QWidget(3qt)QWidget(3qt)NAME
QWidget - The base class of all user interface objects
#include <qwidget.h>
Inherits QObject and QPaintDevice.
Inherited by QButton, QComboBox, QDial, QDialog, QFrame,
QGLWidget, QHeader, QLineEdit, QMainWindow, QNPWidget,
QScrollBar, QSemiModal, QSizeGrip, QSlider, QStatusBar,
QTabBar, QTabWidget, QToolBar, QWorkspace and QXtWidget.
Public Members
QWidget ( QWidget * parent=0, const char * name=0, WFlags
f=0 )
~QWidget ()
WId winId () const
QStyle& style () const
void setStyle ( QStyle * )
bool isTopLevel () const
bool isModal () const
bool isPopup () const
bool isDesktop () const
bool isEnabled () const
bool isEnabledTo ( QWidget * ) const
bool isEnabledToTLW () const (obsolete)
QRect frameGeometry () const
const QRect& geometry () const
int x () const
int y () const
QPoint pos () const
QSize frameSize () const
QSize size () const
int width () const
int height () const
QRect rect () const
QRect childrenRect () const
QRegion childrenRegion () const
QSize minimumSize () const
QSize maximumSize () const
int minimumWidth () const
int minimumHeight () const
int maximumWidth () const
int maximumHeight () const
void setMinimumSize ( const QSize & )
virtual void setMinimumSize ( int minw, int minh )
void setMaximumSize ( const QSize & )
virtual void setMaximumSize ( int maxw, int maxh )
void setMinimumWidth ( int minw )
void setMinimumHeight ( int minh )
void setMaximumWidth ( int maxw )
void setMaximumHeight ( int maxh )
QSize sizeIncrement () const
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void setSizeIncrement ( const QSize & )
virtual void setSizeIncrement ( int w, int h )
QSize baseSize () const
void setBaseSize ( const QSize & )
void setBaseSize ( int basew, int baseh )
void setFixedSize ( const QSize & )
void setFixedSize ( int w, int h )
void setFixedWidth ( int w )
void setFixedHeight ( int h )
QPoint mapToGlobal ( const QPoint & ) const
QPoint mapFromGlobal ( const QPoint & ) const
QPoint mapToParent ( const QPoint & ) const
QPoint mapFromParent ( const QPoint & ) const
QPoint mapTo ( QWidget *, const QPoint & ) const
QPoint mapFrom ( QWidget *, const QPoint & ) const
QWidget* topLevelWidget () const
enum BackgroundMode { FixedColor, FixedPixmap,
NoBackground, PaletteForeground, PaletteButton,
PaletteLight, PaletteMidlight, PaletteDark,
PaletteMid, PaletteText, PaletteBrightText,
PaletteBase, PaletteBackground, PaletteShadow,
PaletteHighlight, PaletteHighlightedText,
PaletteButtonText, X11ParentRelative }
BackgroundMode backgroundMode () const
virtual void setBackgroundMode ( BackgroundMode )
const QColor& backgroundColor () const
const QColor& foregroundColor () const
virtual void setBackgroundColor ( const QColor & )
const QPixmap* backgroundPixmap () const
virtual void setBackgroundPixmap ( const QPixmap & )
const QColorGroup& colorGroup () const
const QPalette& palette () const
bool ownPalette () const
virtual void setPalette ( const QPalette & )
void unsetPalette ()
QFont font () const
bool ownFont () const
virtual void setFont ( const QFont & )
void unsetFont ()
QFontMetrics fontMetrics () const
QFontInfo fontInfo () const
enum PropagationMode { NoChildren, AllChildren, SameFont,
SamePalette = SameFont }
PropagationMode fontPropagation () const (obsolete)
virtual void setFontPropagation ( PropagationMode )
(obsolete)
PropagationMode palettePropagation () const (obsolete)
virtual void setPalettePropagation ( PropagationMode )
(obsolete)
const QCursor& cursor () const
bool ownCursor () const
virtual void setCursor ( const QCursor & )
virtual void unsetCursor ()
QString caption () const
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const QPixmap* icon () const
QString iconText () const
bool hasMouseTracking () const
virtual void setMask ( const QBitmap & )
virtual void setMask ( const QRegion & )
void clearMask ()
enum FocusPolicy { NoFocus = 0, TabFocus = 0x1, ClickFocus
= 0x2, StrongFocus = 0x3, WheelFocus = 0x7 }
bool isActiveWindow () const
virtual void setActiveWindow ()
bool isFocusEnabled () const
FocusPolicy focusPolicy () const
virtual void setFocusPolicy ( FocusPolicy )
bool hasFocus () const
virtual void setFocusProxy ( QWidget * )
QWidget* focusProxy () const
void grabMouse ()
void grabMouse ( const QCursor & )
void releaseMouse ()
void grabKeyboard ()
void releaseKeyboard ()
bool isUpdatesEnabled () const
virtual bool close ( bool alsoDelete )
bool isVisible () const
bool isVisibleTo ( QWidget * ) const
bool isVisibleToTLW () const (obsolete)
QRect visibleRect () const
bool isHidden () const
bool isMinimized () const
bool isMaximized () const
virtual QSize sizeHint () const
virtual QSize minimumSizeHint () const
virtual QSizePolicy sizePolicy () const
void setSizePolicy ( QSizePolicy )
virtual int heightForWidth ( int ) const
virtual void adjustSize ()
QLayout* layout () const
void updateGeometry ()
virtual void reparent ( QWidget * parent, WFlags, const
QPoint &, bool showIt=FALSE )
void reparent ( QWidget * parent, const QPoint &, bool
showIt=FALSE )
void erase ()
void erase ( int x, int y, int w, int h )
void erase ( const QRect & )
void erase ( const QRegion & )
void scroll ( int dx, int dy )
void scroll ( int dx, int dy, const QRect & )
void drawText ( int x, int y, const QString & )
void drawText ( const QPoint &, const QString & )
QWidget* focusWidget () const
QRect microFocusHint () const
bool acceptDrops () const
virtual void setAcceptDrops ( bool on )
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virtual void setAutoMask ( bool )
bool autoMask () const
enum BackgroundOrigin { WidgetOrigin, ParentOrigin }
void setBackgroundOrigin ( BackgroundOrigin )
BackgroundOrigin backgroundOrigin () const
virtual bool customWhatsThis () const
QWidget* parentWidget () const
bool testWState ( uint n ) const (internal)
bool testWFlags ( WFlags f ) const
void setPalette ( const QPalette &, bool iReallyMeanIt )
(obsolete)
void setFont ( const QFont &, bool iReallyMeanIt )
(obsolete)
Public Slots
virtual void setEnabled ( bool )
void setDisabled ( bool )
virtual void setCaption ( const QString & )
virtual void setIcon ( const QPixmap & )
virtual void setIconText ( const QString & )
virtual void setMouseTracking ( bool enable )
virtual void setFocus ()
void clearFocus ()
virtual void setUpdatesEnabled ( bool enable )
void update ()
void update ( int x, int y, int w, int h )
void update ( const QRect & )
void repaint ()
void repaint ( bool erase )
void repaint ( int x, int y, int w, int h, bool erase=TRUE
)
void repaint ( const QRect &, bool erase=TRUE )
void repaint ( const QRegion &, bool erase=TRUE )
virtual void show ()
virtual void hide ()
virtual void showMinimized ()
virtual void showMaximized ()
void showFullScreen ()
virtual void showNormal ()
virtual void polish ()
void constPolish () const
bool close ()
void raise ()
void lower ()
void stackUnder ( QWidget * )
virtual void move ( int x, int y )
void move ( const QPoint & )
virtual void resize ( int w, int h )
void resize ( const QSize & )
virtual void setGeometry ( int x, int y, int w, int h )
virtual void setGeometry ( const QRect & )
Static Public Members
void setTabOrder ( QWidget *, QWidget * )
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QWidget* mouseGrabber ()
QWidget* keyboardGrabber ()
QWidget* find ( WId )
QWidgetMapper* wmapper () (internal)
Protected Members
virtual bool event ( QEvent * )
virtual void mousePressEvent ( QMouseEvent * )
virtual void mouseReleaseEvent ( QMouseEvent * )
virtual void mouseDoubleClickEvent ( QMouseEvent * )
virtual void mouseMoveEvent ( QMouseEvent * )
virtual void wheelEvent ( QWheelEvent * )
virtual void keyPressEvent ( QKeyEvent * )
virtual void keyReleaseEvent ( QKeyEvent * )
virtual void focusInEvent ( QFocusEvent * )
virtual void focusOutEvent ( QFocusEvent * )
virtual void enterEvent ( QEvent * )
virtual void leaveEvent ( QEvent * )
virtual void paintEvent ( QPaintEvent * )
virtual void moveEvent ( QMoveEvent * )
virtual void resizeEvent ( QResizeEvent * )
virtual void closeEvent ( QCloseEvent * )
virtual void dragEnterEvent ( QDragEnterEvent * )
virtual void dragMoveEvent ( QDragMoveEvent * )
virtual void dragLeaveEvent ( QDragLeaveEvent * )
virtual void dropEvent ( QDropEvent * )
virtual void showEvent ( QShowEvent * )
virtual void hideEvent ( QHideEvent * )
virtual void customEvent ( QCustomEvent * )
virtual void updateMask ()
virtual void styleChange ( QStyle & )
virtual void enabledChange ( bool )
virtual void backgroundColorChange ( const QColor & )
virtual void backgroundPixmapChange ( const QPixmap & )
virtual void paletteChange ( const QPalette & )
virtual void fontChange ( const QFont & )
virtual int metric ( int ) const
virtual void create ( WId = 0, bool initializeWindow =
TRUE, bool destroyOldWindow = TRUE )
virtual void destroy ( bool destroyWindow = TRUE, bool
destroySubWindows = TRUE )
uint getWState () const (internal)
virtual void setWState ( uint ) (internal)
void clearWState ( uint n ) (internal)
WFlags getWFlags () const
virtual void setWFlags ( WFlags )
void clearWFlags ( WFlags n )
virtual void setFRect ( const QRect & ) (internal)
virtual void setCRect ( const QRect & ) (internal)
virtual bool focusNextPrevChild ( bool next )
QWExtra* extraData () (internal)
QTLWExtra* topData () (internal)
QFocusData* focusData ()
virtual void setKeyCompression ( bool )
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virtual void setMicroFocusHint ( int x, int y, int w, int
h, bool text=TRUE )
Properties
Type Name READ WRITE Options
--------------------------------------------------------------------------------------------------
bool isTopLevel isTopLevel
bool isModal isModal
bool isPopup isPopup
bool isDesktop isDesktop
bool enabled isEnabled setEnabled
QRect geometry geometry setGeometry
QRect frameGeometry frameGeometry
int x x
int y y
QPoint pos pos
QSize frameSize frameSize
QSize size size resize DESIGNABLE false
int width width
int height height
QRect rect rect
QRect childrenRect childrenRect
QRegion childrenRegion childrenRegion
QSizePolicy sizePolicy sizePolicy setSizePolicy
QSize minimumSize minimumSize setMinimumSize
QSize maximumSize maximumSize setMaximumSize
int minimumWidth minimumWidth setMinimumWidth STORED false
int minimumHeight minimumHeight setMinimumHeight STORED false
int maximumWidth maximumWidth setMaximumWidth STORED false
int maximumHeight maximumHeight setMaximumHeight STORED false
QSize sizeIncrement sizeIncrement setSizeIncrement
QSize baseSize baseSize setBaseSize
BackgroundMode backgroundMode backgroundMode setBackgroundMode DESIGNABLE false
QColor backgroundColor backgroundColor setBackgroundColor DESIGNABLE false
QColor foregroundColor foregroundColor
QPixmap backgroundPixmap backgroundPixmap setBackgroundPixmap DESIGNABLE false
QColorGroup colorGroup colorGroup
QPalette palette palette setPalette RESET unsetPalette
bool ownPalette ownPalette
QFont font font setFont RESET unsetFont
bool ownFont ownFont
QCursor cursor cursor setCursor RESET unsetCursor
bool ownCursor ownCursor
QString caption caption setCaption
QPixmap icon icon setIcon
QString iconText iconText setIconText
bool mouseTracking hasMouseTracking setMouseTracking
bool isActiveWindow isActiveWindow
bool focusEnabled isFocusEnabled
FocusPolicy focusPolicy focusPolicy setFocusPolicy
bool focus hasFocus
bool updatesEnabled isUpdatesEnabled setUpdatesEnabled DESIGNABLE false
bool visible isVisible
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QRect visibleRect visibleRect
bool hidden isHidden
bool minimized isMinimized
QSize sizeHint sizeHint
QSize minimumSizeHint minimumSizeHint
QRect microFocusHint microFocusHint
bool acceptDrops acceptDrops setAcceptDrops
bool autoMask autoMask setAutoMask
BackgroundOrigin backgroundOrigin backgroundOrigin setBackgroundOrigin
bool customWhatsThis customWhatsThis
DESCRIPTION
The QWidget class is the base class of all user interface
objects.
The widget is the atom of the user interface: It receives
mouse, keyboard and other events from the window system,
and paints a representation of itself on the screen. Every
widget is rectangular, and they are sorted in a Z-order. A
widget is clipped by its parent and by the widgets in
front of it.
