRecording = false;
    _keyButton->releaseKeyboard();
    _keyButton->setDown(false);

    if (!wasRecording || _keySequence == _oldKeySequence) {
        // The sequence hasn't changed
        updateShortcutDisplay();
        return;
    }

    if (!isKeySequenceAvailable(_keySequence)) {
        _keySequence = _oldKeySequence;
    }
    else if (wasRecording) {
        emit keySequenceChanged(_keySequence, _conflictingIndex);
    }
    updateShortcutDisplay();
}


void KeySequenceWidget::cancelRecording()
{
    _keySequence = _oldKeySequence;
    doneRecording();
}


void KeySequenceWidget::setKeySequence(const QKeySequence &seq)
{
    // oldKeySequence holds the key sequence before recording started, if setKeySequence()
    // is called while not recording then set oldKeySequence to the existing sequence so
    // that the keySequenceChanged() signal is emitted if the new and previous key
    // sequences are different
    if (!isRecording())
        _oldKeySequence = _keySequence;

    _keySequence = seq;
    _clearButton->setVisible(!_keySequence.isEmpty());
    doneRecording();
}


void KeySequenceWidget::clear()
{
    setKeySequence(QKeySequence());
    // setKeySequence() won't emit a signal when we're not recording
    emit keySequenceChanged(QKeySequence());
}


bool KeySequenceWidget::isKeySequenceAvailable(const QKeySequence &seq)
{
    if (seq.isEmpty())
        return true;

    // We need to access the root model, not the filtered one
    for (int cat = 0; cat < _shortcutsModel->rowCount(); cat++) {
        QModelIndex catIdx = _shortcutsModel->index(cat, 0);
        for (int r = 0; r < _shortcutsModel->rowCount(catIdx); r++) {
            QModelIndex actIdx = _shortcutsModel->index(r, 0, catIdx);
            Q_ASSERT(actIdx.isValid());
            if (actIdx.data(ShortcutsModel::ActiveShortcutRole).value<QKeySequence>() != seq)
                continue;

            if (!actIdx.data(ShortcutsModel::IsConfigurableRole).toBool()) {
                QMessageBox::warning(this, tr("Shortcut Conflict"),
                    tr("The \"%1\" shortcut is already in use, and cannot be configured.\nPlease choose another one.").arg(seq.toString(QKeySequence::NativeText)),
                    QMessageBox::Ok);
                return false;
            }

            QMessageBox box(QMessageBox::Warning, tr("Shortcut Conflict"),
                (tr("The \"%1\" shortcut is ambiguous with the shortcut for the following action:")
                 + "<br><ul><li>%2</li></ul><br>"
                 + tr("Do you want to reassign this shortcut to the selected action?")
                ).arg(seq.toString(QKeySequence::NativeText), actIdx.data().toString()),
                QMessageBox::Cancel, this);
            box.addButton(tr("Reassign"), QMessageBox::AcceptRole);
            if (box.exec() == QMessageBox::Cancel)
                return false;

            _conflictingIndex = actIdx;
            return true;
        }
    }
    return true;
}

#include "moc_keysequencewidget.cpp"