source: trunk/src/gui/widgets/qcheckbox.cpp@ 215

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qcheckbox.h"
#include "qapplication.h"
#include "qbitmap.h"
#include "qicon.h"
#include "qstylepainter.h"
#include "qstyle.h"
#include "qstyleoption.h"
#include "qevent.h"

#include "private/qabstractbutton_p.h"

QT_BEGIN_NAMESPACE

class QCheckBoxPrivate : public QAbstractButtonPrivate
{
    Q_DECLARE_PUBLIC(QCheckBox)
public:
    QCheckBoxPrivate()
        : QAbstractButtonPrivate(QSizePolicy::CheckBox), tristate(false), noChange(false),
          hovering(true), publishedState(Qt::Unchecked) {}

    uint tristate : 1;
    uint noChange : 1;
    uint hovering : 1;
    uint publishedState : 2;

    void init();
};

/*!
    \class QCheckBox
    \brief The QCheckBox widget provides a checkbox with a text label.

    \ingroup basicwidgets
    \mainclass

    A QCheckBox is an option button that can be switched on (checked)
    or off (unchecked). Checkboxes are typically used to represent
    features in an application that can be enabled or disabled without
    affecting others, but different types of behavior can be
    implemented.

    A QButtonGroup can be used to group check buttons visually.

    Whenever a checkbox is checked or cleared it emits the signal
    stateChanged(). Connect to this signal if you want to trigger an
    action each time the checkbox changes state. You can use
    isChecked() to query whether or not a checkbox is checked.

    In addition to the usual checked and unchecked states, QCheckBox
    optionally provides a third state to indicate "no change". This
    is useful whenever you need to give the user the option of neither
    checking nor unchecking a checkbox. If you need this third state,
    enable it with setTristate(), and use checkState() to query the current
    toggle state.

    Just like QPushButton, a checkbox displays text, and optionally a
    small icon. The icon is set with setIcon(). The text can be set in
    the constructor or with setText(). A shortcut key can be specified
    by preceding the preferred character with an ampersand. For
    example:

    \snippet doc/src/snippets/code/src_gui_widgets_qcheckbox.cpp 0

    In this example the shortcut is \e{Alt+A}. See the \l
    {QShortcut#mnemonic}{QShortcut} documentation for details (to
    display an actual ampersand, use '&&').

    Important inherited functions: text(), setText(), text(),
    pixmap(), setPixmap(), accel(), setAccel(), isToggleButton(),
    setDown(), isDown(), isOn(), checkState(), autoRepeat(),
    isExclusiveToggle(), group(), setAutoRepeat(), toggle(),
    pressed(), released(), clicked(), toggled(), checkState(), and
    stateChanged().

    \table 100%
    \row \o \inlineimage macintosh-checkbox.png Screenshot of a Macintosh style checkbox
         \o A checkbox shown in the \l{Macintosh Style Widget Gallery}{Macintosh widget style}.
    \row \o \inlineimage windows-checkbox.png Screenshot of a Windows XP style checkbox
         \o A checkbox shown in the \l{Windows XP Style Widget Gallery}{Windows XP widget style}.
    \row \o \inlineimage plastique-checkbox.png Screenshot of a Plastique style checkbox
         \o A checkbox shown in the \l{Plastique Style Widget Gallery}{Plastique widget style}.
    \endtable

    \sa QAbstractButton, QRadioButton, {fowler}{GUI Design Handbook: Check Box}
*/

/*!
    \enum QCheckBox::ToggleState
    \compat

    \value Off  Use Qt::Unchecked instead.
    \value NoChange  Use Qt::PartiallyChecked instead.
    \value On  Use Qt::Checked instead.
*/

/*!
    \fn void QCheckBox::stateChanged(int state)

    This signal is emitted whenever the check box's state changes,
    i.e. whenever the user checks or unchecks it.

    \a state contains the check box's new Qt::CheckState.
*/

/*!
    \property QCheckBox::tristate
    \brief whether the checkbox is a tri-state checkbox

    The default is false; i.e. the checkbox has only two states.
*/

void QCheckBoxPrivate::init()
{
    Q_Q(QCheckBox);
    q->setCheckable(true);
    q->setMouseTracking(true);
    q->setForegroundRole(QPalette::WindowText);
    setLayoutItemMargins(QStyle::SE_CheckBoxLayoutItem);
}

/*!
    Initialize \a option with the values from this QCheckBox. This method is useful
    for subclasses when they need a QStyleOptionButton, but don't want to fill
    in all the information themselves.

    \sa QStyleOption::initFrom()
*/
void QCheckBox::initStyleOption(QStyleOptionButton *option) const
{
    if (!option)
        return;
    Q_D(const QCheckBox);
    option->initFrom(this);
    if (d->down)
        option->state |= QStyle::State_Sunken;
    if (d->tristate && d->noChange)
        option->state |= QStyle::State_NoChange;
    else
        option->state |= d->checked ? QStyle::State_On : QStyle::State_Off;
    if (testAttribute(Qt::WA_Hover) && underMouse()) {
        if (d->hovering)
            option->state |= QStyle::State_MouseOver;
        else
            option->state &= ~QStyle::State_MouseOver;
    }
    option->text = d->text;
    option->icon = d->icon;
    option->iconSize = iconSize();
}

/*!
    Constructs a checkbox with the given \a parent, but with no text.

    The \a parent argument is passed on to the QAbstractButton constructor.
*/

QCheckBox::QCheckBox(QWidget *parent)
    : QAbstractButton (*new QCheckBoxPrivate, parent)
{
    Q_D(QCheckBox);
    d->init();
}

/*!
    Constructs a checkbox with the given \a parent and \a text.

