QMdiArea 类

QMdiArea 小部件提供在其中显示 MDI 窗口的区域。 更多...

Header: #include <QMdiArea>
CMake: find_package(Qt6 COMPONENTS Widgets REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Widgets)
qmake: QT += widgets
继承: QAbstractScrollArea


enum AreaOption { DontMaximizeSubWindowOnActivation }
flags AreaOptions
enum ViewMode { SubWindowView, TabbedView }
enum WindowOrder { CreationOrder, StackingOrder, ActivationHistoryOrder }



QMdiArea (QWidget * parent = nullptr)
virtual ~QMdiArea ()
QMdiArea::WindowOrder activationOrder () const
QMdiSubWindow * activeSubWindow () const
QMdiSubWindow * addSubWindow (QWidget * widget , Qt::WindowFlags windowFlags = Qt::WindowFlags())
QBrush background () const
QMdiSubWindow * currentSubWindow () const
bool documentMode () const
void removeSubWindow (QWidget * widget )
void setActivationOrder (QMdiArea::WindowOrder order )
void setBackground (const QBrush & background )
void setDocumentMode (bool enabled )
void setOption (QMdiArea::AreaOption option , bool on = true)
void setTabPosition (QTabWidget::TabPosition position )
void setTabShape (QTabWidget::TabShape shape )
void setTabsClosable (bool closable )
void setTabsMovable (bool movable )
void setViewMode (QMdiArea::ViewMode mode )
QList<QMdiSubWindow *> subWindowList (QMdiArea::WindowOrder order = CreationOrder) const
QTabWidget::TabPosition tabPosition () const
QTabWidget::TabShape tabShape () const
bool tabsClosable () const
bool tabsMovable () const
bool testOption (QMdiArea::AreaOption option ) const
QMdiArea::ViewMode viewMode () const


virtual QSize minimumSizeHint () const override
virtual QSize sizeHint () const override



void subWindowActivated (QMdiSubWindow * window )


virtual void childEvent (QChildEvent * childEvent ) override
virtual bool event (QEvent * event ) override
virtual bool eventFilter (QObject * object , QEvent * event ) override
virtual void paintEvent (QPaintEvent * paintEvent ) override
virtual void resizeEvent (QResizeEvent * resizeEvent ) override
virtual void scrollContentsBy (int dx , int dy ) override
virtual void showEvent (QShowEvent * showEvent ) override
virtual void timerEvent (QTimerEvent * timerEvent ) override
virtual bool viewportEvent (QEvent * event ) override


virtual void setupViewport (QWidget * viewport ) override


QMdiArea functions, essentially, like a window manager for MDI windows. For instance, it draws the windows it manages on itself and arranges them in a cascading or tile pattern. QMdiArea is commonly used as the center widget in a QMainWindow to create MDI applications, but can also be placed in any layout. The following code adds an area to a main window:

    QMainWindow *mainWindow = new QMainWindow;

Unlike the window managers for top-level windows, all window flags ( Qt::WindowFlags ) are supported by QMdiArea as long as the flags are supported by the current widget style. If a specific flag is not supported by the style (e.g., the WindowShadeButtonHint ), you can still shade the window with showShaded().

Subwindows in QMdiArea are instances of QMdiSubWindow . They are added to an MDI area with addSubWindow (). It is common to pass a QWidget , which is set as the internal widget, to this function, but it is also possible to pass a QMdiSubWindow directly. The class inherits QWidget , and you can use the same API as with a normal top-level window when programming. QMdiSubWindow also has behavior that is specific to MDI windows. See the QMdiSubWindow class description for more details.

A subwindow becomes active when it gets the keyboard focus, or when setFocus () is called. The user activates a window by moving focus in the usual ways. The MDI area emits the subWindowActivated () signal when the active window changes, and the activeSubWindow () function returns the active subwindow.

The convenience function subWindowList () returns a list of all subwindows. This information could be used in a popup menu containing a list of windows, for example.

The subwindows are sorted by the current WindowOrder . This is used for the subWindowList () and for activateNextSubWindow () 和 activatePreviousSubWindow (). Also, it is used when cascading or tiling the windows with cascadeSubWindows () 和 tileSubWindows ().

QMdiArea provides two built-in layout strategies for subwindows: cascadeSubWindows () 和 tileSubWindows (). Both are slots and are easily connected to menu entries.

注意: The default scroll bar property for QMdiArea is Qt::ScrollBarAlwaysOff .

另请参阅 QMdiSubWindow .


enum QMdiArea:: AreaOption
flags QMdiArea:: AreaOptions

This enum describes options that customize the behavior of the QMdiArea .

常量 描述
QMdiArea::DontMaximizeSubWindowOnActivation 0x1 When the active subwindow is maximized, the default behavior is to maximize the next subwindow that is activated. Set this option if you do not want this behavior.

The AreaOptions type is a typedef for QFlags <AreaOption>. It stores an OR combination of AreaOption values.

enum QMdiArea:: ViewMode

This enum describes the view mode of the area; i.e. how sub-windows will be displayed.

