The QWidget class is the base class of all user interface objects. More...
#include <qwidget.h>
Inherits QObject and QPaintDevice.
Inherited by QButton, QComboBox, QDialog, QFrame, QGLWidget, QHeader, QLineEdit, QMainWindow, QNPWidget, QScrollBar, QSemiModal, QSizeGrip, QSlider, QStatusBar, QTabBar, QTabWidget, QToolBar and QXtWidget.
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. The widget name is little used at the moment - the
dumpObjectTree() debugging function uses it, and you can access it using
name(). It will become more important when our visual GUI builder is
ready (you can name a a widget in the builder, and connect() to it by
name in your code).
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 every other event to one of the more specialized handlers above.
When writing a widget, there are a few more things to look out for.
sizePolicy() lets you supply good defaults for the layout management handling, so that other widgets can contain yours easily. sizeHint() indicates a "good" size for the widget.
See also: QEvent, QPainter, QGridLayout and QBoxLayout.
Examples: tabdialog/tabdialog.cpp drawlines/connect.cpp mainlyQt/editor.cpp xform/xform.cpp qiconview/main.cpp layout/layout.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 in the widget.
The following values are valid:
PaletteForeground
- use palette() . fillForeground()
PaletteBackground
- use palette() . fillBackground()
PaletteButton
- use palette() . fillButton()
PaletteLight
- use palette() . fillLight()
PaletteMidlight
- use palette() . fillMidlight()
PaletteDark
- use palette() . fillDark()
PaletteMid
- use palette() . fillMid()
PaletteText
- use palette() . fillText()
PaletteBrightText
- use palette() . fillBrightText()
PaletteButtonText
- use palette() . fillButtonText()
PaletteBase
- use palette() . fillBase()
PaletteShadow
- use palette() . fillShadow()
PaletteHighlight
- use palette() . fillHighlight()
PaletteHighlightedText
- use palette() . fillHighlightedText()
NoBackground
- no color or pixmap is used - the paintEvent() must completely
cover the drawing area. This can help avoid flicker.
See also: setBackgroundMode() and backgroundMode().
If a widget's propagation mode is NoChildren, changes to that
widget's font or palette do not affect the widget's children. IF it
is AllChildren, all children are affected. If it is SameFont
or SamePalette (mostly the default mode) then changes affect
those child widget for which no separate font/palette has been set,
but no other children.
See also: setFont() and setPalette().
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. Unless the newly created widget is reparented, it will be deleted when the parent is deleted.
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 these flags:
WStyle_NormalBorder gives the window a normal border. Cannot
be combined with WStyle_DialogBorder or WStyle_NoBorder.
WStyle_DialogBorder gives the window a thin dialog
border. Cannot be combined with WStyle_NormalBorder or WStyle_NoBorder.
WStyle_NoBorder gives a borderless window. Note that the
user cannot move or resize a borderless window via the window
system. Cannot be combined with WStyle_NormalBorder or WStyle_DialogBorder.
WStyle_Title gives the window a title bar.
WStyle_SysMenu adds a window system menu.
WStyle_Minimize adds a minimize button.
WStyle_Maximize adds a maximize button.
WStyle_MinMax is equal to (WStyle_Minimize | WStyle_Maximize)
.
WStyle_Tool makes the window a tool window. A tool window
is a small window that lives for a short time and it is typically
used for creating popup windows. It there is a parent, the tool
window will be kept on top of it. If there isn't a parent, you may
consider passing WStyle_StaysOnTop as well. If the window system
supports it, a tool window will be decorated with a somewhat lighter
frame. It can, however, be combined with WStyle_NoBorder as
well.
WStyle_StaysOnTop informs the window system that the window
should stay on top of all other windows.
WStyle_Dialog indicates that the window is a logical
subwindow of its parent, in other words: a dialog. The window will
not get its own taskbar entry and be kept on top of its parent by
the window system. Usually, it will also be minimized when the
parent is minized. If not customized, the window is decorated
slightly less. WStyle_Dialog is implied by WType_Modal. It is
implicitely defined when using the class QDialog.
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 *toolTip = new QLabel( 0, "myToolTip",
WStyle_Customize | WStyle_NoBorder |
WStyle_Tool );
The widget flags are defined in qnamespace.h (which is included by qwidget.h).
