QButton(3qt)QButton(3qt)NAMEQButton - The abstract base class of button widgets,
providing functionality common to buttons
#include <qbutton.h>
Inherits QWidget.
Inherited by QCheckBox, QPushButton, QRadioButton and
QToolButton.
Public Members
QButton ( QWidget * parent=0, const char * name=0, WFlags
f=0 )
~QButton ()
QString text () const
virtual void setText ( const QString & )
const QPixmap* pixmap () const
virtual void setPixmap ( const QPixmap & )
int accel () const
virtual void setAccel ( int )
bool isToggleButton () const
enum ToggleType { SingleShot, Toggle, Tristate }
ToggleType toggleType () const
virtual void setDown ( bool )
bool isDown () const
bool isOn () const
enum ToggleState { Off, NoChange, On }
ToggleState state () const
bool autoResize () const (obsolete)
virtual void setAutoResize ( bool ) (obsolete)
bool autoRepeat () const
virtual void setAutoRepeat ( bool )
bool isExclusiveToggle () const
QButtonGroup* group () const
Public Slots
void animateClick ()
void toggle ()
Signals
void pressed ()
void released ()
void clicked ()
void toggled ( bool )
void stateChanged ( int )
Protected Members
void setToggleButton ( bool )
virtual void setToggleType ( ToggleType )
void setOn ( bool )
virtual void setState ( ToggleState )
virtual bool hitButton ( const QPoint & pos ) const
Trolltech AS 13 June 2001 1
QButton(3qt)QButton(3qt)
virtual void drawButton ( QPainter * )
virtual void drawButtonLabel ( QPainter * )
virtual void paintEvent ( QPaintEvent * )
Properties
l l l l l
- - - - -
l l l l l.
Type Name READ WRITE Options
QString text text setText
QPixmap pixmap pixmap setPixmap
int accel accel setAccel
bool toggleButton isToggleButton
ToggleType toggleType toggleType
bool down isDown setDown DESIGNABLE false
bool on isOn
ToggleState toggleState state
bool autoResize autoResize setAutoResize
bool autoRepeat autoRepeat setAutoRepeat
bool exclusiveToggle isExclusiveToggle
DESCRIPTION
The QButton class is the abstract base class of button
widgets, providing functionality common to buttons.
The QButton class implements an abstract button, and lets
subclasses specify how to reply to user actions and how to
draw the button.
QButton provides both push and toggle buttons. The
QRadioButton and QCheckBox classes provide only toggle
buttons, QPushButton and QToolButton provide both toggle
and push buttons.
Any button can have either a text or pixmap label.
setText() sets the button to be a text button and
setPixmap() sets it to be a pixmap button. The text/pixmap
is manipulated as necessary to create "disabled"
appearance when the button is disabled.
QButton provides most of the states used for buttons:
isDown() determines whether the button is pressed down.
isOn() determines whether the button is on. Only toggle
buttons can be switched on and off (see below).
isEnabled() determines whether the button can be pressed
by the user.
setAutoRepeat() determines whether the button will
auto-repeat if the user holds it down.
Trolltech AS 13 June 2001 2
QButton(3qt)QButton(3qt)setToggleButton() determines whether the button is a
toggle button or not.
The difference between isDown() and isOn() is as follows:
When the user clicks a toggle button to toggle it on, the
button is first pressed, then released into on state. When
the user clicks it again (to toggle it off) the button
moves first to the pressed state, then to the off state
(isOn() and isDown() are both FALSE).
Default buttons (as used in many dialogs) are provided by
QPushButton::setDefault() and
QPushButton::setAutoDefault().
QButton provides four signals:
pressed() is emitted when the left mouse button is pressed
while the mouse cursor is inside the button.
released() is emitted when the left mouse button is
released.
clicked() is emitted when the button is first pressed then
released, or when the accelerator key is typed, or when
animateClick() is called.
toggled(bool) is emitted when the state of a toggle button
changes.
stateChanged(int) is emitted when the state of a tristate
toggle button changes.
If the button is a text button with "&" in its text,
QButton creates an automatic accelerator key. This code
creates a push button labelled "Rock & Roll" (where the c
is underscored). The button gets an automatic accelerator
key, Alt-C:
QPushButton *p = new QPushButton( "Ro&ck && Roll", this );
In this example, when the user presses Alt-C the button
will call animateClick().
You can also set a custom accelerator using the setAccel()
function. This is useful mostly for pixmap buttons since
they have no automatic accelerator.
QPushButton *p;
p->setPixmap( QPixmap("print.png") );
p->setAccel( ALT+Key_F7 );
All of the buttons provided by Qt (QPushButton,
QToolButton, QCheckBox and QRadioButton) can display both
text and pixmaps.
Trolltech AS 13 June 2001 3
QButton(3qt)QButton(3qt)
To subclass QButton, you have to reimplement at least
drawButton() (to draw the button's outskirts) and
drawButtonLabel() (to draw its text or pixmap). It is
generally advisable to reimplement sizeHint() as well, and
sometimes hitButton() (to determine whether a button press
is within the button).
