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QEvent Class Reference
[модуль QtCore ]

The QEvent class is the base class of all event classes. Event objects contain event parameters. More...

 #include <QEvent>

Inherited by QAccessibleEvent, QActionEvent, QChildEvent, QCloseEvent, QCustomEvent, QDragLeaveEvent, QDropEvent, QDynamicPropertyChangeEvent, QFileOpenEvent, QFocusEvent, QGraphicsSceneEvent, QHelpEvent, QHideEvent, QHoverEvent, QIconDragEvent, QInputEvent, QInputMethodEvent, QMoveEvent, QPaintEvent, QResizeEvent, QShortcutEvent, QShowEvent, QStatusTipEvent, QTimerEvent, QWhatsThisClickedEvent, and QWindowStateChangeEvent.

Открытые типы

  • enum Type { None, AccessibilityDescription, AccessibilityHelp, AccessibilityPrepare, ..., MaxUser }

Свойства

Открытые функции


Подробное описание

The QEvent class is the base class of all event classes. Event objects contain event parameters.

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 QObjects.

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.

See also QObject::event(), QObject::installEventFilter(), QWidget::event(), QCoreApplication::sendEvent(), QCoreApplication::postEvent(), and QCoreApplication::processEvents().


Описание типов членов

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:


Constant Value Description
QEvent::None 0 Not an event.
QEvent::AccessibilityDescription 130 Used to query accessibility description texts ( QAccessibleEvent).
QEvent::AccessibilityHelp 119 Used to query accessibility help texts ( QAccessibleEvent).
QEvent::AccessibilityPrepare 86 Accessibility information is requested.
QEvent::ActionAdded 114 A new action has been added ( QActionEvent).
QEvent::ActionChanged 113 An action has been changed ( QActionEvent).
QEvent::ActionRemoved 115 An action has been removed ( QActionEvent).
QEvent::ActivationChange 99 A widget's top-level window activation state has changed.
QEvent::ApplicationActivate 121 The application has been made available to the user.
QEvent::ApplicationDeactivate 122 The application has been suspended, and is unavailable to the user.
QEvent::ApplicationFontChange 36 The default application font has changed.
QEvent::ApplicationLayoutDirectionChange 37 The default application layout direction has changed.
QEvent::ApplicationPaletteChange 38 The default application palette has changed.
QEvent::ApplicationWindowIconChange 35 The application's icon has changed.
QEvent::ChildAdded 68 An object gets a child ( QChildEvent).
QEvent::ChildPolished 69 A widget child gets polished ( QChildEvent).
QEvent::ChildRemoved 71 An object loses a child ( QChildEvent).
QEvent::Clipboard 40 The clipboard contents have changed (QClipboardEvent).
QEvent::Close 19 Widget was closed ( QCloseEvent).
QEvent::ContentsRectChange 178 The margins of the widget's content rect changed.
QEvent::ContextMenu 82 Context popup menu ( QContextMenuEvent).
QEvent::DeferredDelete 52 The object will be deleted after it has cleaned up.
QEvent::DragEnter 60 The cursor enters a widget during a drag and drop operation ( QDragEnterEvent).
QEvent::DragLeave 62 The cursor leaves a widget during a drag and drop operation ( QDragLeaveEvent).
QEvent::DragMove 61 A drag and drop operation is in progress ( QDragMoveEvent).
QEvent::Drop 63 A drag and drop operation is completed ( QDropEvent).
QEvent::EnabledChange 98 Widget's enabled state has changed.
QEvent::Enter 10 Mouse enters widget's boundaries.
QEvent::EnterEditFocus 150 An editor widget gains focus for editing.
QEvent::EnterWhatsThisMode 124 Send to toplevel widgets when the application enters "What's This?" mode.
QEvent::FileOpen 116 File open request ( QFileOpenEvent).
QEvent::FocusIn 8 Widget gains keyboard focus ( QFocusEvent).