A widget that isn't embedded in a parent widget is called
a top-level widget. Usually, top-level widgets are windows
with a frame and a title bar (though it is also possible
to create top level widgets without such decoration by the
use of widget flags). In Qt, QMainWindow and the various
subclasses of QDialog are the most common top-level
windows.
A widget without a parent widget is always a top-level
widget.
The opposite of top-level widgets are child widgets. Those
are child windows in their parent widgets. You usually
cannot distinguish a child widget from its parent
visually. Most other widgets in Qt are useful only as
child widgets. (You can make a e.g. button into a top-
level widget, but most people prefer to put their buttons
in e.g. dialogs.)
QWidget has many member functions, but some of them have
little direct functionality - for example it has a font
but never uses it itself. There are many subclasses which
provide real functionality, as diverse as QPushButton,
QListBox and QTabDialog.
Groups of functions:
Window functions: show(), hide(), raise(), lower(),
close().
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Top level windows: caption(), setCaption(), icon(),
setIcon(), iconText(), setIconText(), isActiveWindow(),
setActiveWindow(), showMinimized(). showMaximized(),
showFullScreen(), showNormal().
Window contents: update(), repaint(), erase(), scroll(),
updateMask().
Geometry: pos(), size(), rect(), x(), y(), width(),
height(), sizePolicy(), setSizePolicy(), sizeHint(),
updateGeometry(), layout(), move(), resize(),
setGeometry(), frameGeometry(), geometry(),
childrenRect(), adjustSize(), mapFromGlobal(),
mapFromParent()mapToGlobal(), mapToParent(),
maximumSize(), minimumSize(), sizeIncrement(),
setMaximumSize(), setMinimumSize(), setSizeIncrement(),
setBaseSize(), setFixedSize()
Mode: isVisible(), isVisibleTo(), visibleRect(),
isMinimized(), isDesktop(), isEnabled(), isEnabledTo(),
isModal(), isPopup(), isTopLevel(), setEnabled(),
hasMouseTracking(), setMouseTracking(),
isUpdatesEnabled(), setUpdatesEnabled(),
Look and feel: style(), setStyle(), cursor(), setCursor()font(), setFont(), palette(), setPalette(),
backgroundMode(), setBackgroundMode(), backgroundPixmap(),
setBackgroundPixmap(), setTranslateBackground(),
backgroundColor(), colorGroup(), fontMetrics(),
fontInfo().
Keyboard focus functions: isFocusEnabled(),
setFocusPolicy(), focusPolicy(), hasFocus(), setFocus(),
clearFocus(), setTabOrder(), setFocusProxy().
Mouse and keyboard grabbing: grabMouse(), releaseMouse(),
grabKeyboard(), releaseKeyboard(), mouseGrabber(),
keyboardGrabber().
Event handlers: event(), mousePressEvent(),
mouseReleaseEvent(), mouseDoubleClickEvent(),
mouseMoveEvent(), keyPressEvent(), keyReleaseEvent(),
focusInEvent(), focusOutEvent(), wheelEvent(),
enterEvent(), leaveEvent(), paintEvent(), moveEvent(),
resizeEvent(), closeEvent(), dragEnterEvent(),
dragMoveEvent(), dragLeaveEvent(), dropEvent(),
childEvent(), showEvent(), hideEvent(), customEvent().
Change handlers: backgroundColorChange(),
backgroundPixmapChange(), enabledChange(), fontChange(),
paletteChange(), styleChange().
System functions: parentWidget(), topLevelWidget(),
reparentolish((), winId(), find(), metric().
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Internal kernel functions: setFRect(), setCRect(),
focusNextPrevChild(), wmapper(), clearWFlags(),
getWFlags(), setWFlags(), testWFlags().
What's this help: customWhatsThis()
Every widget's constructor accepts two or three standard
arguments:
QWidget *parent = 0 is the parent of the new widget. If it
is 0 (the default), the new widget will be a top-level
window. If not, it will be a child of parent, and be
constrained by parent's geometry (Unless you specify
WType_TopLevel as widget flag).
const char *name = 0 is the widget name of the new widget.
You can access it using name(). The widget name is little
used by programmers but is quite useful with GUI builders
such as the Qt Designer (you can name a widget in the
builder, and connect() to it by name in your code). The
dumpObjectTree() debugging function also uses it.
WFlags f = 0 (where available) sets the widget flags; the
default is good for almost all widgets, but to get e.g.
top-level widgets without a window system frame you must
use special flags.
The tictac/tictac.cpp example program is good example of a
simple widget. It contains a few event handlers (as all
widgets must), a few custom routines that are peculiar to
it (as all useful widgets must), and has a few children
and connections. Everything it does is done in response to
an event: This is by far the most common way to design GUI
applications.
You will need to supply the content for your widgets
yourself, but here is a brief run-down of the events,
starting with the most common ones:
paintEvent() - called whenever the widget needs to be
repainted. Every widget which displays output must
implement it, and it is sensible to never paint on the
screen outside paintEvent().
resizeEvent() - called when the widget has been resized.
mousePressEvent() - called when a mouse button is pressed.
There are six mouse-related events, mouse press and mouse
release events are by far the most important. A widget
receives mouse press events when the widget is inside it,
or when it has grabbed the mouse using grabMouse().
mouseReleaseEvent() - called when a mouse button is
released. A widget receives mouse release events when it
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has received the corresponding mouse press event. This
means that if the user presses the mouse inside your
widget, then drags the mouse to somewhere else, then
releases, your widget receives the release event. There is
one exception, however: If a popup menu appears while the
mouse button is held down, that popup steals the mouse
events at once.
mouseDoubleClickEvent() - not quite as obvious as it might
seem. If the user double-clicks, the widget receives a
mouse press event (perhaps a mouse move event or two if
he/she does not hold the mouse quite steady), a mouse
release event and finally this event. It is not possible
to distinguish a click from a double click until you've
seen whether the second click arrives. (This is one reason
why most GUI books recommend that double clicks be an
extension of single clicks, rather than trigger a
different action.)
If your widget only contains child widgets, you probably
do not need to implement any event handlers.
Widgets that accept keyboard input need to reimplement a
few more event handlers:
keyPressEvent() - called whenever a key is pressed, and
again when a key has been held down long enough for it to
auto-repeat. Note that the Tab and shift-Tab keys are only
passed to the widget if they are not used by the
focus-change mechanisms. To force those keys to be
processed by your widget, you must reimplement
QWidget::event().
focusInEvent() - called when the widget gains keyboard
focus (assuming you have called setFocusPolicy(), of
course). Well written widgets indicate that they own the
keyboard focus in a clear but discreet way.
focusOutEvent() - called when the widget loses keyboard
focus.
Some widgets will need to reimplement some more obscure
event handlers, too:
mouseMoveEvent() - called whenever the mouse moves while a
button is held down. This is useful for e.g. dragging. If
you call setMouseTracking(TRUE), you get mouse move events
even when no buttons are held down. (Note that
applications which make use of mouse tracking are often
not very useful on low-bandwidth X connections.)
keyReleaseEvent() - called whenever a key is released, and
also while it is held down if the key is auto-repeating.
In that case the widget receives a key release event and
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immediately a key press event for every repeat. Note that
the Tab and shift-Tab keys are only passed to the widget
if they are not used by the focus-change mechanisms. To
force those keys to be processed by your widget, you must
reimplement QWidget::event().
wheelEvent()-- called whenever the user turns the mouse
wheel while the widget has the focus.
enterEvent() - called when the mouse enters the widget's
screen space. (This excludes screen space owned by any
children of the widget.)
leaveEvent() - called when the mouse leaves the widget's
screen space.
moveEvent() - called when the widget has been moved
relative to its parent.
closeEvent() - called when the user closes the widget (or
when close() is called).
There are also some really obscure events. They are listed
in qevent.h and you need to reimplement event() to handle
them. The default implementation of event() handles Tab
and shift-Tab (to move the keyboard focus), and passes on
most other events to one of the more specialized handlers
above.
When writing a widget, there are a few more things to look
out for.
In the constructor, be sure to set up your member
variables early on, before there's any chance that you
might receive an event.
It is almost always useful to reimplement sizeHint() and
to set the correct size policy with setSizePolicy(), so
users of your class can set up layout management more
easily. A size policy lets you supply good defaults for
the layout management handling, so that other widgets can
contain and manage yours easily. sizeHint() indicates a
"good" size for the widget.
If your widget is a top-level window, setCaption() and
setIcon() set the title bar and icon respectively.
See also QEvent, QPainter, QGridLayout and QBoxLayout.
Examples: iconview/main.cpp drawlines/connect.cpp
mainlyQt/editor.cpp xform/xform.cpp layout/layout.cpp
i18n/main.cpp popup/popup.cpp menu/menu.cpp
progress/progress.cpp qmag/qmag.cpp splitter/splitter.cpp
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forever/forever.cpp desktop/desktop.cpp
scrollview/scrollview.cpp customlayout/main.cpp
Member Type Documentation
QWidget::BackgroundMode
This enum describes how the background of a widget
changes, as the widget's palette changes.
The background is what the widget contains when
paintEvent() is called. To minimize flicker, this should
be the most common color or pixmap in the widget. For
PaletteBackground, use colorGroup().brush(
QColorGroup::Background ), and so on. There are also three
special values, listed at the end:
PaletteForeground
PaletteBackground
PaletteButton
PaletteLight
PaletteMidlight
PaletteDark
PaletteMid
PaletteText
PaletteBrightText
PaletteButtonText
PaletteBase
PaletteShadow
PaletteHighlight
PaletteHighlightedText
NoBackground - the widget is not cleared before
paintEvent(). If the widget's paint event always draws on
all the pixels, using this mode can be both fast and
flicker-free.
FixedColor - the widget is cleared to a fixed color,
normally different from all the ones in the palette(). Set
using setBackgroundColor().
FixedPixmap - the widget is cleared to a fixed pixmap,
normally different from all the ones in the palette(). Set
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using setBackgroundPixmap().
FixedColor and FixedPixmap sometimes are just the right
thing, but if you use them, make sure that your
application looks right when the desktop color scheme has
been changed. (On X11, a quick way to test is e.g.
"./yourapp -bg paleblue". On Windows, you have to use the
control panel.)
See also setBackgroundMode(), backgroundMode(),
setBackgroundPixmap() and setBackgroundColor().
QWidget::BackgroundOrigin
This enum defines the origin used to draw a widget's
background pixmap.
WidgetOrigin - the pixmap is drawn in the widget's
coordinate system.
ParentOrigin - the pixmap is drawn in the parent's
coordinate system.
QWidget::FocusPolicy
This enum type defines the various policies a widget can
have with respect to acquiring keyboard focus.
The policy can be:
QWidget::TabFocus - the widget accepts focus by tabbing.
QWidget::ClickFocus - the widget accepts focus by
clicking.
QWidget::StrongFocus - the widget accepts focus by both
tabbing and clicking.
QWidget::WheelFocus - like StrongFocus plus the widget
accepts focus by using the mouse wheel.
QWidget::NoFocus - the widget does not accept focus.
QWidget::PropagationMode
This member 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.
This enum used to determine how fonts and palette changes
are propagated to children of a widget.
MEMBER FUNCTION DOCUMENTATIONQWidget::QWidget ( QWidget * parent=0, const char * name=0,
WFlags f=0 )
Constructs a widget which is a child of parent, with the
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name name and widget flags set to f.
If parent is 0, the new widget becomes a top-level window.
If parent is another widget, this widget becomes a child
window inside parent. The new widget is deleted when
parent is.
The name is sent to the QObject constructor.
The widget flags argument f is normally 0, but it can be
set to customize the window frame of a top-level widget
(i.e. parent must be zero). To customize the frame, set
the WStyle_Customize flag OR'ed with any of the
Qt::WidgetFlags.
Note that the X11 version of Qt may not be able to deliver
all combinations of style flags on all systems. This is
because on X11, Qt can only ask the window manager, and
the window manager can override the application's
settings. On Windows, Qt can set whatever flags you want.
Example:
QLabel *spashScreen = new QLabel( 0, "mySplashScreen",
WStyle_Customize | WStyle_NoBorder |
WStyle_Tool );
QWidget::~QWidget ()
Destructs the widget.
All children of this widget are deleted first. The
application exits if this widget is (was) the main widget.
bool QWidget::acceptDrops () const
Returns TRUE if drop events are enabled for this widget.
See also setAcceptDrops().
void QWidget::adjustSize () [virtual]
Adjusts the size of the widget to fit the contents.
Uses sizeHint() if valid (i.e if the size hint's width and
height are equal to or greater than 0), otherwise sets the
size to the children rectangle (the union of all child
widget geometries).
See also sizeHint() and childrenRect().
Examples: xform/xform.cpp
Reimplemented in QMessageBox.
bool QWidget::autoMask () const
Returns whether or not the widget has the auto mask
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feature enabled.
See also setAutoMask(), updateMask(), setMask() and
clearMask().
const QColor & QWidget::backgroundColor () const
Returns the background color of this widget, which is
normally set implicitly by setBackgroundMode(), but can
also be set explicitly by setBackgroundColor().
If there is a background pixmap (set using
setBackgroundPixmap()), then the return value of this
function is indeterminate.
See also setBackgroundColor(), foregroundColor(),
colorGroup() and palette().
Examples: grapher/grapher.cpp xform/xform.cpp
void QWidget::backgroundColorChange ( const QColor &
oldBackgroundColor ) [virtual protected]
This virtual function is called from setBackgroundColor().
oldBackgroundColor is the previous background color; you
can get the new background color from backgroundColor().
