Qt Jambi Home

com.trolltech.qt.gui
Class QPushButton

java.lang.Object
  extended by com.trolltech.qt.QSignalEmitter
      extended by com.trolltech.qt.QtJambiObject
          extended by com.trolltech.qt.core.QObject
              extended by com.trolltech.qt.gui.QWidget
                  extended by com.trolltech.qt.gui.QAbstractButton
                      extended by com.trolltech.qt.gui.QPushButton
All Implemented Interfaces:
QPaintDeviceInterface, QtJambiInterface

public class QPushButton
extends QAbstractButton

The QPushButton widget provides a command button.

The push button, or command button, is perhaps the most commonly used widget in any graphical user interface. Push (click) a button to command the computer to perform some action, or to answer a question. Typical buttons are OK, Apply, Cancel, Close, Yes, No and Help.

A command button is rectangular and typically displays a text label describing its action. A shortcut key can be specified by preceding the preferred character with an ampersand in the text. For example:

    QPushButton *button = new QPushButton("&Download", this);

In this example the shortcut is Alt+D. See the QShortcut documentation for details (to display an actual ampersand, use '&&').

Push buttons display a textual label, and optionally a small icon. These can be set using the constructors and changed later using setText and setIcon. If the button is disabled the appearance of the text and icon will be manipulated with respect to the GUI style to make the button look "disabled".

A push button emits the signal clicked when it is activated by the mouse, the Spacebar or by a keyboard shortcut. Connect to this signal to perform the button's action. Push buttons also provide less commonly used signals, for example, pressed and released.

Command buttons in dialogs are by default auto-default buttons, i.e. they become the default push button automatically when they receive the keyboard input focus. A default button is a push button that is activated when the user presses the Enter or Return key in a dialog. You can change this with setAutoDefault. Note that auto-default buttons reserve a little extra space which is necessary to draw a default-button indicator. If you do not want this space around your buttons, call setAutoDefault(false).

Being so central, the button widget has grown to accommodate a great many variations in the past decade. The Microsoft style guide now shows about ten different states of Windows push buttons and the text implies that there are dozens more when all the combinations of features are taken into consideration.

The most important modes or states are:

As a general rule, use a push button when the application or dialog window performs an action when the user clicks on it (such as Apply, Cancel, Close and Help) and when the widget is supposed to have a wide, rectangular shape with a text label. Small, typically square buttons that change the state of the window rather than performing an action (such as the buttons in the top-right corner of the QFileDialog) are not command buttons, but tool buttons. Qt provides a special class (QToolButton) for these buttons.

If you need toggle behavior (see setCheckable) or a button that auto-repeats the activation signal when being pushed down like the arrows in a scroll bar (see setAutoRepeat), a command button is probably not what you want. When in doubt, use a tool button.

A variation of a command button is a menu button. These provide not just one command, but several, since when they are clicked they pop up a menu of options. Use the method setMenu to associate a popup menu with a push button.

Other classes of buttons are option buttons (see QRadioButton) and check boxes (see QCheckBox).

Screenshot of a Macintosh style push buttonA push button shown in the Macintosh widget style.

Note that when a button's width becomes smaller than 50 or its height becomes smaller than 30, the button's corners are changed from round to square. Use the setMinimumSize function to prevent this behavior.

Screenshot of a Windows XP style push buttonA push button shown in the Windows XP widget style.
Screenshot of a Plastique style push buttonA push button shown in the Plastique widget style.

In Qt, the QAbstractButton base class provides most of the modes and other API, and QPushButton provides GUI logic. See QAbstractButton for more information about the API.

See Also:
QToolButton, QRadioButton, QCheckBox, GUI Design Handbook: Push Button

Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.gui.QWidget
QWidget.RenderFlag, QWidget.RenderFlags
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I>
 
Field Summary
 
Fields inherited from class com.trolltech.qt.gui.QAbstractButton
clicked, pressed, released, toggled
 
Fields inherited from class com.trolltech.qt.gui.QWidget
customContextMenuRequested
 
Constructor Summary
QPushButton()
          Equivalent to QPushButton(0).
QPushButton(QIcon icon, java.lang.String text)
          Equivalent to QPushButton(icon, text, 0).
QPushButton(QIcon icon, java.lang.String text, QWidget parent)
          Constructs a push button with an icon and a text, and a parent.
QPushButton(QWidget parent)
          Constructs a push button with no text and a parent.
QPushButton(java.lang.String text)
          Equivalent to QPushButton(text, 0).
QPushButton(java.lang.String text, QWidget parent)
          Constructs a push button with the parent parent and the text text.
 
