path: root/src/corelib/kernel/qcoreevent.cpp

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** 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 "qcoreevent.h"
#include "qcoreapplication.h"
#include "qcoreapplication_p.h"

#include "qmutex.h"
#include "qset.h"

QT_BEGIN_NAMESPACE

/*!
    \class QEvent
    \brief The QEvent class is the base class of all
    event classes. Event objects contain event parameters.

    \ingroup events
    \ingroup environment

    Qt's main event loop (QCoreApplication::exec()) fetches native
    window system events from the event queue, translates them into
    QEvents, and sends the translated events to \l{QObject}s.

    In general, events come from the underlying window system
    (spontaneous() returns true), but it is also possible to manually
    send events using QCoreApplication::sendEvent() and
    QCoreApplication::postEvent() (spontaneous() returns false).

    QObjects receive events by having their QObject::event() function
    called. The function can be reimplemented in subclasses to
    customize event handling and add additional event types;
    QWidget::event() is a notable example. By default, events are
    dispatched to event handlers like QObject::timerEvent() and
    QWidget::mouseMoveEvent(). QObject::installEventFilter() allows an
    object to intercept events destined for another object.

    The basic QEvent contains only an event type parameter and an
    "accept" flag.  The accept flag set with accept(), and cleared
    with ignore(). It is set by default, but don't rely on this as
    subclasses may choose to clear it in their constructor.

    Subclasses of QEvent contain additional parameters that describe
    the particular event.

    \sa QObject::event(), QObject::installEventFilter(),
        QWidget::event(), QCoreApplication::sendEvent(),
        QCoreApplication::postEvent(), QCoreApplication::processEvents()
*/


/*!
    \enum QEvent::Type

    This enum type defines the valid event types in Qt. The event
    types and the specialized classes for each type are as follows:

