QButton Class Reference
The QButton class is the abstract base class of button widgets, providing functionality common to buttons.
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#include <qbutton.h>
Inherits QWidget.
Inherited by QCheckBox, QPushButton, QRadioButton and QToolButton.
List of all member functions.
Public Members
Public Slots
Signals
Protected Members
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virtual voidÂ
setState ( ToggleState )Â
virtual boolÂ
hitButton ( const QPoint & pos ) const
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Properties
| Type | Name | READ | WRITE | Options
|
|---|
| QString | text | text | setText |
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| QPixmap | pixmap | pixmap | setPixmap |
|
| int | accel | accel | setAccel |
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| bool | toggleButton | isToggleButton | |
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| ToggleType | toggleType | toggleType | |
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| bool | down | isDown | setDown | DESIGNABLE false
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| bool | on | isOn | |
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| ToggleState | toggleState | state | |
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| bool | autoResize | autoResize | setAutoResize |
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| bool | autoRepeat | autoRepeat | setAutoRepeat |
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| bool | exclusiveToggle | isExclusiveToggle | |
|
Detailed 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.
- 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.
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
This enum defines the state of a toggle button at any moment. The possible values are:
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Off - the button is in the "off" state
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NoChange - the button is in the default/unchanged state
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On - the button is in the "on" state
This enum type defines what a button can do in response to a
mouse/keyboard press:
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SingleShot - pressing the button causes an action, then the
button returns to the unpressed state.
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Toggle - pressing the button toggles it between an On and
and Off state.
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Tristate - pressing the button cycles between the three
states On, Off and NoChange
Member Function Documentation
QButton::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.
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().
See also drawButtonLabel() and paintEvent().
Reimplemented in QToolButton, QPushButton, QRadioButton and QCheckBox.
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 QToolButton, QCheckBox, QPushButton and QRadioButton.
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 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 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
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 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:
layout/layout.cpp
xform/xform.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.
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().
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