Method Summary
 boolean autoDefault()
          Returns whether the push button is an auto default button.
 boolean event(QEvent e)
          

This is the main event handler; it handles event arg__1. You can reimplement this function in a subclass, but we recommend using one of the specialized event handlers instead.

Key press and release events are treated differently from other events. event checks for Tab and Shift+Tab and tries to move the focus appropriately. If there is no widget to move the focus to (or the key press is not Tab or Shift+Tab), event calls keyPressEvent.

Mouse and tablet event handling is also slightly special: only when the widget is enabled, event will call the specialized handlers such as mousePressEvent; otherwise it will discard the event.

This function returns true if the event was recognized, otherwise it returns false. If the recognized event was accepted (see QEvent::accepted), any further processing such as event propagation to the parent widget stops.

protected  void focusInEvent(QFocusEvent arg__1)
          

This event handler can be reimplemented in a subclass to receive keyboard focus events (focus received) for the widget. The event is passed in the arg__1 parameter

A widget normally must setFocusPolicy to something other than Qt::NoFocus in order to receive focus events. (Note that the application programmer can call setFocus on any widget, even those that do not normally accept focus.)

The default implementation updates the widget (except for windows that do not specify a focusPolicy).

protected  void focusOutEvent(QFocusEvent arg__1)
          

This event handler can be reimplemented in a subclass to receive keyboard focus events (focus lost) for the widget. The events is passed in the arg__1 parameter.

A widget normally must setFocusPolicy to something other than Qt::NoFocus in order to receive focus events. (Note that the application programmer can call setFocus on any widget, even those that do not normally accept focus.)

The default implementation updates the widget (except for windows that do not specify a focusPolicy).

static QPushButton fromNativePointer(QNativePointer nativePointer)
          This function returns the QPushButton instance pointed to by nativePointer
protected  void initStyleOption(QStyleOptionButton option)
          Initialize option with the values from this QPushButton.
 boolean isDefault()
          Returns whether the push button is the default button.
 boolean isFlat()
          Returns whether the button border is raised.
protected  void keyPressEvent(QKeyEvent arg__1)
          

This event handler, for event arg__1, can be reimplemented in a subclass to receive key press events for the widget.

A widget must call setFocusPolicy to accept focus initially and have focus in order to receive a key press event.

If you reimplement this handler, it is very important that you ignore() the event if you do not understand it, so that the widget's parent can interpret it.

The default implementation closes popup widgets if the user presses Esc. Otherwise the event is ignored.

 QMenu menu()
          Returns the button's associated popup menu or 0 if no popup menu has been set.
 QSize minimumSizeHint()
          

Returns the recommended minimum size for the widget.

protected  void paintEvent(QPaintEvent arg__1)
          

This event handler can be reimplemented in a subclass to receive paint events which are passed in the arg__1 parameter.

A paint event is a request to repaint all or part of the widget. It can happen as a result of repaint or update, or because the widget was obscured and has now been uncovered, or for many other reasons.

Many widgets can simply repaint their entire surface when asked to, but some slow widgets need to optimize by painting only the requested region: QPaintEvent::region(). This speed optimization does not change the result, as painting is clipped to that region during event processing. QListView and QTableView do this, for example.

Qt also tries to speed up painting by merging multiple paint events into one. When update is called several times or the window system sends several paint events, Qt merges these events into one event with a larger region (see QRegion::united()). repaint does not permit this optimization, so we suggest using update whenever possible.

When the paint event occurs, the update region has normally been erased, so that you're painting on the widget's background.

The background can be set using setBackgroundRole and setPalette.

From Qt 4.0, QWidget automatically double-buffers its painting, so there's no need to write double-buffering code in paintEvent to avoid flicker.

Note: Under X11 it is possible to toggle the global double buffering by calling qt_x11_set_global_double_buffer(). Example usage:

    ...
    extern void qt_x11_set_global_double_buffer(bool);
    qt_x11_set_global_double_buffer(false);
    ...

