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The QWidget class is the base class of all user interface objects. More...
#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.
| 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 | ||
| 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 |
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:
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:
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:
Some widgets will need to reimplement some more obscure event handlers, too:
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.
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 forever/forever.cpp desktop/desktop.cpp scrollview/scrollview.cpp customlayout/main.cpp
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 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().
WidgetOrigin - the pixmap is drawn in the widget's coordinate system.
ParentOrigin - the pixmap is drawn in the parent's coordinate system.
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.
This enum used to determine how fonts and palette changes are propagated to children of a widget.
Constructs a widget which is a child of parent, with the 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 );
Destructs the widget.
All children of this widget are deleted first. The application exits if this widget is (was) the main widget.
Returns TRUE if drop events are enabled for this widget.
See also setAcceptDrops().
[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.
Returns whether or not the widget has the auto mask feature enabled.
See also setAutoMask(), updateMask(), setMask() and clearMask().
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
[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().
Returns the mode most recently set by setBackgroundMode(). The default is PaletteBackground.
See also BackgroundMode and setBackgroundMode().
Returns the current background origin.
See also setBackgroundOrigin().
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().
[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().
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().
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().
Examples: i18n/main.cpp
Returns the bounding rectangle of the widget's children.
Explicitely hidden children are excluded.
See also childrenRegion().
Returns the combined region of the widget's children geometry().
Explicitely hidden children are excluded.
See also childrenRect().
[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 keyboard input focus, i.e. it must call setFocusPolicy().
See also hasFocus(), setFocus(), focusInEvent(), focusOutEvent(), setFocusPolicy() and QApplication::focusWidget().
Removes any mask set by setMask().
See also setMask().
[protected]Clears the widget flags f.
Widget flags are a combination of Qt::WidgetFlags.
See also testWFlags(), getWFlags() and setWFlags().
[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
[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().
[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 QDialog, QPopupMenu and QProgressDialog.
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().
[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().
[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.
Returns the widget cursor. If no cursor has been set the parent widget's cursor is returned.
See also setCursor() and unsetCursor();.
[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.
[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.
[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.
[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 to provide drag-and-drop in your application.
See also QTextDrag, QImageDrag and QDragEnterEvent.
Reimplemented in QMultiLineEdit and QLineEdit.
[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.
[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.
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().
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
[virtual protected]This event handler is called when the drag is dropped on 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 QDropEvent.
Reimplemented in QMultiLineEdit and QLineEdit.
[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.
[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.
Erases the area defined by reg, without generating a paint event.
Child widgets are not affected.
Examples: drawlines/connect.cpp
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().
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.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
[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.
[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 winId().
[protected]Returns a pointer to the focus data for this widget's top-level widget.
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().
[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 QLineEdit, QDial, QTable, QMenuBar, QRadioButton, QListBox, QTabBar, QListView, QPushButton, QButton, QGroupBox, QComboBox, QPopupMenu, QTextView, QSlider and QMultiLineEdit.
[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.
See also focusData().
Reimplemented in QMultiLineEdit, QScrollView, QPopupMenu and QButton.
[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 QTable, QListBox, QTextView, QLineEdit, QListView, QButton, QSlider, QPushButton, QDial, QMultiLineEdit, QTabBar, QPopupMenu and QMenuBar.
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().
Returns a pointer to the focus proxy, or 0 if there is no focus proxy.
See also setFocusProxy().
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.
Returns the font currently set for the widget.
fontInfo() tells you what font is actually being used.
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
[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, QGroupBox and QLabel.
Returns the font info for the widget's current font. Equivalent to QFontInto(widget->font()).
See also font(), fontMetrics() and setFont().
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
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().
Returns the foreground color of this widget.
The foreground color is also accessible as colorGroup().foreground().
See also backgroundColor() and colorGroup().
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().
Returns the size of the window system frame (for top level widgets).
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
[protected]Returns the widget flags for this this widget.
Widget flags are a combination of Qt::WidgetFlags.
See also testWFlags(), setWFlags() and clearWFlags().
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().
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.
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().
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
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().
Returns TRUE if mouse tracking is enabled for this widget, or FALSE if mouse tracking is disabled.
See also setMouseTracking().