    \value None                             Not an event.
    \value AccessibilityDescription         Used to query accessibility description texts (QAccessibleEvent).
    \value AccessibilityHelp                Used to query accessibility help texts (QAccessibleEvent).
    \value AccessibilityPrepare             Accessibility information is requested.
    \value ActionAdded                      A new action has been added (QActionEvent).
    \value ActionChanged                    An action has been changed (QActionEvent).
    \value ActionRemoved                    An action has been removed (QActionEvent).
    \value ActivationChange                 A widget's top-level window activation state has changed.
    \value ApplicationActivate              The application has been made available to the user.
    \value ApplicationActivated             This enum has been deprecated. Use ApplicationActivate instead.
    \value ApplicationDeactivate            The application has been suspended, and is unavailable to the user.
    \value ApplicationFontChange            The default application font has changed.
    \value ApplicationLayoutDirectionChange The default application layout direction has changed.
    \value ApplicationPaletteChange         The default application palette has changed.
    \value ApplicationWindowIconChange      The application's icon has changed.
    \value ChildAdded                       An object gets a child (QChildEvent).
    \value ChildInserted                    An object gets a child (QChildEvent). Qt3Support only, use ChildAdded instead.
    \value ChildPolished                    A widget child gets polished (QChildEvent).
    \value ChildRemoved                     An object loses a child (QChildEvent).
    \value Clipboard                        The clipboard contents have changed (QClipboardEvent).
    \value Close                            Widget was closed (QCloseEvent).
    \value ContentsRectChange               The margins of the widget's content rect changed.
    \value ContextMenu                      Context popup menu (QContextMenuEvent).
    \value CursorChange                     The widget's cursor has changed.
    \value DeferredDelete                   The object will be deleted after it has cleaned up.
    \value DragEnter                        The cursor enters a widget during a drag and drop operation (QDragEnterEvent).
    \value DragLeave                        The cursor leaves a widget during a drag and drop operation (QDragLeaveEvent).
    \value DragMove                         A drag and drop operation is in progress (QDragMoveEvent).
    \value Drop                             A drag and drop operation is completed (QDropEvent).
    \value EnabledChange                    Widget's enabled state has changed.
    \value Enter                            Mouse enters widget's boundaries.
    \value EnterEditFocus                   An editor widget gains focus for editing.
    \value EnterWhatsThisMode               Send to toplevel widgets when the application enters "What's This?" mode.
    \value FileOpen                         File open request (QFileOpenEvent).
    \value FocusIn                          Widget gains keyboard focus (QFocusEvent).
    \value FocusOut                         Widget loses keyboard focus (QFocusEvent).
    \value FontChange                       Widget's font has changed.
    \value GrabKeyboard                     Item gains keyboard grab (QGraphicsItem only).
    \value GrabMouse                        Item gains mouse grab (QGraphicsItem only).
    \value GraphicsSceneContextMenu         Context popup menu over a graphics scene (QGraphicsSceneContextMenuEvent).
    \value GraphicsSceneDragEnter           The cursor enters a graphics scene during a drag and drop operation.
    \value GraphicsSceneDragLeave           The cursor leaves a graphics scene during a drag and drop operation.
    \value GraphicsSceneDragMove            A drag and drop operation is in progress over a scene.
    \value GraphicsSceneDrop                A drag and drop operation is completed over a scene.
    \value GraphicsSceneHelp                The user requests help for a graphics scene (QHelpEvent).
    \value GraphicsSceneHoverEnter          The mouse cursor enters a hover item in a graphics scene (QGraphicsSceneHoverEvent).
    \value GraphicsSceneHoverLeave          The mouse cursor leaves a hover item in a graphics scene (QGraphicsSceneHoverEvent).
    \value GraphicsSceneHoverMove           The mouse cursor moves inside a hover item in a graphics scene (QGraphicsSceneHoverEvent).
    \value GraphicsSceneMouseDoubleClick    Mouse press again (double click) in a graphics scene (QGraphicsSceneMouseEvent).
    \value GraphicsSceneMouseMove           Move mouse in a graphics scene (QGraphicsSceneMouseEvent).
    \value GraphicsSceneMousePress          Mouse press in a graphics scene (QGraphicsSceneMouseEvent).
    \value GraphicsSceneMouseRelease        Mouse release in a graphics scene (QGraphicsSceneMouseEvent).
    \value GraphicsSceneMove          Widget was moved (QGraphicsSceneMoveEvent).
    \value GraphicsSceneResize          Widget was resized (QGraphicsSceneResizeEvent).
    \value GraphicsSceneWheel               Mouse wheel rolled in a graphics scene (QGraphicsSceneWheelEvent).
    \value Hide                             Widget was hidden (QHideEvent).
    \value HideToParent                     A child widget has been hidden.
    \value HoverEnter                       The mouse cursor enters a hover widget (QHoverEvent).
    \value HoverLeave                       The mouse cursor leaves a hover widget (QHoverEvent).
    \value HoverMove                        The mouse cursor moves inside a hover widget (QHoverEvent).
    \value IconDrag                         The main icon of a window has been dragged away (QIconDragEvent).
    \value IconTextChange                   Widget's icon text has been changed.
