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java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QObject
com.trolltech.qt.gui.QWidget
public class QWidget
The QWidget
class is the base class of all user interface objects. The widget is the atom of the user interface: it receives mouse, keyboard and other events from the window system, and paints a representation of itself on the screen. Every widget is rectangular, and they are sorted in a Z-order. A widget is clipped by its parent and by the widgets in front of it.
A widget that isn't embedded in a parent widget is called a window. Usually, windows have a frame and a title bar, although it is also possible to create windows without such decoration using suitable window flags). In Qt, QMainWindow
and the various subclasses of QDialog
are the most common window types.
Every widget's constructor accepts one or two standard arguments:
Qt::Window
as window flag).QWidget
has many member functions, but some of them have little direct functionality; for example, QWidget
has a font property, but never uses this itself. There are many subclasses which provide real functionality, such as QLabel
, QPushButton
, QListWidget
, and QTabWidget
.setWindowTitle()
and setWindowIcon()
set the title bar and icon respectively. Non-window widgets are child widgets, and are displayed within their parent widgets. Most widgets in Qt are mainly useful as child widgets. For example, it is possible to display a button as a top-level window, but most people prefer to put their buttons inside other widgets, such as QDialog
.
QGroupBox
widget being used to hold various child widgets in a layout provided by QGridLayout
. The QLabel
child widgets have been outlined to indicate their full sizes. If you want to use a QWidget
to hold child widgets you will usually want to add a layout to the parent QWidget
. See Layout Classes for more information about these.Composite Widgets
When a widgets is used as a container to group a number of child widgets, it is known as a composite widget. These can be created by constructing a widget with the required visual properties - a QFrame
, for example - and adding child widgets to it, usually managed by a layout. The above diagram shows such a composite widget that was created using Qt Designer.
Composite widgets can also be created by subclassing a standard widget, such as QWidget
or QFrame
, and adding the necessary layout and child widgets in the constructor of the subclass. Many of the examples provided with Qt use this approach, and it is also covered in the Qt Tutorial.Custom Widgets and Painting
Since QWidget
is a subclass of QPaintDevice
, subclasses can be used to display custom content that is composed using a series of painting operations with an instance of the QPainter
class. This approach contrasts with the canvas-style approach used by the Graphics View Framework where items are added to a scene by the application and are rendered by the framework itself.
Each widget performs all painting operations from within its paintEvent()
function. This is called whenever the widget needs to be redrawn, either as a result of some external change or when requested by the application.
The Analog Clock example shows how a simple widget can handle paint events.Size Hints and Size Policies
When implementing a new widget, it is almost always useful to reimplement sizeHint()
to provide a reasonable default size for the widget and to set the correct size policy with setSizePolicy()
.
By default, composite widgets which do not provide a size hint will be sized according to the space requirements of their child widgets.
The size policy lets you supply good default behavior for the layout management system, so that other widgets can contain and manage yours easily. The default size policy indicates that the size hint represents the preferred size of the widget, and this is often good enough for many widgets.Events
Widgets respond to events that are typically caused by user actions. Qt delivers events to widgets by calling specific event handler functions with instances of QEvent
subclasses containing information about each event.
If your widget only contains child widgets, you probably do not need to implement any event handlers. If you want to detect a mouse click in a child widget call the child's underMouse()
function inside the widget's mousePressEvent()
.
The Scribble example implements a wider set of events to handle mouse movement, button presses, and window resizing.
You will need to supply the behavior and content for your own widgets, but here is a brief overview of the events that are relevant to QWidget
, starting with the most common ones:
paintEvent()
is called whenever the widget needs to be repainted. Every widget which displays custom content must implement it. Painting using a QPainter
can only take place in a paintEvent()
or a function called by a paintEvent()
.resizeEvent()
is called when the widget has been resized.mousePressEvent()
is called when a mouse button is pressed when the mouse is inside it, or when it has grabbed the mouse using grabMouse()
.mouseReleaseEvent()
is called when a mouse button is released. A widget receives mouse release events when it has received the corresponding mouse press event. This means that if the user presses the mouse inside your widget, then drags the mouse to somewhere else before releasing the mouse button, your widget receives the release event. There is one exception: if a popup menu appears while the mouse button is held down, this popup immediately steals the mouse events.mouseDoubleClickEvent()
is called when the user double clicks in the widget. If the user double-clicks, the widget receives a mouse press event, a mouse release event and finally this event instead of a second mouse press event. (Some mouse move events may also be received if the user doesn't hold the mouse steady during this operation.) It is not possible to distinguish a click from a double click until the second click arrives. (This is one reason why most GUI books recommend that double clicks be an extension of single clicks, rather than trigger a different action.)keyPressEvent()
is called whenever a key is pressed, and again when a key has been held down long enough for it to auto-repeat. Note that the Tab and Shift+Tab keys are only passed to the widget if they are not used by the focus-change mechanisms. To force those keys to be processed by your widget, you must reimplement QWidget::event()
.focusInEvent()
is called when the widget gains keyboard focus (assuming you have called setFocusPolicy()
). Well written widgets indicate that they own the keyboard focus in a clear but discreet way.focusOutEvent()
is called when the widget loses keyboard focus.mouseMoveEvent()
is called whenever the mouse moves while a button is held down. This can be useful during drag and drop operations. If you call setMouseTracking
(true), you get mouse move events even when no buttons are held down. (See also the guide to Drag and Drop.)keyReleaseEvent()
is called whenever a key is released, and also while it is held down if the key is auto-repeating. In that case the widget receives a pair of key release and key press events for every repeat. Note that the Tab and Shift+Tab keys are only passed to the widget if they are not used by the focus-change mechanisms. To force those keys to be processed by your widget, you must reimplement QWidget::event()
.wheelEvent()
is called whenever the user turns the mouse wheel while the widget has the focus.enterEvent()
is called when the mouse enters the widget's screen space. (This excludes screen space owned by any children of the widget.)leaveEvent()
is called when the mouse leaves the widget's screen space. Note that if the mouse enters a child widget it will not cause a leaveEvent
.moveEvent()
is called when the widget has been moved relative to its parent.closeEvent()
is called when the user closes the widget (or when close()
is called).QEvent::Type
documentation. You need to reimplement event()
directly to handle these. 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. Events and the mechanism used to deliver them are covered in the Events and Event Filters document.Groups of Functions and Properties
Widget Style Sheets
In addition to the standard widget styles for each platform, widgets can also be styled according to rules specified in a style sheet
. This feature enables you to customize the appearance of specific widgets to provide visual cues to users about their purpose; for example, a button could be styled in a particular way to indicate that it performs a destructive action.
The use of widgets style sheets is described in more detail in Qt Style Sheets.Transparency and Double Buffering
From Qt 4.0, QWidget
automatically double-buffers its painting, so there's no need to write double-buffering code in paintEvent()
to avoid flicker. Additionally, it became possible for widgets to propagate their contents to children, in order to enable transparency effects, by setting the Qt::WA_ContentsPropagated
widget attribute - this is now deprecated in Qt 4.1.
In Qt 4.1, the contents of parent widgets are propagated by default to each of their children. Custom widgets can be written to take advantage of this feature by only updating irregular regions (to create non-rectangular child widgets), or by using painting with colors that have less than the full alpha component. The following diagram shows how attributes and properties of a custom widget can be fine-tuned to achieve different effects.
QLabel
showing a pixmap) then different properties and widget attributes are set to achieve different effects: autoFillBackground
property set. This property is used with custom widgets that rely on the widget to supply a default background, and do not paint over their entire area with an opaque brush.Qt::WA_OpaquePaintEvent
widget attribute set. This indicates that the widget will paint over its entire area with opaque colors. The widget's area will initially be uninitialized (represented in the diagram by a red diagonal grid pattern that shines through the overpainted area). This is useful for widgets that need to paint their own specialized contents quickly and that do not need a default filled background.setBackgroundRole()
with the QPalette::Window
role), set the autoFillBackground
property, and only implement the necessary drawing functionality in the widget's paintEvent()
. For rapidly updating custom widgets that constantly paint over their entire areas with opaque content, such as video streaming widgets, it is better to set the widget's Qt::WA_OpaquePaintEvent
, avoiding any unnecessary overhead associated with repainting the widget's background.
If a widget has both the Qt::WA_OpaquePaintEvent
widget attribute and the autoFillBackground
property set, the Qt::WA_OpaquePaintEvent
attribute takes precedence. You should choose just one of these depending on your requirements.
In Qt 4.1, the contents of parent widgets are also propagated to standard Qt widgets. This can lead to some unexpected results if the parent widget is decorated in a non-standard way, as shown in the diagram below.
autoFillBackground
property. QEvent
, QPainter
, QGridLayout
, and QBoxLayout
.
