QAction Class

The QAction class provides an abstract user interface action that can be inserted into widgets. More...

• List of all members, including inherited members

Public Types

Properties

Public Functions

Public Slots

Signals

Reimplemented Protected Functions

Detailed Description

In applications many common commands can be invoked via menus, toolbar buttons, and keyboard shortcuts. Since the user expects each command to be performed in the same way, regardless of the user interface used, it is useful to represent each command as an action.

Actions can be added to menus and toolbars, and will automatically keep them in sync. For example, in a word processor, if the user presses a Bold toolbar button, the Bold menu item will automatically be checked.

Actions can be created as independent objects, but they may also be created during the construction of menus; the QMenu class contains convenience functions for creating actions suitable for use as menu items.

A QAction may contain an icon, menu text, a shortcut, status text, "What's This?" text, and a tooltip. Most of these can be set in the constructor. They can also be set independently with setIcon(), setText(), setIconText(), setShortcut(), setStatusTip(), setWhatsThis(), and setToolTip(). For menu items, it is possible to set an individual font with setFont().

Actions are added to widgets using QWidget::addAction() or QGraphicsWidget::addAction(). Note that an action must be added to a widget before it can be used; this is also true when the shortcut should be global (i.e., Qt::ApplicationShortcut as Qt::ShortcutContext).

Once a QAction has been created it should be added to the relevant menu and toolbar, then connected to the slot which will perform the action. For example:

    const QIcon openIcon = QIcon::fromTheme("document-open", QIcon(":/images/open.png"));
    QAction *openAct = new QAction(openIcon, tr("&Open..."), this);
    openAct->setShortcuts(QKeySequence::Open);
    openAct->setStatusTip(tr("Open an existing file"));
    connect(openAct, &QAction::triggered, this, &MainWindow::open);
    fileMenu->addAction(openAct);
    fileToolBar->addAction(openAct);

We recommend that actions are created as children of the window they are used in. In most cases actions will be children of the application's main window.

See also QMenu, QToolBar, and Application Example.

Member Type Documentation

enum QAction::ActionEvent

This enum type is used when calling QAction::activate()

enum QAction::MenuRole

This enum describes how an action should be moved into the application menu on macOS.

Setting this value only has effect on items that are in the immediate menus of the menubar, not the submenus of those menus. For example, if you have File menu in your menubar and the File menu has a submenu, setting the MenuRole for the actions in that submenu have no effect. They will never be moved.

enum QAction::Priority

This enum defines priorities for actions in user interface.

This enum was introduced or modified in Qt 4.6.

See also priority.

QApplication app(argc, argv);
app.setAttribute(Qt::AA_DontShowIconsInMenus);  // Icons are *no longer shown* in menus
// ...
QAction *myAction = new QAction();
// ...
myAction->setIcon(SomeIcon);
myAction->setIconVisibleInMenu(true);   // Icon *will* be shown in menus for *this* action.

Member Function Documentation

QAction::QAction(const QIcon &icon, const QString &text, QObject *parent = nullptr)

Constructs an action with an icon and some text and parent. If parent is an action group the action will be automatically inserted into the group.

The action uses a stripped version of text (e.g. "&Menu Option..." becomes "Menu Option") as descriptive text for tool buttons. You can override this by setting a specific description with setText(). The same text will be used for tooltips unless you specify a different text using setToolTip().

QAction::QAction(const QString &text, QObject *parent = nullptr)

Constructs an action with some text and parent. If parent is an action group the action will be automatically inserted into the group.

The action uses a stripped version of text (e.g. "&Menu Option..." becomes "Menu Option") as descriptive text for tool buttons. You can override this by setting a specific description with setText(). The same text will be used for tooltips unless you specify a different text using setToolTip().

QAction::QAction(QObject *parent = nullptr)

Constructs an action with parent. If parent is an action group the action will be automatically inserted into the group.

Note: The parent argument is optional since Qt 5.7.

[signal] void QAction::changed()

This signal is emitted when an action has changed. If you are only interested in actions in a given widget, you can watch for QWidget::actionEvent() sent with an QEvent::ActionChanged.

Note: Notifier signal for property autoRepeat. Notifier signal for property checkable. Notifier signal for property enabled. Notifier signal for property font. Notifier signal for property icon. Notifier signal for property iconText. Notifier signal for property iconVisibleInMenu. Notifier signal for property menuRole. Notifier signal for property shortcut. Notifier signal for property shortcutContext. Notifier signal for property shortcutVisibleInContextMenu. Notifier signal for property statusTip. Notifier signal for property text. Notifier signal for property toolTip. Notifier signal for property visible. Notifier signal for property whatsThis.

See also QWidget::actionEvent().

