QActionGroup Class

The QActionGroup class groups actions together. More...

Header: #include <QActionGroup>
qmake: QT += widgets
Inherits: QObject

Public Types

enum class ExclusionPolicy { None, Exclusive, ExclusiveOptional }

Properties

Public Functions

QActionGroup(QObject *parent)
virtual ~QActionGroup()
QList<QAction *> actions() const
QAction *addAction(QAction *action)
QAction *addAction(const QString &text)
QAction *addAction(const QIcon &icon, const QString &text)
QAction *checkedAction() const
QActionGroup::ExclusionPolicy exclusionPolicy() const
bool isEnabled() const
bool isExclusive() const
bool isVisible() const
void removeAction(QAction *action)

Public Slots

void setDisabled(bool b)
void setEnabled(bool)
void setExclusionPolicy(QActionGroup::ExclusionPolicy policy)
void setExclusive(bool b)
void setVisible(bool)

Signals

void hovered(QAction *action)
void triggered(QAction *action)

Detailed Description

In some situations it is useful to group QAction objects together. For example, if you have a Left Align action, a Right Align action, a Justify action, and a Center action, only one of these actions should be active at any one time. One simple way of achieving this is to group the actions together in an action group.

Here's a example (from the Menus example):

    alignmentGroup = new QActionGroup(this);
    alignmentGroup->addAction(leftAlignAct);
    alignmentGroup->addAction(rightAlignAct);
    alignmentGroup->addAction(justifyAct);
    alignmentGroup->addAction(centerAct);
    leftAlignAct->setChecked(true);

Here we create a new action group. Since the action group is exclusive by default, only one of the actions in the group is checked at any one time.

Alignment options in a QMenu

A QActionGroup emits an triggered() signal when one of its actions is chosen. Each action in an action group emits its triggered() signal as usual.

As stated above, an action group is exclusive by default; it ensures that at most only one checkable action is active at any one time. If you want to group checkable actions without making them exclusive, you can turn off exclusiveness by calling setExclusive(false).

By default the active action of an exclusive group cannot be unchecked. In some cases it may be useful to allow unchecking all the actions, you can allow this by calling setExclusionPolicy(QActionGroup::ExclusionPolicy::ExclusiveOptional).

Actions can be added to an action group using addAction(), but it is usually more convenient to specify a group when creating actions; this ensures that actions are automatically created with a parent. Actions can be visually separated from each other by adding a separator action to the group; create an action and use QAction's setSeparator() function to make it considered a separator. Action groups are added to widgets with the QWidget::addActions() function.

See also QAction.

Member Type Documentation

enum class QActionGroup::ExclusionPolicy

This enum specifies the different policies that can be used to control how the group performs exclusive checking on checkable actions.

ConstantValueDescription
QActionGroup::ExclusionPolicy::None0The actions in the group can be checked independently of each other.
QActionGroup::ExclusionPolicy::Exclusive1Exactly one action can be checked at any one time. This is the default policy.
QActionGroup::ExclusionPolicy::ExclusiveOptional2At most one action can be checked at any one time. The actions can also be all unchecked.

This enum was introduced or modified in Qt 5.14.

See also exclusionPolicy.

Property Documentation

enabled : bool

This property holds whether the action group is enabled

Each action in the group will be enabled or disabled unless it has been explicitly disabled.

Access functions:

bool isEnabled() const
void setEnabled(bool)

See also QAction::setEnabled().

exclusionPolicy : QActionGroup::ExclusionPolicy

This property holds the group exclusive checking policy

If exclusionPolicy is set to Exclusive, only one checkable action in the action group can ever be active at any time. If the user chooses another checkable action in the group, the one they chose becomes active and the one that was active becomes inactive. If exclusionPolicy is set to ExclusionOptional the group is exclusive but the active checkable action in the group can be unchecked leaving the group with no actions checked.

This property was introduced in Qt 5.14.

Access functions:

QActionGroup::ExclusionPolicy exclusionPolicy() const
void setExclusionPolicy(QActionGroup::ExclusionPolicy policy)

See also QAction::checkable.

visible : bool

This property holds whether the action group is visible

Each action in the action group will match the visible state of this group unless it has been explicitly hidden.

Access functions:

bool isVisible() const
void setVisible(bool)

See also QAction::setEnabled().

Member Function Documentation

QActionGroup::QActionGroup(QObject *parent)

Constructs an action group for the parent object.

The action group is exclusive by default. Call setExclusive(false) to make the action group non-exclusive. To make the group exclusive but allow unchecking the active action call instead setExclusionPolicy(QActionGroup::ExclusionPolicy::ExclusiveOptional)

[signal] void QActionGroup::hovered(QAction *action)

This signal is emitted when the given action in the action group 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 QActionGroup::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 group is disabled; otherwise it is enabled.

[slot] void QActionGroup::setExclusive(bool b)

Enable or disable the group exclusion checking

This is a convenience method that calls setExclusionPolicy(ExclusionPolicy::Exclusive) when b is true, else setExclusionPolicy(QActionGroup::ExclusionPolicy::None).

See also isExclusive() and QActionGroup::exclusionPolicy.

[signal] void QActionGroup::triggered(QAction *action)

This signal is emitted when the given action in the action group is activated by the user; for example, when the user clicks a menu option, toolbar button, or presses an action's shortcut key combination.

Connect to this signal for command actions.

See also QAction::activate().

[virtual] QActionGroup::~QActionGroup()

Destroys the action group.

QList<QAction *> QActionGroup::actions() const

Returns the list of this groups's actions. This may be empty.

QAction *QActionGroup::addAction(QAction *action)

Adds the action to this group, and returns it.

Normally an action is added to a group by creating it with the group as its parent, so this function is not usually used.

See also QAction::setActionGroup().

QAction *QActionGroup::addAction(const QString &text)

Creates and returns an action with text. The newly created action is a child of this action group.

Normally an action is added to a group by creating it with the group as parent, so this function is not usually used.

See also QAction::setActionGroup().

QAction *QActionGroup::addAction(const QIcon &icon, const QString &text)

Creates and returns an action with text and an icon. The newly created action is a child of this action group.

Normally an action is added to a group by creating it with the group as its parent, so this function is not usually used.

See also QAction::setActionGroup().

QAction *QActionGroup::checkedAction() const

Returns the currently checked action in the group, or nullptr if none are checked.

bool QActionGroup::isExclusive() const

Returns true if the group is exclusive

The group is exclusive if the ExclusionPolicy is either Exclusive or ExclusionOptional.

void QActionGroup::removeAction(QAction *action)

Removes the action from this group. The action will have no parent as a result.

See also QAction::setActionGroup().

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