Nested Class Summary | |
---|---|
static class |
QWidget.RenderFlag
This enum describes how to render the widget when calling QWidget::render() . |
static class |
QWidget.RenderFlags
This is a flags class for com.trolltech.qt.gui.QWidget.RenderFlag |
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
---|
QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9 |
Field Summary | |
---|---|
QSignalEmitter.Signal1 |
customContextMenuRequested
This signal is emitted when the widget's contextMenuPolicy is Qt::CustomContextMenu , and the user has requested a context menu on the widget. |
Constructor Summary | |
---|---|
QWidget()
Constructs a widget which is a child of parent, with widget flags set to f. |
|
QWidget(QWidget parent)
Constructs a widget which is a child of parent, with widget flags set to f. |
|
QWidget(QWidget parent,
Qt.WindowFlags f)
Constructs a widget which is a child of parent, with widget flags set to f. |
|
QWidget(QWidget parent,
Qt.WindowType[] f)
Constructs a widget which is a child of parent, with widget flags set to f. |
Method Summary | |
---|---|
boolean |
acceptDrops()
This property holds whether drop events are enabled for this widget. |
java.lang.String |
accessibleDescription()
This property holds the widget's description as seen by assistive technologies. |
java.lang.String |
accessibleName()
This property holds the widget's name as seen by assistive technologies. |
protected void |
actionEvent(QActionEvent arg__1)
This event handler is called with the given event whenever the widget's actions are changed. |
java.util.List |
actions()
Returns the (possibly empty) list of this widget's actions. |
void |
activateWindow()
Sets the top-level widget containing this widget to be the active window. |
void |
addAction(QAction action)
Appends the action action to this widget's list of actions. |
void |
addActions(java.util.List actions)
Appends the actions actions to this widget's list of actions. |
void |
adjustSize()
Adjusts the size of the widget to fit the contents. |
boolean |
autoFillBackground()
This property holds whether the widget background is filled automatically. |
QPalette.ColorRole |
backgroundRole()
Returns the background role of the widget. |
QSize |
baseSize()
This property holds the base size of the widget. |
protected void |
changeEvent(QEvent arg__1)
This event handler can be reimplemented to handle state changes. |
QWidget |
childAt(int x,
int y)
Returns the visible child widget at the position (x, y) in the widget's coordinate system. |
QWidget |
childAt(QPoint p)
Returns the visible child widget at point p in the widget's own coordinate system. |
QRect |
childrenRect()
This property holds the bounding rectangle of the widget's children. |
QRegion |
childrenRegion()
This property holds the combined region occupied by the widget's children. |
void |
clearFocus()
Takes keyboard input focus from the widget. |
void |
clearMask()
Removes any mask set by setMask() . |
boolean |
close()
Closes this widget. |
protected void |
closeEvent(QCloseEvent arg__1)
This event handler is called with the given event when Qt receives a window close request for a top-level widget from the window system. |
QRect |
contentsRect()
Returns the area inside the widget's margins. |
protected void |
contextMenuEvent(QContextMenuEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive widget context menu events. |
Qt.ContextMenuPolicy |
contextMenuPolicy()
This property holds how the widget shows a context menu. |
QCursor |
cursor()
This property holds the cursor shape for this widget. |
int |
depth()
Returns the bit depth (number of bit planes) of the paint device. |
protected void |
destroy()
Frees up window system resources. |
protected void |
destroy(boolean destroyWindow)
Frees up window system resources. |
protected void |
destroy(boolean destroyWindow,
boolean destroySubWindows)
Frees up window system resources. |
protected void |
dragEnterEvent(QDragEnterEvent arg__1)
This event handler is called when a drag is in progress and the mouse enters this widget. |
protected void |
dragLeaveEvent(QDragLeaveEvent arg__1)
This event handler is called when a drag is in progress and the mouse leaves this widget. |
protected void |
dragMoveEvent(QDragMoveEvent arg__1)
This event handler is called if a drag is in progress, and when any of the following conditions occur. |
protected void |
dropEvent(QDropEvent arg__1)
This event handler is called when the drag is dropped on this widget. |
long |
effectiveWinId()
Returns the effective window system identifier of the widget, i.e. |
void |
ensurePolished()
Ensures that the widget has been polished by QStyle (i.e., has a proper font and palette). |
protected void |
enterEvent(QEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget enter events which are passed in the event parameter. |
protected void |
focusInEvent(QFocusEvent arg__1)
This event handler can be reimplemented in a subclass to receive keyboard focus events (focus received) for the widget. |
protected boolean |
focusNextChild()
Finds a new widget to give the keyboard focus to, as appropriate for Tab, and returns true if it can find a new widget, or false if it can't. |
protected boolean |
focusNextPrevChild(boolean next)
Finds a new widget to give the keyboard focus to, as appropriate for Tab and Shift+Tab, and returns true if it can find a new widget, or false if it can't. |
protected void |
focusOutEvent(QFocusEvent arg__1)
This event handler can be reimplemented in a subclass to receive keyboard focus events (focus lost) for the widget. |
Qt.FocusPolicy |
focusPolicy()
This property holds the way the widget accepts keyboard focus. |
protected boolean |
focusPreviousChild()
Finds a new widget to give the keyboard focus to, as appropriate for Shift+Tab, and returns true if it can find a new widget, or false if it can't. |
QWidget |
focusProxy()
Returns the focus proxy, or 0 if there is no focus proxy. |
QWidget |
focusWidget()
Returns the last child of this widget that setFocus had been called on. |
QFont |
font()
This property holds the font currently set for the widget. |
QFontInfo |
fontInfo()
Returns the font info for the widget's current font. |
QFontMetrics |
fontMetrics()
Returns the font metrics for the widget's current font. |
QPalette.ColorRole |
foregroundRole()
Returns the foreground role. |
QRect |
frameGeometry()
This property holds geometry of the widget relative to its parent including any window frame. |
QSize |
frameSize()
This property holds the size of the widget including any window frame. |
static QWidget |
fromNativePointer(QNativePointer nativePointer)
|
QRect |
geometry()
This property holds the geometry of the widget relative to its parent and excluding the window frame. |
QContentsMargins |
getContentsMargins()
Returns the widget's contents margins. |
void |
grabKeyboard()
Grabs the keyboard input. |
void |
grabMouse()
Grabs the mouse input. |
void |
grabMouse(QCursor arg__1)
Grabs the mouse input and changes the cursor shape. |
int |
grabShortcut(QKeySequence key)
Adds a shortcut to Qt's shortcut system that watches for the given key sequence in the given context. |
int |
grabShortcut(QKeySequence key,
Qt.ShortcutContext context)
Adds a shortcut to Qt's shortcut system that watches for the given key sequence in the given context. |
boolean |
hasFocus()
This property holds whether this widget (or its focus proxy) has the keyboard input focus. |
boolean |
hasMouseTracking()
This property holds whether mouse tracking is enabled for the widget. |
int |
height()
Returns the height of the paint device in default coordinate system units (e.g. |
int |
heightForWidth(int arg__1)
Returns the preferred height for this widget, given the width w. |
int |
heightMM()
Returns the height of the paint device in millimeters. |
void |
hide()
Hides the widget. |
protected void |
hideEvent(QHideEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget hide events. |
QInputContext |
inputContext()
This function returns the QInputContext for this widget. |
protected void |
inputMethodEvent(QInputMethodEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive Input Method composition events. |
java.lang.Object |
inputMethodQuery(Qt.InputMethodQuery arg__1)
This method is only relevant for input widgets. |
void |
insertAction(QAction before,
QAction action)
Inserts the action action to this widget's list of actions, before the action before. |
void |
insertActions(QAction before,
java.util.List actions)
Inserts the actions actions to this widget's list of actions, before the action before. |
boolean |
isActiveWindow()
This property holds whether this widget's window is the active window. |
boolean |
isAncestorOf(QWidget child)
Returns true if this widget is a parent, (or grandparent and so on to any level), of the given child, and both widgets are within the same window; otherwise returns false. |
boolean |
isEnabled()
This property holds whether the widget is enabled. |
boolean |
isEnabledTo(QWidget arg__1)
Returns true if this widget would become enabled if ancestor is enabled; otherwise returns false. |
boolean |
isFullScreen()
This property holds whether the widget is full screen. |
boolean |
isHidden()
Returns true if the widget is hidden, otherwise returns false. |
boolean |
isMaximized()
This property holds whether this widget is maximized. |
boolean |
isMinimized()
This property holds whether this widget is minimized (iconified). |
boolean |
isModal()
This property holds whether the widget is a modal widget. |
boolean |
isVisible()
This property holds whether the widget is visible. |
boolean |
isVisibleTo(QWidget arg__1)
Returns true if this widget would become visible if ancestor is shown; otherwise returns false. |
boolean |
isWindow()
Returns true if the widget is an independent window, otherwise returns false. |
boolean |
isWindowModified()
This property holds whether the document shown in the window has unsaved changes. |
static QWidget |
keyboardGrabber()
Returns the widget that is currently grabbing the keyboard input. |
protected void |
keyPressEvent(QKeyEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive key press events for the widget. |
protected void |
keyReleaseEvent(QKeyEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive key release events for the widget. |
protected void |
languageChange()
|
QLayout |
layout()
Returns the layout manager that is installed on this widget, or 0 if no layout manager is installed. |
Qt.LayoutDirection |
layoutDirection()
This property holds the layout direction for this widget. |
protected void |
leaveEvent(QEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget leave events which are passed in the event parameter. |
QLocale |
locale()
This property holds the widget's locale. |
int |
logicalDpiX()
Returns the horizontal resolution of the device in dots per inch, which is used when computing font sizes. |
int |
logicalDpiY()
Returns the vertical resolution of the device in dots per inch, which is used when computing font sizes. |
void |
lower()
Lowers the widget to the bottom of the parent widget's stack. |
QPoint |
mapFrom(QWidget arg__1,
QPoint arg__2)
Translates the widget coordinate pos from the coordinate system of parent to this widget's coordinate system. |
QPoint |
mapFromGlobal(QPoint arg__1)
Translates the global screen coordinate pos to widget coordinates. |
QPoint |
mapFromParent(QPoint arg__1)
Translates the parent widget coordinate pos to widget coordinates. |
QPoint |
mapTo(QWidget arg__1,
QPoint arg__2)
Translates the widget coordinate pos to the coordinate system of parent. |
QPoint |
mapToGlobal(QPoint arg__1)
Translates the widget coordinate pos to global screen coordinates. |
QPoint |
mapToParent(QPoint arg__1)
Translates the widget coordinate pos to a coordinate in the parent widget. |
QRegion |
mask()
Returns the mask currently set on a widget. |
int |
maximumHeight()
This property holds the widget's maximum height. |
QSize |
maximumSize()
This property holds the widget's maximum size. |
int |
maximumWidth()
This property holds the widget's maximum width. |
int |
metric(QPaintDevice.PaintDeviceMetric arg__1)
Returns the metric information for the given paint device metric. |
int |
minimumHeight()
This property holds the widget's minimum height. |
QSize |
minimumSize()
This property holds the widget's minimum size. |
QSize |
minimumSizeHint()
This property holds the recommended minimum size for the widget. |
int |
minimumWidth()
This property holds the widget's minimum width. |
protected void |
mouseDoubleClickEvent(QMouseEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive mouse double click events for the widget. |
static QWidget |
mouseGrabber()