常量 描述
QMdiArea::SubWindowView 0 Display sub-windows with window frames (default).
QMdiArea::TabbedView 1 Display sub-windows with tabs in a tab bar.

另请参阅 setViewMode ().

enum QMdiArea:: WindowOrder

Specifies the criteria to use for ordering the list of child windows returned by subWindowList ()。函数 cascadeSubWindows () 和 tileSubWindows () follow this order when arranging the windows.

常量 描述
QMdiArea::CreationOrder 0 The windows are returned in the order of their creation.
QMdiArea::StackingOrder 1 The windows are returned in the order in which they are stacked, with the top-most window being last in the list.
QMdiArea::ActivationHistoryOrder 2 The windows are returned in the order in which they were activated.

另请参阅 subWindowList ().


activationOrder : WindowOrder

This property holds the ordering criteria for subwindow lists

This property specifies the ordering criteria for the list of subwindows returned by subWindowList (). By default, it is the window creation order.


QMdiArea::WindowOrder activationOrder () const
void setActivationOrder (QMdiArea::WindowOrder order )

另请参阅 subWindowList ().

background : QBrush

This property holds the background brush for the workspace

This property sets the background brush for the workspace area itself. By default, it is a gray color, but can be any brush (e.g., colors, gradients or pixmaps).


QBrush background () const
void setBackground (const QBrush & background )

documentMode : bool

This property holds whether the tab bar is set to document mode in tabbed view mode.



bool documentMode () const
void setDocumentMode (bool enabled )

另请参阅 QTabBar::documentMode and setViewMode ().

tabPosition : QTabWidget::TabPosition

This property holds the position of the tabs in tabbed view mode.

此特性的可能值,描述通过 QTabWidget::TabPosition 枚举。


QTabWidget::TabPosition tabPosition () const
void setTabPosition (QTabWidget::TabPosition position )

另请参阅 QTabWidget::TabPosition and setViewMode ().

tabShape : QTabWidget::TabShape

This property holds the shape of the tabs in tabbed view mode.

此特性的可能值, QTabWidget::Rounded (默认) 或 QTabWidget::Triangular .


QTabWidget::TabShape tabShape () const
void setTabShape (QTabWidget::TabShape shape )

另请参阅 QTabWidget::TabShape and setViewMode ().

tabsClosable : bool

This property holds whether the tab bar should place close buttons on each tab in tabbed view mode.

Tabs are not closable by default.


bool tabsClosable () const
void setTabsClosable (bool closable )

另请参阅 QTabBar::tabsClosable and setViewMode ().

tabsMovable : bool

This property holds whether the user can move the tabs within the tabbar area in tabbed view mode.

Tabs are not movable by default.


bool tabsMovable () const
void setTabsMovable (bool movable )

另请参阅 QTabBar::movable and setViewMode ().

viewMode : ViewMode

This property holds the way sub-windows are displayed in the QMdiArea .

默认情况下, SubWindowView is used to display sub-windows.


QMdiArea::ViewMode viewMode () const
void setViewMode (QMdiArea::ViewMode mode )

另请参阅 ViewMode , setTabShape (),和 setTabPosition ().


QMdiArea:: QMdiArea ( QWidget * parent = nullptr)

Constructs an empty mdi area. parent 会被传递给 QWidget 的构造函数。

[slot] void QMdiArea:: activateNextSubWindow ()

Gives the keyboard focus to another window in the list of child windows. The window activated will be the next one determined by the current activation order .

另请参阅 activatePreviousSubWindow () 和 QMdiArea::WindowOrder .

[slot] void QMdiArea:: activatePreviousSubWindow ()

Gives the keyboard focus to another window in the list of child windows. The window activated will be the previous one determined by the current activation order .

另请参阅 activateNextSubWindow () 和 QMdiArea::WindowOrder .

[slot] void QMdiArea:: cascadeSubWindows ()

Arranges all the child windows in a cascade pattern.

另请参阅 tileSubWindows ().

[slot] void QMdiArea:: closeActiveSubWindow ()

Closes the active subwindow.

另请参阅 closeAllSubWindows ().

[slot] void QMdiArea:: closeAllSubWindows ()

Closes all subwindows by sending a QCloseEvent to each window. You may receive subWindowActivated () signals from subwindows before they are closed (if the MDI area activates the subwindow when another is closing).

Subwindows that ignore the close event will remain open.

另请参阅 closeActiveSubWindow ().

[slot] void QMdiArea:: setActiveSubWindow ( QMdiSubWindow * window )

Activates the subwindow window 。若 window is nullptr , any current active window is deactivated.

另请参阅 activeSubWindow ().

[override virtual protected slot] void QMdiArea:: setupViewport ( QWidget * viewport )

重实现: QAbstractScrollArea::setupViewport (QWidget *viewport).

此槽被调用通过 QAbstractScrollArea after setViewport () has been called. Reimplement this function in a subclass of QMdiArea to initialize the new viewport before it is used.

另请参阅 setViewport ().

[signal] void QMdiArea:: subWindowActivated ( QMdiSubWindow * window )

QMdiArea emits this signal after window has been activated. When window is nullptr , QMdiArea has just deactivated its last active window, and there are no active windows on the workspace.