    \value InputMethod                      An input method is being used (QInputMethodEvent).
    \value KeyPress                         Key press (QKeyEvent).
    \value KeyRelease                       Key release (QKeyEvent).
    \value LanguageChange                   The application translation changed.
    \value LayoutDirectionChange            The direction of layouts changed.
    \value LayoutRequest                    Widget layout needs to be redone.
    \value Leave                            Mouse leaves widget's boundaries.
    \value LeaveEditFocus                   An editor widget loses focus for editing.
    \value LeaveWhatsThisMode               Send to toplevel widgets when the application leaves "What's This?" mode.
    \value LocaleChange                     The system locale has changed.
    \value NonClientAreaMouseButtonDblClick A mouse double click occurred outside the client area.
    \value NonClientAreaMouseButtonPress    A mouse button press occurred outside the client area.
    \value NonClientAreaMouseButtonRelease  A mouse button release occurred outside the client area.
    \value NonClientAreaMouseMove           A mouse move occurred outside the client area.
    \value MacSizeChange                    The user changed his widget sizes (Mac OS X only).
    \value MenubarUpdated                   The window's menu bar has been updated.
    \value MetaCall                         An asynchronous method invocation via QMetaObject::invokeMethod().
    \value ModifiedChange                   Widgets modification state has been changed.
    \value MouseButtonDblClick              Mouse press again (QMouseEvent).
    \value MouseButtonPress                 Mouse press (QMouseEvent).
    \value MouseButtonRelease               Mouse release (QMouseEvent).
    \value MouseMove                        Mouse move (QMouseEvent).
    \value MouseTrackingChange              The mouse tracking state has changed.
    \value Move                             Widget's position changed (QMoveEvent).
    \value Paint                            Screen update necessary (QPaintEvent).
    \value PaletteChange                    Palette of the widget changed.
    \value ParentAboutToChange              The widget parent is about to change.
    \value ParentChange                     The widget parent has changed.
    \value Polish                           The widget is polished.
    \value PolishRequest                    The widget should be polished.
    \value QueryWhatsThis                   The widget should accept the event if it has "What's This?" help.
    \value Resize                           Widget's size changed (QResizeEvent).
    \value Shortcut                         Key press in child for shortcut key handling (QShortcutEvent).
    \value ShortcutOverride                 Key press in child, for overriding shortcut key handling (QKeyEvent).
    \value Show                             Widget was shown on screen (QShowEvent).
    \value ShowToParent                     A child widget has been shown.
    \value SockAct                          Socket activated, used to implement QSocketNotifier.
    \value StatusTip                        A status tip is requested (QStatusTipEvent).
    \value StyleChange                      Widget's style has been changed.
    \value TabletMove                       Wacom tablet move (QTabletEvent).
    \value TabletPress                      Wacom tablet press (QTabletEvent).
    \value TabletRelease                    Wacom tablet release (QTabletEvent).
    \value OkRequest                        Ok button in decoration pressed. Supported only for Windows CE.
    \value TabletEnterProximity             Wacom tablet enter proximity event (QTabletEvent), sent to QApplication.
    \value TabletLeaveProximity             Wacom tablet leave proximity event (QTabletEvent), sent to QApplication.
    \value Timer                            Regular timer events (QTimerEvent).
    \value ToolBarChange                    The toolbar button is toggled on Mac OS X.
    \value ToolTip                          A tooltip was requested (QHelpEvent).
    \value ToolTipChange                    The widget's tooltip has changed.
    \value UngrabKeyboard                   Item loses keyboard grab (QGraphicsItem only).
    \value UngrabMouse                      Item loses mouse grab (QGraphicsItem only).
    \value UpdateLater                      The widget should be queued to be repainted at a later time.
    \value UpdateRequest                    The widget should be repainted.
    \value WhatsThis                        The widget should reveal "What's This?" help (QHelpEvent).
    \value WhatsThisClicked                 A link in a widget's "What's This?" help was clicked.
    \value Wheel                            Mouse wheel rolled (QWheelEvent).
    \value WinEventAct                      A Windows-specific activation event has occurred.
    \value WindowActivate                   Window was activated.
    \value WindowBlocked                    The window is blocked by a modal dialog.
    \value WindowDeactivate                 Window was deactivated.
    \value WindowIconChange                 The window's icon has changed.
    \value WindowStateChange                The \l{QWidget::windowState()}{window's state} (minimized, maximized or full-screen) has changed (QWindowStateChangeEvent).
    \value WindowTitleChange                The window title has changed.
    \value WindowUnblocked                  The window is unblocked after a modal dialog exited.
    \value ZOrderChange                     The widget's z-order has changed. This event is never sent to top level windows.
    \value KeyboardLayoutChange             The keyboard layout has changed.
    \value DynamicPropertyChange            A dynamic property was added, changed or removed from the object.