Note: In general, one should refrain from calling update or repaint inside of paintEvent. For example, calling update or repaint on children inside a paintEvent results in undefined behavior; the child may or may not get a paint event.

 void setAutoDefault(boolean arg__1)
          Sets whether the push button is an auto default button to arg__1.
 void setDefault(boolean arg__1)
          Sets whether the push button is the default button to arg__1.
 void setFlat(boolean arg__1)
          Sets whether the button border is raised to arg__1.
 void setMenu(QMenu menu)
          Associates the popup menu menu with this push button.
 void showMenu()
          Shows (pops up) the associated popup menu.
 QSize sizeHint()
          

Returns the recommended size for the widget.

 
Methods inherited from class com.trolltech.qt.gui.QAbstractButton
animateClick, animateClick, autoExclusive, autoRepeat, autoRepeatDelay, autoRepeatInterval, changeEvent, checkStateSet, click, group, hitButton, icon, iconSize, isCheckable, isChecked, isDown, keyReleaseEvent, mouseMoveEvent, mousePressEvent, mouseReleaseEvent, nextCheckState, setAutoExclusive, setAutoRepeat, setAutoRepeatDelay, setAutoRepeatInterval, setCheckable, setChecked, setDown, setIcon, setIconSize, setShortcut, setShortcut, setShortcut, setText, shortcut, text, timerEvent, toggle
 
Methods inherited from class com.trolltech.qt.gui.QWidget
acceptDrops, accessibleDescription, accessibleName, actionEvent, actions, activateWindow, addAction, addActions, adjustSize, autoFillBackground, backgroundRole, baseSize, childAt, childAt, childrenRect, childrenRegion, clearFocus, clearMask, close, closeEvent, contentsRect, contextMenuEvent, contextMenuPolicy, createWinId, cursor, depth, destroy, destroy, destroy, devType, dragEnterEvent, dragLeaveEvent, dragMoveEvent, dropEvent, ensurePolished, enterEvent, focusNextChild, focusNextPrevChild, focusPolicy, focusPreviousChild, focusProxy, focusWidget, font, fontInfo, fontMetrics, foregroundRole, frameGeometry, frameSize, geometry, getContentsMargins, grabKeyboard, grabMouse, grabMouse, grabShortcut, grabShortcut, hasFocus, hasMouseTracking, height, heightForWidth, heightMM, hide, hideEvent, inputContext, inputMethodEvent, inputMethodQuery, insertAction, insertActions, isActiveWindow, isAncestorOf, isEnabled, isEnabledTo, isFullScreen, isHidden, isLeftToRight, isMaximized, isMinimized, isModal, isRightToLeft, isVisible, isVisibleTo, isWindow, isWindowModified, keyboardGrabber, layout, layoutDirection, leaveEvent, locale, logicalDpiX, logicalDpiY, lower, mapFrom, mapFromGlobal, mapFromParent, mapTo, mapToGlobal, mapToParent, mask, maximumHeight, maximumSize, maximumWidth, metric, minimumHeight, minimumSize, minimumWidth, mouseDoubleClickEvent, mouseGrabber, move, move, moveEvent, nextInFocusChain, normalGeometry, numColors, overrideWindowFlags, overrideWindowFlags, overrideWindowState, overrideWindowState, paintEngine, paintingActive, palette, parentWidget, physicalDpiX, physicalDpiY, pos, raise, rect, releaseKeyboard, releaseMouse, releaseShortcut, removeAction, render, render, render, render, render, repaint, repaint, repaint, repaint, resetInputContext, resize, resize, resizeEvent, restoreGeometry, saveGeometry, scroll, scroll, setAcceptDrops, setAccessibleDescription, setAccessibleName, setAttribute, setAttribute, setAutoFillBackground, setBackgroundRole, setBaseSize, setBaseSize, setContentsMargins, setContentsMargins, setContextMenuPolicy, setCursor, setDisabled, setEnabled, setFixedHeight, setFixedSize, setFixedSize, setFixedWidth, setFocus, setFocus, setFocusPolicy, setFocusProxy, setFont, setForegroundRole, setGeometry, setGeometry, setHidden, setInputContext, setLayout, setLayoutDirection, setLocale, setMask, setMask, setMaximumHeight, setMaximumSize, setMaximumSize, setMaximumWidth, setMinimumHeight, setMinimumSize, setMinimumSize, setMinimumWidth, setMouseTracking, setPalette, setParent, setParent, setParent, setShortcutAutoRepeat, setShortcutAutoRepeat, setShortcutEnabled, setShortcutEnabled, setSizeIncrement, setSizeIncrement, setSizePolicy, setSizePolicy, setStatusTip, setStyle, setStyleSheet, setTabOrder, setToolTip, setUpdatesEnabled, setVisible, setWhatsThis, setWindowFlags, setWindowFlags, setWindowIcon, setWindowIconText, setWindowModality, setWindowModified, setWindowOpacity, setWindowRole, setWindowState, setWindowState, setWindowTitle, show, showEvent, showFullScreen, showMaximized, showMinimized, showNormal, size, sizeIncrement, sizePolicy, stackUnder, statusTip, style, styleSheet, tabletEvent, testAttribute, toolTip, underMouse, unsetCursor, unsetLayoutDirection, unsetLocale, update, update, update, update, updateGeometry, updateMicroFocus, updatesEnabled, visibleRegion, whatsThis, wheelEvent, width, widthMM, window, windowFlags, windowIcon, windowIconText, windowModality, windowOpacity, windowRole, windowState, windowTitle, windowType, winId, x, y
 