Returns the widget that is currently grabbing the mouse input. |
protected void |
mouseMoveEvent(QMouseEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive mouse move events for the widget. |
protected void |
mousePressEvent(QMouseEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive mouse press events for the widget. |
protected void |
mouseReleaseEvent(QMouseEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive mouse release events for the widget. |
void |
move(int x,
int y)
This property holds the position of the widget within its parent widget. |
void |
move(QPoint arg__1)
This property holds the position of the widget within its parent widget. |
protected void |
moveEvent(QMoveEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget move events which are passed in the event parameter. |
QWidget |
nativeParentWidget()
Returns the native parent for this widget, i.e. |
QWidget |
nextInFocusChain()
Returns the next widget in this widget's focus chain. |
QRect |
normalGeometry()
This property holds the geometry of the widget as it will appear when shown as a normal (not maximized or fullscreen) toplevel widget. |
int |
numColors()
Returns the number of different colors available for the paint device. |
void |
overrideWindowFlags(Qt.WindowFlags type)
Sets the window flags for the widget to flags, without telling the window system. |
void |
overrideWindowFlags(Qt.WindowType[] type)
Sets the window flags for the widget to flags, without telling the window system. |
QPaintEngine |
paintEngine()
Returns a pointer to the paint engine used for drawing on the device. |
protected void |
paintEvent(QPaintEvent arg__1)
This event handler can be reimplemented in a subclass to receive paint events which are passed in the event parameter. |
boolean |
paintingActive()
Returns true if the device is currently being painted on, i.e. |
QPalette |
palette()
This property holds the widget's palette. |
QWidget |
parentWidget()
Returns the parent of this widget, or 0 if it does not have any parent widget. |
int |
physicalDpiX()
Returns the horizontal resolution of the device in dots per inch. |
int |
physicalDpiY()
Returns the horizontal resolution of the device in dots per inch. |
QPoint |
pos()
This property holds the position of the widget within its parent widget. |
void |
raise()
Raises this widget to the top of the parent widget's stack. |
QRect |
rect()
This property holds the internal geometry of the widget excluding any window frame. |
void |
releaseKeyboard()
Releases the keyboard grab. |
void |
releaseMouse()
Releases the mouse grab. |
void |
releaseShortcut(int id)
Removes the shortcut with the given id from Qt's shortcut system. |
void |
removeAction(QAction action)
Removes the action action from this widget's list of actions. |
void |
render(QPaintDeviceInterface target)
Renders the sourceRegion of this widget into the target using renderFlags to determine how to render. |
void |
render(QPaintDeviceInterface target,
QPoint targetOffset)
Renders the sourceRegion of this widget into the target using renderFlags to determine how to render. |
void |
render(QPaintDeviceInterface target,
QPoint targetOffset,
QRegion sourceRegion)
Renders the sourceRegion of this widget into the target using renderFlags to determine how to render. |
void |
render(QPaintDeviceInterface target,
QPoint targetOffset,
QRegion sourceRegion,
QWidget.RenderFlag[] renderFlags)
Renders the sourceRegion of this widget into the target using renderFlags to determine how to render. |
void |
render(QPaintDeviceInterface target,
QPoint targetOffset,
QRegion sourceRegion,
QWidget.RenderFlags renderFlags)
Renders the sourceRegion of this widget into the target using renderFlags to determine how to render. |
void |
render(QPainter painter,
QPoint targetOffset)
Renders the widget into the painter's QPainter::device() . |
void |
render(QPainter painter,
QPoint targetOffset,
QRegion sourceRegion)
Renders the widget into the painter's QPainter::device() . |
void |
render(QPainter painter,
QPoint targetOffset,
QRegion sourceRegion,
QWidget.RenderFlag[] renderFlags)
Renders the widget into the painter's QPainter::device() . |
void |
render(QPainter painter,
QPoint targetOffset,
QRegion sourceRegion,
QWidget.RenderFlags renderFlags)
Renders the widget into the painter's QPainter::device() . |
void |
repaint()
Repaints the widget directly by calling paintEvent() immediately, unless updates are disabled or the widget is hidden. |
void |
repaint(int x,
int y,
int w,
int h)
This version repaints a rectangle (x, y, w, h) inside the widget. |
void |
repaint(QRect arg__1)
This version repaints a rectangle r inside the widget. |
void |
repaint(QRegion arg__1)
This version repaints a region rgn inside the widget. |
protected void |
resetInputContext()
This function can be called on the widget that currently has focus to reset the input method operating on it. |
void |
resize(int w,
int h)
This property holds the size of the widget excluding any window frame. |
void |
resize(QSize arg__1)
This property holds the size of the widget excluding any window frame. |
protected void |
resizeEvent(QResizeEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget resize events which are passed in the event parameter. |
boolean |
restoreGeometry(QByteArray geometry)
Restores the geometry and state top-level widgets stored in the byte array geometry. |
QByteArray |
saveGeometry()
Saves the current geometry and state for top-level widgets. |
void |
scroll(int dx,
int dy)
Scrolls the widget including its children dx pixels to the right and dy downward. |
void |
scroll(int dx,
int dy,
QRect arg__3)
This version only scrolls r and does not move the children of the widget. |
void |
setAcceptDrops(boolean on)
This property holds whether drop events are enabled for this widget. |
void |
setAccessibleDescription(java.lang.String description)
This property holds the widget's description as seen by assistive technologies. |
void |
setAccessibleName(java.lang.String name)
This property holds the widget's name as seen by assistive technologies. |
void |
setAttribute(Qt.WidgetAttribute arg__1)
Sets the attribute attribute on this widget if on is true; otherwise clears the attribute. |
void |
setAttribute(Qt.WidgetAttribute arg__1,
boolean on)
Sets the attribute attribute on this widget if on is true; otherwise clears the attribute. |
void |
setAutoFillBackground(boolean enabled)
This property holds whether the widget background is filled automatically. |
void |
setBackgroundRole(QPalette.ColorRole arg__1)
Sets the background role of the widget to role. |
void |
setBaseSize(int basew,
int baseh)
This property holds the base size of the widget. |
void |
setBaseSize(QSize arg__1)
This property holds the base size of the widget. |
void |
setContentsMargins(int left,
int top,
int right,
int bottom)
Sets the margins around the contents of the widget to have the sizes left, top, right, and bottom. |
void |
setContentsMargins(QContentsMargins margins)
Sets the margins around the contents of the widget. |
void |
setContextMenuPolicy(Qt.ContextMenuPolicy policy)
This property holds how the widget shows a context menu. |
void |
setCursor(QCursor arg__1)
This property holds the cursor shape for this widget. |
void |
setDisabled(boolean arg__1)
Disables widget input events if disable is true; otherwise enables input events. |
void |
setEnabled(boolean arg__1)
This property holds whether the widget is enabled. |
void |
setFixedHeight(int h)
Sets both the minimum and maximum heights of the widget to h without changing the widths. |
void |
setFixedSize(int w,
int h)
Sets the width of the widget to w and the height to h. |
void |
setFixedSize(QSize arg__1)
Sets both the minimum and maximum sizes of the widget to s, thereby preventing it from ever growing or shrinking. |
void |
setFixedWidth(int w)
Sets both the minimum and maximum width of the widget to w without changing the heights. |
void |
setFocus()
Gives the keyboard input focus to this widget (or its focus proxy) if this widget or one of its parents is the active window . |
void |
setFocus(Qt.FocusReason reason)
Gives the keyboard input focus to this widget (or its focus proxy) if this widget or one of its parents is the active window . |
void |
setFocusPolicy(Qt.FocusPolicy policy)
This property holds the way the widget accepts keyboard focus. |
void |
setFocusProxy(QWidget arg__1)
Sets the widget's focus proxy to widget w. |
void |
setFont(QFont arg__1)
This property holds the font currently set for the widget. |
void |
setForegroundRole(QPalette.ColorRole arg__1)
Sets the foreground role of the widget to role. |
void |
setGeometry(int x,
int y,
int w,
int h)
This property holds the geometry of the widget relative to its parent and excluding the window frame. |
void |
setGeometry(QRect arg__1)
This property holds the geometry of the widget relative to its parent and excluding the window frame. |
void |
setHidden(boolean hidden)
Convenience function, equivalent to setVisible (!hidden). |
void |
setInputContext(QInputContext arg__1)
This function sets the input context context on this widget. |
void |
setLayout(QLayout arg__1)
Sets the layout manager for this widget to layout. |
void |
setLayoutDirection(Qt.LayoutDirection direction)
This property holds the layout direction for this widget. |
void |
setLocale(QLocale locale)
This property holds the widget's locale. |
void |
setMask(QBitmap arg__1)
Causes only the pixels of the widget for which bitmap has a corresponding 1 bit to be visible. |
void |
setMask(QRegion arg__1)
Causes only the parts of the widget which overlap region to be visible. |
void |
setMaximumHeight(int maxh)
This property holds the widget's maximum height. |
void |
setMaximumSize(int maxw,
int maxh)
This property holds the widget's maximum size. |
void |
setMaximumSize(QSize arg__1)
This property holds the widget's maximum size. |
void |
setMaximumWidth(int maxw)
This property holds the widget's maximum width. |
void |
setMinimumHeight(int minh)
This property holds the widget's minimum height. |
void |
setMinimumSize(int minw,
int minh)
This property holds the widget's minimum size. |
void |
setMinimumSize(QSize arg__1)
This property holds the widget's minimum size. |
void |
setMinimumWidth(int minw)
This property holds the widget's minimum width. |
void |
setMouseTracking(boolean enable)
This property holds whether mouse tracking is enabled for the widget. |
void |
setPalette(QPalette arg__1)
This property holds the widget's palette. |
void |
setParent(QWidget parent)
Sets the parent of the widget to parent, and resets the window flags. |
void |
setParent(QWidget parent,
Qt.WindowFlags f)
This function also takes widget flags, f as an argument. |
void |
setParent(QWidget parent,
Qt.WindowType[] f)
This function also takes widget flags, f as an argument. |
void |
setShortcutAutoRepeat(int id)
If enable is true, auto repeat of the shortcut with the given id is enabled; otherwise it is disabled. |
void |
setShortcutAutoRepeat(int id,
boolean enable)
If enable is true, auto repeat of the shortcut with the given id is enabled; otherwise it is disabled. |
void |
setShortcutEnabled(int id)
If enable is true, the shortcut with the given id is enabled; otherwise the shortcut is disabled. |
void |
setShortcutEnabled(int id,
boolean enable)
If enable is true, the shortcut with the given id is enabled; otherwise the shortcut is disabled. |
void |
setSizeIncrement(int w,
int h)
This property holds the size increment of the widget. |
void |
setSizeIncrement(QSize arg__1)
This property holds the size increment of the widget. |
void |
setSizePolicy(QSizePolicy.Policy horizontal,
QSizePolicy.Policy vertical)
This property holds the default layout behavior of the widget. |
void |
setSizePolicy(QSizePolicy arg__1)
This property holds the default layout behavior of the widget. |
void |
setStatusTip(java.lang.String arg__1)
This property holds the widget's status tip. |
void |
setStyle(QStyle arg__1)
Sets the widget's GUI style to style. |
void |
setStyleSheet(java.lang.String styleSheet)
This property holds the widget's style sheet. |
static void |
setTabOrder(QWidget arg__1,
QWidget arg__2)
Moves the second widget around the ring of focus widgets so that keyboard focus moves from the first widget to the second widget when the Tab key is pressed. |
void |
setToolTip(java.lang.String arg__1)
This property holds the widget's tooltip. |
void |
setUpdatesEnabled(boolean enable)
This property holds whether updates are enabled. |
void |
setVisible(boolean visible)
This property holds whether the widget is visible. |
void |
setWhatsThis(java.lang.String arg__1)
This property holds the widget's What's This help text. |
void |