QEvent::FocusOut 9 Widget loses keyboard focus ( QFocusEvent).
QEvent::FontChange 97 Widget's font has changed.
QEvent::GraphicsSceneContextMenu 159 Context popup menu over a graphics scene ( QGraphicsSceneContextMenuEvent).
QEvent::GraphicsSceneDragEnter 164 The cursor enters a graphics scene during a drag and drop operation.
QEvent::GraphicsSceneDragLeave 166 The cursor leaves a graphics scene during a drag and drop operation.
QEvent::GraphicsSceneDragMove 165 A drag and drop operation is in progress over a scene.
QEvent::GraphicsSceneDrop 167 A drag and drop operation is completed over a scene.
QEvent::GraphicsSceneHelp 163 The user requests help for a graphics scene ( QHelpEvent).
QEvent::GraphicsSceneHoverEnter 160 The mouse cursor enters a hover item in a graphics scene ( QGraphicsSceneHoverEvent).
QEvent::GraphicsSceneHoverLeave 162 The mouse cursor leaves a hover item in a graphics scene ( QGraphicsSceneHoverEvent).
QEvent::GraphicsSceneHoverMove 161 The mouse cursor moves inside a hover item in a graphics scene ( QGraphicsSceneHoverEvent).
QEvent::GraphicsSceneMouseDoubleClick 158 Mouse press again (double click) in a graphics scene ( QGraphicsSceneMouseEvent).
QEvent::GraphicsSceneMouseMove 155 Move mouse in a graphics scene ( QGraphicsSceneMouseEvent).
QEvent::GraphicsSceneMousePress 156 Mouse press in a graphics scene ( QGraphicsSceneMouseEvent).
QEvent::GraphicsSceneMouseRelease 157 Mouse release in a graphics scene ( QGraphicsSceneMouseEvent).
QEvent::GraphicsSceneWheel 168 Mouse wheel rolled in a graphics scene ( QGraphicsSceneWheelEvent).
QEvent::Hide 18 Widget was hidden ( QHideEvent).
QEvent::HideToParent 27 A child widget has been hidden.
QEvent::HoverEnter 127 The mouse cursor enters a hover widget ( QHoverEvent).
QEvent::HoverLeave 128 The mouse cursor leaves a hover widget ( QHoverEvent).
QEvent::HoverMove 129 The mouse cursor moves inside a hover widget ( QHoverEvent).
QEvent::IconDrag 96 The main icon of a window has been dragged away ( QIconDragEvent).
QEvent::IconTextChange 101 Widget's icon text has been changed.
QEvent::InputMethod 83 An input method is being used ( QInputMethodEvent).
QEvent::KeyPress 6 Key press ( QKeyEvent).
QEvent::KeyRelease 7 Key release ( QKeyEvent).
QEvent::LanguageChange 89 The application translation changed.
QEvent::LayoutDirectionChange 90 The direction of layouts changed.
QEvent::LayoutRequest 76 Widget layout needs to be redone.
QEvent::Leave 11 Mouse leaves widget's boundaries.
QEvent::LeaveEditFocus 151 An editor widget loses focus for editing.
QEvent::LeaveWhatsThisMode 125 Send to toplevel widgets when the application leaves "What's This?" mode.
QEvent::LocaleChange 88 The system locale has changed.
QEvent::NonClientAreaMouseButtonDblClick 176 A mouse double click occurred outside the client area.
QEvent::NonClientAreaMouseButtonPress 174 A mouse button press occurred outside the client area.
QEvent::NonClientAreaMouseButtonRelease 175 A mouse button release occurred outside the client area.
QEvent::NonClientAreaMouseMove 173 A mouse move occurred outside the client area.
QEvent::MacSizeChange 177 The user changed his widget sizes (Mac OS X only).
QEvent::MenubarUpdated 153 The window's menu bar has been updated.
QEvent::MetaCall 43 An asynchronous method invocation via QMetaObject::invokeMethod().
QEvent::ModifiedChange 102 Widgets modification state has been changed.
QEvent::MouseButtonDblClick 4 Mouse press again ( QMouseEvent).
QEvent::MouseButtonPress 2 Mouse press ( QMouseEvent).
QEvent::MouseButtonRelease 3 Mouse release ( QMouseEvent).
QEvent::MouseMove 5 Mouse move ( QMouseEvent).
QEvent::MouseTrackingChange 109 The mouse tracking state has changed.
QEvent::Move 13 Widget's position changed ( QMoveEvent).