Methods inherited from class com.trolltech.qt.core.QObject
blockSignals, childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, property, removeEventFilter, setObjectName, setParent, setProperty, signalsBlocked, startTimer, thread
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
disconnect, disconnect, signalSender
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QPushButton

public QPushButton(java.lang.String text)

Equivalent to QPushButton(text, 0).


QPushButton

public QPushButton(java.lang.String text,
                   QWidget parent)

Constructs a push button with the parent parent and the text text.


QPushButton

public QPushButton(QIcon icon,
                   java.lang.String text)

Equivalent to QPushButton(icon, text, 0).


QPushButton

public QPushButton(QIcon icon,
                   java.lang.String text,
                   QWidget parent)

Constructs a push button with an icon and a text, and a parent.

Note that you can also pass a QPixmap object as an icon (thanks to the implicit type conversion provided by C++).


QPushButton

public QPushButton()

Equivalent to QPushButton(0).


QPushButton

public QPushButton(QWidget parent)

Constructs a push button with no text and a parent.

Method Detail

autoDefault

public final boolean autoDefault()

Returns whether the push button is an auto default button.

If this property is set to true then the push button is an auto default button.

In some GUI styles a default button is drawn with an extra frame around it, up to 3 pixels or more. Qt automatically keeps this space free around auto-default buttons, i.e. auto-default buttons may have a slightly larger size hint.

This property's default is true for buttons that have a QDialog parent; otherwise it defaults to false.

See the default property for details of how default and auto-default interact.

See Also:
setAutoDefault

isDefault

public final boolean isDefault()

Returns whether the push button is the default button.

Default and autodefault buttons decide what happens when the user presses enter in a dialog.

A button with this property set to true (i.e., the dialog's default button,) will automatically be pressed when the user presses enter, with one exception: if an autoDefault button currently has focus, the autoDefault button is pressed. When the dialog has autoDefault buttons but no default button, pressing enter will press either the autoDefault button that currently has focus, or if no button has focus, the next autoDefault button in the focus chain.

In a dialog, only one push button at a time can be the default button. This button is then displayed with an additional frame (depending on the GUI style).

The default button behavior is provided only in dialogs. Buttons can always be clicked from the keyboard by pressing Spacebar when the button has focus.

If the default property is set to false on the current default button while the dialog is visible, a new default will automatically be assigned the next time a pushbutton in the dialog receives focus.

This property's default is false.


isFlat

public final boolean isFlat()

Returns whether the button border is raised.

This property's default is false. If this property is set, most styles will not paint the button background unless the button is being pressed. setAutoFillBackground can be used to ensure that the background is filled using the QPalette::Button brush.


menu

public final QMenu menu()

Returns the button's associated popup menu or 0 if no popup menu has been set.

See Also:
setMenu

setAutoDefault

public final void setAutoDefault(boolean arg__1)

Sets whether the push button is an auto default button to arg__1.