Reimplement this function if your widget needs to know
when its background color changes. You will almost
certainly need to call this implementation of the
function.
See also setBackgroundColor(), backgroundColor(),
setPalette(), repaint() and update().
QWidget::BackgroundMode QWidget::backgroundMode() const
Returns the mode most recently set by setBackgroundMode().
The default is PaletteBackground.
See also BackgroundMode and setBackgroundMode().
QWidget::BackgroundOrigin QWidget::backgroundOrigin() const
Returns the current background origin.
See also setBackgroundOrigin().
const QPixmap * QWidget::backgroundPixmap () const
Returns the background pixmap if one has been set. If the
widget has backgroundMode() NoBackground, the return value
is a pixmap for which QPixmao:isNull() is true. If the
widget has no pixmap is the background, the return value
is a null pointer.
See also setBackgroundPixmap() and setBackgroundMode().
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QWidget(3qt)QWidget(3qt)void QWidget::backgroundPixmapChange ( const QPixmap &
oldBackgroundPixmap ) [virtual protected]
This virtual function is called from
setBackgroundPixmap(). oldBackgroundPixmap is the previous
background pixmap; you can get the new background pixmap
from backgroundPixmap().
Reimplement this function if your widget needs to know
when its background pixmap changes. You will almost
certainly need to call this implementation of the
function.
See also setBackgroundPixmap(), backgroundPixmap(),
repaint() and update().
QSize QWidget::baseSize () const
Returns the widget base size
The base size is used to calculate a proper widget size in
case the widget defines sizeIncrement().
See also setBaseSize() and setSizeIncrement().
QString QWidget::caption () const
Returns the widget caption. If no caption has been set
(common for child widgets), this functions returns a null
string.
See also setCaption(), icon(), iconText() and
QString::isNull().
QRect QWidget::childrenRect () const
Returns the bounding rectangle of the widget's children.
Explicitely hidden children are excluded.
See also childrenRegion().
QRegion QWidget::childrenRegion () const
Returns the combined region of the widget's children
geometry().
Explicitely hidden children are excluded.
See also childrenRect().
void QWidget::clearFocus () [slot]
Takes keyboard input focus from the widget.
If the widget has active focus, a focus out event is sent
to this widget to tell it that it is about to lose the
focus.
This widget must enable focus setting in order to get the
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QWidget(3qt)QWidget(3qt)
keyboard input focus, i.e. it must call setFocusPolicy().
See also hasFocus(), setFocus(), focusInEvent(),
focusOutEvent(), setFocusPolicy() and
QApplication::focusWidget().
void QWidget::clearMask ()
Removes any mask set by setMask().
See also setMask().
void QWidget::clearWFlags ( WFlags f ) [protected]
Clears the widget flags f.
Widget flags are a combination of Qt::WidgetFlags.
See also testWFlags(), getWFlags() and setWFlags().
bool QWidget::close () [slot]
Closes this widget. Returns TRUE if the widget was closed,
otherwise FALSE.
First it sends the widget a QCloseEvent. The widget is
hidden if it accepts the close event. The default
implementation of QWidget::closeEvent() accepts the close
event.
The QApplication::lastWindowClosed() signal is emitted
when the last visible top level widget is closed.
See also close(bool).
Examples: popup/popup.cpp
bool QWidget::close ( bool alsoDelete ) [virtual]
Closes this widget. Returns TRUE if the widget was closed,
otherwise FALSE.
If alsoDelete is TRUE or the widget has the
WDestructiveClose widget flag, the widget is also deleted.
The widget can prevent itself from being closed by
rejecting the QCloseEvent it gets.
The QApplication::lastWindowClosed() signal is emitted
when the last visible top level widget is closed.
Note that closing the QApplication::mainWidget()
terminates the application.
See also closeEvent(), QCloseEvent, hide(),
QApplication::quit(), QApplication::setMainWidget() and
QApplication::lastWindowClosed().
Trolltech AS 13 June 2001 17
QWidget(3qt)QWidget(3qt)void QWidget::closeEvent ( QCloseEvent * e ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget close events.
The default implementation calls e->accept(), which hides
this widget. See the QCloseEvent documentation for more
details.
See also event(), hide(), close() and QCloseEvent.
Reimplemented in QPopupMenu, QDialog and QProgressDialog.
const QColorGroup & QWidget::colorGroup () const
Returns the current color group of the widget palette.
The color group is determined by the state of the widget.
A disabled widget returns the QPalette::disabled() color
group, a widget in the window with keyboard focus returns
the QPalette::active() color group, and all inactive
widgets return the QPalette::inactive() color group.
See also palette() and setPalette().
void QWidget::constPolish () const [slot]
Ensures that the widget is properly initialized by calling
polish().
Call constPolish() from functions like sizeHint() that
depends on the widget being initialized, and that may be
called before show().
Warning: Do not call constPolish() on a widget from inside
that widget's constructor.
See also polish().
void QWidget::create ( WId window = 0, bool initializeWindow =
TRUE, bool destroyOldWindow = TRUE ) [virtual protected]
Creates a new widget window if window is null, otherwise
sets the widget's window to window.
Initializes the window (sets the geometry etc.) if
initializeWindow is TRUE. If initializeWindow is FALSE, no
initialization is performed. This parameter makes only
sense if window is a valid window.
Destroys the old window if destroyOldWindow is TRUE. If
destroyOldWindow is FALSE, you are responsible for
destroying the window yourself (using platform native
code).
The QWidget constructor calls create(0,TRUE,TRUE) to
create a window for this widget.
Trolltech AS 13 June 2001 18
QWidget(3qt)QWidget(3qt)const QCursor & QWidget::cursor () const
Returns the widget cursor. If no cursor has been set the
parent widget's cursor is returned.
See also setCursor() and unsetCursor();.
void QWidget::customEvent ( QCustomEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive custom events. Custom events are user-defined
events with a type value at least as large as the "User"
item of the QEvent::Type enum, and is typically a
QCustomEvent or QCustomEvent subclass.
See also event() and QCustomEvent.
bool QWidget::customWhatsThis () const [virtual]
Returns whether the widget wants to handle What's This
help manually. The default implementation returns FALSE,
which means the widget will not receive any events in
Whats This mode.
The widget may leave Whats This mode by calling
QWhatsThis::leaveWhatsThisMode(), with or without actually
displaying any help text.
You may also reimplement customWhatsThis() if your widget
is a so-called "passive interactor" that is supposed to
work under all circumstances. Simply don't call
QWhatsThis::leaveWhatsThisMode() in that case.
See also QWhatsThis::inWhatsThisMode() and
QWhatsThis::leaveWhatsThisMode().
Reimplemented in QPopupMenu and QMenuBar.
void QWidget::destroy ( bool destroyWindow = TRUE, bool
destroySubWindows = TRUE ) [virtual protected]
Frees up window system resources. Destroys the widget
window if destroyWindow is TRUE.
destroy() calls itself recursively for all the child
widgets, passing destroySubWindows for the destroyWindow
parameter. To have more control over destruction of
subwidgets, destroy subwidgets selectively first.
This function is usually called from the QWidget
destructor.
void QWidget::dragEnterEvent ( QDragEnterEvent * ) [virtual
protected]
This event handler is called when a drag is in progress
and the mouse enters this widget.
See the Drag-and-drop documentation for an overview of how
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QWidget(3qt)QWidget(3qt)
to provide drag-and-drop in your application.
See also QTextDrag, QImageDrag and QDragEnterEvent.
Reimplemented in QMultiLineEdit and QLineEdit.
void QWidget::dragLeaveEvent ( QDragLeaveEvent * ) [virtual
protected]
This event handler is called when a drag is in progress
and the mouse leaves this widget.
See the Drag-and-drop documentation for an overview of how
to provide drag-and-drop in your application.
See also QTextDrag, QImageDrag and QDragLeaveEvent.
Reimplemented in QMultiLineEdit.
void QWidget::dragMoveEvent ( QDragMoveEvent * ) [virtual
protected]
This event handler is called when a drag is in progress
and the mouse enters this widget, and whenever it moves
within the widget.
See the Drag-and-drop documentation for an overview of how
to provide drag-and-drop in your application.
See also QTextDrag, QImageDrag and QDragMoveEvent.
Reimplemented in QMultiLineEdit.
void QWidget::drawText ( int x, int y, const QString & str )
Writes str at position x,y.
The y position is the base line position of the text. The
text is drawn using the default font and the default
foreground color.
This function is provided for convenience. You will
generally get more flexible results and often higher speed
by using a a painter instead.
See also setFont(), foregroundColor() and
QPainter::drawText().
void QWidget::drawText ( const QPoint & pos, const QString & str
)
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::dropEvent ( QDropEvent * ) [virtual protected]
This event handler is called when the drag is dropped on
this widget.
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QWidget(3qt)QWidget(3qt)
See the Drag-and-drop documentation for an overview of how
to provide drag-and-drop in your application.
See also QTextDrag, QImageDrag and QDropEvent.
Reimplemented in QLineEdit and QMultiLineEdit.
void QWidget::enabledChange ( bool oldEnabled ) [virtual
protected]
This virtual function is called from setEnabled().
oldEnabled is the previous setting; you can get the new
setting from isEnabled().
Reimplement this function if your widget needs to know
when it becomes enabled or disabled. You will almost
certainly need to update the widget using update().
The default implementation repaints the visible part of
the widget.
See also setEnabled(), isEnabled(), repaint(), update()
and visibleRect().
Reimplemented in QListView and QButton.
void QWidget::enterEvent ( QEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget enter events.
An event is sent to the widget when the mouse cursor
enters the widget.
See also leaveEvent(), mouseMoveEvent() and event().
Reimplemented in QToolButton.
void QWidget::erase ( const QRegion & reg )
Erases the area defined by reg, without generating a paint
event.
Child widgets are not affected.
Examples: drawlines/connect.cpp
void QWidget::erase ( int x, int y, int w, int h )
Erases the specified area (x,y,w,h) in the widget without
generating a paint event.
If w is negative, it is replaced with width() - x. If h is
negative, it is replaced width height() - y.
Child widgets are not affected.
See also repaint().
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QWidget(3qt)QWidget(3qt)void QWidget::erase ()
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
This version erases the entire widget.
void QWidget::erase ( const QRect & r )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
bool QWidget::event ( QEvent * e ) [virtual protected]
This is the main event handler. You may reimplement this
function in a subclass, but we recommend using one of the
specialized event handlers instead.
The main event handler first passes an event through all
event filters that have been installed. If none of the
filters intercept the event, it calls one of the
specialized event handlers.
Key press/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().
This function returns TRUE if it is able to pass the event
over to someone, or FALSE if nobody wanted the event.
See also closeEvent(), focusInEvent(), focusOutEvent(),
enterEvent(), keyPressEvent(), keyReleaseEvent(),
leaveEvent(), mouseDoubleClickEvent(), mouseMoveEvent(),
mousePressEvent(), mouseReleaseEvent(), moveEvent(),
paintEvent(), resizeEvent(), QObject::event() and
QObject::timerEvent().
Reimplemented from QObject.
QWidget * QWidget::find ( WId id ) [static]
Returns a pointer to the widget with window
identifer/handle id.
The window identifier type depends by the underlying
window system, see qwindowdefs.h for the actual
definition. If there is no widget with this identifier, a
null pointer is returned.
See also wmapper() and id().
QFocusData * QWidget::focusData () [protected]
Returns a pointer to the focus data for this widget's top-
level widget.
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Focus data always belongs to the top-level widget. The
focus data list contains all the widgets in this top-level
widget that can accept focus, in tab order. An iterator
points to the current focus widget (focusWidget() returns
a pointer to this widget).
This information is useful for implementing advanced
versions of focusNextPrevChild().
void QWidget::focusInEvent ( QFocusEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive keyboard focus events (focus received) for the
widget.
A widget normally must setFocusPolicy() to something other
than 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 if it
accepts focus (see focusPolicy()). It also calls
setMicroFocusHint(), hinting any system-specific input
tools about the focus of the user's attention.
See also focusOutEvent(), setFocusPolicy(),
keyPressEvent(), keyReleaseEvent(), event() and
QFocusEvent.
Reimplemented in QListBox, QTabBar, QLineEdit, QSlider,
QGroupBox, QComboBox, QPushButton, QButton,
QMultiLineEdit, QPopupMenu, QMenuBar, QTable, QDial,
QListView, QTextView and QRadioButton.
bool QWidget::focusNextPrevChild ( bool next ) [virtual
protected]
Finds a new widget to give the keyboard focus to, as
appropriate for Tab/shift-Tab, and returns TRUE if is can
find a new widget and FALSE if it can't,
If next is true, this function searches "forwards", if
next is FALSE, "backwards".
Sometimes, you will want to reimplement this function. For
example, a web browser might reimplement it to move its
"current active link" forwards or backwards, and call
QWidget::focusNextPrevChild() only when it reaches the
last/first.
Child widgets call focusNextPrevChild() on their parent
widgets, and only the top-level widget will thus make the
choice of where to redirect focus. By overriding this
method for an object, you thus gain control of focus
traversal for all child widgets.
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QWidget(3qt)QWidget(3qt)
See also focusData().
Reimplemented in QButton, QPopupMenu, QMultiLineEdit and
QScrollView.
void QWidget::focusOutEvent ( QFocusEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive keyboard focus events (focus lost) for the widget.