QEvent::Paint 12 Screen update necessary ( QPaintEvent).
QEvent::PaletteChange 39 Palette of the widget changed.
QEvent::ParentAboutToChange 131 The widget parent is about to change.
QEvent::ParentChange 21 The widget parent has changed.
QEvent::Polish 75 The widget is polished.
QEvent::PolishRequest 74 The widget should be polished.
QEvent::QueryWhatsThis 123 The widget should accept the event if it has "What's This?" help.
QEvent::Resize 14 Widget's size changed ( QResizeEvent).
QEvent::Shortcut 117 Key press in child for shortcut key handling ( QShortcutEvent).
QEvent::ShortcutOverride 51 Key press in child, for overriding shortcut key handling ( QKeyEvent).
QEvent::Show 17 Widget was shown on screen ( QShowEvent).
QEvent::ShowToParent 26 A child widget has been shown.
QEvent::SockAct 50 Socket activated, used to implement QSocketNotifier.
QEvent::StatusTip 112 A status tip is requested ( QStatusTipEvent).
QEvent::StyleChange 100 Widget's style has been changed.
QEvent::TabletMove 87 Wacom tablet move ( QTabletEvent).
QEvent::TabletPress 92 Wacom tablet press ( QTabletEvent).
QEvent::TabletRelease 93 Wacom tablet release ( QTabletEvent).
QEvent::TabletEnterProximity 171 Wacom tablet enter proximity event ( QTabletEvent), sent to QApplication.
QEvent::TabletLeaveProximity 172 Wacom tablet leave proximity event ( QTabletEvent), sent to QApplication.
QEvent::Timer 1 Regular timer events ( QTimerEvent).
QEvent::ToolBarChange 120 The toolbar button is toggled on Mac OS X.
QEvent::ToolTip 110 A tooltip was requested ( QHelpEvent).
QEvent::UpdateLater 78 The widget should be queued to be repainted at a later time.
QEvent::UpdateRequest 77 The widget should be repainted.
QEvent::WhatsThis 111 The widget should reveal "What's This?" help ( QHelpEvent).
QEvent::WhatsThisClicked 118 A link in a widget's "What's This?" help was clicked.
QEvent::Wheel 31 Mouse wheel rolled ( QWheelEvent).
QEvent::WinEventAct 132 A Windows-specific activation event has occurred.
QEvent::WindowActivate 24 Window was activated.
QEvent::WindowBlocked 103 The window is blocked by a modal dialog.
QEvent::WindowDeactivate 25 Window was deactivated.
QEvent::WindowIconChange 34 The window's icon has changed.
QEvent::WindowStateChange 105 The window's state (minimized, maximized or full-screen) has changed ( QWindowStateChangeEvent).
QEvent::WindowTitleChange 33 The window title has changed.
QEvent::WindowUnblocked 104 The window is unblocked after a modal dialog exited.
QEvent::ZOrderChange 126 The widget's z-order has changed. This event is never sent to top level windows.
QEvent::KeyboardLayoutChange 169 The keyboard layout has changed.
QEvent::DynamicPropertyChange 170 A dynamic property was added, changed or removed from the object.

User events should have values between User and MaxUser:


Constant Value Description
QEvent::User 1000 User-defined event.
QEvent::MaxUser 65535 Last user event ID.

Описание свойств

accepted : bool

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().

Функции доступа:

  • bool isAccepted () const
  • void setAccepted ( bool accepted )

Описание функций-членов

QEvent::QEvent ( Type type )

Contructs an event object of type type.

QEvent::~QEvent () [virtual]

Destroys the event. If it was posted, it will be removed from the list of events to be posted.

void QEvent::accept ()

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

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

See also ignore().

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.

See also accept().

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.

Type QEvent::type () const

Returns the event type.


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Qt 4.3.2