[slot] void QAction::hover()

This is a convenience slot that calls activate(Hover).

[signal] void QAction::hovered()

This signal is emitted when an action is highlighted by the user; for example, when the user pauses with the cursor over a menu option, toolbar button, or presses an action's shortcut key combination.

See also QAction::activate().

[slot] void QAction::setDisabled(bool b)

This is a convenience function for the enabled property, that is useful for signals--slots connections. If b is true the action is disabled; otherwise it is enabled.

[slot] void QAction::toggle()

This is a convenience function for the checked property. Connect to it to change the checked state to its opposite state.

[signal] void QAction::toggled(bool checked)

This signal is emitted whenever a checkable action changes its isChecked() status. This can be the result of a user interaction, or because setChecked() was called. As setChecked() changes the QAction, it emits changed() in addition to toggled().

checked is true if the action is checked, or false if the action is unchecked.

Note: Notifier signal for property checked.

See also QAction::activate(), QAction::triggered(), and checked.

[slot] void QAction::trigger()

This is a convenience slot that calls activate(Trigger).

[signal] void QAction::triggered(bool checked = false)

This signal is emitted when an action is activated by the user; for example, when the user clicks a menu option, toolbar button, or presses an action's shortcut key combination, or when trigger() was called. Notably, it is not emitted when setChecked() or toggle() is called.

If the action is checkable, checked is true if the action is checked, or false if the action is unchecked.

See also QAction::activate(), QAction::toggled(), and checked.

[virtual] QAction::~QAction()

Destroys the object and frees allocated resources.

QActionGroup *QAction::actionGroup() const

Returns the action group for this action. If no action group manages this action then 0 will be returned.

See also QActionGroup and QAction::setActionGroup().

void QAction::activate(QAction::ActionEvent event)

Sends the relevant signals for ActionEvent event.

Action based widgets use this API to cause the QAction to emit signals as well as emitting their own.

QList<QGraphicsWidget *> QAction::associatedGraphicsWidgets() const

Returns a list of widgets this action has been added to.

This function was introduced in Qt 4.5.

See also QWidget::addAction() and associatedWidgets().

QList<QWidget *> QAction::associatedWidgets() const

Returns a list of widgets this action has been added to.

This function was introduced in Qt 4.2.

See also QWidget::addAction() and associatedGraphicsWidgets().

QVariant QAction::data() const

Returns the user data as set in QAction::setData.

See also setData().

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

Reimplements: QObject::event(QEvent *e).

bool QAction::isSeparator() const

Returns true if this action is a separator action; otherwise it returns false.

See also QAction::setSeparator().

QMenu *QAction::menu() const

Returns the menu contained by this action. Actions that contain menus can be used to create menu items with submenus, or inserted into toolbars to create buttons with popup menus.

See also setMenu() and QMenu::addAction().

QWidget *QAction::parentWidget() const

Returns the parent widget.

void QAction::setActionGroup(QActionGroup *group)

Sets this action group to group. The action will be automatically added to the group's list of actions.

Actions within the group will be mutually exclusive.

See also QActionGroup and QAction::actionGroup().

void QAction::setData(const QVariant &userData)

Sets the action's internal data to the given userData.

See also data().

void QAction::setMenu(QMenu *menu)

Sets the menu contained by this action to the specified menu.

See also menu().

void QAction::setSeparator(bool b)

If b is true then this action will be considered a separator.

How a separator is represented depends on the widget it is inserted into. Under most circumstances the text, submenu, and icon will be ignored for separator actions.

See also QAction::isSeparator().

void QAction::setShortcuts(const QList<QKeySequence> &shortcuts)

Sets shortcuts as the list of shortcuts that trigger the action. The first element of the list is the primary shortcut.

This function was introduced in Qt 4.2.

See also shortcuts() and shortcut.

void QAction::setShortcuts(QKeySequence::StandardKey key)

Sets a platform dependent list of shortcuts based on the key. The result of calling this function will depend on the currently running platform. Note that more than one shortcut can assigned by this action. If only the primary shortcut is required, use setShortcut instead.

This function was introduced in Qt 4.2.

See also QKeySequence::keyBindings().

QKeySequence QAction::shortcut() const

Returns the primary shortcut.

Note: Getter function for property shortcut.

See also setShortcuts().

QList<QKeySequence> QAction::shortcuts() const

Returns the list of shortcuts, with the primary shortcut as the first element of the list.

This function was introduced in Qt 4.2.

See also setShortcuts().

bool QAction::showStatusText(QWidget *widget = nullptr)

Updates the relevant status bar for the widget specified by sending a QStatusTipEvent to its parent widget. Returns true if an event was sent; otherwise returns false.

If a null widget is specified, the event is sent to the action's parent.

See also statusTip.