    User events should have values between \c User and \c{MaxUser}:

    \value User                             User-defined event.
    \value MaxUser                          Last user event ID.

    For convenience, you can use the registerEventType() function to
    register and reserve a custom event type for your
    application. Doing so will allow you to avoid accidentally
    re-using a custom event type already in use elsewhere in your
    application.

    \omitvalue Accel
    \omitvalue AccelAvailable
    \omitvalue AccelOverride
    \omitvalue AcceptDropsChange
    \omitvalue ActivateControl
    \omitvalue CaptionChange
    \omitvalue ChildInsertedRequest
    \omitvalue ChildInserted
    \omitvalue Create
    \omitvalue DeactivateControl
    \omitvalue Destroy
    \omitvalue DragResponse
    \omitvalue EmbeddingControl
    \omitvalue HelpRequest
    \omitvalue IconChange
    \omitvalue LayoutHint
    \omitvalue Quit
    \omitvalue Reparent
    \omitvalue ShowWindowRequest
    \omitvalue Speech
    \omitvalue Style
    \omitvalue ThreadChange
    \omitvalue ZeroTimerEvent
    \omitvalue ApplicationActivated
    \omitvalue ApplicationDeactivated
    \omitvalue MacGLWindowChange
    \omitvalue NetworkReplyUpdated
    \omitvalue FutureCallOut
    \omitvalue CocoaRequestModal
    \omitvalue Wrapped
    \omitvalue Signal
*/

/*!
    Contructs an event object of type \a type.
*/
QEvent::QEvent(Type type)
    : d(0), t(type), posted(false), spont(false), m_accept(true)
{}

/*!
    Destroys the event. If it was \link
    QCoreApplication::postEvent() posted \endlink,
    it will be removed from the list of events to be posted.
*/

QEvent::~QEvent()
{
    if (posted && QCoreApplication::instance())
        QCoreApplicationPrivate::removePostedEvent(this);
}


/*!
    \property  QEvent::accepted
    the accept flag of the event object

    Setting the accept parameter indicates that the event receiver
    wants the event. Unwanted events might be propagated to the parent
    widget. By default, isAccepted() is set to true, but don't rely on
    this as subclasses may choose to clear it in their constructor.

    For convenience, the accept flag can also be set with accept(),
    and cleared with ignore().
*/

/*!
    \fn void QEvent::accept()

    Sets the accept flag of the event object, the equivalent of
    calling setAccepted(true).

    Setting the accept parameter indicates that the event receiver
    wants the event. Unwanted events might be propagated to the parent
    widget.

    \sa ignore()
*/


/*!
    \fn void QEvent::ignore()

    Clears the accept flag parameter of the event object, the
    equivalent of calling setAccepted(false).

    Clearing the accept parameter indicates that the event receiver
    does not want the event. Unwanted events might be propgated to the
    parent widget.

    \sa accept()
*/


/*!
    \fn QEvent::Type QEvent::type() const

    Returns the event type.
*/

/*!
    \fn bool QEvent::spontaneous() const

    Returns true if the event originated outside the application (a
    system event); otherwise returns false.

    The return value of this function is not defined for paint events.
*/

class QEventUserEventRegistration
{
public:
    QMutex mutex;
    QSet<int> set;
};
Q_GLOBAL_STATIC(QEventUserEventRegistration, userEventRegistrationHelper)

/*!
    \since 4.4
    \threadsafe

    Registers and returns a custom event type. The \a hint provided
    will be used if it is available, otherwise it will return a value
    between QEvent::User and QEvent::MaxUser that has not yet been
    registered. The \a hint is ignored if its value is not between
    QEvent::User and QEvent::MaxUser.
*/
int QEvent::registerEventType(int hint)
{
    QEventUserEventRegistration *userEventRegistration
        = userEventRegistrationHelper();
    if (!userEventRegistration)
        return -1;

    QMutexLocker locker(&userEventRegistration->mutex);

    // if the type hint hasn't been registered yet, take it
    if (hint >= QEvent::User && hint <= QEvent::MaxUser && !userEventRegistration->set.contains(hint)) {
        userEventRegistration->set.insert(hint);
        return hint;
    }

    // find a free event type, starting at MaxUser and decreasing
    int id = QEvent::MaxUser;
    while (userEventRegistration->set.contains(id) && id >= QEvent::User)
        --id;
    if (id >= QEvent::User) {
        userEventRegistration->set.insert(id);
        return id;
    }
    return -1;
}

/*!
    \class QTimerEvent
    \brief The QTimerEvent class contains parameters that describe a
    timer event.

    \ingroup events

    Timer events are sent at regular intervals to objects that have
    started one or more timers. Each timer has a unique identifier. A
    timer is started with QObject::startTimer().

    The QTimer class provides a high-level programming interface that
    uses signals instead of events. It also provides single-shot timers.

    The event handler QObject::timerEvent() receives timer events.