To reduce flickering the QButton::paintEvent() sets up a
pixmap that the drawButton() function draws in. You should
not reimplement paintEvent() for a subclass of QButton
unless you want to take over all drawing.
See also QButtonGroup.
Examples: scrollview/scrollview.cpp
Member Type Documentation
QButton::ToggleState
This enum defines the state of a toggle button at any
moment. The possible values are:
Off - the button is in the "off" state
NoChange - the button is in the default/unchanged state
On - the button is in the "on" state
QButton::ToggleType
This enum type defines what a button can do in response to
a mouse/keyboard press:
SingleShot - pressing the button causes an action, then
the button returns to the unpressed state.
Toggle - pressing the button toggles it between an On and
and Off state.
Tristate - pressing the button cycles between the three
states On, Off and NoChange
MEMBER FUNCTION DOCUMENTATIONQButton::QButton ( QWidget * parent=0, const char * name=0,
WFlags f=0 )
Constructs a standard button with a parent widget and a
name.
If parent is a QButtonGroup, this constructor calls
QButtonGroup::insert().
QButton::~QButton ()
Destructs the button, deleting all its child widgets.
Trolltech AS 13 June 2001 4
QButton(3qt)QButton(3qt)int QButton::accel () const
Returns the accelerator key currently set for the button,
or 0 if no accelerator key has been set.
See also setAccel().
void QButton::animateClick () [slot]
Performs an animated click: The button is pressed and a
short while later released.
pressed(), released(), clicked(), toggled(), and
stateChanged() signals are emitted as appropriate.
This function does nothing if the button is disabled.
See also setAccel().
bool QButton::autoRepeat () const
Returns TRUE if the button is auto-repeating, else FALSE.
The default is FALSE.
See also setAutoRepeat().
bool QButton::autoResize () const
This function is obsolete. It is provided to keep old
source working, and will probably be removed in a future
version of Qt. We strongly advise against using it in new
code.
Strange pre-layout stuff.
Returns TRUE if auto-resizing is enabled, or FALSE if
auto-resizing is disabled.
Auto-resizing is disabled by default.
See also setAutoResize().
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, or when the accelerator key is
typed, or when animateClick() is called.
See also pressed(), released() and toggled().
void QButton::drawButton ( QPainter * ) [virtual protected]
Draws the button. The default implementation does nothing.
This virtual function is reimplemented by subclasses to
draw real buttons. At some point in time, these
reimplementations are supposed to call drawButtonLabel().
Trolltech AS 13 June 2001 5
QButton(3qt)QButton(3qt)
See also drawButtonLabel() and paintEvent().
Reimplemented in QRadioButton, QCheckBox, QToolButton and
QPushButton.
void QButton::drawButtonLabel ( QPainter * ) [virtual protected]
Draws the button text or pixmap.
This virtual function is reimplemented by subclasses to
draw real buttons. It's invoked by drawButton().
See also drawButton() and paintEvent().
Reimplemented in QRadioButton, QToolButton, QCheckBox and
QPushButton.
void QButton::enabledChange ( bool e ) [virtual protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QButton::focusInEvent ( QFocusEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
bool QButton::focusNextPrevChild ( bool next ) [virtual]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QButton::focusOutEvent ( QFocusEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
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 setGroup() and QButtonGroup.
bool QButton::hitButton ( const QPoint & pos ) const [virtual
protected]
Returns TRUE if pos is inside the clickable button
Trolltech AS 13 June 2001 6
QButton(3qt)QButton(3qt)
rectangle, or FALSE if it is outside.
Per default, the clickable area is the entire widget.
Subclasses may reimplement it, though.
Reimplemented in QRadioButton.
bool QButton::isDown () const
Returns TRUE if the button pressed down, or FALSE if it is
standing up.
See also setDown().
bool QButton::isExclusiveToggle () const
Returns TRUE if this button behaves exclusively inside a
QButtonGroup. In that case, this button can only be
toggled off by another button being toggled on.
bool QButton::isOn () const
Returns TRUE if this toggle button is switched on, or
FALSE if it is switched off.
See also setOn() and isToggleButton().
Examples: qmag/qmag.cpp
bool QButton::isToggleButton () const
Returns TRUE if the button is a toggle button.
See also setToggleButton().
void QButton::keyPressEvent ( QKeyEvent * e ) [virtual protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QButton::keyReleaseEvent ( QKeyEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QButton::mouseMoveEvent ( QMouseEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QButton::mousePressEvent ( QMouseEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
Trolltech AS 13 June 2001 7
QButton(3qt)QButton(3qt)
affected.
Reimplemented from QWidget.
void QButton::mouseReleaseEvent ( QMouseEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QButton::paintEvent ( QPaintEvent * event ) [virtual
protected]
Handles paint events for buttons. Small and typically
complex buttons (less than 300x100 pixels) are painted
double-buffered to reduce flicker. The actually drawing is
done in the virtual functions drawButton() and
drawButtonLabel().