Destroys 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: movies/main.cpp
Reimplemented in QMessageBox.
Returns whether or not a widget has the auto mask feature enabled.
See also: setAutoMask(), updateMask(), setMask() and clearMask().
Returns the background color of this widget.
The background color is independent of the color group.
Setting a new palette overwrites the background color.
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 update the widget using either repaint(TRUE) or update().
The default implementation calls update()
See also: setBackgroundColor(), backgroundColor(), setPalette(), repaint() and update().
Returns the mode most recently set by setBackgroundMode(). The default is PaletteBackground
Returns the background pixmap, or null if no background pixmap has not been set. If the widget has been made empty, this function will return a pixmap which isNull() rather than 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 update the widget using either repaint(TRUE) or update().
The default implementation calls update()
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, or a null string if no caption has been set.
See also: setCaption(), icon() and iconText().
Returns the bounding rectangle of the widget's children.
Returns the combined region of the widget's children geometry().
[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 loose 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]For internal use only.
[protected]For internal use only.
[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. Otherwise, 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 QPopupMenu, QDialog 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 focus returns the QPalette::active() color group and a normal widget returns the QPalette::normal() color group.
See also: palette() and setPalette().
[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.
QCustomEvent is a user-defined event type which contains a Warning:void*. This event class is internally used to implement Qt enhancements. It is
not advisable to use QCustomEvent in normal applications, where other
event types and the signal/slot mechanism can do the job.
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 never call QWhatsThis::leaveWhatsThisMode() in that case.
See also: QWhatsThis::inWhatsThisMode() and QWhatsThis::leaveWhatsThisMode().
Reimplemented in QMenuBar and QPopupMenu.
[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.
[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.
[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 either repaint(TRUE) or 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 and QXtWidget.
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.
[protected]For internal use only.
[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().
[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 must accept focus initially in order to receive focus events.
The default implementation calls repaint() since the widget's color group changes from normal to active. You may want to call repaint(FALSE) to reduce flicker in any reimplementation. It also calls setMicroFocusHint(), hinting any system-specific input tools about the focus of the user's attention.
As a special case to support applications not utilizing focus, Top-level widgets that have NoFocus policy will receive focus events and gain keyboard events, but the repaint is not done by default.
See also: focusOutEvent(), setFocusPolicy(), keyPressEvent(), keyReleaseEvent(), event() and QFocusEvent.
Reimplemented in QPushButton, QListBox, QButton, QXtWidget, QMultiLineEdit, QLineEdit, QSlider, QComboBox, QListView and QRadioButton.
[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 QButton and QScrollView.
[virtual protected]This event handler can be reimplemented in a subclass to receive keyboard focus events (focus lost) for the widget.
A widget must accept focus initially in order to receive focus events.
The default implementation calls repaint( visibleRect() ) since the widget's color group changes from active to normal. You may want to call repaint( visibleRect(), FALSE) to reduce flicker in any reimplementation.
See also: focusInEvent(), setFocusPolicy(), keyPressEvent(), keyReleaseEvent(), event() and QFocusEvent.
Reimplemented in QListBox, QButton, QMenuBar, QMultiLineEdit, QLineEdit, QPushButton, QSlider, QXtWidget and QListView.
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 or the default application font.
See also: setFont(), fontInfo(), fontMetrics() and QApplication::font().
Examples: grapher/grapher.cpp xform/xform.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 either repaint(TRUE) or update().
The default implementation calls update
See also: setFont(), font(), repaint() and update().
Reimplemented in QMenuBar.
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
Returns the font propagation mode of this widget. The default
font propagation mode is NoChildren, but you can set it to SameFont or AllChildren.
See also: setFontPropagation().
Returns the foreground color of this widget.
The foreground color equals colorGroup().foreground().
See also: backgroundColor() and colorGroup().
Returns the geometry of the widget, relative to its parent and including the window frame.
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 also: frameGeometry(), size() and rect().
Examples: qmag/qmag.cpp
[protected]For internal use only.
[protected]For internal use only.
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.
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 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, QLabel and QTextView.
[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 \link hideEvent() instead.