setWindowFilePath(java.lang.String filePath)
This property holds the file path associated with a widget. |
void |
setWindowFlags(Qt.WindowFlags type)
Window flags are a combination of a type (e.g. |
void |
setWindowFlags(Qt.WindowType[] type)
Window flags are a combination of a type (e.g. |
void |
setWindowIcon(QIcon icon)
This property holds the widget's icon. |
void |
setWindowIconText(java.lang.String arg__1)
This property holds the widget's icon text. |
void |
setWindowModality(Qt.WindowModality windowModality)
This property holds which windows are blocked by the modal widget. |
void |
setWindowModified(boolean arg__1)
This property holds whether the document shown in the window has unsaved changes. |
void |
setWindowOpacity(double level)
This property holds The level of opacity for the window. |
void |
setWindowRole(java.lang.String arg__1)
Sets the window's role to role. |
void |
setWindowState(Qt.WindowState[] state)
Sets the window state to windowState. |
void |
setWindowState(Qt.WindowStates state)
Sets the window state to windowState. |
void |
setWindowTitle(java.lang.String arg__1)
This property holds the window title (caption). |
void |
show()
Shows the widget and its child widgets. |
protected void |
showEvent(QShowEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget show events which are passed in the event parameter. |
void |
showFullScreen()
Shows the widget in full-screen mode. |
void |
showMaximized()
Shows the widget maximized. |
void |
showMinimized()
Shows the widget minimized, as an icon. |
void |
showNormal()
Restores the widget after it has been maximized or minimized. |
QSize |
size()
This property holds the size of the widget excluding any window frame. |
QSize |
sizeHint()
This property holds the recommended size for the widget. |
QSize |
sizeIncrement()
This property holds the size increment of the widget. |
QSizePolicy |
sizePolicy()
This property holds the default layout behavior of the widget. |
void |
stackUnder(QWidget arg__1)
Places the widget under w in the parent widget's stack. |
java.lang.String |
statusTip()
This property holds the widget's status tip. |
QStyle |
style()
Returns the widget's style object, i.e., the style in which the widget is drawn. |
java.lang.String |
styleSheet()
This property holds the widget's style sheet. |
protected void |
tabletEvent(QTabletEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive tablet events for the widget. |
boolean |
testAttribute(Qt.WidgetAttribute arg__1)
Returns true if attribute attribute is set on this widget; otherwise returns false. |
java.lang.String |
toolTip()
This property holds the widget's tooltip. |
boolean |
underMouse()
Returns true if the widget is under the mouse cursor; otherwise returns false. |
void |
unsetCursor()
This property holds the cursor shape for this widget. |
void |
unsetLayoutDirection()
This property holds the layout direction for this widget. |
void |
unsetLocale()
This property holds the widget's locale. |
void |
update()
Updates the widget unless updates are disabled or the widget is hidden. |
void |
update(int x,
int y,
int w,
int h)
This version updates a rectangle (x, y, w, h) inside the widget. |
void |
update(QRect arg__1)
This version updates a rectangle r inside the widget. |
void |
update(QRegion arg__1)
This version repaints a region rgn inside the widget. |
void |
updateGeometry()
Notifies the layout system that this widget has changed and may need to change geometry. |
protected void |
updateMicroFocus()
Updates the widget's micro focus. |
boolean |
updatesEnabled()
This property holds whether updates are enabled. |
QRegion |
visibleRegion()
Returns the unobscured region where paint events can occur. |
java.lang.String |
whatsThis()
This property holds the widget's What's This help text. |
protected void |
wheelEvent(QWheelEvent arg__1)
This event handler, for event event, can be reimplemented in a subclass to receive wheel events for the widget. |
int |
width()
Returns the width of the paint device in default coordinate system units (e.g. |
int |
widthMM()
Returns the width of the paint device in millimeters. |
QWidget |
window()
Returns the window for this widget, i.e. |
java.lang.String |
windowFilePath()
This property holds the file path associated with a widget. |
Qt.WindowFlags |
windowFlags()
Window flags are a combination of a type (e.g. |
QIcon |
windowIcon()
This property holds the widget's icon. |
java.lang.String |
windowIconText()
This property holds the widget's icon text. |
Qt.WindowModality |
windowModality()
This property holds which windows are blocked by the modal widget. |
double |
windowOpacity()
This property holds The level of opacity for the window. |
java.lang.String |
windowRole()
Returns the window's role, or an empty string. |
Qt.WindowStates |
windowState()
Returns the current window state. |
java.lang.String |
windowTitle()
This property holds the window title (caption). |
Qt.WindowType |
windowType()
Returns the window type of this widget. |
long |
winId()
Returns the window system identifier of the widget. |
int |
x()
This property holds the x coordinate of the widget relative to its parent including any window frame. |
int |
y()
This property holds the y coordinate of the widget relative to its parent and including any window frame. |
Methods inherited from class com.trolltech.qt.core.QObject |
---|
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty |
Methods inherited from class com.trolltech.qt.QtJambiObject |
---|
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
---|
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class java.lang.Object |
---|
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
---|
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Field Detail |
---|
public final QSignalEmitter.Signal1 customContextMenuRequested
contextMenuPolicy
is Qt::CustomContextMenu
, and the user has requested a context menu on the widget. The position pos is the position of the context menu event that the widget receives. Normally this is in widget coordinates. The exception to this rule is QAbstractScrollArea
and its subclasses that map the context menu event to coordinates of the viewport()
. mapToGlobal()
, QMenu
, and contextMenuPolicy
.
Constructor Detail |
---|
public QWidget(QWidget parent, Qt.WindowType[] f)
If parent is 0, the new widget becomes a window. If parent is another widget, this widget becomes a child window inside parent. The new widget is deleted when its parent is deleted.
The widget flags argument, f, is normally 0, but it can be set to customize the frame of a window (i.e. parent must be 0). To customize the frame, use a value composed from the bitwise OR of any of the window flags.
If you add a child widget to an already visible widget you must explicitly show the child to make it visible.
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.
windowFlags
.
public QWidget(QWidget parent)
If parent is 0, the new widget becomes a window. If parent is another widget, this widget becomes a child window inside parent. The new widget is deleted when its parent is deleted.
The widget flags argument, f, is normally 0, but it can be set to customize the frame of a window (i.e. parent must be 0). To customize the frame, use a value composed from the bitwise OR of any of the window flags.
If you add a child widget to an already visible widget you must explicitly show the child to make it visible.
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.
windowFlags
.
public QWidget()
If parent is 0, the new widget becomes a window. If parent is another widget, this widget becomes a child window inside parent. The new widget is deleted when its parent is deleted.
The widget flags argument, f, is normally 0, but it can be set to customize the frame of a window (i.e. parent must be 0). To customize the frame, use a value composed from the bitwise OR of any of the window flags.
If you add a child widget to an already visible widget you must explicitly show the child to make it visible.
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.
windowFlags
.
public QWidget(QWidget parent, Qt.WindowFlags f)
If parent is 0, the new widget becomes a window. If parent is another widget, this widget becomes a child window inside parent. The new widget is deleted when its parent is deleted.
The widget flags argument, f, is normally 0, but it can be set to customize the frame of a window (i.e. parent must be 0). To customize the frame, use a value composed from the bitwise OR of any of the window flags.
If you add a child widget to an already visible widget you must explicitly show the child to make it visible.
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.
windowFlags
.
Method Detail |
---|
public final boolean acceptDrops()
If the widget is the desktop (QWidget::(windowType()
== Qt::Desktop
)), this may fail if another application is using the desktop; you can call acceptDrops()
to test if this occurs.
Warning: Do not modify this property in a Drag&Drop event handler.
public final java.lang.String accessibleDescription()
QAccessibleInterface::text()
.
public final java.lang.String accessibleName()
QAccessibleInterface::text()
.
public final java.util.List actions()
contextMenuPolicy
, insertAction()
, and removeAction()
.
public final void activateWindow()
An active window is a visible top-level window that has the keyboard input focus.
This function performs the same operation as clicking the mouse on the title bar of a top-level window. On X11, the result depends on the Window Manager. If you want to ensure that the window is stacked on top as well you should also call raise()
. Note that the window must be visible, otherwise activateWindow()
has no effect.
On Windows, if you are calling this when the application is not currently the active one then it will not make it the active window. It will change the color of the taskbar entry to indicate that the window has changed in some way. This is because Microsoft do not allow an application to interrupt what the user is currently doing in another application.
isActiveWindow()
, window()
, and show()
.
public final void addAction(QAction action)
All QWidgets
have a list of QAction
s, however they can be represented graphically in many different ways. The default use of the QAction
list (as returned by actions()
) is to create a context QMenu
.
A QWidget
should only have one of each action.
removeAction()
, insertAction()
, actions()
, and QMenu
.
public final void addActions(java.util.List actions)
removeAction()
, QMenu
, and addAction()
.
public final void adjustSize()
Uses sizeHint()
if valid (i.e if the size hint's width and height are >= 0); otherwise sets the size to the children rectangle that covers all child widgets (the union of all child widget rectangles).
For windows, the screen size is also taken into account, and if the sizeHint()
is less than (200, 100) and the size policy is expanding, the window is made to be at least (200, 100).
sizeHint()
, and childrenRect()
.
public final boolean autoFillBackground()
palette
. In addition, Windows are always filled with QPalette::Window
, unless the WA_OpaquePaintEvent
or WA_NoSystemBackground
attributes are set.
Warning: Use this property with caution in conjunction with Qt Style Sheets. When a widget has a style sheet with a valid background or a border-image, this property is automatically disabled.
Qt::WA_OpaquePaintEvent
, and Qt::WA_NoSystemBackground
.
public final QPalette.ColorRole backgroundRole()
The background role defines the brush from the widget's palette
that is used to render the background.
If no explicit background role is set, the widget inherts its parent widget's background role.
setBackgroundRole()
, and foregroundRole()
.
public final QSize baseSize()
sizeIncrement()
. setSizeIncrement()
.
public final QWidget childAt(QPoint p)
public final QWidget childAt(int x, int y)
public final QRect childrenRect()
childrenRegion()
, and geometry()
.
public final QRegion childrenRegion()
childrenRect()
, geometry()
, and mask()
.
public final void clearFocus()
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()
.
hasFocus()
, setFocus()
, focusInEvent()
, focusOutEvent()
, setFocusPolicy()
, and QApplication::focusWidget()
.
public final void clearMask()
setMask()
. setMask()
.
public final boolean close()
First it sends the widget a QCloseEvent
. The widget is hidden
if it accepts
the close event. If it ignores
the event, nothing happens. The default implementation of QWidget::closeEvent()
accepts the close event.
If the widget has the Qt::WA_DeleteOnClose
flag, the widget is also deleted. A close events is delivered to the widget no matter if the widget is visible or not.