A widget normally must setFocusPolicy() to something other
than 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 calls repaint() since the
widget's colorGroup() changes from active to normal, so
the widget probably needs repainting. It also calls
setMicroFocusHint(), hinting any system-specific input
tools about the focus of the user's attention.
See also focusInEvent(), setFocusPolicy(),
keyPressEvent(), keyReleaseEvent(), event() and
QFocusEvent.
Reimplemented in QMenuBar, QMultiLineEdit, QTextView,
QPopupMenu, QTabBar, QDial, QTable, QSlider, QListView,
QListBox, QButton, QLineEdit and QPushButton.
QWidget::FocusPolicy QWidget::focusPolicy() const
Returns QWidget::TabFocus if the widget accepts focus by
tabbing, QWidget::ClickFocus if the widget accepts focus
by clicking, QWidget::StrongFocus if it accepts both and
QWidget::NoFocus if it does not accept focus at all.
See also isFocusEnabled(), setFocusPolicy(),
focusInEvent(), focusOutEvent(), keyPressEvent(),
keyReleaseEvent() and isEnabled().
QWidget * QWidget::focusProxy () const
Returns a pointer to the focus proxy, or 0 if there is no
focus proxy.
See also setFocusProxy().
QWidget * QWidget::focusWidget () const
Returns the focus widget in this widget's window. This is
not the same as QApplication::focusWidget(), which returns
the focus widget in the currently active window.
QFont QWidget::font () const
Returns the font currently set for the widget.
fontInfo() tells you what font is actually being used.
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QWidget(3qt)QWidget(3qt)
As long as no special font has been set, this is either a
special font for the widget class, the parent's font or -
if this widget is a toplevel widget - the default
application font.
See also setFont(), fontInfo(), fontMetrics() and
QApplication::font().
Examples: grapher/grapher.cpp xform/xform.cpp
menu/menu.cpp
void QWidget::fontChange ( const QFont & oldFont ) [virtual
protected]
This virtual function is called from setFont(). oldFont is
the previous font; you can get the new font from font().
Reimplement this function if your widget needs to know
when its font changes. You will almost certainly need to
update the widget using update().
The default implementation updates the widget including
its geometry.
See also setFont(), font(), update() and updateGeometry().
Reimplemented in QMenuBar, QLabel and QGroupBox.
QFontInfo QWidget::fontInfo () const
Returns the font info for the widget's current font.
Equivalent to QFontInto(widget->font()).
See also font(), fontMetrics() and setFont().
QFontMetrics QWidget::fontMetrics () const
Returns the font metrics for the widget's current font.
Equivalent to QFontMetrics(widget->font()).
See also font(), fontInfo() and setFont().
Examples: xform/xform.cpp drawdemo/drawdemo.cpp
qmag/qmag.cpp
QWidget::PropagationMode QWidget::fontPropagation() 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.
The return value is meaningless
See also setFontPropagation().
const QColor & QWidget::foregroundColor () const
Returns the foreground color of this widget.
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QWidget(3qt)QWidget(3qt)
The foreground color is also accessible as
colorGroup().foreground().
See also backgroundColor() and colorGroup().
QRect QWidget::frameGeometry () const
Returns the geometry of the widget, relative to its parent
and including the window frame.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also geometry(), x(), y() and pos().
QSize QWidget::frameSize () const
Returns the size of the window system frame (for top level
widgets).
const QRect & QWidget::geometry () const
Returns the geometry of the widget, relative to its parent
widget and excluding the window frame.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also frameGeometry(), size() and rect().
Examples: qmag/qmag.cpp
WFlags QWidget::getWFlags () const [protected]
Returns the widget flags for this this widget.
Widget flags are a combination of Qt::WidgetFlags.
See also testWFlags(), setWFlags() and clearWFlags().
void QWidget::grabKeyboard ()
Grabs all keyboard input.
This widget will receive all keyboard events, independent
of the active window.
Warning: Grabbing the keyboard might lock the terminal.
See also releaseKeyboard(), grabMouse() and
releaseMouse().
void QWidget::grabMouse ()
Grabs the mouse input.
This widget will be the only one to receive mouse events
until releaseMouse() is called.
Warning: Grabbing the mouse might lock the terminal.
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QWidget(3qt)QWidget(3qt)
It is almost never necessary to grab the mouse when using
Qt since Qt grabs and releases it sensibly. In particular,
Qt grabs the mouse when a button is pressed and keeps it
until the last button is released.
Beware that only widgets actually shown on the screen may
grab the mouse input.
See also releaseMouse(), grabKeyboard() and
releaseKeyboard().
void QWidget::grabMouse ( const QCursor & cursor )
Grabs the mouse input and changes the cursor shape.
The cursor will assume shape cursor (for as long as the
mouse focus is grabbed) and this widget will be the only
one to receive mouse events until releaseMouse() is
called().
Warning: Grabbing the mouse might lock the terminal.
See also releaseMouse(), grabKeyboard(), releaseKeyboard()
and setCursor().
Examples: qmag/qmag.cpp
bool QWidget::hasFocus () const
Returns TRUE if this widget (or its focus proxy) has the
keyboard input focus, otherwise FALSE.
Equivalent to qApp->focusWidget() == this.
See also setFocus(), clearFocus(), setFocusPolicy() and
QApplication::focusWidget().
bool QWidget::hasMouseTracking () const
Returns TRUE if mouse tracking is enabled for this widget,
or FALSE if mouse tracking is disabled.
See also setMouseTracking().
int QWidget::height () const
Returns the height of the widget, excluding the window
frame.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also geometry(), width() and size().
Examples: grapher/grapher.cpp xform/xform.cpp
drawdemo/drawdemo.cpp qmag/qmag.cpp
Trolltech AS 13 June 2001 27
QWidget(3qt)QWidget(3qt)int QWidget::heightForWidth ( int w ) const [virtual]
Returns the preferred height for this widget, given the
width w. The default implementation returns 0, indicating
that the preferred height does not depend on the width.
Warning: Does not look at the widget's layout.
Reimplemented in QTextView, QMenuBar and QLabel.
void QWidget::hide () [virtual slot]
Hides the widget.
You almost never have to reimplement this function. If you
need to do something after a widget is hidden, use
hideEvent() instead.
See also isHhideEvent(), isHidden(), show(),
showMinimized(), isVisible() and close().
Examples: xform/xform.cpp popup/popup.cpp
progress/progress.cpp scrollview/scrollview.cpp
Reimplemented in QPopupMenu, QToolBar, QDialog and
QMenuBar.
void QWidget::hideEvent ( QHideEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget hide events.
Hide events are sent to widgets right after they have been
hidden.
See also event() and QHideEvent.
const QPixmap * QWidget::icon () const
Returns the widget icon pixmap, or null if no icon has
been set.
See also setIcon(), iconText() and caption().
QString QWidget::iconText () const
Returns the widget icon text. If no icon text has been set
(common for child widgets), this functions returns a null
string.
See also setIconText(), icon(), caption() and
QString::isNull().
bool QWidget::isActiveWindow () const
Returns TRUE if this widget is in the active window, i.e.
the window that has keyboard focus.
When popup windows are visible, this function returns TRUE
for both the active window and the popup.
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QWidget(3qt)QWidget(3qt)
See also setActiveWindow() and
QApplication::activeWindow().
bool QWidget::isDesktop () const
Returns TRUE if the widget is a desktop widget, otherwise
FALSE.
A desktop widget is also a top-level widget.
See also isTopLevel() and QApplication::desktop().
bool QWidget::isEnabled () const
Returns TRUE if the widget is enabled, or FALSE if it is
disabled.
See also setEnabled().
bool QWidget::isEnabledTo ( QWidget * ancestor ) const
Returns TRUE if this widget would become enabled if
ancestor is enabled.
This is the case if neither the widget itself nor every
parent up to but excluding ancestor has been explicitly
disabled.
isEnabledTo(0) is equivalent to isEnabled().
See also setEnabled() and isEnabled().
bool QWidget::isEnabledToTLW () 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.
This function is deprecated. It is equivalent to
isEnabled()
See also setEnabled() and isEnabled().
bool QWidget::isFocusEnabled () const
Returns TRUE if the widget accepts keyboard focus, or
FALSE if it does not.
Keyboard focus is initially disabled (i.e. focusPolicy()
== QWidget::NoFocus).
You must enable keyboard focus for a widget if it
processes keyboard events. This is normally done from the
widget's constructor. For instance, the QLineEdit
constructor calls setFocusPolicy(QWidget::StrongFocus).
See also setFocusPolicy(), focusInEvent(),
focusOutEvent(), keyPressEvent(), keyReleaseEvent() and
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QWidget(3qt)QWidget(3qt)isEnabled().
bool QWidget::isHidden () const
Returns TRUE if the widget is explicitly hidden, or FALSE
if it is visible or would become visible if all its
ancestors became visible.
See also hide(), show(), isVisible() and isVisibleTo().
bool QWidget::isMaximized () const
Returns TRUE if this widget is a top-level widget that is
maximized, or else FALSE.
Note that due to limitations in some window-systems, this
does not always report expected results (eg. if the user
on X11 maximizes the window via the window manager, Qt has
no way of telling this from any other resize). This will
improve as window manager protocols advance.
See also showMaximized().
bool QWidget::isMinimized () const
Returns TRUE if this widget is a top-level widget that is
minimized (iconified), or else FALSE.
See also showMinimized(), isVisible(), show(), hide() and
showNormal().
bool QWidget::isModal () const
Returns TRUE if the widget is a modal widget, otherwise
FALSE.
A modal widget is also a top-level widget.
See also isTopLevel() and QDialog.
bool QWidget::isPopup () const
Returns TRUE if the widget is a popup widget, otherwise
FALSE.
A popup widget is created by specifying the widget flag
WType_Popup to the widget constructor.
A popup widget is also a top-level widget.
See also isTopLevel().
bool QWidget::isTopLevel () const
Returns TRUE if the widget is a top-level widget,
otherwise FALSE.
A top-level widget is a widget which usually has a frame
and a caption (title bar). Popup and desktop widgets are
also top-level widgets.
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QWidget(3qt)QWidget(3qt)
A top-level widgets can have a parent widget. It will then
be grouped with its parent: deleted when the parent is
deleted, minimized when the parent is minimized etc. If
supported by the window manager, it will also have a
common taskbar entry with its parent.
QDialog and QMainWindow widgets are by default top-level,
even if a parent widget is specified in the constructor.
This behavior is specified by the WType_TopLevel widget
flag.
Child widgets are the opposite of top-level widgets.
See also topLevelWidget(), isModal(), isPopup(),
isDesktop() and parentWidget().
bool QWidget::isUpdatesEnabled () const
Returns TRUE if updates are enabled, otherwise FALSE.
See also setUpdatesEnabled().
bool QWidget::isVisible () const
Returns TRUE if the widget itself is visible, or else
FALSE.
Calling show() sets the widget to visible status if all
its parent widgets up to the toplevel widget are visible.
If an ancestor is not visible, the widget won't become
visible until all its ancestors are shown.
Calling hide() hides a widget explicitly. An explicitly
hidden widget will never become visible, even if all its
ancestors become visible.
Iconified top-level widgets also have hidden status, as
well as having isMinimized() return TRUE. Windows that
live on another virtual desktop (on platforms that support
this concept) also have hidden status.
This function returns TRUE if the widget currently is
obscured by other windows on the screen, but would be
visible if moved.
A widget receives show- and hide events when its
visibility status changes. Between a hide and a show
event, there is no need in wasting any CPU on preparing or
displaying information to the user. A video application,
for example, might simply stop generating new frames.
See also show(), hide(), isHidden(), isVisibleTo(),
isMinimized(), showEvent() and hideEvent().
bool QWidget::isVisibleTo ( QWidget * ancestor ) const
Returns TRUE if this widget would become visible if
Trolltech AS 13 June 2001 31
QWidget(3qt)QWidget(3qt)
ancestor is shown.
This is the case if neither the widget itself nor every
parent up to but excluding ancestor has been explicitly
hidden.
This function returns TRUE if the widget it is obscured by
other windows on the screen, but would be visible if
moved.
isVisibleTo(0) is very similar to isVisible(), with the
exception that it does not cover the iconfied-case or the
situation where the window lives on another virtual
desktop.
See also show(), hide() and isVisible().
bool QWidget::isVisibleToTLW () 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.
This function is deprecated. It is equivalent to
isVisible()
See also show(), hide() and isVisible().
void QWidget::keyPressEvent ( QKeyEvent * e ) [virtual protected]
This event handler 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 you hit
escape. Otherwise the event is ignored.
See also keyReleaseEvent(), QKeyEvent::ignore(),
setFocusPolicy(), focusInEvent(), focusOutEvent(), event()
and QKeyEvent.
Reimplemented in QComboBox, QDial, QTextBrowser, QSlider,
QMultiLineEdit, QLineEdit, QMessageBox, QScrollBar,
QFileDialog, QTable, QButton, QDialog, QTextView,
QMenuBar, QListBox, QListView, QPopupMenu and QTabBar.
void QWidget::keyReleaseEvent ( QKeyEvent * e ) [virtual
protected]
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This event handler can be reimplemented in a subclass to
receive key release events for the widget.
A widget must accept focus initially and have focus in
order to receive a key release event.
If you reimplement this handler, it is very important that
you ignore() the release if you do not understand it, so
that the widget's parent can interpret it.