See also: \hideEvent(), show(), showMinimized(), isVisible() and close().
Examples: xform/xform.cpp popup/popup.cpp progress/progress.cpp scrollview/scrollview.cpp
Reimplemented in 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, or a null string if no icon text has been set.
See also: setIconText(), icon() and caption().
Returns TRUE if the top-level widget containing this widget is the active window.
See also: setActiveWindow() and topLevelWidget().
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 and every parent up to but excluding ancestor is enabled, otherwise returns FALSE.
See also: setEnabled() and isEnabled().
Returns TRUE if this widget and every parent up to the top level widget is enabled, otherwise returns FALSE.
This is equivalent to isEnabledTo(0).
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 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 set to visible status, or else FALSE. Calling show() sets the widget to visible status; calling hide() sets it to hidden status. Iconified top-level widgets also have hidden status, as well as having isMinimized() return TRUE.
If a widget is set to visible status, but its parent widget is set to hidden status, this function returns TRUE. isVisibleToTLW() looks at the visibility status of the parent widgets up to the top level widget.
This function returns TRUE if the widget currently is obscured by other windows on the screen, but would be visible if moved.
See also: show(), hide(), isVisibleToTLW() and isMinimized().
Returns TRUE if this widget and every parent up to but excluding ancestor is visible, otherwise returns FALSE.
This function returns TRUE if the widget it is obscured by other windows on the screen, but would be visible if moved.
See also: show(), hide() and isVisible().
Returns TRUE if this widget and every parent up to the top level widget is visible, otherwise returns FALSE.
This function returns TRUE if the widget it is obscured by other windows on the screen, but would be visible if moved.
This is equivalent to isVisibleTo(0).
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 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 press 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.
As a special case to support applications not utilizing focus, Top-level widgets that have NoFocus policy will receive keyboard events.
See also: keyReleaseEvent(), QKeyEvent::ignore(), setFocusPolicy(), focusInEvent(), focusOutEvent(), event() and QKeyEvent.
Reimplemented in QComboBox, QButton, QTextBrowser, QSlider, QDialog, QMultiLineEdit, QLineEdit, QTextView, QMessageBox, QMenuBar, QListBox, QListView, QPopupMenu, QScrollBar, QFileDialog and QTabBar.
[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.
[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 QToolButton, QMenuBar, QXtWidget, QMultiLineEdit and QLineEdit.
[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().
Translates the global screen coordinate pos to widget coordinates.
See also: mapToGlobal().
Translates the parent widget coordinate pos to widget coordinates.
Same as mapFromGlobal() if the widget has no parent.
See also: mapToParent().
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().
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().
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 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 QWidgetStack, QSplitter, QLineEdit, QMultiLineEdit, QSlider, QProgressBar, QTabWidget, QListBox, QListView and QScrollView.
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 QComboBox, QMultiLineEdit, QLineEdit and QListBox.
[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, QListBox, QSlider, QScrollBar, QButton, QPopupMenu, QMultiLineEdit, QSizeGrip, QLineEdit and QComboBox.
[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 QListBox, QScrollBar, QLineEdit, QButton, QSlider, QTabBar, QComboBox, QSizeGrip, QPopupMenu, QMenuBar and QMultiLineEdit.
[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, QSlider, QListBox, QMenuBar, QLineEdit, QMultiLineEdit and QComboBox.
[virtual slot]Moves the widget to the position (x,y) relative to the parent widget.
A move event is generated immediately if the widget is visible. If the widget is invisible, the move event is generated when show() is called.
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 also: pos(), resize(), setGeometry() and moveEvent().
Examples: xform/xform.cpp
Reimplemented in QSemiModal and QDialog.
[slot]This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Examples: xform/xform.cpp drawdemo/drawdemo.cpp popup/popup.cpp
[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.
[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. 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, QScrollBar, QSizeGrip, QButton, QToolBar, QLineEdit, QFrame, QGLWidget, QMainWindow, QStatusBar, QTabBar, QPopupMenu, QGroupBox, QSlider, QTableView, QHeader and QComboBox.
Returns the widget palette.
As long as no special palette has been set, this is either a special palette for the widget class, the palette of the parent widget or 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 update the widget using either repaint(TRUE) or update().
The default implementation calls update().
