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qcheckbox.cpp

/****************************************************************************
**
** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 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 GNU
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** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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****************************************************************************/

#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"

class QCheckBoxPrivate : public QAbstractButtonPrivate
{
    Q_DECLARE_PUBLIC(QCheckBox)
public:
    QCheckBoxPrivate():tristate(false), noChange(false), hovering(true), publishedState(Qt::Unchecked){}
    uint tristate : 1;
    uint noChange : 1;
    uint hovering : 1;
    uint publishedState : 2;
    void init();
    QStyleOptionButton getStyleOption() const;
};

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

    \ingroup basic
    \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:

    \code
        QCheckBox *checkbox = new QCheckBox("C&ase sensitive", this);
    \endcode

    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 ToggleState.
*/

/*!
    \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);
}

QStyleOptionButton QCheckBoxPrivate::getStyleOption() const
{
    Q_Q(const QCheckBox);
    QStyleOptionButton opt;
    opt.init(q);
    if (down)
        opt.state |= QStyle::State_Sunken;
    if (tristate && noChange)
        opt.state |= QStyle::State_NoChange;
    else
        opt.state |= checked ? QStyle::State_On : QStyle::State_Off;
    if (q->testAttribute(Qt::WA_Hover) &&  q->underMouse()) {
        if (hovering)
            opt.state |= QStyle::State_MouseOver;
        else
            opt.state &= ~QStyle::State_MouseOver;
    }
    opt.text = text;
    opt.icon = icon;
    opt.iconSize = q->iconSize();
    return opt;
}

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

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

00171 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.
*/

00184 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.

    \sa setCheckState() Qt::CheckState
*/
00210 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.

    \sa checkState() Qt::CheckState
*/
00223 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
*/
00245 QSize QCheckBox::sizeHint() const
{
    Q_D(const QCheckBox);
    ensurePolished();
    QFontMetrics fm = fontMetrics();
    QStyleOptionButton opt = d->getStyleOption();
    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()));
    return (style()->sizeFromContents(QStyle::CT_CheckBox, &opt, sz, this)
            .expandedTo(QApplication::globalStrut()));
}

/*!\reimp
*/
00261 void QCheckBox::paintEvent(QPaintEvent *)
{
    Q_D(QCheckBox);
    QStylePainter p(this);
    QStyleOptionButton opt = d->getStyleOption();
    p.drawControl(QStyle::CE_CheckBox, opt);
}

/*!
    \reimp
*/
00272 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*/
00291 bool QCheckBox::hitButton(const QPoint &pos) const
{
    Q_D(const QCheckBox);
    QStyleOptionButton opt = d->getStyleOption();
    return style()->subElementRect(QStyle::SE_CheckBoxClickRect, &opt, this).contains(pos);
}

/*!\reimp*/
00299 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*/
00311 void QCheckBox::nextCheckState()
{
    Q_D(QCheckBox);
    if (d->tristate)
        setCheckState((Qt::CheckState)((checkState() + 1) % 3));
    else {
        QAbstractButton::nextCheckState();
        QCheckBox::checkStateSet();
    }
}

/*!
    \reimp
*/
00325 bool QCheckBox::event(QEvent *e)
{
    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.
*/

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