See also drawButton() and drawButtonLabel().
Reimplemented from QWidget.
const QPixmap * QButton::pixmap () const
Returns the button pixmap, or 0 if the button has no
pixmap.
void QButton::pressed () [signal]
This signal is emitted when the button is pressed down.
See also released() and clicked().
void QButton::released () [signal]
This signal is emitted when the button is released.
See also pressed(), clicked() and toggled().
void QButton::setAccel ( int key ) [virtual]
Specifies an accelerator key for the button, or removes
the accelerator if key is 0.
Setting a button text containing a shortcut character (for
example the 'x' in E&xit) automatically defines an
ALT+letter accelerator for the button. You only need to
call this function in order to specify a custom
accelerator.
Example:
QPushButton *b1 = new QPushButton;
b1->setText( "&OK" ); // sets accel ALT+'O'
QPushButton *b2 = new QPushButton;
b2->setPixmap( printIcon ); // pixmap instead of text
b2->setAccel( CTRL+'P' ); // custom accel
Trolltech AS 13 June 2001 8
QButton(3qt)QButton(3qt)
See also accel(), setText() and QAccel.
void QButton::setAutoRepeat ( bool enable ) [virtual]
Turns on auto-repeat for the button if enable is TRUE, or
turns it off if enable is FALSE.
When auto-repeat is enabled, the clicked() signal is
emitted at regular intervals while the buttons is down.
setAutoRepeat() has no effect for toggle buttons.
See also isDown(), autoRepeat() and clicked().
void QButton::setAutoResize ( bool enable ) [virtual]
This function is obsolete. It is provided to keep old
source working, and will probably be removed in a future
version of Qt. We strongly advise against using it in new
code.
Strange pre-layout stuff.
Enables auto-resizing if enable is TRUE, or disables it if
enable is FALSE.
When auto-resizing is enabled, the button will resize
itself whenever the contents change.
See also autoResize() and adjustSize().
void QButton::setDown ( bool enable ) [virtual]
Sets the state of the button to pressed down if enable is
TRUE or to standing up if enable is FALSE.
If the button is a toggle button, it is not toggled. Call
toggle() as well if you need to do that. The pressed() and
released() signals are not emitted by this function.
This method is provided in case you need to reimplement
the mouse event handlers.
See also isDown(), setOn(), toggle() and toggled().
void QButton::setOn ( bool enable ) [protected]
Switches a toggle button on if enable is TRUE or off if
enable is FALSE. This function should be called only for
toggle buttons.
See also isOn() and isToggleButton().
void QButton::setPixmap ( const QPixmap & pixmap ) [virtual]
Sets the button to display pixmap
If pixmap is monochrome (i.e. it is a QBitmap or its depth
is 1) and it does not have a mask, this function sets the
Trolltech AS 13 June 2001 9
QButton(3qt)QButton(3qt)
pixmap to be its own mask. The purpose of this is to draw
transparent bitmaps, which is important for e.g. toggle
buttons.
See also pixmap(), setText(), setAccel() and
QPixmap::mask().
void QButton::setState ( ToggleState t ) [protected]
This protected function sets the button state into state t
but does not cause repainting.
See also setToggleType().
void QButton::setText ( const QString & text ) [virtual]
Sets the button to display text.
If the text contains an ampersand, QButton creates an
automatic accelerator for it, such as Alt-c for "&Cancel".
See also text(), setPixmap(), setAccel() and
QPixmap::mask().
Examples: xform/xform.cpp layout/layout.cpp qmag/qmag.cpp
void QButton::setToggleButton ( bool enable ) [protected]
Makes the button a toggle button if enable is TRUE, or a
normal button if enable is FALSE.
Note that this function is protected. It is called from
subclasses to enable the toggle functionality. QCheckBox
and QRadioButton are toggle buttons. QPushButton is
initially not a toggle button, but
QPushButton::setToggleButton() can be called to create
toggle buttons.
See also isToggleButton().
void QButton::setToggleType ( ToggleType type ) [protected]
Sets the type of toggling behavior. The default is
SingleShot.
Subclasses use this, and present it with a more
comfortable interface.
QButton::ToggleState QButton::state() const
Returns the state of the button.
See also ToggleState, ToggleType and setState().
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.
Trolltech AS 13 June 2001 10
QButton(3qt)QButton(3qt)
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 button text, or null string if the button has
no text.
See also setText().
void QButton::toggle () [slot]
if this is a toggle button, toggles it.
QButton::ToggleType QButton::toggleType() const
Returns the current toggle type.
See also setToggleType().
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().
SEE ALSO
http://doc.trolltech.com/qbutton.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2001 Trolltech AS,
http://www.trolltech.com. See the license file included
in the distribution for a complete license statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports
make our job much simpler. Thank you.
In case of content or formattting problems with this
manual page, please report them to qt-bugs@trolltech.com.
Please include the name of the manual page (qbutton.3qt)
and the Qt version (2.3.1).
Trolltech AS 13 June 2001 11