    The \a parent argument is passed on to the QAbstractButton constructor.
*/

QCheckBox::QCheckBox(const QString &text, QWidget *parent)
    : QAbstractButton (*new QCheckBoxPrivate, parent)
{
    Q_D(QCheckBox);
    d->init();
    setText(text);
}

void QCheckBox::setTristate(bool y)
{
    Q_D(QCheckBox);
    d->tristate = y;
}

bool QCheckBox::isTristate() const
{
    Q_D(const QCheckBox);
    return d->tristate;
}


/*!
    Returns the check box's check state.
    If you do not need tristate support, you can also
    use \l QAbstractButton::isChecked() which returns
    a boolean.

    \sa setCheckState() Qt::CheckState
*/
Qt::CheckState QCheckBox::checkState() const
{
    Q_D(const QCheckBox);
    if (d->tristate &&  d->noChange)
        return Qt::PartiallyChecked;
    return d->checked ? Qt::Checked : Qt::Unchecked;
}

/*!
    Sets the check box's check state to \a state.
    If you do not need tristate support, you can also
    use \l QAbstractButton::setChecked() which takes
    a boolean.

    \sa checkState() Qt::CheckState
*/
void QCheckBox::setCheckState(Qt::CheckState state)
{
    Q_D(QCheckBox);
    if (state == Qt::PartiallyChecked) {
        d->tristate = true;
        d->noChange = true;
    } else {
        d->noChange = false;
    }
    d->blockRefresh = true;
    setChecked(state != Qt::Unchecked);
    d->blockRefresh = false;
    d->refresh();
    if ((uint)state != d->publishedState) {
        d->publishedState = state;
        emit stateChanged(state);
    }
}


/*!\reimp
*/
QSize QCheckBox::sizeHint() const
{
    Q_D(const QCheckBox);
    if (d->sizeHint.isValid())
        return d->sizeHint;
    ensurePolished();
    QFontMetrics fm = fontMetrics();
    QStyleOptionButton opt;
    initStyleOption(&opt);
    QSize sz = style()->itemTextRect(fm, QRect(0, 0, 1, 1), Qt::TextShowMnemonic, false,
                                     text()).size();
    if (!opt.icon.isNull())
        sz = QSize(sz.width() + opt.iconSize.width() + 4, qMax(sz.height(), opt.iconSize.height()));
    d->sizeHint = (style()->sizeFromContents(QStyle::CT_CheckBox, &opt, sz, this)
                  .expandedTo(QApplication::globalStrut()));
    return d->sizeHint;
}

/*!\reimp
*/
void QCheckBox::paintEvent(QPaintEvent *)
{
    QStylePainter p(this);
    QStyleOptionButton opt;
    initStyleOption(&opt);
    p.drawControl(QStyle::CE_CheckBox, opt);
}

/*!
    \reimp
*/
void QCheckBox::mouseMoveEvent(QMouseEvent *e)
{
    Q_D(QCheckBox);
    if (testAttribute(Qt::WA_Hover)) {
        bool hit = false;
        if (underMouse())
            hit = hitButton(e->pos());

        if (hit != d->hovering) {
            update(rect());
            d->hovering = hit;
        }
    }

    QAbstractButton::mouseMoveEvent(e);
}


/*!\reimp*/
bool QCheckBox::hitButton(const QPoint &pos) const
{
    QStyleOptionButton opt;
    initStyleOption(&opt);
    return style()->subElementRect(QStyle::SE_CheckBoxClickRect, &opt, this).contains(pos);
}

/*!\reimp*/
void QCheckBox::checkStateSet()
{
    Q_D(QCheckBox);
    d->noChange = false;
    Qt::CheckState state = checkState();
    if ((uint)state != d->publishedState) {
        d->publishedState = state;
        emit stateChanged(state);
    }
}

/*!\reimp*/
void QCheckBox::nextCheckState()
{
    Q_D(QCheckBox);
    if (d->tristate)
        setCheckState((Qt::CheckState)((checkState() + 1) % 3));
    else {
        QAbstractButton::nextCheckState();
        QCheckBox::checkStateSet();
    }
}

/*!
    \reimp
*/
bool QCheckBox::event(QEvent *e)
{
    Q_D(QCheckBox);
    if (e->type() == QEvent::StyleChange
#ifdef Q_WS_MAC
            || e->type() == QEvent::MacSizeChange
#endif
            )
        d->setLayoutItemMargins(QStyle::SE_CheckBoxLayoutItem);
    return QAbstractButton::event(e);
}

#ifdef QT3_SUPPORT
/*!
    Use one of the constructors that doesn't take the \a name
    argument and then use setObjectName() instead.
*/
QCheckBox::QCheckBox(QWidget *parent, const char* name)
    : QAbstractButton (*new QCheckBoxPrivate, parent)
{
    Q_D(QCheckBox);
    setObjectName(QString::fromAscii(name));
    d->init();
}

/*!
    Use one of the constructors that doesn't take the \a name
    argument and then use setObjectName() instead.
*/
QCheckBox::QCheckBox(const QString &text, QWidget *parent, const char* name)
    : QAbstractButton (*new QCheckBoxPrivate, parent)
{
    Q_D(QCheckBox);
    setObjectName(QString::fromAscii(name));
    d->init();
    setText(text);
}

#endif


/*!
    \fn void QCheckBox::setNoChange()
    \compat

    Use setCheckState() instead.
*/

/*!
    \fn void QCheckBox::setState(ToggleState state)
    \compat

    Use setCheckState() instead.
*/

/*!
    \fn QCheckBox::ToggleState QCheckBox::state() const
    \compat

    Use checkState() instead.
*/

QT_END_NAMESPACE