The QApplication::lastWindowClosed()
signal is emitted when the last visible primary window (i.e. window with no parent) with the Qt::WA_QuitOnClose
attribute set is closed. By default this attribute is set for all widgets except transient windows such as splash screens, tool windows, and popup menus.
public final QRect contentsRect()
setContentsMargins()
, and getContentsMargins()
.
public final Qt.ContextMenuPolicy contextMenuPolicy()
Qt::DefaultContextMenu
, which means the contextMenuEvent()
handler is called. Other values are Qt::NoContextMenu
, Qt::PreventContextMenu
, Qt::ActionsContextMenu
, and Qt::CustomContextMenu
. With Qt::CustomContextMenu
, the signal customContextMenuRequested()
is emitted. contextMenuEvent()
, customContextMenuRequested()
, and actions()
.
public final QCursor cursor()
list of predefined cursor objects
for a range of useful shapes. An editor widget might use an I-beam cursor:
setCursor(Qt.IBeamCursor);If no cursor has been set, or after a call to
unsetCursor()
, the parent's cursor is used. QApplication::setOverrideCursor()
.
public final int depth()
depth
in interface QPaintDeviceInterface
protected final void destroy(boolean destroyWindow)
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.
protected final void destroy()
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.
protected final void destroy(boolean destroyWindow, boolean destroySubWindows)
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.
public final long effectiveWinId()
Note: We recommend that you do not store this value as it is likely to change during run-time.
nativeParentWidget()
.
public final void ensurePolished()
QStyle
(i.e., has a proper font and palette). QWidget
calls this function after it has been fully constructed but before it is shown the very first time. You can call this function if you want to ensure that the widget is polished before doing an operation, e.g., the correct font size might be needed in the widget's sizeHint()
reimplementation. Note that this function is called from the default implementation of sizeHint()
.
Polishing is useful for final initialization that must happen after all constructors (from base classes as well as from subclasses) have been called.
If you need to change some settings when a widget is polished, reimplement event()
and handle the QEvent::Polish
event type.
Note: The function is declared const so that it can be called from other const functions (e.g., sizeHint()
).
event()
.
protected final boolean focusNextChild()
focusPreviousChild()
.
public final Qt.FocusPolicy focusPolicy()
Qt::TabFocus
if the widget accepts keyboard focus by tabbing, Qt::ClickFocus
if the widget accepts focus by clicking, Qt::StrongFocus
if it accepts both, and Qt::NoFocus
(the default) if it does not accept focus at all. 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
(Qt::StrongFocus
).
focusInEvent()
, focusOutEvent()
, keyPressEvent()
, keyReleaseEvent()
, and enabled
.
protected final boolean focusPreviousChild()
focusNextChild()
.
public final QWidget focusProxy()
setFocusProxy()
.
public final QWidget focusWidget()
setFocus
had been called on. For top level widgets this is the widget that will get focus in case this window gets activated This is not the same as QApplication::focusWidget()
, which returns the focus widget in the currently active window.
public final QFont font()
fontInfo()
function reports the actual font that is being used by the widget. As long as no special font has been set, or after setFont
(QFont()) is called, this is either a special font for the widget class, the parent's font or (if this widget is a top level widget), the default application font.
This code fragment sets a 12 point helvetica bold font:
QFont font("Helvetica", 12, QFont.Bold); setFont(font);Note that when a child widget is given a different font to that of its parent widget, it will still inherit the parent's font properties unless these have been set explicitly on the child's font. For example, if the parent's font is bold, the child widget's font will be bold as well if not specified otherwise like this:
QFont font; font.setBold(false); setFont(font);In addition to setting the font,
setFont()
informs all children about the change. Note: If Qt Style Sheets are used on the same widget as setFont()
, style sheets will take precedence if the settings conflict.
fontInfo()
, and fontMetrics()
.
public final QFontInfo fontInfo()
QFontInto
(widget->font()
). font()
, fontMetrics()
, and setFont()
.
public final QFontMetrics fontMetrics()
QFontMetrics
(widget->font()
). font()
, fontInfo()
, and setFont()
.
public final QPalette.ColorRole foregroundRole()
The foreground role defines the color from the widget's palette
that is used to draw the foreground.
If no explicit foreground role is set, the function returns a role that contrasts with the background role.
setForegroundRole()
, and backgroundRole()
.
public final QRect frameGeometry()
geometry()
, x()
, y()
, and pos()
.
public final QSize frameSize()
public final QRect geometry()
moveEvent()
) and/or a resize event (resizeEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive appropriate events before it is shown. The size component is adjusted if it lies outside the range defined by minimumSize()
and maximumSize()
.
Warning: Calling setGeometry()
inside resizeEvent()
or moveEvent()
can lead to infinite recursion.
See the Window Geometry documentation for an overview of window geometry.
frameGeometry()
, rect()
, move()
, resize()
, moveEvent()
, resizeEvent()
, minimumSize()
, and maximumSize()
.
public final void grabKeyboard()
This widget receives all keyboard events until releaseKeyboard()
is called; other widgets get no keyboard events at all. Mouse events are not affected. Use grabMouse()
if you want to grab that.
The focus widget is not affected, except that it doesn't receive any keyboard events. setFocus()
moves the focus as usual, but the new focus widget receives keyboard events only after releaseKeyboard()
is called.
If a different widget is currently grabbing keyboard input, that widget's grab is released first.
releaseKeyboard()
, grabMouse()
, releaseMouse()
, and focusWidget()
.
public final void grabMouse()
This widget receives all mouse events until releaseMouse()
is called; other widgets get no mouse events at all. Keyboard events are not affected. Use grabKeyboard()
if you want to grab that.
Warning: Bugs in mouse-grabbing applications very often lock the terminal. Use this function with extreme caution, and consider using the -nograb command line option while debugging.
It is almost never necessary to grab the mouse when using Qt, as Qt grabs and releases it sensibly. In particular, Qt grabs the mouse when a mouse button is pressed and keeps it until the last button is released.
Note that only visible widgets can grab mouse input. If isVisible()
returns false for a widget, that widget cannot call grabMouse()
.
releaseMouse()
, grabKeyboard()
, releaseKeyboard()
, and grabKeyboard()
.
public final void grabMouse(QCursor arg__1)
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.
releaseMouse()
, grabKeyboard()
, releaseKeyboard()
, and setCursor()
.
public final int grabShortcut(QKeySequence key)
Qt::ApplicationShortcut
, the shortcut applies to the application as a whole. Otherwise, it is either local to this widget, Qt::WidgetShortcut
, or to the window itself, Qt::WindowShortcut
. If the same key sequence has been grabbed by several widgets, when the key sequence occurs a QEvent::Shortcut
event is sent to all the widgets to which it applies in a non-deterministic order, but with the ``ambiguous'' flag set to true.
Warning: You should not normally need to use this function; instead create QAction
s with the shortcut key sequences you require (if you also want equivalent menu options and toolbar buttons), or create QShortcut
s if you just need key sequences. Both QAction
and QShortcut
handle all the event filtering for you, and provide signals which are triggered when the user triggers the key sequence, so are much easier to use than this low-level function.
releaseShortcut()
, and setShortcutEnabled()
.
public final int grabShortcut(QKeySequence key, Qt.ShortcutContext context)
Qt::ApplicationShortcut
, the shortcut applies to the application as a whole. Otherwise, it is either local to this widget, Qt::WidgetShortcut
, or to the window itself, Qt::WindowShortcut
. If the same key sequence has been grabbed by several widgets, when the key sequence occurs a QEvent::Shortcut
event is sent to all the widgets to which it applies in a non-deterministic order, but with the ``ambiguous'' flag set to true.
Warning: You should not normally need to use this function; instead create QAction
s with the shortcut key sequences you require (if you also want equivalent menu options and toolbar buttons), or create QShortcut
s if you just need key sequences. Both QAction
and QShortcut
handle all the event filtering for you, and provide signals which are triggered when the user triggers the key sequence, so are much easier to use than this low-level function.
releaseShortcut()
, and setShortcutEnabled()
.
public final boolean hasFocus()
setFocus()
, clearFocus()
, setFocusPolicy()
, and QApplication::focusWidget()
.
public final boolean hasMouseTracking()
If mouse tracking is enabled, the widget receives mouse move events even if no buttons are pressed.
mouseMoveEvent()
.
public final int height()
QPixmap
and QWidget
). heightMM()
.
height
in interface QPaintDeviceInterface
public final int heightMM()
height()
.
heightMM
in interface QPaintDeviceInterface
public final void hide()
setVisible
(false). Note: If you are working with QDialog
or its subclasses and you invoke the show()
function after this function, the dialog will be displayed in its original position.
hideEvent()
, isHidden()
, show()
, setVisible()
, isVisible()
, and close()
.
public final QInputContext inputContext()
QInputContext
for this widget. By default the input context is inherited from the widgets parent. For toplevels it is inherited from QApplication
. You can override this and set a special input context for this widget by using the setInputContext()
method.
setInputContext()
.
public final void insertAction(QAction before, QAction action)
A QWidget
should only have one of each action.
removeAction()
, addAction()
, QMenu
, contextMenuPolicy
, and actions()
.
public final void insertActions(QAction before, java.util.List actions)
A QWidget
can have at most one of each action.
removeAction()
, QMenu
, insertAction()
, and contextMenuPolicy
.
public final boolean isActiveWindow()
When popup windows are visible, this property is true for both the active window and for the popup.
activateWindow()
, and QApplication::activeWindow()
.
public final boolean isAncestorOf(QWidget child)
public final boolean isEnabled()
Some widgets display themselves differently when they are disabled. For example a button might draw its label grayed out. If your widget needs to know when it becomes enabled or disabled, you can use the changeEvent()
with type QEvent::EnabledChange
.
Disabling a widget implicitly disables all its children. Enabling respectively enables all child widgets unless they have been explicitly disabled.
isEnabledTo()
, QKeyEvent
, QMouseEvent
, and changeEvent()
.
public final boolean isEnabledTo(QWidget arg__1)
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()
.
setEnabled()
, and enabled
.
public final boolean isFullScreen()
windowState()
, minimized
, and maximized
.
public final boolean isHidden()
A hidden widget will only become visible when show()
is called on it. It will not be automatically shown when the parent is shown.
To check visiblity, use !isVisible()
instead (notice the exclamation mark).
isHidden()
implies !isVisible()
, but a widget can be not visible and not hidden at the same time. This is the case for widgets that are children of widgets that are not visible.