The default implementation ignores the event.
See also keyPressEvent(), QKeyEvent::ignore(),
setFocusPolicy(), focusInEvent(), focusOutEvent(), event()
and QKeyEvent.
Reimplemented in QButton.
QWidget * QWidget::keyboardGrabber () [static]
Returns a pointer to the widget that is currently grabbing
the keyboard input.
If no widget in this application is currently grabbing the
keyboard, 0 is returned.
See also grabMouse() and mouseGrabber().
QLayout* QWidget::layout () const
Returns a pointer to the layout engine that manages the
geometry of this widget's children.
If the widget does not have a layout, layout() returns a
null pointer.
See also sizePolicy().
void QWidget::leaveEvent ( QEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget leave events.
A leave event is sent to the widget when the mouse cursor
leaves the widget.
See also enterEvent(), mouseMoveEvent() and event().
Reimplemented in QMenuBar, QMultiLineEdit, QSpinBox,
QToolButton and QLineEdit.
void QWidget::lower () [slot]
Lowers the widget to the bottom of the parent widget's
stack.
If there are siblings of this widget that overlap it on
the screen, this widget will be obscured by its siblings
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QWidget(3qt)QWidget(3qt)
afterwards.
See also raise() and stackUnder().
QPoint QWidget::mapFrom ( QWidget * parent, const QPoint & pos )
const
Translates the widget coordinate pos from the coordinate
system of parent to this widget's coordinate system, which
must be non-null and be a parent widget of this.
See also mapTo(), mapFromParent() and mapFromGlobal().
QPoint QWidget::mapFromGlobal ( const QPoint & pos ) const
Translates the global screen coordinate pos to widget
coordinates.
See also mapToGlobal(), mapFrom() and mapFromParent().
QPoint QWidget::mapFromParent ( const QPoint & pos ) const
Translates the parent widget coordinate pos to widget
coordinates.
Same as mapFromGlobal() if the widget has no parent.
See also mapToParent(), mapFrom() and mapFromGlobal().
QPoint QWidget::mapTo ( QWidget * parent, const QPoint & pos )
const
Translates the widget coordinate pos to the coordinate
system of parent, which must be non-null and be a parent
widget of this.
See also mapFrom(), mapToParent() and mapToGlobal().
QPoint QWidget::mapToGlobal ( const QPoint & pos ) const
Translates the widget coordinate pos to global screen
coordinates. For example,
mapToGlobal(QPoint(0,0))
would give the global coordinates of the top-left pixel of
the widget.
See also mapFromGlobal(), mapTo() and mapToParent().
Examples: popup/popup.cpp
QPoint QWidget::mapToParent ( const QPoint & pos ) const
Translates the widget coordinate pos to a coordinate in
the parent widget.
Same as mapToGlobal() if the widget has no parent.
See also mapFromParent(), mapTo() and mapToGlobal().
Trolltech AS 13 June 2001 34
QWidget(3qt)QWidget(3qt)int QWidget::maximumHeight () const
Returns the widget's maximum height.
See also maximumSize() and maximumWidth().
QSize QWidget::maximumSize () const
Returns the maximum widget size.
The widget cannot be resized to a larger size than the
maximum widget size.
See also maximumWidth(), maximumHeight(),
setMaximumSize(), minimumSize() and sizeIncrement().
int QWidget::maximumWidth () const
Returns the widget's maximum width.
See also maximumSize() and maximumHeight().
int QWidget::metric ( int m ) const [virtual protected]
Internal implementation of the virtual
QPaintDevice::metric() function.
Use the QPaintDeviceMetrics class instead.
Reimplemented from QPaintDevice.
QRect QWidget::microFocusHint () const
Returns the currently set micro focus hint for this
widget.
See also setMicroFocusHint().
int QWidget::minimumHeight () const
Returns the widget's minimum height.
See also minimumSize() and minimumWidth().
QSize QWidget::minimumSize () const
Returns the minimum widget size.
The widget cannot be resized to a smaller size than the
minimum widget size.
If the returned minimum size equals (0,0) then it means
that there are no constraints on the minimum size.
However, Qt does nevertheless not allow you to shrink
widgets to less than 1 pixel width/height.
See also maximumWidth(), maximumHeight(),
setMinimumSize(), maximumSize() and sizeIncrement().
QSize QWidget::minimumSizeHint () const [virtual]
Returns a recommended minimum size for the widget, or an
Trolltech AS 13 June 2001 35
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invalid size if no minimum size is recommended.
The default implementation returns an invalid size if
there is no layout for this widget, the layout's minimum
size otherwise.
See also QSize::isValid(), resize(), setMinimumSize() and
sizePolicy().
Reimplemented in QMenuBar, QWidgetStack, QSlider,
QListBox, QDialog, QDial, QIconView, QSplitter, QLineEdit,
QToolBar, QMultiLineEdit, QProgressBar, QLabel,
QTabWidget, QMainWindow, QTabBar, QListView and
QScrollView.
int QWidget::minimumWidth () const
Returns the widget's minimum width.
See also minimumSize() and minimumHeight().
void QWidget::mouseDoubleClickEvent ( QMouseEvent * e ) [virtual
protected]
This event handler can be reimplemented in a subclass to
receive mouse double click events for the widget.
The default implementation generates a normal mouse press
event.
Note that the widgets gets a mousePressEvent() and a
mouseReleaseEvent() before the mouseDoubleClickEvent().
See also mousePressEvent(), mouseReleaseEvent(),
mouseMoveEvent(), event() and QMouseEvent.
Reimplemented in QMultiLineEdit, QLineEdit, QListBox and
QComboBox.
QWidget * QWidget::mouseGrabber () [static]
Returns a pointer to the widget that is currently grabbing
the mouse input.
If no widget in this application is currently grabbing the
mouse, 0 is returned.
See also grabMouse() and keyboardGrabber().
void QWidget::mouseMoveEvent ( QMouseEvent * ) [virtual
protected]
This event handler can be reimplemented in a subclass to
receive mouse move events for the widget.
If mouse tracking is switched off, mouse move events only
occur if a mouse button is down while the mouse is being
moved. If mouse tracking is switched on, mouse move events
Trolltech AS 13 June 2001 36
QWidget(3qt)QWidget(3qt)
occur even if no mouse button is down.
QMouseEvent::pos() reports the position of the mouse
cursor, relative to this widget. For press and release
events, the position is usually the same as the position
of the last mouse move event, but it might be different if
the user moves and clicks the mouse fast. This is a
feature of the underlying window system, not Qt.
See also setMouseTracking(), mousePressEvent(),
mouseReleaseEvent(), mouseDoubleClickEvent(), event() and
QMouseEvent.
Reimplemented in QSlider, QPopupMenu, QSizeGrip, QMenuBar,
QDial, QListBox, QScrollBar, QButton, QMultiLineEdit,
QHeader, QLineEdit and QComboBox.
void QWidget::mousePressEvent ( QMouseEvent * e ) [virtual
protected]
This event handler can be reimplemented in a subclass to
receive mouse press events for the widget.
If you create new widgets in the mousePressEvent() the
mouseReleaseEvent() may not end up where you expect,
depending on the underlying window system (or X11 window
manager), the widgets' location and maybe more.
The default implementation implements the closing of popup
widgets when you click outside the window. For other
widget types it does nothing.
See also mouseReleaseEvent(), mouseDoubleClickEvent(),
mouseMoveEvent(), event() and QMouseEvent.
Reimplemented in QScrollBar, QLineEdit, QButton, QSlider,
QSizeGrip, QPopupMenu, QMenuBar, QMultiLineEdit, QListBox,
QDial, QTabBar, QComboBox and QHeader.
void QWidget::mouseReleaseEvent ( QMouseEvent * ) [virtual
protected]
This event handler can be reimplemented in a subclass to
receive mouse release events for the widget.
See also mouseReleaseEvent(), mouseDoubleClickEvent(),
mouseMoveEvent(), event() and QMouseEvent.
Reimplemented in QScrollBar, QButton, QPopupMenu, QTabBar,
QHeader, QListBox, QMenuBar, QDial, QSlider, QLineEdit,
QMultiLineEdit and QComboBox.
void QWidget::move ( int x, int y ) [virtual slot]
Moves the widget to the position (x,y) relative to the
parent widget and including the window frame.
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QWidget(3qt)QWidget(3qt)
If the widget is visible, it receives a move event
immediately. If the widget is not shown yet, it is
guaranteed to receive an event before it actually becomes
visible.
This function is virtual, and all other overloaded move()
implementations call it.
Warning: If you call move() or setGeometry() from
moveEvent(), you may see infinite recursion.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also pos(), resize(), setGeometry() and moveEvent().
Examples: drawdemo/drawdemo.cpp popup/popup.cpp
Reimplemented in QSemiModal, QPushButton and QDialog.
void QWidget::move ( const QPoint & ) [slot]
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::moveEvent ( QMoveEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget move events. When the widget receives this
event, it is already at the new position.
The old position is accessible through
QMoveEvent::oldPos().
See also resizeEvent(), event(), move() and QMoveEvent.
Reimplemented in QXtWidget and QToolButton.
bool QWidget::ownCursor () const
Returns whether the widget uses its own cursor or its
parent widget's cursor.
bool QWidget::ownFont () const
Returns whether the widget uses its own font or its
natural default font.
See also setFont() and unsetFont().
bool QWidget::ownPalette () const
Returns whether the widget uses its own palette or its
natural default palette.
See also setPalette() and unsetPalette().
Trolltech AS 13 June 2001 38
QWidget(3qt)QWidget(3qt)void QWidget::paintEvent ( QPaintEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget paint events.
When the paint event occurs, the update region
QPaintEvent::region() normally has been cleared to the
background color or pixmap. An exception is when
repaint(FALSE) is called or the widget sets the
WRepaintNoErase or WResizeNoErase flag. Inside the paint
event handler, QPaintEvent::erased() carries this
information.
For many widgets it is sufficient to redraw the entire
widget each time, but some need to consider the update
rectangle or region of the QPaintEvent to avoid slow
update.
During paintEvent(), any QPainter you create on the widget
will be clipped to at most the area covered by the update
region.
update() and repaint() can be used to force a paint event.
See also event(), repaint(), update(), QPainter, QPixmap
and QPaintEvent.
Reimplemented in QTabDialog, QSizeGrip, QButton, QFrame,
QGLWidget, QStatusBar, QGroupBox, QDial, QTableView,
QHeader, QScrollBar, QToolBar, QLineEdit, QMainWindow,
QTabBar, QPopupMenu, QSlider and QComboBox.
const QPalette & QWidget::palette () const
Returns the widget palette.
As long as no special palette has been set, this is either
a special palette for the widget class, the parent's
palette or - if this widget is a toplevel widget - the
default application palette.
See also setPalette(), colorGroup() and
QApplication::palette().
void QWidget::paletteChange ( const QPalette & oldPalette )
[virtual protected]
This virtual function is called from setPalette().
oldPalette is the previous palette; you can get the new
palette from palette().
Reimplement this function if your widget needs to know
when its palette changes. You will almost certainly need
to call this implementation of the function.
See also setPalette() and palette().
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QWidget(3qt)QWidget(3qt)
Reimplemented in QTextView.
QWidget::PropagationMode QWidget::palettePropagation() 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.
The return value is meaningless.
QWidget * QWidget::parentWidget () const
Returns a pointer to the parent of this widget, or a null
pointer if it does not have any parent widget.
void QWidget::polish () [virtual slot]
Delayed initialization of a widget.
This function will be called after a widget has been fully
created and before it is shown the very first time.
Polishing is useful for final initialization depending on
an instantiated widget. This is something a constructor
cannot guarantee since the initialization of the
subclasses might not be finished.
After this function, the widget has a proper font and
palette and QApplication::polish() has been called.
Remember to call QWidget's implementation when
reimplementing this function.
See also constPolish() and QApplication::polish().
Examples: menu/menu.cpp
QPoint QWidget::pos () const
Returns the position of the widget in its parent widget,
including the window frame.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also move(), frameGeometry(), x() and y().
Examples: qmag/qmag.cpp
void QWidget::raise () [slot]
Raises this widget to the top of the parent widget's
stack.
If there are any siblings of this widget that overlap it
on the screen, this widget will be visually in front of
its siblings afterwards.
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See also lower() and stackUnder().
QRect QWidget::rect () const
Returns the the internal geometry of the widget, excluding
the window frame. rect() equals
QRect(0,0,width(),height()).
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also size().
Examples: grapher/grapher.cpp menu/menu.cpp
desktop/desktop.cpp picture/picture.cpp
void QWidget::releaseKeyboard ()
Releases the keyboard grab.
See also grabKeyboard(), grabMouse() and releaseMouse().
void QWidget::releaseMouse ()
Releases the mouse grab.
See also grabMouse(), grabKeyboard() and
releaseKeyboard().
Examples: qmag/qmag.cpp
void QWidget::repaint ( const QRegion & reg, bool erase=TRUE )
[slot]
Repaints the widget directly by calling paintEvent()
directly, unless updates are disabled or the widget is
hidden.
Erases the widget region reg if erase is TRUE.
Use repaint if your widget needs to be repainted
immediately, for example when doing some animation. In all
other cases, update() is to be preferred. Calling update()
many times in a row will generate a single paint event.
Warning: If you call repaint() in a function which may
itself be called from paintEvent(), you may see infinite
recursion. The update() function never generates
recursion.
