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# QCheckBox Class Reference

The QCheckBox widget provides a checkbox with a text label. More...

`#include <qcheckbox.h>`

Inherits QButton.

List of all member functions.

## Public Members

- QCheckBox ( QWidget * parent, const char * name = 0 )
- QCheckBox ( const QString & text, QWidget * parent, const char * name = 0 )
- bool isChecked () const
- void setNoChange ()
- void setTristate ( bool y = TRUE )
- bool isTristate () const

## Public Slots

- void setChecked ( bool check )

## Important Inherited Members

- QString text () const
- virtual void setText ( const QString & )
- const QPixmap * pixmap () const
- virtual void setPixmap ( const QPixmap & )
- QKeySequence accel () const
- virtual void setAccel ( const QKeySequence & )
- bool isToggleButton () const
- virtual void setDown ( bool )
- bool isDown () const
- bool isOn () const
- ToggleState state () const
- bool autoRepeat () const
- virtual void setAutoRepeat ( bool )
- bool isExclusiveToggle () const
- QButtonGroup * group () const
- void toggle ()
- void pressed ()
- void released ()
- void clicked ()
- void toggled ( bool on )
- void stateChanged ( int state )

## Properties

- bool autoMask - whether the checkbox is automatically masked (read only)
- bool checked - whether the checkbox is checked
- bool tristate - whether the checkbox is a tri-state checkbox

## Detailed Description

The QCheckBox widget provides a checkbox with a text label.

QCheckBox and QRadioButton are both option buttons. That is, they can be switched on (checked) or off (unchecked). The classes differ in how the choices for the user are restricted. Radio buttons define a "one of many" choice, whereas checkboxes provide "many of many" choices.

Although it is technically possible to implement radio behavior with checkboxes and vice versa, we strongly recommended sticking with the well-known semantics.

A QButtonGroup can be used to group check buttons visually.

Whenever a checkbox is checked or cleared it emits the signal toggled(). Connect to this signal if you want to trigger an action each time the checkbox changes state. You can use isChecked() to query whether or not a checkbox is checked.

In addition to the usual checked and unchecked states, QCheckBox optionally provides a third state to indicate "no change". This is useful whenever you need to give the user the option of neither checking nor unchecking a checkbox. If you need this third state, enable it with setTristate() and use state() to query the current toggle state. When a tristate checkbox changes state, it emits the stateChanged() signal.

Just like QPushButton, a checkbox can display text or a pixmap. The text can be set in the constructor or with setText(); the pixmap is set with setPixmap().

See also QButton, QRadioButton, Fowler: Check Box and Basic Widgets.

## Member Function Documentation

### QCheckBox::QCheckBox ( QWidget * parent, const char * name = 0 )

Constructs a checkbox with no text.

The parent and name arguments are sent to the QWidget constructor.

### QCheckBox::QCheckBox ( const QString & text, QWidget * parent, const char * name = 0 )

Constructs a checkbox with text text.

The parent and name arguments are sent to the QWidget constructor.

### QKeySequence QButton::accel () const

Returns the accelerator associated with the button. See the "accel" property for details.

### bool QButton::autoRepeat () const

Returns TRUE if autoRepeat is enabled; otherwise returns FALSE. See the "autoRepeat" property for details.

### void QButton::clicked ()`[signal]`

This signal is emitted when the button is activated (i.e. first pressed down and then released when the mouse cursor is inside the button), when the accelerator key is typed or when animateClick() is called.

The QButtonGroup::clicked() signal does the same job, if you want to connect several buttons to the same slot.

See also pressed(), released() and toggled().

Examples: fonts/simple-qfont-demo/viewer.cpp, listbox/listbox.cpp, network/clientserver/client/client.cpp, network/ftpclient/ftpmainwindow.cpp, richtext/richtext.cpp, t2/main.cpp and t4/main.cpp.

### QButtonGroup * QButton::group () const

Returns a pointer to the group of which this button is a member.

If the button is not a member of any QButtonGroup, this function returns 0.

See also QButtonGroup.

### bool QCheckBox::isChecked () const

Returns TRUE if the checkbox is checked; otherwise returns FALSE. See the "checked" property for details.

### bool QButton::isDown () const

Returns TRUE if the button is pressed; otherwise returns FALSE. See the "down" property for details.

### bool QButton::isExclusiveToggle () const

Returns TRUE if the button is an exclusive toggle; otherwise returns FALSE. See the "exclusiveToggle" property for details.

