Qt 4.8: QButtonGroup Class Reference

Qt Reference Documentation

- Qt 4.8
- ALL VERSIONS

- A
- A
- A
- Print

# QButtonGroup Class Reference

The QButtonGroup class provides a container to organize groups of button widgets. More...

     #include <QButtonGroup>

Inherits: QObject.

- List of all members, including inherited members
- Qt 3 support members

## Properties

- exclusive : bool

- 1 property inherited from QObject

## Public Functions

| QButtonGroup ( QObject * parent = 0 )
| ~QButtonGroup ()
void | addButton ( QAbstractButton * button )
void | addButton ( QAbstractButton * button, int id )
QAbstractButton * | button ( int id ) const
QList<QAbstractButton *> | buttons () const
QAbstractButton * | checkedButton () const
int | checkedId () const
bool | exclusive () const
int | id ( QAbstractButton * button ) const
void | removeButton ( QAbstractButton * button )
void | setExclusive ( bool )
void | setId ( QAbstractButton * button, int id )

- 29 public functions inherited from QObject

## Signals

void | buttonClicked ( QAbstractButton * button )
void | buttonClicked ( int id )
void | buttonPressed ( QAbstractButton * button )
void | buttonPressed ( int id )
void | buttonReleased ( QAbstractButton * button )
void | buttonReleased ( int id )

- 1 signal inherited from QObject

### Additional Inherited Members

- 1 public slot inherited from QObject
- 7 static public members inherited from QObject
- 8 protected functions inherited from QObject

## Detailed Description

The QButtonGroup class provides a container to organize groups of button widgets.

QButtonGroup provides an abstract container into which button widgets can be placed. It does not provide a visual representation of this container (see QGroupBox for a container widget), but instead manages the states of each of the buttons in the group.

An exclusive button group switches off all checkable (toggle) buttons except the one that was clicked. By default, a button group is exclusive. The buttons in a button group are usually checkable QPushButton's, QCheckBoxes (normally for non-exclusive button groups), or QRadioButtons. If you create an exclusive button group, you should ensure that one of the buttons in the group is initially checked; otherwise, the group will initially be in a state where no buttons are checked.

A button is added to the group with addButton(). It can be removed from the group with removeButton(). If the group is exclusive, the currently checked button is available as checkedButton(). If a button is clicked the buttonClicked() signal is emitted. For a checkable button in an exclusive group this means that the button was checked. The list of buttons in the group is returned by buttons().

In addition, QButtonGroup can map between integers and buttons. You can assign an integer id to a button with setId(), and retrieve it with id(). The id of the currently checked button is available with checkedId(), and there is an overloaded signal buttonClicked() which emits the id of the button. The id `-1` is reserved by QButtonGroup to mean "no such button". The purpose of the mapping mechanism is to simplify the representation of enum values in a user interface.

See also QGroupBox, QPushButton, QCheckBox, and QRadioButton.

## Property Documentation

### exclusive : bool

This property holds whether the button group is exclusive.

If this property is true then only one button in the group can be checked at any given time. The user can click on any button to check it, and that button will replace the existing one as the checked button in the group.

In an exclusive group, the user cannot uncheck the currently checked button by clicking on it; instead, another button in the group must be clicked to set the new checked button for that group.

By default, this property is true.

Access functions:

bool | exclusive () const
void | setExclusive ( bool )

## Member Function Documentation

### QButtonGroup::QButtonGroup ( QObject * parent = 0 )

Constructs a new, empty button group with the given parent.

See also addButton() and setExclusive().

### QButtonGroup::~QButtonGroup ()

Destroys the button group.

### void QButtonGroup::addButton ( QAbstractButton * button )

Adds the given button to the end of the group's internal list of buttons. An id will be assigned to the button by this QButtonGroup. Automatically assigned ids are guaranteed to be negative, starting with -2. If you are also assigning your own ids, use positive values to avoid conflicts.

See also removeButton() and buttons().

### void QButtonGroup::addButton ( QAbstractButton * button, int id )

Adds the given button to the button group, with the given id. It is recommended to assign only positive ids.

See also removeButton() and buttons().

### QAbstractButton * QButtonGroup::button ( int id ) const

Returns the button with the specified id, or 0 if no such button exists.

This function was introduced in Qt 4.1.

### void QButtonGroup::buttonClicked ( QAbstractButton * button )`[signal]`

This signal is emitted when the given button is clicked. A button is clicked when it is first pressed and then released, when its shortcut key is typed, or programmatically when QAbstractButton::click() or QAbstractButton::animateClick() is called.

See also checkedButton() and QAbstractButton::clicked().

### void QButtonGroup::buttonClicked ( int id )`[signal]`

This signal is emitted when a button with the given id is clicked.

See also checkedButton() and QAbstractButton::clicked().

### void QButtonGroup::buttonPressed ( QAbstractButton * button )`[signal]`

This signal is emitted when the given button is pressed down.

This function was introduced in Qt 4.2.

See also QAbstractButton::pressed().

### void QButtonGroup::buttonPressed ( int id )`[signal]`

This signal is emitted when a button with the given id is pressed down.

This function was introduced in Qt 4.2.

See also QAbstractButton::pressed().

### void QButtonGroup::buttonReleased ( QAbstractButton * button )`[signal]`

This signal is emitted when the given button is released.

This function was introduced in Qt 4.2.

See also QAbstractButton::released().

### void QButtonGroup::buttonReleased ( int id )`[signal]`

This signal is emitted when a button with the given id is released.

This function was introduced in Qt 4.2.

See also QAbstractButton::released().

### QList<QAbstractButton *> QButtonGroup::buttons () const

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

See also addButton() and removeButton().

### QAbstractButton * QButtonGroup::checkedButton () const

Returns the button group's checked button, or 0 if no buttons are checked.

See also buttonClicked().

### int QButtonGroup::checkedId () const

Returns the id of the checkedButton(), or -1 if no button is checked.

This function was introduced in Qt 4.1.

See also setId().

### int QButtonGroup::id ( QAbstractButton * button ) const

Returns the id for the specified button, or -1 if no such button exists.

This function was introduced in Qt 4.1.

See also setId().

### void QButtonGroup::removeButton ( QAbstractButton * button )

Removes the given button from the button group.

See also addButton() and buttons().

### void QButtonGroup::setId ( QAbstractButton * button, int id )

Sets the id for the specified button. Note that id can not be -1.

This function was introduced in Qt 4.1.

See also id().