Widgets are hidden if they were created as independent windows or as children of visible widgets, or if hide()
or setVisible
(false) was called.
public final boolean isMaximized()
Note that due to limitations in some window-systems, this does not always report the expected results (e.g. if the user on X11 maximizes the window via the window manager, Qt has no way of distinguishing this from any other resize). This is expected to improve as window manager protocols evolve.
windowState()
, showMaximized()
, visible
, show()
, hide()
, showNormal()
, and minimized
.
public final boolean isMinimized()
showMinimized()
, visible
, show()
, hide()
, showNormal()
, and maximized
.
public final boolean isModal()
isWindow()
, windowModality
, and QDialog
.
public final boolean isVisible()
setVisible
(true) or show()
sets the widget to visible status if all its parent widgets up to the window are visible. If an ancestor is not visible, the widget won't become visible until all its ancestors are shown. If its size or position has changed, Qt guarantees that a widget gets move and resize events just before it is shown. If the widget has not been resized yet, Qt will adjust the widget's size to a useful default using adjustSize()
. Calling setVisible
(false) or hide()
hides a widget explicitly. An explicitly hidden widget will never become visible, even if all its ancestors become visible, unless you show it.
A widget receives show and hide events when its visibility status changes. Between a hide and a show event, there is no need to waste CPU cycles preparing or displaying information to the user. A video application, for example, might simply stop generating new frames.
A widget that happens to be obscured by other windows on the screen is considered to be visible. The same applies to iconified windows and windows that exist on another virtual desktop (on platforms that support this concept). A widget receives spontaneous show and hide events when its mapping status is changed by the window system, e.g. a spontaneous hide event when the user minimizes the window, and a spontaneous show event when the window is restored again.
You almost never have to reimplement the setVisible()
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 the Polish event delivered to the event()
function.
show()
, hide()
, isHidden()
, isVisibleTo()
, isMinimized()
, showEvent()
, and hideEvent()
.
public final boolean isVisibleTo(QWidget arg__1)
The true case occurs if neither the widget itself nor any parent up to but excluding ancestor has been explicitly hidden.
This function will still return true if the widget is obscured by other windows on the screen, but could be physically visible if it or they were to be moved.
isVisibleTo
(0) is identical to isVisible()
.
show()
, hide()
, and isVisible()
.
public final boolean isWindow()
A window is a widget that isn't visually the child of any other widget and that usually has a frame and a window title
.
A window can have a parent widget
. It will then be grouped with its parent and 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 windows, even if a parent widget is specified in the constructor. This behavior is specified by the Qt::Window
flag.
window()
, isModal()
, and parentWidget()
.
public final boolean isWindowModified()
The window title must contain a "[*]" placeholder, which indicates where the '*' should appear. Normally, it should appear right after the file name (e.g., "document1.txt[*] - Text Editor"). If the window isn't modified, the placeholder is simply removed.
windowTitle
, Application Example, SDI Example, and MDI Example.
public final QLayout layout()
The layout manager sets the geometry of the widget's children that have been added to the layout.
setLayout()
, sizePolicy()
, and Layout Classes.
public final Qt.LayoutDirection layoutDirection()
QApplication::layoutDirection
.
public final QLocale locale()
If the widget displays dates or numbers, these should be formatted using the widget's locale.
QLocale
, and QLocale::setDefault()
.
public final int logicalDpiX()
widthMM()
. Note that if the logicalDpiX()
doesn't equal the physicalDpiX()
, the corresponding QPaintEngine
must handle the resolution mapping.
logicalDpiY()
, and physicalDpiX()
.
logicalDpiX
in interface QPaintDeviceInterface
public final int logicalDpiY()
heightMM()
. Note that if the logicalDpiY()
doesn't equal the physicalDpiY()
, the corresponding QPaintEngine
must handle the resolution mapping.
logicalDpiX()
, and physicalDpiY()
.
logicalDpiY
in interface QPaintDeviceInterface
public final void lower()
After this call the widget will be visually behind (and therefore obscured by) any overlapping sibling widgets.
raise()
, and stackUnder()
.
public final QPoint mapFrom(QWidget arg__1, QPoint arg__2)
mapTo()
, mapFromParent()
, mapFromGlobal()
, and underMouse()
.
public final QPoint mapFromGlobal(QPoint arg__1)
mapToGlobal()
, mapFrom()
, and mapFromParent()
.
public final QPoint mapFromParent(QPoint arg__1)
Same as mapFromGlobal()
if the widget has no parent.
mapToParent()
, mapFrom()
, mapFromGlobal()
, and underMouse()
.
public final QPoint mapTo(QWidget arg__1, QPoint arg__2)
mapFrom()
, mapToParent()
, mapToGlobal()
, and underMouse()
.
public final QPoint mapToGlobal(QPoint arg__1)
mapFromGlobal()
, mapTo()
, and mapToParent()
.
public final QPoint mapToParent(QPoint arg__1)
Same as mapToGlobal()
if the widget has no parent.
mapFromParent()
, mapTo()
, mapToGlobal()
, and underMouse()
.
public final QRegion mask()
setMask()
, clearMask()
, QRegion::isEmpty()
, and Shaped Clock Example.
public final int maximumHeight()
maximumSize()
.height()
. It is limited by the QWIDGETSIZE_MAX macro, i.e. the largest allowed height is 16777215. maximumSize
, and maximumWidth
.
public final QSize maximumSize()
The property is limited by the QWIDGETSIZE_MAX macro, i.e. the largest allowed size is QSize
(16777215, 16777215).
maximumWidth
, maximumHeight
, minimumSize
, and sizeIncrement
.
public final int maximumWidth()
maximumSize()
.width()
. It is limited by the QWIDGETSIZE_MAX macro, i.e. the largest allowed width is 16777215. maximumSize
, and maximumHeight
.
public final int minimumHeight()
minimumSize()
.height()
. minimumSize
, and minimumWidth
.
public final QSize minimumSize()
The minimum size set by this function will override the minimum size defined by QLayout
. In order to unset the minimum size, use QSize
(0, 0).
minimumWidth
, minimumHeight
, maximumSize
, and sizeIncrement
.
public final int minimumWidth()
minimumSize()
.width()
. minimumSize
, and minimumHeight
.
public final void move(QPoint arg__1)
When changing the position, the widget, if visible, receives a move event (moveEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive an event before it is shown.
Warning: Calling move()
or setGeometry()
inside moveEvent()
can lead to infinite recursion.
See the Window Geometry documentation for an overview of window geometry.
frameGeometry
, size
, x()
, and y()
.
public final void move(int x, int y)
When changing the position, the widget, if visible, receives a move event (moveEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive an event before it is shown.
Warning: Calling move()
or setGeometry()
inside moveEvent()
can lead to infinite recursion.
See the Window Geometry documentation for an overview of window geometry.
frameGeometry
, size
, x()
, and y()
.
public final QWidget nativeParentWidget()
effectiveWinId()
.
public final QWidget nextInFocusChain()
public final QRect normalGeometry()
QWidget::windowState()
, and QWidget::geometry
.
public final int numColors()
INT_MAX
is returned instead.
numColors
in interface QPaintDeviceInterface
public final void overrideWindowFlags(Qt.WindowType[] type)
Warning: Do not call this function unless you really know what you're doing.
setWindowFlags()
.
public final void overrideWindowFlags(Qt.WindowFlags type)
Warning: Do not call this function unless you really know what you're doing.
setWindowFlags()
.
public final boolean paintingActive()
QPainter::begin()
but not yet called QPainter::end()
for this device; otherwise returns false. QPainter::isActive()
.
paintingActive
in interface QPaintDeviceInterface
public final QPalette palette()
Note: The palette's background color will only have an effect on the appearance of the widget if the autoFillBackground
property is set.
Warning: Do not use this function in conjunction with Qt Style Sheets. When using style sheets, the palette of a widget can be customized using the "color", "background-color", "selection-color", "selection-background-color" and "alternate-background-color".
QApplication::palette()
.
public final QWidget parentWidget()
public final int physicalDpiX()
Note that if the physicalDpiX()
doesn't equal the logicalDpiX()
, the corresponding QPaintEngine
must handle the resolution mapping.
physicalDpiY()
, and logicalDpiX()
.
physicalDpiX
in interface QPaintDeviceInterface
public final int physicalDpiY()
Note that if the physicalDpiY()
doesn't equal the logicalDpiY()
, the corresponding QPaintEngine
must handle the resolution mapping.
physicalDpiX()
, and logicalDpiY()
.
physicalDpiY
in interface QPaintDeviceInterface
public final QPoint pos()
When changing the position, the widget, if visible, receives a move event (moveEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive an event before it is shown.
Warning: Calling move()
or setGeometry()
inside moveEvent()
can lead to infinite recursion.
See the Window Geometry documentation for an overview of window geometry.
frameGeometry
, size
, x()
, and y()
.
public final void raise()
After this call the widget will be visually in front of any overlapping sibling widgets.
Note: When using activateWindow()
, you can call this function to ensure that the window is stacked on top.
lower()
, and stackUnder()
.
public final QRect rect()
QRect
(0, 0, width()
, height()
). See the Window Geometry documentation for an overview of window geometry.
size
.
public final void releaseKeyboard()
grabKeyboard()
, grabMouse()
, and releaseMouse()
.
public final void releaseMouse()
grabMouse()
, grabKeyboard()
, and releaseKeyboard()
.
public final void releaseShortcut(int id)
QEvent::Shortcut
events for the shortcut's key sequence (unless it has other shortcuts with the same key sequence). Warning: You should not normally need to use this function since Qt's shortcut system removes shortcuts automatically when their parent widget is destroyed. It is best to use QAction
or QShortcut
to handle shortcuts, since they are easier to use than this low-level function. Note also that this is an expensive operation.
grabShortcut()
, and setShortcutEnabled()
.
public final void removeAction(QAction action)
insertAction()
, actions()
, and insertAction()
.
public final void render(QPaintDeviceInterface target, QPoint targetOffset, QRegion sourceRegion, QWidget.RenderFlag[] renderFlags)
QPixmap pixmap(widget.size()); widget.render(ixmap);If sourceRegion is a null region, this function will use
QWidget::rect()
as the region, i.e. the entire widget. Note: Make sure to call QPainter::end()
for the given target's active painter (if any) before rendering. For example:
QPainter painter(this); ... painter.end(); myWidget.render(this);
public final void render(QPaintDeviceInterface target, QPoint targetOffset, QRegion sourceRegion)
QPixmap pixmap(widget.size()); widget.render(ixmap);If sourceRegion is a null region, this function will use
QWidget::rect()
as the region, i.e. the entire widget. Note: Make sure to call QPainter::end()
for the given target's active painter (if any) before rendering. For example:
QPainter painter(this); ... painter.end(); myWidget.render(this);
public final void render(QPaintDeviceInterface target, QPoint targetOffset)
QPixmap pixmap(widget.size()); widget.render(ixmap);If sourceRegion is a null region, this function will use
QWidget::rect()
as the region, i.e. the entire widget. Note: Make sure to call QPainter::end()
for the given target's active painter (if any) before rendering. For example:
QPainter painter(this); ... painter.end(); myWidget.render(this);
public final void render(QPaintDeviceInterface target)
QPixmap pixmap(widget.size()); widget.render(ixmap);If sourceRegion is a null region, this function will use
QWidget::rect()
as the region, i.e. the entire widget. Note: Make sure to call QPainter::end()
for the given target's active painter (if any) before rendering. For example:
QPainter painter(this); ... painter.end(); myWidget.render(this);
public final void render(QPaintDeviceInterface target, QPoint targetOffset, QRegion sourceRegion, QWidget.RenderFlags renderFlags)
QPixmap pixmap(widget.size()); widget.render(ixmap);If sourceRegion is a null region, this function will use
QWidget::rect()
as the region, i.e. the entire widget. Note: Make sure to call QPainter::end()
for the given target's active painter (if any) before rendering. For example:
QPainter painter(this); ... painter.end(); myWidget.render(this);
public final void render(QPainter painter, QPoint targetOffset, QRegion sourceRegion, QWidget.RenderFlag[] renderFlags)
QPainter::device()
. Transformations and settings applied to the painter will be used when rendering.