### bool QButton::isOn () const

Returns TRUE if the button is toggled; otherwise returns FALSE. See the "on" property for details.

### bool QButton::isToggleButton () const

Returns TRUE if the button is a toggle button; otherwise returns FALSE. See the "toggleButton" property for details.

### bool QCheckBox::isTristate () const

Returns TRUE if the checkbox is a tri-state checkbox; otherwise returns FALSE. See the "tristate" property for details.

### const QPixmap * QButton::pixmap () const

Returns the pixmap shown on the button. See the "pixmap" property for details.

### void QButton::pressed ()`[signal]`

This signal is emitted when the button is pressed down.

See also released() and clicked().

Examples: network/httpd/httpd.cpp and popup/popup.cpp.

### void QButton::released ()`[signal]`

This signal is emitted when the button is released.

See also pressed(), clicked() and toggled().

### void QButton::setAccel ( const QKeySequence & )`[virtual]`

Sets the accelerator associated with the button. See the "accel" property for details.

### void QButton::setAutoRepeat ( bool )`[virtual]`

Sets whether autoRepeat is enabled. See the "autoRepeat" property for details.

### void QCheckBox::setChecked ( bool check )`[slot]`

Sets whether the checkbox is checked to check. See the "checked" property for details.

### void QButton::setDown ( bool )`[virtual]`

Sets whether the button is pressed. See the "down" property for details.

### void QCheckBox::setNoChange ()

Sets the checkbox to the "no change" state.

See also tristate.

### void QButton::setPixmap ( const QPixmap & )`[virtual]`

Sets the pixmap shown on the button. See the "pixmap" property for details.

### void QButton::setText ( const QString & )`[virtual]`

Sets the text shown on the button. See the "text" property for details.

### void QCheckBox::setTristate ( bool y = TRUE )

Sets whether the checkbox is a tri-state checkbox to y. See the "tristate" property for details.

### ToggleState QButton::state () const

Returns TRUE if the button is toggled; otherwise returns FALSE. See the "toggleState" property for details.

### void QButton::stateChanged ( int state )`[signal]`

This signal is emitted whenever a toggle button changes status. state is 2 if the button is on, 1 if it is in the "no change" state or 0 if the button is off.

This may be the result of a user action, toggle() slot activation, setState(), or because setOn() was called.

See also clicked().

### QString QButton::text () const

Returns the text shown on the button. See the "text" property for details.

### void QButton::toggle ()`[slot]`

Toggles the state of a toggle button.

See also on, setOn(), toggled() and toggleButton.

### void QButton::toggled ( bool on )`[signal]`

This signal is emitted whenever a toggle button changes status. on is TRUE if the button is on, or FALSE if the button is off.

This may be the result of a user action, toggle() slot activation, or because setOn() was called.

See also clicked().

Example: listbox/listbox.cpp.

## Property Documentation

### QKeySequence accel

This property holds the accelerator associated with the button.

This property is 0 if there is no accelerator set. If you set this property to 0 then any current accelerator is removed.

Set this property's value with setAccel() and get this property's value with accel().

### bool autoMask

This property holds whether the checkbox is automatically masked.

See also QWidget::autoMask.

### bool autoRepeat

This property holds whether autoRepeat is enabled.

If autoRepeat is enabled then the clicked() signal is emitted at regular intervals if the button is down. This property has no effect on toggle buttons.

Set this property's value with setAutoRepeat() and get this property's value with autoRepeat().

### bool checked

This property holds whether the checkbox is checked.

Set this property's value with setChecked() and get this property's value with isChecked().

### QPixmap pixmap

This property holds the pixmap shown on the button.

If the pixmap is monochrome (i.e., it is a QBitmap or its depth is 1) and it does not have a mask, this property will set the pixmap to be its own mask. The purpose of this is to draw transparent bitmaps which are important for toggle buttons, for example.

pixmap() returns 0 if no pixmap was set.

Set this property's value with setPixmap() and get this property's value with pixmap().

### QString text

This property holds the text shown on the button.

This property will return a null string if the button has no text. If the text has an ampersand ('&') in it, then an accelerator is automatically created for it using the character after the '&' as the accelerator key.

Set this property's value with setText() and get this property's value with text().

### bool tristate

This property holds whether the checkbox is a tri-state checkbox.

Set this property's value with setTristate() and get this property's value with isTristate().

This file is part of the Qt toolkit, copyright © 1995-2001 Trolltech, all rights reserved.