另请参阅 QMdiArea::activeSubWindow ().

[slot] void QMdiArea:: tileSubWindows ()

Arranges all child windows in a tile pattern.

另请参阅 cascadeSubWindows ().

[virtual] QMdiArea:: ~QMdiArea ()

销毁 MDI 区域。

QMdiSubWindow *QMdiArea:: activeSubWindow () const

Returns a pointer to the current active subwindow. If no window is currently active, nullptr 被返回。

Subwindows are treated as top-level windows with respect to window state, i.e., if a widget outside the MDI area is the active window, no subwindow will be active. Note that if a widget in the window in which the MDI area lives gains focus, the window will be activated.

另请参阅 setActiveSubWindow () 和 Qt::WindowState .

QMdiSubWindow *QMdiArea:: addSubWindow ( QWidget * widget , Qt::WindowFlags windowFlags = Qt::WindowFlags())

添加 widget as a new subwindow to the MDI area. If windowFlags are non-zero, they will override the flags set on the widget.

widget can be either a QMdiSubWindow or another QWidget (in which case the MDI area will create a subwindow and set the widget as the internal widget).

注意: Once the subwindow has been added, its parent will be the viewport widget QMdiArea .

    QMdiArea mdiArea;
    QMdiSubWindow *subWindow1 = new QMdiSubWindow;
    QMdiSubWindow *subWindow2 =

When you create your own subwindow, you must set the Qt::WA_DeleteOnClose widget attribute if you want the window to be deleted when closed in the MDI area. If not, the window will be hidden and the MDI area will not activate the next subwindow.

返回 QMdiSubWindow that is added to the MDI area.

另请参阅 removeSubWindow ().

[override virtual protected] void QMdiArea:: childEvent ( QChildEvent * childEvent )

重实现: QObject::childEvent (QChildEvent *event).

QMdiSubWindow *QMdiArea:: currentSubWindow () const

Returns a pointer to the current subwindow, or nullptr if there is no current subwindow.

This function will return the same as activeSubWindow () if the QApplication containing QMdiArea is active.

另请参阅 activeSubWindow () 和 QApplication::activeWindow ().

[override virtual protected] bool QMdiArea:: event ( QEvent * event )

重实现: QAbstractScrollArea::event (QEvent *event).

[override virtual protected] bool QMdiArea:: eventFilter ( QObject * object , QEvent * event )

重实现: QObject::eventFilter (QObject *watched, QEvent *event).

[override virtual] QSize QMdiArea:: minimumSizeHint () const

重实现: QAbstractScrollArea::minimumSizeHint () const.

[override virtual protected] void QMdiArea:: paintEvent ( QPaintEvent * paintEvent )

重实现: QAbstractScrollArea::paintEvent (QPaintEvent *event).

void QMdiArea:: removeSubWindow ( QWidget * widget )

移除 widget from the MDI area. The widget must be either a QMdiSubWindow or a widget that is the internal widget of a subwindow. Note widget is never actually deleted by QMdiArea . If a QMdiSubWindow is passed in, its parent is set to nullptr and it is removed; but if an internal widget is passed in, the child widget is set to nullptr QMdiSubWindow is not removed.

另请参阅 addSubWindow ().

[override virtual protected] void QMdiArea:: resizeEvent ( QResizeEvent * resizeEvent )

重实现: QAbstractScrollArea::resizeEvent (QResizeEvent *event).

[override virtual protected] void QMdiArea:: scrollContentsBy ( int dx , int dy )

重实现: QAbstractScrollArea::scrollContentsBy (int dx, int dy).

void QMdiArea:: setOption ( QMdiArea::AreaOption option , bool on = true)

on is true, option is enabled on the MDI area; otherwise it is disabled. See AreaOption for the effect of each option.

另请参阅 AreaOption and testOption ().

[override virtual protected] void QMdiArea:: showEvent ( QShowEvent * showEvent )

重实现: QWidget::showEvent (QShowEvent *event).

[override virtual] QSize QMdiArea:: sizeHint () const

重实现: QAbstractScrollArea::sizeHint () const.

QList < QMdiSubWindow *> QMdiArea:: subWindowList ( QMdiArea::WindowOrder order = CreationOrder) const

Returns a list of all subwindows in the MDI area. If order is CreationOrder (the default), the windows are sorted in the order in which they were inserted into the workspace. If order is StackingOrder , the windows are listed in their stacking order, with the topmost window as the last item in the list. If order is ActivationHistoryOrder , the windows are listed according to their recent activation history.

另请参阅 WindowOrder .

bool QMdiArea:: testOption ( QMdiArea::AreaOption option ) const

返回 true if option 被启用;否则返回 false .

另请参阅 AreaOption and setOption ().

[override virtual protected] void QMdiArea:: timerEvent ( QTimerEvent * timerEvent )

重实现: QObject::timerEvent (QTimerEvent *event).

[override virtual protected] bool QMdiArea:: viewportEvent ( QEvent * event )

重实现: QAbstractScrollArea::viewportEvent (QEvent *event).