Note: The painter must be active. On Mac OS X the widget will be rendered into a QPixmap
and then drawn by the painter.
QPainter::device()
.
public final void render(QPainter painter, QPoint targetOffset, QRegion sourceRegion)
QPainter::device()
. Transformations and settings applied to the painter will be used when rendering.
Note: The painter must be active. On Mac OS X the widget will be rendered into a QPixmap
and then drawn by the painter.
QPainter::device()
.
public final void render(QPainter painter, QPoint targetOffset)
QPainter::device()
. Transformations and settings applied to the painter will be used when rendering.
Note: The painter must be active. On Mac OS X the widget will be rendered into a QPixmap
and then drawn by the painter.
QPainter::device()
.
public final void render(QPainter painter, QPoint targetOffset, QRegion sourceRegion, QWidget.RenderFlags renderFlags)
QPainter::device()
. Transformations and settings applied to the painter will be used when rendering.
Note: The painter must be active. On Mac OS X the widget will be rendered into a QPixmap
and then drawn by the painter.
QPainter::device()
.
public final void repaint()
paintEvent()
immediately, unless updates are disabled or the widget is hidden. We suggest only using repaint()
if you need an immediate repaint, for example during animation. In almost all circumstances update()
is better, as it permits Qt to optimize for speed and minimize flicker.
Warning: If you call repaint()
in a function which may itself be called from paintEvent()
, you may get infinite recursion. The update()
function never causes recursion.
update()
, paintEvent()
, and setUpdatesEnabled()
.
public final void repaint(QRect arg__1)
public final void repaint(QRegion arg__1)
public final void repaint(int x, int y, int w, int h)
If w is negative, it is replaced with width() - x, and if h is negative, it is replaced width height() - y.
protected final void resetInputContext()
QInputContext
, and QInputContext::reset()
.
public final void resize(QSize arg__1)
resizeEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive an event before it is shown. The size is adjusted if it lies outside the range defined by minimumSize()
and maximumSize()
.
Warning: Calling resize()
or setGeometry()
inside resizeEvent()
can lead to infinite recursion.
Note that setting size to QSize
(0, 0) will cause the widget to not appear on screen. This also applies to windows.
pos
, geometry
, minimumSize
, maximumSize
, and resizeEvent()
.
public final void resize(int w, int h)
resizeEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive an event before it is shown. The size is adjusted if it lies outside the range defined by minimumSize()
and maximumSize()
.
Warning: Calling resize()
or setGeometry()
inside resizeEvent()
can lead to infinite recursion.
Note that setting size to QSize
(0, 0) will cause the widget to not appear on screen. This also applies to windows.
pos
, geometry
, minimumSize
, maximumSize
, and resizeEvent()
.
public final boolean restoreGeometry(QByteArray geometry)
If the restored geometry is off-screen, it will be modified to be inside the the available screen geometry.
To restore geometry saved using QSettings
, you can use code like this:
QSettings settings("MyCompany", "MyApp"); myWidget.restoreGeometry(settings.value("myWidget/geometry").toByteArray());See the Window Geometry documentation for an overview of geometry issues with windows.
saveGeometry()
, and QSettings
.
public final QByteArray saveGeometry()
To save the geometry when the window closes, you can implement a close event like this:
void MyWidget.closeEvent(QCloseEvent vent) { QSettings settings("MyCompany", "MyApp"); settings.setValue("geometry", saveGeometry()); QWidget.closeEvent(event); }See the Window Geometry documentation for an overview of geometry issues with windows.
restoreGeometry()
.
public final void scroll(int dx, int dy)
After scrolling, the widgets will receive paint events for the areas that need to be repainted. For widgets that Qt knows to be opaque, this is only the newly exposed parts. For example, if an opaque widget is scrolled 8 pixels to the left, only an 8-pixel wide stripe at the right edge needs updating.
Since widgets propagate the contents of their parents by default, you need to set the autoFillBackground
property, or use setAttribute()
to set the Qt::WA_OpaquePaintEvent
attribute, to make a widget opaque.
For widgets that use contents propagation, a scroll will cause an update of the entire scroll area.
Transparency and Double Buffering
.
public final void scroll(int dx, int dy, QRect arg__3)
If r is empty or invalid, the result is undefined.
QScrollArea
.
public final void setAcceptDrops(boolean on)
If the widget is the desktop (QWidget::(windowType()
== Qt::Desktop
)), this may fail if another application is using the desktop; you can call acceptDrops()
to test if this occurs.
Warning: Do not modify this property in a Drag&Drop event handler.
public final void setAccessibleDescription(java.lang.String description)
QAccessibleInterface::text()
.
public final void setAccessibleName(java.lang.String name)
QAccessibleInterface::text()
.
public final void setAttribute(Qt.WidgetAttribute arg__1)
testAttribute()
.
public final void setAttribute(Qt.WidgetAttribute arg__1, boolean on)
testAttribute()
.
public final void setAutoFillBackground(boolean enabled)
palette
. In addition, Windows are always filled with QPalette::Window
, unless the WA_OpaquePaintEvent
or WA_NoSystemBackground
attributes are set.
Warning: Use this property with caution in conjunction with Qt Style Sheets. When a widget has a style sheet with a valid background or a border-image, this property is automatically disabled.
Qt::WA_OpaquePaintEvent
, and Qt::WA_NoSystemBackground
.
public final void setBackgroundRole(QPalette.ColorRole arg__1)
The background role defines the brush from the widget's palette
that is used to render the background.
If role is QPalette::NoRole
, then the widget inherits its parent's background role.
backgroundRole()
, and foregroundRole()
.
public final void setBaseSize(QSize arg__1)
sizeIncrement()
. setSizeIncrement()
.
public final void setBaseSize(int basew, int baseh)
sizeIncrement()
. setSizeIncrement()
.
public final void setContentsMargins(int left, int top, int right, int bottom)
Changing the margins will trigger a resizeEvent()
.
contentsRect()
, and getContentsMargins()
.
public final void setContextMenuPolicy(Qt.ContextMenuPolicy policy)
Qt::DefaultContextMenu
, which means the contextMenuEvent()
handler is called. Other values are Qt::NoContextMenu
, Qt::PreventContextMenu
, Qt::ActionsContextMenu
, and Qt::CustomContextMenu
. With Qt::CustomContextMenu
, the signal customContextMenuRequested()
is emitted. contextMenuEvent()
, customContextMenuRequested()
, and actions()
.
public final void setCursor(QCursor arg__1)
list of predefined cursor objects
for a range of useful shapes. An editor widget might use an I-beam cursor:
setCursor(Qt.IBeamCursor);If no cursor has been set, or after a call to
unsetCursor()
, the parent's cursor is used. QApplication::setOverrideCursor()
.
public final void setDisabled(boolean arg__1)
See the enabled
documentation for more information.
isEnabledTo()
, QKeyEvent
, QMouseEvent
, and changeEvent()
.
public final void setEnabled(boolean arg__1)
Some widgets display themselves differently when they are disabled. For example a button might draw its label grayed out. If your widget needs to know when it becomes enabled or disabled, you can use the changeEvent()
with type QEvent::EnabledChange
.
Disabling a widget implicitly disables all its children. Enabling respectively enables all child widgets unless they have been explicitly disabled.
isEnabledTo()
, QKeyEvent
, QMouseEvent
, and changeEvent()
.
public final void setFixedHeight(int h)
sizeHint()
, minimumSize()
, maximumSize()
, and setFixedSize()
.
public final void setFixedSize(QSize arg__1)
This will override the default size constraints set by QLayout
.
Alternatively, if you want the widget to have a fixed size based on its contents, you can call QLayout::setSizeConstraint
(QLayout::SetFixedSize
);
maximumSize
, and minimumSize
.
public final void setFixedSize(int w, int h)
public final void setFixedWidth(int w)
sizeHint()
, minimumSize()
, maximumSize()
, and setFixedSize()
.
public final void setFocus()
active window
.
public final void setFocus(Qt.FocusReason reason)
active window
. The reason argument will be passed into any focus event sent from this function, it is used to give an explanation of what caused the widget to get focus. First, a focus out event is sent to the focus widget (if any) to tell it that it is about to lose the focus. Then a focus in event is sent to this widget to tell it that it just received the focus. (Nothing happens if the focus in and focus out widgets are the same.)
setFocus()
gives focus to a widget regardless of its focus policy, but does not clear any keyboard grab (see grabKeyboard()
).
Be aware that if the widget is hidden, it will not accept focus until it is shown.
Warning: If you call setFocus()
in a function which may itself be called from focusOutEvent()
or focusInEvent()
, you may get an infinite recursion.
setFocusPolicy()
QApplication::focusWidget()
grabKeyboard()
grabMouse()
, {Keyboard Focus}
hasFocus()
, clearFocus()
, focusInEvent()
, and focusOutEvent()
.
public final void setFocusPolicy(Qt.FocusPolicy policy)
Qt::TabFocus
if the widget accepts keyboard focus by tabbing, Qt::ClickFocus
if the widget accepts focus by clicking, Qt::StrongFocus
if it accepts both, and Qt::NoFocus
(the default) if it does not accept focus at all. 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
(Qt::StrongFocus
).
focusInEvent()
, focusOutEvent()
, keyPressEvent()
, keyReleaseEvent()
, and enabled
.
public final void setFocusProxy(QWidget arg__1)
Some widgets can "have focus", but create a child widget, such as QLineEdit
, to actually handle the focus. In this case, the widget can set the line edit to be its focus proxy.
setFocusProxy()
sets the widget which will actually get focus when "this widget" gets it. If there is a focus proxy, setFocus()
and hasFocus()
operate on the focus proxy.
focusProxy()
.
public final void setFont(QFont arg__1)
fontInfo()
function reports the actual font that is being used by the widget. As long as no special font has been set, or after setFont
(QFont()) is called, this is either a special font for the widget class, the parent's font or (if this widget is a top level widget), the default application font.
