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
- enabled : bool
- exclusionPolicy : QActionGroup::ExclusionPolicy
- visible : bool
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 |
| 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(ExclusionPolicy policy) |
| void | setExclusive(bool b) |
| void | setVisible(bool) |
Signals
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.
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.
| Constant | Value | Description |
|---|---|---|
QActionGroup::ExclusionPolicy::None | 0 | The actions in the group can be checked independently of each other. |
QActionGroup::ExclusionPolicy::Exclusive | 1 | Exactly one action can be checked at any one time. This is the default policy. |
QActionGroup::ExclusionPolicy::ExclusiveOptional | 2 | At 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:
| ExclusionPolicy | exclusionPolicy() const |
| void | setExclusionPolicy(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().