See also update(), paintEvent(), setUpdatesEnabled() and
erase().
void QWidget::repaint ( int x, int y, int w, int h, bool
erase=TRUE ) [slot]
Repaints the widget directly by calling paintEvent()
directly, unless updates are disabled or the widget is
hidden.
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Erases the widget area (x,y,w,h) if erase is TRUE.
If w is negative, it is replaced with width() - x. If h is
negative, it is replaced width height() - y.
Use repaint if your widget needs to be repainted
immediately, for example when doing some animation. In all
other cases, update() is to be preferred. Calling update()
many times in a row will generate a single paint event.
Warning: If you call repaint() in a function which may
itself be called from paintEvent(), you may see infinite
recursion. The update() function never generates
recursion.
See also update(), paintEvent(), setUpdatesEnabled() and
erase().
Examples: xform/xform.cpp qmag/qmag.cpp
void QWidget::repaint () [slot]
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
This version erases and repaints the entire widget.
void QWidget::repaint ( bool erase ) [slot]
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
This version repaints the entire widget.
void QWidget::repaint ( const QRect & r, bool erase=TRUE ) [slot]
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::reparent ( QWidget * parent, WFlags f, const QPoint
& p, bool showIt=FALSE ) [virtual]
Reparents the widget. The widget gets a new parent, new
widget flags (f, but as usual, use 0) at a new position in
its new parent (p).
If showIt is TRUE, show() is called once the widget has
been reparented.
If the new parent widget is in a different top-level
widget, the reparented widget and its children are
appended to the end of the TAB chain of the new parent
widget, in the same internal order as before. If one of
the moved widgets had keyboard focus, reparent() calls
clearFocus() for that widget.
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QWidget(3qt)QWidget(3qt)
If the new parent widget is in the same top-level widget
as the old parent, reparent doesn't change the TAB order
or keyboard focus.
Warning: Reparenting widgets should be a real exception.
In normal applications, you will almost never need it.
Dynamic masks can be achieved much easier and cleaner with
classes like QWidgetStack or on a higher abstraction
level, QWizard.
See also getWFlags().
void QWidget::reparent ( QWidget * parent, const QPoint & p, bool
showIt=FALSE )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
A convenience version of reparent that does not take
widget flags as argument.
Calls reparent(parent, getWFlags()&~WType_Mask, p, showit
).
void QWidget::resize ( int w, int h ) [virtual slot]
Resizes the widget to size w by h pixels.
If the widget is visible, it receives a resize event
immediately. If the widget is not shown yet, it is
guaranteed to receive an event before it actually becomes
visible.
The size is adjusted if it is outside the minimum or
maximum widget size.
This function is virtual, and all other overloaded
resize() implementations call it.
Warning: If you call resize() or setGeometry() from
resizeEvent(), you may see infinite recursion.
See also size(), move(), setGeometry(), resizeEvent(),
minimumSize() and maximumSize().
Examples: aclock/main.cpp checklists/main.cpp
buttongroups/main.cpp drawdemo/drawdemo.cpp qmag/qmag.cpp
qwerty/main.cpp rot13/rot13.cpp
Reimplemented in QSemiModal and QDialog.
void QWidget::resize ( const QSize & ) [slot]
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
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Examples: rangecontrols/main.cpp themes/main.cpp
listviews/main.cpp dclock/main.cpp mainlyXt/editor.cpp
drawdemo/drawdemo.cpp popup/popup.cpp
fileiconview/main.cpp scribble/main.cpp qmag/qmag.cpp
mainlyMotif/editor.cpp richtext/main.cpp
scrollview/scrollview.cpp qfd/qfd.cpp
listboxcombo/main.cpp
void QWidget::resizeEvent ( QResizeEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget resize events. When resizeEvent() is
called, the widget already has its new geometry. The old
size is accessible through QResizeEvent::oldSize(),
though.
The widget will be erased and receive a paint event
immediately after processing the resize event. No drawing
has to (and should) be done inside this handler.
Widgets that have been created with the WResizeNoErase
flag will not be erased. Nevertheless, they will receive a
paint event for their entire area afterwards. Again, no
drawing needs to be done inside this handler.
The default implementation calls updateMask() if the
widget has automatic masking enabled.
See also moveEvent(), event(), resize(), QResizeEvent and
paintEvent().
Reimplemented in QScrollBar, QMultiLineEdit, QCheckBox,
QSlider, QWidgetStack, QTabDialog, QRadioButton, QTabBar,
QDial, QComboBox, QWorkspace, QGroupBox, QLineEdit,
QSpinBox, QDialog, QProgressDialog, QMessageBox,
QScrollView, QSplitter, QFileDialog, QTabWidget,
QPushButton, QListView, QMenuBar, QMainWindow, QStatusBar,
QToolBar, QGLWidget, QTableView, QListBox, QFrame,
QXtWidget, QTable, QTextView and QLabel.
void QWidget::scroll ( int dx, int dy, const QRect & r )
Scrolls r dx pixels to the right and dy downwards. Both dx
and dy may be negative.
If r is empty or invalid, the result is undefined.
After scrolling, scroll() sends a paint event for the the
part of r that is read but not written. For example, when
scrolling 10 pixels rightwards, the leftmost ten pixels of
r need repainting. The paint event may be delivered
immediately or later, depending on some heuristics.
This version of scroll() does not move the children of
this widget.
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See also QScrollView, erase() and bitBlt().
void QWidget::scroll ( int dx, int dy )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
This version of the function scrolls the entire widget and
moves the widget's children along with the scroll.
See also bitBlt() and QScrollView.
void QWidget::setAcceptDrops ( bool on ) [virtual]
Announces to the system that this widget may be able to
accept drop events.
If the widgets is the desktop, this may fail if another
application is using the desktop - you can call
acceptDrops() to test if this occurs.
See also acceptDrops().
Examples: scrollview/scrollview.cpp
void QWidget::setActiveWindow () [virtual]
Sets the top-level widget containing this widget to be the
active window.
An active window is a visible top-level window that has
the keyboard input focus.
This function performs the same operation as clicking the
mouse on the title bar of a top-level window. On X11, the
result depends on the Window Manager. If you want to
ensure that the window is stacked on top as well, call
raise() in addition. Note that the window has be to
visible, otherwise setActiveWindow() has no effect.
On Windows, if you are calling this when the application
is not currently the active one then it will not make it
the active window. It will flash the task bar entry blue
to indicate that the window has done something. This is
due to Microsoft not allowing an application to interrupt
what the user is currently doing in another application.
See also isActiveWindow(), topLevelWidget() and show().
Reimplemented in QXtWidget.
void QWidget::setAutoMask ( bool enable ) [virtual]
Transparent widgets use a mask to define their visible
region. QWidget has some built-in support to make the task
of recalculating the mask easier. When setting auto mask
to TRUE, updateMask() will be called whenever the widget
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QWidget(3qt)QWidget(3qt)
is resized or changes its focus state.
Note: When you re-implement resizeEvent(), focusInEvent()
or focusOutEvent() in your custom widgets and still want
to ensure that the auto mask calculation works, you will
have to add
if ( autoMask() )
updateMask();
at the end of your event handlers. Same holds for all
member functions that change the appearance of the widget
in a way that a recalculation of the mask is necessary.
While being a technically appealing concept, masks have
one big drawback: when using complex masks that cannot be
expressed easily with relatively simple regions, they tend
to be very slow on some window systems. The classic
example is a transparent label. The complex shape of its
contents makes it necessary to represent its mask by a
bitmap, which consumes both memory and time. If all you
want is to blend the background of several neighboring
widgets together seamlessly, you may probably want to use
setBackgroundOrigin() rather than a mask.
See also autoMask(), updateMask(), setMask(), clearMask()
and setBackgroundOrigin().
Examples: aclock/main.cpp
Reimplemented in QLabel.
void QWidget::setBackgroundColor ( const QColor & color )
[virtual]
Sets the widget to be cleared to the fixed color color
before paintEvent() is called.
Note that using this function is very often a mistake.
Here are the most common mistakes:
If you want to set the background color of a widget to one
of the" usual" colors, setBackgroundMode() is usually the
best function. For example, man widgets that usually use
white backgrounds (and black text on it) can use this:
thatWidget->setBackgroundMode( QWidget::PaletteBase );
If you want to change the color scheme of a widget, the
setPalette() function is better suited. Here is how to set
thatWidget to use a light green (RGB value 80, 255, 80) as
background color, with shades of green used for all the 3D
effects:
thatWidget->setPalette( QPalette( QColor(80, 255, 80) ) );
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A fixed background color sometimes is just the right
thing, but if you use it, make sure that your application
looks right when the desktop color scheme has been
changed. (On X11, a quick way to test is e.g. "./yourapp
-bg paleblue". On Windows, you have to use the control
panel.)
See also setPalette(), QApplication::setPalette(),
backgroundColor(), setBackgroundPixmap() and
setBackgroundMode().
Examples: drawlines/connect.cpp xform/xform.cpp
drawdemo/drawdemo.cpp splitter/splitter.cpp
desktop/desktop.cpp hello/main.cpp customlayout/main.cpp
void QWidget::setBackgroundMode ( BackgroundMode m )
Tells the window system how to clear this widget when
sending a paint event. In other words, this decides how
the widgets looks when paintEvent() is called.
For most widgets the default (PaletteBackground, normally
gray) suffices, but some need to use PaletteBase (the
background color for text output, normally white) and a
few need other colors.
QListBox, which is "sunken" and uses the base color to
contrast with its environment, does this:
setBackgroundMode( PaletteBase );
Note that two of the BackgroundMode values cannot be used
with this function. For FixedPixmap, call
setBackgroundPixmap() instead, and for FixedColor, call
setBackgroundColor().
void QWidget::setBackgroundOrigin ( BackgroundOrigin origin )
Sets the widget's background to be drawn relative to
origin, which is either of WidgetOrigin (the default) or
ParentOrigin.
This makes a difference only if the widget has a
background pixmap where the positioning matters. In such
case, using ParentOrigin for several neighboring widgets
makes the background blend together seamlessly.
See also backgroundOrigin(), backgroundPixmap() and
setBackgroundMode().
void QWidget::setBackgroundPixmap ( const QPixmap & pixmap )
[virtual]
Sets the background pixmap of the widget to pixmap.
The background pixmap is tiled to cover the entire widget.
Note that some widgets do not work well with a background
Trolltech AS 13 June 2001 47
QWidget(3qt)QWidget(3qt)
pixmap, for example QLineEdit.
If pixmap is part of the widget's palette(), we recommend
calling setBackgroundMode() instead.
A fixed background pixmap sometimes is just the right
thing, but if you use it, make sure that your application
looks right when the desktop color scheme has been
changed. (On X11, a quick way to test is e.g. "./yourapp
-bg paleblue". On Windows, you have to use the control
panel.)
See also setBackgroundMode(), backgroundPixmap(),
backgroundPixmapChange() and setBackgroundColor().
Examples: desktop/desktop.cpp
void QWidget::setBaseSize ( int basew, int baseh )
Sets the base size of the widget. The base size is
important only in combination with size increments. See
setSizeIncrement() for details.
See also baseSize().
void QWidget::setBaseSize ( const QSize & )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::setCaption ( const QString & caption ) [virtual
slot]
Sets the window caption (title) to caption.
See also caption(), setIcon() and setIconText().
Examples: action/main.cpp rangecontrols/main.cpp
iconview/main.cpp validator/main.cpp themes/main.cpp
listviews/main.cpp checklists/main.cpp wizard/main.cpp
application/main.cpp buttongroups/main.cpp
drawdemo/drawdemo.cpp lineedits/main.cpp popup/popup.cpp
listbox/main.cpp menu/menu.cpp progress/progress.cpp
tabdialog/main.cpp progressbar/main.cpp tooltip/main.cpp
richtext/main.cpp forever/forever.cpp addressbook/main.cpp
movies/main.cpp hello/main.cpp listboxcombo/main.cpp
mdi/main.cpp dirview/main.cpp
void QWidget::setCursor ( const QCursor & cursor ) [virtual]
Sets the widget cursor shape to cursor.
The mouse cursor will assume this shape when it's over
this widget. See a list of predefined cursor objects with
a range of useful shapes in the QCursor documentation.
An editor widget would for example use an I-beam cursor:
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QWidget(3qt)QWidget(3qt)
setCursor( ibeamCursor );
See also cursor(), unsetCursor() and
QApplication::setOverrideCursor().
Examples: cursor/cursor.cpp
void QWidget::setDisabled ( bool disable ) [slot]
Disables widget input events if disable is TRUE, otherwise
enables input events.
An enabled widget receives keyboard and mouse events; a
disabled widget does not. Note that an enabled widget
receives keyboard events only when it is in focus.
Some widgets display themselves differently when they are
disabled. For example a button might draw its label grayed
out. If your widget needs to know when it becomes enabled
or disabled, you can reimplement the enabledChange()
function.
Disabling a widget implicitely disables all its children.
Enabling respectively enables all child widgets unless
they have been explicitly disabled.
See also setEnabled(), isEnabled(), isEnabledTo(),
QKeyEvent, QMouseEvent and enabledChange().
void QWidget::setEnabled ( bool enable ) [virtual slot]
Enables widget input events if enable is TRUE, otherwise
disables input events.
An enabled widget receives keyboard and mouse events; a
disabled widget does not. Note that an enabled widget
receives keyboard events only when it is in focus.