See also: setPalette() and palette().
Reimplemented in QTextView.
Returns the palette propagation mode of this widget. The default
palette propagation mode is NoChildren, but you can set it to SamePalette or AllChildren.
See also: setPalettePropagation().
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 just 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.
The default implementation sets the WState_Polished widget state
and calls QApplication::polish().
See also: QApplication::polish().
Returns the position of the widget in its parent widget, including the window frame.
See also: 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().
Returns the the internal geometry of the widget, excluding the window frame. rect() equals QRect(0,0,width(),height()).
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(), grabKeyboard() and releaseKeyboard().
Examples: qmag/qmag.cpp
[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.
Calling repaint() is usually faster than doing an update(), but 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().
[slot]Repaints the widget directly by calling paintEvent() directly, unless updates are disabled or the widget is hidden.
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.
Doing a repaint() is usually faster than doing an update(), but 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 forever/forever.cpp
[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.
[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.
[slot]This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
[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.
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().
[virtual slot]Resizes the widget to size w by h pixels.
A resize event is generated immediately if the widget is visible. If the widget is invisible, the resize event is generated when show() is called.
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 xform/xform.cpp drawdemo/drawdemo.cpp qmag/qmag.cpp qwerty/main.cpp rot13/rot13.cpp
Reimplemented in QSemiModal and QDialog.
[slot]This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Examples: rangecontrols/main.cpp themes/main.cpp listviews/main.cpp checklists/main.cpp buttons_groups/main.cpp dclock/main.cpp xform/xform.cpp mainlyXt/editor.cpp i18n/main.cpp drawdemo/drawdemo.cpp lineedits/main.cpp popup/popup.cpp scribble/main.cpp qmag/qmag.cpp progressbar/main.cpp mainlyMotif/editor.cpp richtext/main.cpp scrollview/scrollview.cpp qfd/qfd.cpp listbox_combo/main.cpp qfileiconview/main.cpp
[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 QScrollView, QFileDialog, QScrollBar, QMultiLineEdit, QListView, QSlider, QMenuBar, QMainWindow, QWidgetStack, QTabDialog, QGLWidget, QComboBox, QTableView, QListBox, QGroupBox, QLineEdit, QSpinBox, QFrame, QXtWidget, QProgressDialog, QMessageBox and QTextView.
Scrolls the contents of the widget dx pixels rightwards and dy pixels downwards. If dx/dy is negative, the scroll direction is leftwards/upwards. Child widgets are moved accordingly.
Warning: You might find that QScrollView offers a higher-level of functionality than using this function.
The areas of the widget that are exposed will be erased and paint events may be generated immediately, or after some further event processing.
Warning: If you call scroll() in a function which may itself be called from the moveEvent() or paintEvent() of a direct child of the widget being scrolled, you may see infinite recursion.
See also: erase() and bitBlt().
Scrolls the area r of this widget dx pixels rightwards and dy pixels downwards. If dx/dy is negative, the scroll direction is leftwards/upwards. Child widgets are not moved.
Warning: You might find that QScrollView offers a higher-level of functionality than using this function.
The areas of the widget that are exposed will be erased and paint events may be generated immediately, or after some further event processing.
Warning: If you call scroll() in a function which may itself be called from the moveEvent() or paintEvent() of a direct child of the widget being scrolled, you may see infinite recursion.
See also: erase() and bitBlt().
[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
[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, at least on Windows. 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.
See also: isActiveWindow(), topLevelWidget() and show().
[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 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.
See also: autoMask(), updateMask(), setMask() and clearMask().
Examples: aclock/main.cpp
[virtual]This function is deprecated. Use setBackgroundMode() or setPalette(), as they ensure the appropriate clearing color is used when the widget is in the Active, Normal, or Disabled state.
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) ) );
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
[virtual]Tells the window system which color to clear this widget to when sending a paint event.
In other words, this color is the color of the widget when paintEvent() is called. To minimize flicker, this should be the most common color in the widget.
The fill functions of the colorgroup returns Brushes, which may be either a plain color or a pixmap.