If this property is set to true then the push button is an auto default button.

In some GUI styles a default button is drawn with an extra frame around it, up to 3 pixels or more. Qt automatically keeps this space free around auto-default buttons, i.e. auto-default buttons may have a slightly larger size hint.

This property's default is true for buttons that have a QDialog parent; otherwise it defaults to false.

See the default property for details of how default and auto-default interact.

See Also:
autoDefault

setDefault

public final void setDefault(boolean arg__1)

Sets whether the push button is the default button to arg__1.

Default and autodefault buttons decide what happens when the user presses enter in a dialog.

A button with this property set to true (i.e., the dialog's default button,) will automatically be pressed when the user presses enter, with one exception: if an autoDefault button currently has focus, the autoDefault button is pressed. When the dialog has autoDefault buttons but no default button, pressing enter will press either the autoDefault button that currently has focus, or if no button has focus, the next autoDefault button in the focus chain.

In a dialog, only one push button at a time can be the default button. This button is then displayed with an additional frame (depending on the GUI style).

The default button behavior is provided only in dialogs. Buttons can always be clicked from the keyboard by pressing Spacebar when the button has focus.

If the default property is set to false on the current default button while the dialog is visible, a new default will automatically be assigned the next time a pushbutton in the dialog receives focus.

This property's default is false.

See Also:
isDefault

setFlat

public final void setFlat(boolean arg__1)

Sets whether the button border is raised to arg__1.

This property's default is false. If this property is set, most styles will not paint the button background unless the button is being pressed. setAutoFillBackground can be used to ensure that the background is filled using the QPalette::Button brush.

See Also:
isFlat

setMenu

public final void setMenu(QMenu menu)

Associates the popup menu menu with this push button. This turns the button into a menu button, which in some styles will produce a small triangle to the right of the button's text.

Ownership of the menu is not transferred to the push button.

Screenshot of a Plastique style push button with popup menu.Screenshot of a Cleanlooks style push button with popup menu.Push buttons with popup menus shown in the Plastique widget style (left) and Cleanlooks widget style (right).

See Also:
menu

showMenu

public final void showMenu()

Shows (pops up) the associated popup menu. If there is no such menu, this function does nothing. This function does not return until the popup menu has been closed by the user.


event

public boolean event(QEvent e)

This is the main event handler; it handles event arg__1. You can reimplement this function in a subclass, but we recommend using one of the specialized event handlers instead.

Key press and release events are treated differently from other events. event checks for Tab and Shift+Tab and tries to move the focus appropriately. If there is no widget to move the focus to (or the key press is not Tab or Shift+Tab), event calls keyPressEvent.

Mouse and tablet event handling is also slightly special: only when the widget is enabled, event will call the specialized handlers such as mousePressEvent; otherwise it will discard the event.

This function returns true if the event was recognized, otherwise it returns false. If the recognized event was accepted (see QEvent::accepted), any further processing such as event propagation to the parent widget stops.

Overrides:
event in class QAbstractButton
See Also:
closeEvent, focusInEvent, focusOutEvent, enterEvent, keyPressEvent, keyReleaseEvent, leaveEvent, mouseDoubleClickEvent, mouseMoveEvent, mousePressEvent, mouseReleaseEvent, moveEvent, paintEvent, resizeEvent, QObject::event, QObject::timerEvent

focusInEvent

protected void focusInEvent(QFocusEvent arg__1)

This event handler can be reimplemented in a subclass to receive keyboard focus events (focus received) for the widget. The event is passed in the arg__1 parameter

A widget normally must setFocusPolicy to something other than Qt::NoFocus in order to receive focus events. (Note that the application programmer can call setFocus on any widget, even those that do not normally accept focus.)

The default implementation updates the widget (except for windows that do not specify a focusPolicy).

Overrides:
focusInEvent in class QAbstractButton
See Also:
focusOutEvent, setFocusPolicy, keyPressEvent, keyReleaseEvent, event, QFocusEvent

focusOutEvent

protected void focusOutEvent(QFocusEvent arg__1)

This event handler can be reimplemented in a subclass to receive keyboard focus events (focus lost) for the widget. The events is passed in the arg__1 parameter.