Some widgets display themselves differently when they are
disabled. For example a button might draw its label grayed
out. If your widget needs to know when it becomes enabled
or disabled, you can reimplement the enabledChange()
function.
Disabling a widget implicitely disables all its children.
Enabling respectively enables all child widgets unless
they have been explicitly disabled.
See also isEnabled(), isEnabledTo(), QKeyEvent,
QMouseEvent and enabledChange().
Reimplemented in QScrollView.
void QWidget::setFixedHeight ( int h )
Sets both the minimum and maximum heights of the widget to
h without changing the widths. Provided for convenience.
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See also sizeHint(), minimumSize(), maximumSize(),
setFixedSize() and more.
Examples: layout/layout.cpp
void QWidget::setFixedSize ( const QSize & s )
Sets both the minimum and maximum sizes of the widget to
s, thereby preventing it from ever growing or shrinking.
See also setMaximumSize() and setMinimumSize().
void QWidget::setFixedSize ( int w, int h )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::setFixedWidth ( int w )
Sets both the minimum and maximum width of the widget to w
without changing the heights. Provided for convenience.
See also sizeHint(), minimumSize(), maximumSize(),
setFixedSize() and more.
void QWidget::setFocus () [virtual slot]
Gives the keyboard input focus to the widget (or its focus
proxy).
First, a focus out event is sent to the focus widget (if
any) to tell it that it is about to lose the focus. Then a
focus in event is sent to this widget to tell it that it
just received the focus.
setFocus() gives focus to a widget regardless of its focus
policy.
Warning: If you call setFocus() in a function which may
itself be called from focusOutEvent() or focusInEvent(),
you may see infinite recursion.
See also hasFocus(), clearFocus(), focusInEvent(),
focusOutEvent(), setFocusPolicy() and
QApplication::focusWidget().
Examples: xform/xform.cpp popup/popup.cpp
void QWidget::setFocusPolicy ( FocusPolicy policy )
Enables or disables the keyboard focus for the widget.
The keyboard focus is initially disabled (i.e. policy ==
QWidget::NoFocus).
You must enable keyboard focus for a widget if it
processes keyboard events. This is normally done from the
widget's constructor. For instance, the QLineEdit
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constructor calls setFocusPolicy(QWidget::StrongFocus).
See also isFocusEnabled(), focusInEvent(),
focusOutEvent(), keyPressEvent(), keyReleaseEvent() and
isEnabled().
Examples: rot13/rot13.cpp
void QWidget::setFocusProxy ( QWidget * w ) [virtual]
Sets this widget's focus proxy to w. If w is 0, this
function resets this widget to not have any focus proxy.
Some widgets, such as QComboBox, can "have focus," but
create a child widget to actually handle the focus.
QComboBox, for example, creates a QLineEdit.
setFocusProxy() sets the widget which will actually get
focus when" this widget" gets it. If there is a focus
proxy, focusPolicy(), setFocusPolicy(), setFocus() and
hasFocus() all operate on the focus proxy.
See also focusProxy().
void QWidget::setFont ( const QFont & font ) [virtual]
Sets the font for the widget and informs all children
about the change.
The fontInfo() function reports the actual font that is
being used by the widget.
This code fragment sets a 12 point helvetica bold font:
QFont f("Helvetica", 12, QFont::Bold);
setFont( f );
See also font(), fontChange(), fontInfo(), fontMetrics(),
unsetFont() and ownFont().
Examples: grapher/grapher.cpp xform/xform.cpp
Reimplemented in QFontDialog, QWizard, QTabDialog and
QPopupMenu.
void QWidget::setFont ( const QFont & font, bool )
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.
Use setFont( const QFont& font) instead.
Examples: xform/xform.cpp hello/main.cpp
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QWidget(3qt)QWidget(3qt)void QWidget::setFontPropagation ( PropagationMode )
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.
Calling this function has no effect.
void QWidget::setGeometry ( int x, int y, int w, int h ) [virtual
slot]
Sets the widget geometry to w by h, positioned at x,y in
its parent widget.
If the widget is visible, it receives a move event and/or
resize event immediately. If the widget is not shown yet,
it is guaranteed to receive appropriate events before it
actually becomes visible.
The size is adjusted if it is outside the minimum or
maximum widget size.
This function is virtual, and all other overloaded
setGeometry() implementations call it.
Warning: If you call setGeometry() from resizeEvent() or
moveEvent(), you may see infinite recursion.
See also geometry(), move(), resize(), moveEvent(),
resizeEvent(), minimumSize() and maximumSize().
Reimplemented in QDialog.
void QWidget::setGeometry ( const QRect & ) [virtual slot]
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
Examples: i18n/main.cpp drawdemo/drawdemo.cpp
popup/popup.cpp qmag/qmag.cpp
Reimplemented in QDialog.
void QWidget::setIcon ( const QPixmap & pixmap ) [virtual slot]
Sets the window icon to pixmap.
See also icon(), setIconText(), setCaption() and Setting
the Application Icon
Reimplemented in QMessageBox.
void QWidget::setIconText ( const QString & iconText ) [virtual
slot]
Sets the text of the window's icon to iconText.
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See also iconText(), setIcon() and setCaption().
void QWidget::setKeyCompression ( bool compress ) [virtual
protected]
Enables key event compression, if enable is TRUE, and
disables it if enable is FALSE.
By default key compression is off, so widgets receive one
key press event for each key press (or more, since
autorepeat is usually on). If you turn it on and your
program doesn't keep up with key input, Qt tries to
compress key events so that more than one character can be
processed in each event.
For example, a word processor widget might receive 2, 3 or
more characters in each QKeyEvent::text(), if the layout
recalculation takes too long for the CPU.
If a widget supports multiple character unicode input, it
is always safe to turn the compression on.
See also QKeyEvent::text();.
void QWidget::setMask ( const QBitmap & bitmap ) [virtual]
Causes only the pixels of the widget for which bitmap has
a corresponding 1 bit to be visible. If the region
includes pixels outside the rect() of the widget, window
system controls in that area may or may not be visible,
depending on the platform.
Note that this effect can be slow if the region is
particularly complex.
See also setMask(const, QRegion&) and clearMask().
void QWidget::setMask ( const QRegion & region ) [virtual]
Causes only the parts of the widget which overlap region
to be visible. If the region includes pixels outside the
rect() of the widget, window system controls in that area
may or may not be visible, depending on the platform.
Note that this effect can be slow if the region is
particularly complex.
See also setMask(QBitmap) and clearMask().
void QWidget::setMaximumHeight ( int h )
Sets the maximum height of the widget to h without
changing the width. Provided for convenience.
See also sizeHint(), minimumSize(), maximumSize(),
setFixedSize() and more.
Examples: splitter/splitter.cpp
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QWidget(3qt)QWidget(3qt)void QWidget::setMaximumSize ( int maxw, int maxh ) [virtual]
Sets the maximum size of the widget to w by h pixels.
The widget cannot be resized to a larger size than the
maximum widget size. The widget's size is forced to the
maximum size if the current size is greater.
See also maximumSize(), setMinimumSize(),
setSizeIncrement(), resize() and size().
void QWidget::setMaximumSize ( const QSize & size )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::setMaximumWidth ( int w )
Sets the maximum width of the widget to w without changing
the height. Provided for convenience.
See also sizeHint(), minimumSize(), maximumSize(),
setFixedSize() and more.
void QWidget::setMicroFocusHint ( int x, int y, int width, int
height, bool text=TRUE ) [virtual protected]
When a widget gets focus, it should call setMicroFocusHint
for some appropriate position and size - x, y and w by h.
This has no visual effect, it just provides hints to any
system-specific input handling tools.
The text argument should be TRUE if this is a position for
text input.
In the Windows version of Qt, this method sets the system
caret, which is used for user Accessibility focus
handling. If text is TRUE, it also sets the IME
composition window in Far East Asian language input
systems.
In the X11 version of Qt, if text is TRUE, this method
sets the XIM "spot" point for complex language input
handling.
See also microFocusHint().
void QWidget::setMinimumHeight ( int h )
Sets the minimum height of the widget to h without
changing the width. Provided for convenience.
See also sizeHint(), minimumSize(), maximumSize(),
setFixedSize() and more.
void QWidget::setMinimumSize ( int minw, int minh ) [virtual]
Sets the minimum size of the widget to w by h pixels.
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The widget cannot be resized to a smaller size than the
minimum widget size. The widget's size is forced to the
minimum size if the current size is smaller.
If you use a layout inside the widget, the minimum size
will be set by the layout and not by setMinimumSize,
unless you set the layouts resize mode to
QLayout::FreeResize.
See also minimumSize(), setMaximumSize(),
setSizeIncrement(), resize(), size() and
QLayout::setResizeMode().
Examples: menu/menu.cpp qmag/qmag.cpp
splitter/splitter.cpp
void QWidget::setMinimumSize ( const QSize & size )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::setMinimumWidth ( int w )
Sets the minimum width of the widget to w without changing
the height. Provided for convenience.
See also sizeHint(), minimumSize(), maximumSize(),
setFixedSize() and more.
void QWidget::setMouseTracking ( bool enable ) [virtual slot]
Enables mouse tracking if enable is TRUE, or disables it
if enable is FALSE.
If mouse tracking is disabled (default), this widget only
receives mouse move events when at least one mouse button
is pressed down while the mouse is being moved.
If mouse tracking is enabled, this widget receives mouse
move events even if no buttons are pressed down.
See also hasMouseTracking(), mouseMoveEvent() and
QApplication::setGlobalMouseTracking().
Examples: popup/popup.cpp qmag/qmag.cpp
Reimplemented in QGLWidget.
void QWidget::setName ( const char * name ) [virtual]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QObject.
void QWidget::setPalette ( const QPalette & p, bool )
This function is obsolete. It is provided to keep old
Trolltech AS 13 June 2001 55
QWidget(3qt)QWidget(3qt)
source working, and will probably be removed in a future
version of Qt. We strongly advise against using it in new
code.
Use setPalette( const QPalette& p ) instead.
void QWidget::setPalette ( const QPalette & palette ) [virtual]
Sets the widget palette to palette and informs all
children about the change.
See also QApplication::setPalette(), palette(),
paletteChange(), unsetPalette(), ownPalette() and
colorGroup().
void QWidget::setPalettePropagation ( PropagationMode )
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.
Calling this function has no effect.
void QWidget::setSizeIncrement ( int w, int h ) [virtual]
Sets the size increment of the widget. When the user
resizes the window, the size will move in steps of w
pixels horizontally and h pixels vertically, with
baseSize() as basis. Preferred widget sizes are therefore
for non-negative integers i and j:
width = baseSize().width() + i * sizeIncrement().width();
height = baseSize().height() + j * sizeIncrement().height();
Note that while you can set the size increment for all
widgets, it has no effect except for top-level widgets.
Warning: The size increment has no effect under Windows,
and may be disregarded by the window manager on X.
See also sizeIncrement(), setMinimumSize(),
setMaximumSize(), resize() and size().
void QWidget::setSizeIncrement ( const QSize & )
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
void QWidget::setSizePolicy ( QSizePolicy policy )
Sets the size policy for this widget to policy. The size
policy specifies the default layout behaviour.
The default policy is Preferred/Preferred, which means
that the widget can be freely resized, but prefers to be
the size sizeHint() returns. Button-like widgets set the
size policy to specify that they may stretch horizontally,
Trolltech AS 13 June 2001 56
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but are fixed vertically. The same applies to lineedit
controls (such as QLineEdit, QSpinBox or an editable
QComboBox) and other horizontally orientated widgets (such
as QProgressBar). A QToolButton on the other hand wants to
be squared, therefore it allows growth in both directions.
Widgets that support different directions (such as
QSlider, QScrollBar or QHeader) specify stretching in the
respective direction only. Widgets that can provide
scrollbars (usually subclasses of QScrollView) tend to
specify that they can use additional space, and that they
can survive on less than sizeHint().
See also sizeHint(), QLayout, QSizePolicy and
updateGeometry().
void QWidget::setStyle ( QStyle * style )
Sets the widget's GUI style to style. Ownership of the
style object is not transferred.
If no style is set, the widget uses the application's
style QApplication::style() instead.
Setting a widget's style has no effect on existing or
future child widgets.
Warning: This function is particularly useful for
demonstration purposes, where you want to show Qt's
styling capabilities. Real applications should stay away
from it and use one consistent GUI style instead.
See also style(), QStyle, QApplication::style() and
QApplication::setStyle().
Examples: grapher/grapher.cpp
void QWidget::setTabOrder ( QWidget * first, QWidget * second )
[static]
Moves the second widget around the ring of focus widgets
so that keyboard focus moves from first widget to second
widget when Tab is pressed.
Note that since the tab order of the second widget is
changed, you should order a chain like this:
setTabOrder(a, b ); // a to b
setTabOrder(b, c ); // a to b to c
setTabOrder(c, d ); // a to b to c to d
not like this:
setTabOrder(c, d); // c to d
setTabOrder(a, b); // a to b AND c to d
setTabOrder(b, c); // a to b to c, but not c to d
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If either first or second has a focus proxy, setTabOrder()
substitutes its/their proxies.
See also setFocusPolicy() and setFocusProxy().
Examples: customlayout/main.cpp
void QWidget::setUpdatesEnabled ( bool enable ) [virtual slot]
Enables widget updates if enable is TRUE, or disables
widget updates if enable is FALSE.