If setBackgroundPixmap() or setBackgroundColor() is called, the mode will be one of:
FixedPixmap - the pixmap set by setBackgroundPixmap()
FixedColor - the color set by setBackgroundColor()
These values may not be used as parameters to setBackgroundMode(). 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 );
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) ) );
You can also use QApplication::setPalette() if you want to change the color scheme of your entire application, or of all new widgets.
[virtual]Sets the background pixmap of the widget to pixmap.
This function is deprecated. Use setBackgroundMode() or setPalette(), as they ensure the appropriate clearing pixmap or color is used when the widget is in the Active, Normal, or Disabled state.
The background pixmap is tiled. Some widgets (e.g. QLineEdit) do not work well with a background pixmap.
See also: backgroundPixmap(), backgroundPixmapChange() and setBackgroundColor().
Examples: desktop/desktop.cpp
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().
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
[virtual protected]For internal use only.
[virtual slot]Sets the window caption (title).
See also: caption(), setIcon() and setIconText().
Examples: qdir/qdir.cpp rangecontrols/main.cpp validator/main.cpp themes/main.cpp listviews/main.cpp checklists/main.cpp buttons_groups/main.cpp wizard/main.cpp application/main.cpp qiconview/main.cpp drawdemo/drawdemo.cpp lineedits/main.cpp popup/popup.cpp listbox/main.cpp progress/progress.cpp progressbar/main.cpp richtext/main.cpp tooltip/main.cpp forever/forever.cpp addressbook/main.cpp movies/main.cpp listbox_combo/main.cpp hello/main.cpp dirview/main.cpp
[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:
setCursor( ibeamCursor );
See also: cursor(), unsetCursor() and QApplication::setOverrideCursor().
Examples: cursor/cursor.cpp
[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.
See also: isEnabled(), QKeyEvent and QMouseEvent.
Reimplemented in QScrollView.
[virtual protected]For internal use only.
Sets both the minimum and maximum heights of the widget to h without changing the widths. Provided for convenience.
See also: sizeHint(), minimumSize(), maximumSize(), setFixedSize() and more.
Examples: layout/layout.cpp
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().
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
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.
[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 loose 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. However, QWidget::focusWidget() (which determines where Tab/shift-Tab) moves from) is changed only if the widget accepts focus. This can be used to implement "hidden focus"; see focusNextPrevChild() for details.
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: tabdialog/tabdialog.cpp xform/xform.cpp popup/popup.cpp
[virtual]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 constructor calls
setFocusPolicy(QWidget::StrongFocus).
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
As a special case to support applications not utilizing focus, Top-level widgets that have NoFocus policy will receive focus events and gain keyboard events.
See also: isFocusEnabled(), focusInEvent(), focusOutEvent(), keyPressEvent(), keyReleaseEvent() and isEnabled().
Examples: rot13/rot13.cpp
[virtual]Sets this widget's focus proxy to w.
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.
[virtual]Sets the font for the widget.
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 );
If fontPropagation() is AllChildren or SameFont, setFont()
calls setFont() for children of the object, or those with whom the
object shares the font, respectively. The default for QWidget
is SameChildren.
See also: font(), fontChange(), fontInfo(), fontMetrics() and setFontPropagation().
Examples: grapher/grapher.cpp xform/xform.cpp
Reimplemented in QWizard, QTabDialog and QPopupMenu.
Like setFont(const QFont&) but has an additional flag to indicate whether the font should be fix for the widget. Fixed means that QApplication::setFont() will not touch the current setting. This Function calls setFont(const QFont&).
Examples: xform/xform.cpp hello/main.cpp
[virtual]Sets the font propagation mode to m.
if m is NoChildren (the default), setFont() does not change
any children's fonts. If it is SameFont, setFont() changes the
font of the children that have the exact same font as this widget
(see QFont::isCopyOf() for details). If it is AllChildren,
setFont() changes the font of all children.
See also: fontPropagation(), setFont() and setPalettePropagation().
[virtual slot]Sets the widget geometry to w by h, positioned at x,y in its parent widget.
A resize event and a move event are generated immediately if the widget is visible. If the widget is invisible, the events are generated when show() is called.
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().
Examples: xform/xform.cpp drawdemo/drawdemo.cpp popup/popup.cpp qmag/qmag.cpp
Reimplemented in QDialog.
[virtual slot]This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Reimplemented in QDialog.
