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The QButton class is the abstract base class of button widgets, providing functionality common to buttons. More...
#include <qbutton.h>
Inherits QWidget.
Inherited by QCheckBox, QPushButton, QRadioButton and QToolButton.
| 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 |
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:
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:
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
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
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
Constructs a standard button with a parent widget and a name.
If parent is a QButtonGroup, this constructor calls QButtonGroup::insert().
Destructs the button, deleting all its child widgets.
Returns the accelerator key currently set for the button, or 0 if no accelerator key has been set.
See also setAccel().
[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().
Returns TRUE if the button is auto-repeating, else FALSE.
The default is FALSE.
See also setAutoRepeat().
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().
[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().
[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 QRadioButton, QCheckBox, QToolButton and QPushButton.
[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.
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[virtual]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
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.
[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.
Returns TRUE if the button pressed down, or FALSE if it is standing up.
See also setDown().
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.
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
Returns TRUE if the button is a toggle button.
See also setToggleButton().
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[virtual protected]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QWidget.
[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.
Returns the button pixmap, or 0 if the button has no pixmap.
[signal]This signal is emitted when the button is pressed down.
See also released() and clicked().
[signal]This signal is emitted when the button is released.
See also pressed(), clicked() and toggled().
[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.
[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().
[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().
[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().
[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().
[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().
[protected]This protected function sets the button state into state t but does not cause repainting.
See also setToggleType().
[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
[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().
[protected]Sets the type of toggling behavior. The default is SingleShot.
Subclasses use this, and present it with a more comfortable interface.
Returns the state of the button.
See also ToggleState, ToggleType and setState().
[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().
Returns the button text, or null string if the button has no text.
See also setText().
[slot]if this is a toggle button, toggles it.
Returns the current toggle type.
See also setToggleType().
[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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