Calling update() and repaint() has no effect if updates
are disabled. Paint events from the window system are
processed normally even if updates are disabled.
This function is normally used to disable updates for a
short period of time, for instance to avoid screen flicker
during large changes.
Example:
setUpdatesEnabled( FALSE );
bigVisualChanges();
setUpdatesEnabled( TRUE );
repaint();
See also isUpdatesEnabled(), update(), repaint() and
paintEvent().
Reimplemented in QHeader.
void QWidget::setWFlags ( WFlags f ) [virtual protected]
Sets the widget flags f.
Widget flags are a combination of Qt::WidgetFlags.
See also testWFlags(), getWFlags() and clearWFlags().
void QWidget::show () [virtual slot]
Shows the widget and its child widgets.
If its size or position has changed, Qt guarantees that a
widget gets move and resize events just before the widget
is shown.
You almost never have to reimplement this function. If you
need to change some settings before a widget is shown, use
showEvent() instead. If you need to do some delayed
initialization use polish().
See also showEvent(), hide(), showMinimized(),
showMaximized(), showNormal(), isVisible() and polish().
Examples: showimg/main.cpp rangecontrols/main.cpp
Trolltech AS 13 June 2001 58
QWidget(3qt)QWidget(3qt)
validator/main.cpp listviews/main.cpp aclock/main.cpp
checklists/main.cpp drawlines/connect.cpp dclock/main.cpp
xform/xform.cpp cursor/cursor.cpp layout/layout.cpp
tetrix/tetrix.cpp buttongroups/main.cpp life/main.cpp
i18n/main.cpp drawdemo/drawdemo.cpp lineedits/main.cpp
popup/popup.cpp listbox/main.cpp menu/menu.cpp
progress/progress.cpp qmag/qmag.cpp splitter/splitter.cpp
progressbar/main.cpp tooltip/main.cpp richtext/main.cpp
qwerty/main.cpp forever/forever.cpp rot13/rot13.cpp
xml/tagreader scrollview/scrollview.cpp movies/main.cpp
picture/picture.cpp hello/main.cpp listboxcombo/main.cpp
biff/main.cpp tictac/main.cpp customlayout/main.cpp
Reimplemented in QTableView, QTabBar, QMenuBar,
QWidgetStack, QNPWidget, QToolBar, QWizard, QSemiModal,
QMainWindow, QListView, QDialog, QScrollView, QTabDialog,
QPopupMenu and QProgressBar.
void QWidget::showEvent ( QShowEvent * ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive widget show events.
Non-spontaneous show events are sent to widgets right
before they are shown. Spontaneous show events of toplevel
widgets are delivered afterwards, naturally.
See also event() and QShowEvent.
Reimplemented in QTextBrowser, QProgressDialog, QTable,
QTabWidget, QListBox, QWorkspace, QTextView, QListView and
QHeader.
void QWidget::showFullScreen () [slot]
Shows the widget in full-screen mode.
Calling this function has no effect for other than top-
level widgets.
To return from full-screen mode, call showNormal().
Full-screen mode works fine under Windows, but has certain
problems under X. These problems are due to limitations of
the ICCCM protocol that specifies the communication
between X11 clients and the window manager. ICCCM simply
does not know the concept of non-decorated full-screen
windows. Therefore, the best we can do is to request a
borderless window and place and resize it to fill the
entire screen. Depending on the window manager, this may
or may not work. The borderless window is requested using
MOTIF hints, which are at least partially supported by
virtually all modern window managers.
An alternative would be to bypass the window manager at
all and to create a window with the WX11BypassWM flag.
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This has other severe problems, though, like totally
broken keyboard focus and very strange effects on desktop
changes or when the user raises other windows.
Future window managers that follow modern post-ICCCM
specifications may support full-screen mode properly.
See also showNormal(), showMaximized(), show(), hide() and
isVisible().
void QWidget::showMaximized () [virtual slot]
Shows the widget maximized.
Calling this function has no effect for other than top-
level widgets.
On X11, this function may not work properly with certain
window managers. See the Window Geometry documentation for
details on why.
See also showNormal(), showMinimized(), show(), hide() and
isVisible().
Examples: helpviewer/main.cpp scribble/main.cpp
qwerty/main.cpp
void QWidget::showMinimized () [virtual slot]
Shows the widget minimized, as an icon.
Calling this function has no effect for other than top-
level widgets.
See also showNormal(), showMaximized(), show(), hide(),
isVisible() and isMinimized().
void QWidget::showNormal () [virtual slot]
Restores the widget after it has been maximized or
minimized.
Calling this function has no effect for other than top-
level widgets.
See also showMinimized(), showMaximized(), show(), hide()
and isVisible().
QSize QWidget::size () const
Returns the size of the widget, excluding the window
frame.
See also geometry(), width() and height().
QSize QWidget::sizeHint () const [virtual]
Returns a recommended size for the widget, or an invalid
size if no size is recommended.
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The default implementation returns an invalid size if
there is no layout for this widget, the layout's preferred
size otherwise.
See also QSize::isValid(), minimumSizeHint(),
sizePolicy(), setMinimumSize() and updateGeometry().
Reimplemented in QGroupBox, QToolButton, QSlider, QTable,
QCheckBox, QProgressDialog, QLineEdit, QMenuBar,
QLCDNumber, QPushButton, QScrollBar, QRadioButton,
QListBox, QHBox, QComboBox, QGrid, QSpinBox, QProgressBar,
QHeader, QPopupMenu, QIconView, QDial, QListView, QTabBar,
QMainWindow, QDialog, QLabel, QFrame, QTabWidget,
QWidgetStack, QMultiLineEdit, QSplitter, QCanvasView,
QScrollView, QSizeGrip and QWorkspace.
QSize QWidget::sizeIncrement () const
Returns the widget size increment.
See also setSizeIncrement(), minimumSize() and
maximumSize().
QSizePolicy QWidget::sizePolicy () const [virtual]
Returns the default layout behaviour of this widget.
If there is a QLayout that manages this widget's children,
the size policy specified by that layout is used. If there
is no such QLayout, the result of this function is used.
See also setSizePolicy(), sizeHint(), QLayout, QSizePolicy
and updateGeometry().
Reimplemented in QSlider, QPushButton, QProgressBar,
QRadioButton, QLabel, QScrollBar, QTabBar, QWorkspace,
QToolButton, QLCDNumber, QTabWidget, QFrame, QLineEdit,
QHeader, QCheckBox, QSpinBox, QMultiLineEdit, QScrollView,
QIconView, QSplitter and QSizeGrip.
void QWidget::stackUnder ( QWidget * w ) [slot]
Places the widget under w in the parent widget's stack.
To make this work, the widget itself and w have to be
siblings.
See also raise() and lower().
QStyle& QWidget::style () const
Returns the GUI style for this widget
See also QWidget::setStyle(), QApplication::setStyle() and
QApplication::style().
void QWidget::styleChange ( QStyle & oldStyle ) [virtual
protected]
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This virtual function is called when the style of the
widgets. changes.oldStyle is the previous GUI style; you
can get the new style from style().
Reimplement this function if your widget needs to know
when its GUI style changes. You will almost certainly need
to update the widget using update().
The default implementation updates the widget including
its geometry.
See also QApplication::setStyle(), style(), update() and
updateGeometry().
Reimplemented in QPopupMenu, QComboBox, QProgressBar,
QSlider, QIconView, QMenuBar, QScrollBar, QMainWindow,
QSpinBox, QToolBar, QSplitter, QListView, QProgressDialog,
QTabWidget, QTabBar, QTabDialog and QScrollView.
bool QWidget::testWFlags ( WFlags f ) const
Returns TRUE if any of the widget flags in f are set.
Widget flags are a combination of Qt::WidgetFlags.
See also getWFlags(), setWFlags() and clearWFlags().
QWidget * QWidget::topLevelWidget () const
Returns the top-level widget for this widget, i.e. the
next ancestor widget that has a window-system frame (or at
least may have one).
If the widget is a top-level, the widget itself is
returned.
Typical usage is changing the window caption:
aWidget->topLevelWidget()->setCaption( "New Caption" );
See also isTopLevel().
void QWidget::unsetCursor () [virtual]
Unset the cursor for this widget. The widget will use the
cursor of its parent from now on.
This functions does nothing for top-level windows.
See also cursor(), setCursor() and
QApplication::setOverrideCursor().
void QWidget::unsetFont ()
Unsets the font for this widget. The widget will use its
natural default font from now on. This is either a special
font for the widget class, the parent's font or - if this
widget is a toplevel widget - the default application
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font.
See also setFont() and ownFont().
void QWidget::unsetPalette ()
Unsets the palette for this widget. The widget will use
its natural default palette from now on.
See also setPalette() and ownPalette().
void QWidget::update () [slot]
Updates the widget unless updates are disabled or the
widget is hidden.
Updating the widget will erase the widget contents and
generate an appropriate paint event for the invalidated
region. The paint event is processed after the program has
returned to the main event loop. Calling update() many
times in a row will generate a single paint event.
If the widgets sets the WRepaintNoErase flag, update()
will not erase its contents.
See also repaint(), paintEvent(), setUpdatesEnabled(),
erase() and setWFlags().
Examples: grapher/grapher.cpp drawlines/connect.cpp
drawdemo/drawdemo.cpp desktop/desktop.cpp
scrollview/scrollview.cpp picture/picture.cpp
void QWidget::update ( int x, int y, int w, int h ) [slot]
Updates a rectangle (x, y, w, h) inside the widget unless
updates are disabled or the widget is hidden.
Updating the widget erases the widget area (x,y,w,h) and
generate an appropriate paint event for the invalidated
region. The paint event is processed after the program has
returned to the main event loop. Calling update() many
times in a row will generate a single paint event.
If w is negative, it is replaced with width() - x. If h is
negative, it is replaced width height() - y.
If the widgets sets the WRepaintNoErase flag, update()
will not erase its contents.
See also repaint(), paintEvent(), setUpdatesEnabled() and
erase().
void QWidget::update ( const QRect & r ) [slot]
This is an overloaded member function, provided for
convenience. It differs from the above function only in
what argument(s) it accepts.
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QWidget(3qt)QWidget(3qt)void QWidget::updateGeometry ()
Notifies the layout system that this widget has changed
and may need to change geometry.
Call this function if the sizeHint() or sizePolicy() have
changed.
For explicitly hidden widgets, updateGeometry() is a no-
op. The layout system will be notified as soon as the
widget is shown.
void QWidget::updateMask () [virtual protected]
This function can be reimplemented in a subclass to
support transparent widgets. It is supposed to be called
whenever a widget changes state in a way that the shape
mask has to be recalculated.
See also setAutoMask(), updateMask(), setMask() and
clearMask().
Reimplemented in QCheckBox, QGroupBox, QPushButton,
QSlider, QRadioButton, QTabWidget, QFrame, QTabBar and
QComboBox.
QRect QWidget::visibleRect () const
Returns the currently visible rectangle of the widget.
This function is in particular useful to optimize
immediate repainting of a widget. Typical usage is
repaint( w->visibleRect() );
or
repaint( w->visibleRect(), FALSE );
If nothing is visible, the rectangle returned is empty.
void QWidget::wheelEvent ( QWheelEvent * e ) [virtual protected]
This event handler can be reimplemented in a subclass to
receive wheel events for the widget.
If you reimplement this handler, it is very important that
you ignore() the event if you do not handle it, so that
the widget's parent can interpret it.
The default implementation ignores the event.
See also QWheelEvent::ignore(), QWheelEvent::accept(),
event() and QWheelEvent.
Reimplemented in QSpinBox, QSlider, QScrollView,
QScrollBar, QMultiLineEdit and QDial.
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QWidget(3qt)QWidget(3qt)int QWidget::width () const
Returns the width of the widget, excluding the window
frame.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also geometry(), height() and size().
Examples: grapher/grapher.cpp xform/xform.cpp
drawdemo/drawdemo.cpp menu/menu.cpp qmag/qmag.cpp
WId QWidget::winId () const
Returns the window system identifier of the widget.
Portable in principle, but if you use it you are probably
about to do something non-portable. Be careful.
See also find().
int QWidget::x () const
Returns the x coordinate of the widget, relative to its
parent widget and including the window frame.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also frameGeometry(), y() and pos().
int QWidget::y () const
Returns the y coordinate of the widget, relative to its
parent widget and including the window frame.
See the Window Geometry documentation for an overview of
geometry issues with top-level widgets.
See also frameGeometry(), x() and pos().
Examples: drawdemo/drawdemo.cpp
void QWidget::clearWState ( uint n ) [protected]
For internal use only.
QWExtra * QWidget::extraData () [protected]
For internal use only.
uint QWidget::getWState () const [protected]
For internal use only.
void QWidget::setCRect ( const QRect & r ) [virtual protected]
For internal use only.
void QWidget::setFRect ( const QRect & r ) [virtual protected]
For internal use only.
Trolltech AS 13 June 2001 65
QWidget(3qt)QWidget(3qt)void QWidget::setWState ( uint n ) [virtual protected]
For internal use only.
bool QWidget::testWState ( uint n ) const
For internal use only.
QTLWExtra * QWidget::topData () [protected]
For internal use only.
QWidgetMapper * QWidget::wmapper () [static]
For internal use only.
SEE ALSO
http://doc.trolltech.com/qwidget.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 (qwidget.3qt)
and the Qt version (2.3.1).
Trolltech AS 13 June 2001 66