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
[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 QMenuBar, QTextView and QLabel.
[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 QToolBar, QDialog, QPopupMenu and QMenuBar.
[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.
Returns the widget icon pixmap, or null if no icon has been set.
See also setIcon(), iconText() and caption().
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().
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.
See also setActiveWindow() and QApplication::activeWindow().
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().
Returns TRUE if the widget is enabled, or FALSE if it is disabled.
See also setEnabled().
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().
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().
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 isEnabled().
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().
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().
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().
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.
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().
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.
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().
Returns TRUE if updates are enabled, otherwise FALSE.
See also setUpdatesEnabled().
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().
Returns TRUE if this widget would become visible if 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().
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().
[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 QTabBar, QPopupMenu, QButton, QFileDialog, QTextBrowser, QLineEdit, QDialog, QTable, QTextView, QDial, QMessageBox, QListBox, QMenuBar, QSlider, QListView, QMultiLineEdit, QScrollBar and QComboBox.
[virtual protected]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.
[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().
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().
[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 QLineEdit, QSpinBox, QMenuBar, QToolButton and QMultiLineEdit.
[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 afterwards.
See also raise() and stackUnder().
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().
Translates the global screen coordinate pos to widget coordinates.
See also mapToGlobal(), mapFrom() and mapFromParent().
Translates the parent widget coordinate pos to widget coordinates.
Same as mapFromGlobal() if the widget has no parent.
See also mapToParent(), mapFrom() and mapFromGlobal().
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().
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
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().
Returns the widget's maximum height.
See also maximumSize() and maximumWidth().
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().
Returns the widget's maximum width.
See also maximumSize() and maximumHeight().
[virtual protected]Internal implementation of the virtual QPaintDevice::metric() function.
Use the QPaintDeviceMetrics class instead.
Reimplemented from QPaintDevice.
Returns the currently set micro focus hint for this widget.
See also setMicroFocusHint().
Returns the widget's minimum height.
See also minimumSize() and minimumWidth().
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().
[virtual]Returns a recommended minimum size for the widget, or an 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 QLineEdit, QTabBar, QListBox, QDialog, QMainWindow, QLabel, QSplitter, QListView, QScrollView, QToolBar, QMenuBar, QTabWidget, QSlider, QDial, QProgressBar, QIconView, QWidgetStack and QMultiLineEdit.
Returns the widget's minimum width.
See also minimumSize() and minimumHeight().
[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 QListBox, QMultiLineEdit, QComboBox and QLineEdit.
[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().
[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 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 QMenuBar, QHeader, QPopupMenu, QLineEdit, QButton, QSlider, QDial, QSizeGrip, QListBox, QComboBox, QMultiLineEdit and QScrollBar.
[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 QHeader, QScrollBar, QComboBox, QSlider, QPopupMenu, QListBox, QSizeGrip, QTabBar, QMultiLineEdit, QButton, QDial, QLineEdit and QMenuBar.
[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, QLineEdit, QDial, QListBox, QMultiLineEdit, QButton, QComboBox, QPopupMenu, QSlider, QMenuBar, QTabBar and QHeader.
[virtual slot]Moves the widget to the position (x,y) relative to the parent widget and including the window frame.
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 QDialog, QSemiModal and QPushButton.
[slot]This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
[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.
Returns whether the widget uses its own cursor or its parent widget's cursor.
Returns whether the widget uses its own font or its natural default font.
See also setFont() and unsetFont().
Returns whether the widget uses its own palette or its natural default palette.
See also setPalette() and unsetPalette().
[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 QComboBox, QSlider, QGroupBox, QGLWidget, QScrollBar, QTabBar, QFrame, QHeader, QLineEdit, QSizeGrip, QStatusBar, QTableView, QPopupMenu, QDial, QTabDialog, QToolBar, QMainWindow and QButton.
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().
[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().
Reimplemented in QTextView.
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.
Returns a pointer to the parent of this widget, or a null pointer if it does not have any parent widget.
[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
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
[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.
See also lower() and stackUnder().
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
Releases the keyboard grab.
See also grabKeyboard(), grabMouse() and releaseMouse().
Releases the mouse grab.
See also grabMouse(),