[virtual slot]Sets the window icon pixmap.
See also: icon(), setIconText() and setCaption().
Reimplemented in QMessageBox.
[virtual slot]Sets the text of the window's icon to iconText.
See also: iconText(), setIcon() and setCaption().
[virtual protected]Enables key event compression. Per default, the compression is turned off. If you enable it, the widget receives compressed key press events whenever the user types too fast for your program. That means you may receive an entire word in the QKeyEvent::text() field of they QKeyEvent, instead of one event for each character. This makes sense for a word processor, for example, since it takes almost as much time to insert a single character as it takes to insert a full word, because the required recalculation of the layout of the paragraph is roughly the same.
If a widgets supports multiple byte unicode input, it is always safe (and also recommended!) to turn the compression on.
See also: QKeyEvent::text();.
[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().
[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().
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
[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().
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Sets the maximum width of the widget to w without changing the height. Provided for convenience.
See also: sizeHint(), minimumSize(), maximumSize(), setFixedSize() and more.
[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.
Sets the minimum height of the widget to h without changing the width. Provided for convenience.
See also: sizeHint(), minimumSize(), maximumSize(), setFixedSize() and more.
[virtual]Sets the minimum size of the widget to w by h pixels.
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.
See also: minimumSize(), setMaximumSize(), setSizeIncrement(), resize() and size().
Examples: menu/menu.cpp qmag/qmag.cpp splitter/splitter.cpp
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Sets the minimum width of the widget to w without changing the height. Provided for convenience.
See also: sizeHint(), minimumSize(), maximumSize(), setFixedSize() and more.
[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
[virtual]Reimplemented for internal reasons; the API is not affected.
Reimplemented from QObject.
[virtual]Sets the widget palette to p. The widget background color is set to
colorGroup().background().
If palettePropagation() is AllChildren or SamePalette,
setPalette() calls setPalette() for children of the object, or those
with whom the object shares the palette, respectively. The default
for QWidget is SameChildren.
See also: QApplication::setPalette(), palette(), paletteChange(), colorGroup(), setBackgroundColor() and setPalettePropagation().
Like setPalette(const QPalette&) but has an additional flag to indicate whether the palette should be fix for the widget. Fixed means that QApplication::setPalette() will not touch the current setting. This Function calls setPalette(const QPalette&).
[virtual]Sets the palette propagation mode to m.
if m is NoChildren (the default), setPalette() does not change
any children's palettes. If it is SamePalette, setPalette()
changes the palette of the children that have the exact same palette
as this widget (see QPalette::isCopyOf() for details). If it is
AllChildren, setPalette() changes the palette of all children.
See also: palettePropagation(), setPalette() and setFontPropagation().
[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().
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Sets the widget's GUI style to style. Ownership of the style object is not transfered.
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 childwidgets.
Warning: This function is particularly useful for demonstration purposes, where you want to show Qt's styling capabilities. Real appliations 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
[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
If either first or second has a focus proxy, setTabOrder() substitutes its/their proxies.
See also: setFocusPolicy() and setFocusProxy().
[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 as 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().
[virtual protected]For internal use only.
[virtual protected]For internal use only.
[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(), isVisible() and polish().
Examples: showimg/main.cpp rangecontrols/main.cpp validator/main.cpp listviews/main.cpp aclock/main.cpp checklists/main.cpp buttons_groups/main.cpp drawlines/connect.cpp dclock/main.cpp xform/xform.cpp cursor/cursor.cpp layout/layout.cpp tetrix/tetrix.cpp life/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 richtext/main.cpp tooltip/main.cpp qwerty/main.cpp forever/forever.cpp rot13/rot13.cpp scrollview/scrollview.cpp movies/main.cpp picture/picture.cpp listbox_combo/main.cpp hello/main.cpp biff/main.cpp tictac/main.cpp customlayout/main.cpp
Reimplemented in QTableView, QListView, QTabBar, QDialog, QScrollView, QMenuBar, QTabDialog, QWidgetStack, QPopupMenu, QToolBar, QWizard, QSemiModal and QMainWindow.
[virtual protected]This event handler can be reimplemented in a subclass to receive widget show events.