    \sa QTimer, QObject::timerEvent(), QObject::startTimer(),
    QObject::killTimer()
*/

/*!
    Constructs a timer event object with the timer identifier set to
    \a timerId.
*/
QTimerEvent::QTimerEvent(int timerId)
    : QEvent(Timer), id(timerId)
{}

/*! \internal
*/
QTimerEvent::~QTimerEvent()
{
}

/*!
    \fn int QTimerEvent::timerId() const

    Returns the unique timer identifier, which is the same identifier
    as returned from QObject::startTimer().
*/

/*!
    \class QChildEvent
    \brief The QChildEvent class contains event parameters for child object
    events.

    \ingroup events

    Child events are sent immediately to objects when children are
    added or removed.

    In both cases you can only rely on the child being a QObject (or,
    if QObject::isWidgetType() returns true, a QWidget). This is
    because in the QEvent::ChildAdded case the child is not yet fully
    constructed; in the QEvent::ChildRemoved case it might have
    already been destructed.

    The handler for these events is QObject::childEvent().
*/

/*!
    Constructs a child event object of a particular \a type for the
    \a child.

    \a type can be QEvent::ChildAdded, QEvent::ChildRemoved,
    QEvent::ChildPolished, or QEvent::ChildRemoved.

    \sa child()
*/
QChildEvent::QChildEvent(Type type, QObject *child)
    : QEvent(type), c(child)
{}

/*! \internal
*/
QChildEvent::~QChildEvent()
{
}

/*!
    \fn QObject *QChildEvent::child() const

    Returns the child object that was added or removed.
*/

/*!
    \fn bool QChildEvent::added() const

    Returns true if type() is QEvent::ChildAdded; otherwise returns
    false.
*/

/*!
    \fn bool QChildEvent::removed() const

    Returns true if type() is QEvent::ChildRemoved; otherwise returns
    false.
*/

/*!
    \fn bool QChildEvent::polished() const

    Returns true if type() is QEvent::ChildPolished; otherwise returns
    false.
*/

/*!
    \class QCustomEvent
    \brief The QCustomEvent class provides support for custom events.

    \compat

    QCustomEvent has a \c{void *} that can be used to store custom
    data.

    In Qt 3, QObject::customEvent() took a QCustomEvent pointer. We
    found out that this approach was unsatisfactory, because
    there was often no safe way of deleting the data held in the
    \c{void *}.

    In Qt 4, QObject::customEvent() takes a plain QEvent pointer.
    You can add custom data by subclassing.

    \sa QObject::customEvent(), QCoreApplication::notify()
*/

/*!
    \fn QCustomEvent::QCustomEvent(int type, void *data)

    Constructs a custom event object with the event \a type and a
    pointer to \a data. The value of \a type must be at least as
    large as QEvent::User. By default, the data pointer is set to 0.
*/
#ifdef QT3_SUPPORT
QCustomEvent::QCustomEvent(int type, void *data)
    : QEvent(static_cast<Type>(type))
{
    d = reinterpret_cast<QEventPrivate *>(data);
}

/*! \internal
*/
QCustomEvent::~QCustomEvent()
{
}
#endif
/*!
    \fn void QCustomEvent::setData(void *data)

    \compat

    Sets the generic data pointer to \a data.

    \sa data()
*/

/*!
    \fn void *QCustomEvent::data() const

    \compat

    Returns a pointer to the generic event data.

    \sa setData()
*/

/*!
    \fn bool QChildEvent::inserted() const

    \compat

    A child has been inserted if the event's type() is ChildInserted.
*/

/*!
    \class QDynamicPropertyChangeEvent
    \since 4.2
    \brief The QDynamicPropertyChangeEvent class contains event parameters for dynamic
    property change events.

    \ingroup events

    Dynamic property change events are sent to objects when properties are
    dynamically added, changed or removed using QObject::setProperty().
*/

/*!
    Constructs a dynamic property change event object with the property name set to
    \a name.
*/
QDynamicPropertyChangeEvent::QDynamicPropertyChangeEvent(const QByteArray &name)
    : QEvent(QEvent::DynamicPropertyChange), n(name)
{
}

/*!
    \internal
*/
QDynamicPropertyChangeEvent::~QDynamicPropertyChangeEvent()
{
}

/*!
    \fn QByteArray QDynamicPropertyChangeEvent::propertyName() const

    Returns the name of the dynamic property that was added, changed or
    removed.

    \sa QObject::setProperty(), QObject::dynamicPropertyNames()
*/

QT_END_NAMESPACE