A widget normally must setFocusPolicy to something other than Qt::NoFocus in order to receive focus events. (Note that the application programmer can call setFocus on any widget, even those that do not normally accept focus.)

The default implementation updates the widget (except for windows that do not specify a focusPolicy).

Overrides:
focusOutEvent in class QAbstractButton
See Also:
focusInEvent, setFocusPolicy, keyPressEvent, keyReleaseEvent, event, QFocusEvent

keyPressEvent

protected void keyPressEvent(QKeyEvent arg__1)

This event handler, for event arg__1, can be reimplemented in a subclass to receive key press events for the widget.

A widget must call setFocusPolicy to accept focus initially and have focus in order to receive a key press event.

If you reimplement this handler, it is very important that you ignore() the event if you do not understand it, so that the widget's parent can interpret it.

The default implementation closes popup widgets if the user presses Esc. Otherwise the event is ignored.

Overrides:
keyPressEvent in class QAbstractButton
See Also:
keyReleaseEvent, QKeyEvent::ignore, setFocusPolicy, focusInEvent, focusOutEvent, event, QKeyEvent, Tetrix Example

minimumSizeHint

public QSize minimumSizeHint()

Returns the recommended minimum size for the widget.

If the value of this property is an invalid size, no minimum size is recommended.

The default implementation of minimumSizeHint returns an invalid size if there is no layout for this widget, and returns the layout's minimum size otherwise. Most built-in widgets reimplement minimumSizeHint.

QLayout will never resize a widget to a size smaller than the minimum size hint unless minimumSize is set or the size policy is set to QSizePolicy::Ignore. If minimumSize is set, the minimum size hint will be ignored.

Overrides:
minimumSizeHint in class QWidget
See Also:
QSize::isValid, resize, setMinimumSize, sizePolicy

paintEvent

protected void paintEvent(QPaintEvent arg__1)

This event handler can be reimplemented in a subclass to receive paint events which are passed in the arg__1 parameter.

A paint event is a request to repaint all or part of the widget. It can happen as a result of repaint or update, or because the widget was obscured and has now been uncovered, or for many other reasons.

Many widgets can simply repaint their entire surface when asked to, but some slow widgets need to optimize by painting only the requested region: QPaintEvent::region(). This speed optimization does not change the result, as painting is clipped to that region during event processing. QListView and QTableView do this, for example.

Qt also tries to speed up painting by merging multiple paint events into one. When update is called several times or the window system sends several paint events, Qt merges these events into one event with a larger region (see QRegion::united()). repaint does not permit this optimization, so we suggest using update whenever possible.

When the paint event occurs, the update region has normally been erased, so that you're painting on the widget's background.

The background can be set using setBackgroundRole and setPalette.

From Qt 4.0, QWidget automatically double-buffers its painting, so there's no need to write double-buffering code in paintEvent to avoid flicker.

Note: Under X11 it is possible to toggle the global double buffering by calling qt_x11_set_global_double_buffer(). Example usage:

    ...
    extern void qt_x11_set_global_double_buffer(bool);
    qt_x11_set_global_double_buffer(false);
    ...

Note: In general, one should refrain from calling update or repaint inside of paintEvent. For example, calling update or repaint on children inside a paintEvent results in undefined behavior; the child may or may not get a paint event.

Specified by:
paintEvent in class QAbstractButton
See Also:
event, repaint, update, QPainter, QPixmap, QPaintEvent, Analog Clock Example

sizeHint

public QSize sizeHint()

Returns the recommended size for the widget.

If the value of this property is an invalid size, no size is recommended.

The default implementation of sizeHint returns an invalid size if there is no layout for this widget, and returns the layout's preferred size otherwise.

Overrides:
sizeHint in class QWidget
See Also:
QSize::isValid, minimumSizeHint, sizePolicy, setMinimumSize, updateGeometry

fromNativePointer

public static QPushButton fromNativePointer(QNativePointer nativePointer)
This function returns the QPushButton instance pointed to by nativePointer

Parameters:
nativePointer - the QNativePointer of which object should be returned.

initStyleOption

protected final void initStyleOption(QStyleOptionButton option)
Initialize option with the values from this QPushButton. This method is useful for subclasses when they need a QStyleOptionButton, but don't want to fill in all the information themselves.


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