Non-sponaneous 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 QListView, QTabWidget and QListBox.
[virtual slot]Shows the widget maximized.
Calling this function has no effect for other than top-level widgets.
See also: showNormal(), showMinimized(), show(), hide() and isVisible().
[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().
[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().
Returns the size of the widget, excluding the window frame.
See also: geometry(), width() and height().
[virtual]Returns a recommended size for the widget, or an invalid size if no size is recommended.
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().
Examples: lineedits/main.cpp
Reimplemented in QHeader, QPopupMenu, QToolButton, QSlider, QListView, QTabBar, QLabel, QCheckBox, QTabWidget, QProgressDialog, QLineEdit, QWidgetStack, QLCDNumber, QPushButton, QMultiLineEdit, QScrollBar, QSplitter, QRadioButton, QListBox, QSizeGrip, QComboBox, QSpinBox and QProgressBar.
Returns the widget size increment.
See also: setSizeIncrement(), minimumSize() and maximumSize().
[virtual]This function can be reimplemented in subclasses to specify the default layout behaviour of that subclass.
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.
The default implementation returns a value which means that the widget can be freely resized, but prefers to be the size sizeHint() returns.
See also: sizeHint(), QLayout, QSizePolicy and updateGeometry().
Reimplemented in QLabel, QScrollBar, QSlider, QPushButton, QTabBar, QToolButton, QLCDNumber, QFrame, QLineEdit, QHeader, QCheckBox, QSpinBox, QMultiLineEdit, QProgressBar, QScrollView, QRadioButton, QSplitter and QSizeGrip.
Returns the GUI style for this widget
See also: QWidget::setStyle(), QApplication::setStyle() and QApplication::style().
[virtual protected]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 either repaint(TRUE) or update().
The default implementation calls update().
See also: QApplication::setStyle() and style().
Reimplemented in QPopupMenu, QComboBox, QSplitter, QListView, QProgressDialog, QProgressBar, QTabWidget, QMenuBar, QScrollBar, QMainWindow, QSpinBox and QTabDialog.
Returns TRUE if any of the widget flags in n are set. The widget flags are listed in qnamespace.h, and are strictly for internal use.
For internal use only.
Returns the top-level widget for this widget, i.e. the parent widget that provides the overlapping window.
See also: isTopLevel().
[virtual]Unset the cursor for this widget. The widget will use the cursor of its parent from now on.
This functions does nothing for toplevel windows.
See also: cursor(), setCursor() and QApplication::setOverrideCursor().
[slot]Updates the widget unless updates are disabled or the widget is hidden.
Updating the widget will erase the widget contents and generate a paint event from the window system. The paint event is processed after the program has returned to the main event loop.
See also: repaint(), paintEvent(), setUpdatesEnabled() and erase().
Examples: drawlines/connect.cpp drawdemo/drawdemo.cpp desktop/desktop.cpp picture/picture.cpp
[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), which in turn generates a paint event from the window system. The paint event is processed after the program has returned to the main event loop.
If w is negative, it is replaced with width() - x.
If h is negative, it is replaced width height() - y.
See also: repaint(), paintEvent(), setUpdatesEnabled() and erase().
Examples: grapher/grapher.cpp scrollview/scrollview.cpp
[slot]This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
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.
[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 QTabWidget, QSlider, QFrame and QTabBar.
Returns the currently visible rectangle of the widget. This function is in particular useful to optimize immediate repainting of a windget. Typical usage is
repaint( w->visibleRect() );
or
repaint( w->visibleRect(), FALSE );
If nothing is visible, the rectangle returned is empty.
[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 QScrollBar, QSpinBox, QMultiLineEdit, QSlider and QScrollView.
Returns the width of the widget, excluding the window frame.
See also: geometry(), height() and size().
Examples: grapher/grapher.cpp xform/xform.cpp drawdemo/drawdemo.cpp menu/menu.cpp qmag/qmag.cpp
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().
[static]For internal use only.
Returns the x coordinate of the widget, relative to its parent widget and including the window frame.
See also: frameGeometry(), y() and pos().
Returns the y coordinate of the widget, relative to its parent widget and including the window frame.
See also: frameGeometry(), x() and pos().
Examples: drawdemo/drawdemo.cpp
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