This code fragment sets a 12 point helvetica bold font:
QFont font("Helvetica", 12, QFont.Bold); setFont(font);Note that when a child widget is given a different font to that of its parent widget, it will still inherit the parent's font properties unless these have been set explicitly on the child's font. For example, if the parent's font is bold, the child widget's font will be bold as well if not specified otherwise like this:
QFont font; font.setBold(false); setFont(font);In addition to setting the font,
setFont()
informs all children about the change. Note: If Qt Style Sheets are used on the same widget as setFont()
, style sheets will take precedence if the settings conflict.
fontInfo()
, and fontMetrics()
.
public final void setForegroundRole(QPalette.ColorRole arg__1)
The foreground role defines the color from the widget's palette
that is used to draw the foreground.
If role is QPalette::NoRole
, the widget uses a foreground role that contrasts with the background role.
foregroundRole()
, and backgroundRole()
.
public final void setGeometry(QRect arg__1)
moveEvent()
) and/or a resize event (resizeEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive appropriate events before it is shown. The size component is adjusted if it lies outside the range defined by minimumSize()
and maximumSize()
.
Warning: Calling setGeometry()
inside resizeEvent()
or moveEvent()
can lead to infinite recursion.
See the Window Geometry documentation for an overview of window geometry.
frameGeometry()
, rect()
, move()
, resize()
, moveEvent()
, resizeEvent()
, minimumSize()
, and maximumSize()
.
public final void setGeometry(int x, int y, int w, int h)
moveEvent()
) and/or a resize event (resizeEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive appropriate events before it is shown. The size component is adjusted if it lies outside the range defined by minimumSize()
and maximumSize()
.
Warning: Calling setGeometry()
inside resizeEvent()
or moveEvent()
can lead to infinite recursion.
See the Window Geometry documentation for an overview of window geometry.
frameGeometry()
, rect()
, move()
, resize()
, moveEvent()
, resizeEvent()
, minimumSize()
, and maximumSize()
.
public final void setHidden(boolean hidden)
setVisible
(!hidden). isHidden()
.
public final void setInputContext(QInputContext arg__1)
inputContext()
.
public final void setLayout(QLayout arg__1)
If there already is a layout manager installed on this widget, QWidget
won't let you install another. You must first delete the existing layout manager (returned by layout()
) before you can call setLayout()
with the new layout.
Example:
The following code example is written in c++.
QVBoxLayout *layout = new QVBoxLayout; layout->addWidget(lcd); layout->addWidget(slider); setLayout(layout);An alternative to calling this function is to pass this widget to the layout's constructor.
The QWidget
will take ownership of layout.
layout()
, and Layout Classes.
public final void setLayoutDirection(Qt.LayoutDirection direction)
QApplication::layoutDirection
.
public final void setLocale(QLocale locale)
If the widget displays dates or numbers, these should be formatted using the widget's locale.
QLocale
, and QLocale::setDefault()
.
public final void setMask(QBitmap arg__1)
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.
The following code shows how an image with an alpha channel can be used to generate a mask for a widget:
QLabel topLevelLabel = new QLabel(); QPixmap pixmap = new QPixmap("classpath:tux.png"); topLevelLabel.setPixmap(pixmap); topLevelLabel.setMask(pixmap.mask());The label shown by this code is masked using the image it contains, giving the appearance that an irregularly-shaped image is being drawn directly onto the screen.
Masked widgets receive mouse events only on their visible portions.
mask()
, clearMask()
, windowOpacity()
, and Shaped Clock Example.
public final void setMask(QRegion arg__1)
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.
windowOpacity
.
public final void setMaximumHeight(int maxh)
maximumSize()
.height()
. It is limited by the QWIDGETSIZE_MAX macro, i.e. the largest allowed height is 16777215. maximumSize
, and maximumWidth
.
public final void setMaximumSize(QSize arg__1)
The property is limited by the QWIDGETSIZE_MAX macro, i.e. the largest allowed size is QSize
(16777215, 16777215).
maximumWidth
, maximumHeight
, minimumSize
, and sizeIncrement
.
public final void setMaximumSize(int maxw, int maxh)
The property is limited by the QWIDGETSIZE_MAX macro, i.e. the largest allowed size is QSize
(16777215, 16777215).
maximumWidth
, maximumHeight
, minimumSize
, and sizeIncrement
.
public final void setMaximumWidth(int maxw)
maximumSize()
.width()
. It is limited by the QWIDGETSIZE_MAX macro, i.e. the largest allowed width is 16777215. maximumSize
, and maximumHeight
.
public final void setMinimumHeight(int minh)
minimumSize()
.height()
. minimumSize
, and minimumWidth
.
public final void setMinimumSize(QSize arg__1)
The minimum size set by this function will override the minimum size defined by QLayout
. In order to unset the minimum size, use QSize
(0, 0).
minimumWidth
, minimumHeight
, maximumSize
, and sizeIncrement
.
public final void setMinimumSize(int minw, int minh)
The minimum size set by this function will override the minimum size defined by QLayout
. In order to unset the minimum size, use QSize
(0, 0).
minimumWidth
, minimumHeight
, maximumSize
, and sizeIncrement
.
public final void setMinimumWidth(int minw)
minimumSize()
.width()
. minimumSize
, and minimumHeight
.
public final void setMouseTracking(boolean enable)
If mouse tracking is enabled, the widget receives mouse move events even if no buttons are pressed.
mouseMoveEvent()
.
public final void setPalette(QPalette arg__1)
Note: The palette's background color will only have an effect on the appearance of the widget if the autoFillBackground
property is set.
Warning: Do not use this function in conjunction with Qt Style Sheets. When using style sheets, the palette of a widget can be customized using the "color", "background-color", "selection-color", "selection-background-color" and "alternate-background-color".
QApplication::palette()
.
public final void setParent(QWidget parent)
If the new parent widget is in a different window, 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, setParent()
calls clearFocus()
for that widget.
If the new parent widget is in the same window as the old parent, setting the parent doesn't change the tab order or keyboard focus.
If the "new" parent widget is the old parent widget, this function does nothing.
Note: The widget becomes invisible as part of changing its parent, even if it was previously visible. You must call show()
to make the widget visible again.
Warning: It is very unlikely that you will ever need this function. If you have a widget that changes its content dynamically, it is far easier to use QStackedWidget
.
setWindowFlags()
.
public final void setParent(QWidget parent, Qt.WindowType[] f)
public final void setParent(QWidget parent, Qt.WindowFlags f)
public final void setShortcutAutoRepeat(int id)
grabShortcut()
, and releaseShortcut()
.
public final void setShortcutAutoRepeat(int id, boolean enable)
grabShortcut()
, and releaseShortcut()
.
public final void setShortcutEnabled(int id)
Warning: You should not normally need to use this function since Qt's shortcut system enables/disables shortcuts automatically as widgets become hidden/visible and gain or lose focus. It is best to use QAction
or QShortcut
to handle shortcuts, since they are easier to use than this low-level function.
grabShortcut()
, and releaseShortcut()
.
public final void setShortcutEnabled(int id, boolean enable)
Warning: You should not normally need to use this function since Qt's shortcut system enables/disables shortcuts automatically as widgets become hidden/visible and gain or lose focus. It is best to use QAction
or QShortcut
to handle shortcuts, since they are easier to use than this low-level function.
grabShortcut()
, and releaseShortcut()
.
public final void setSizeIncrement(QSize arg__1)
sizeIncrement()
.width()
pixels horizontally and sizeIncrement
.height()
pixels vertically, with baseSize()
as the basis. Preferred widget sizes are 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 only affects windows.
Warning: The size increment has no effect under Windows, and may be disregarded by the window manager on X.
size
, minimumSize
, and maximumSize
.
public final void setSizeIncrement(int w, int h)
sizeIncrement()
.width()
pixels horizontally and sizeIncrement
.height()
pixels vertically, with baseSize()
as the basis. Preferred widget sizes are 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 only affects windows.
Warning: The size increment has no effect under Windows, and may be disregarded by the window manager on X.
size
, minimumSize
, and maximumSize
.
public final void setSizePolicy(QSizePolicy arg__1)
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 policy is Preferred/Preferred, which means that the widget can be freely resized, but prefers to be the size sizeHint()
returns. Button-like widgets set the size policy to specify that they may stretch horizontally, but are fixed vertically. The same applies to lineedit controls (such as QLineEdit
, QSpinBox
or an editable QComboBox
) and other horizontally orientated widgets (such as QProgressBar
). QToolButton
's are normally square, so they allow growth in both directions. Widgets that support different directions (such as QSlider
, QScrollBar
or QHeader) specify stretching in the respective direction only. Widgets that can provide scroll bars (usually subclasses of QScrollArea
) tend to specify that they can use additional space, and that they can make do with less than sizeHint()
.
sizeHint()
, QLayout
, QSizePolicy
, and updateGeometry()
.
public final void setSizePolicy(QSizePolicy.Policy horizontal, QSizePolicy.Policy vertical)
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 policy is Preferred/Preferred, which means that the widget can be freely resized, but prefers to be the size sizeHint()
returns. Button-like widgets set the size policy to specify that they may stretch horizontally, but are fixed vertically. The same applies to lineedit controls (such as QLineEdit
, QSpinBox
or an editable QComboBox
) and other horizontally orientated widgets (such as QProgressBar
). QToolButton
's are normally square, so they allow growth in both directions. Widgets that support different directions (such as QSlider
, QScrollBar
or QHeader) specify stretching in the respective direction only. Widgets that can provide scroll bars (usually subclasses of QScrollArea
) tend to specify that they can use additional space, and that they can make do with less than sizeHint()
.
sizeHint()
, QLayout
, QSizePolicy
, and updateGeometry()
.
public final void setStatusTip(java.lang.String arg__1)
toolTip
, and whatsThis
.
public final void setStyle(QStyle arg__1)
If no style is set, the widget uses the application's style, QApplication::style()
instead.
Setting a widget's style has no effect on existing or future child widgets.
Warning: This function is particularly useful for demonstration purposes, where you want to show Qt's styling capabilities. Real applications should avoid it and use one consistent GUI style instead.
Warning: Qt style sheets are currently not supported for custom QStyle
subclasses. We plan to address this in some future release.
style()
, QStyle
, QApplication::style()
, and QApplication::setStyle()
.
public final void setStyleSheet(java.lang.String styleSheet)
Note: Qt style sheets are currently not supported for QMacStyle (the default style on Mac OS X). We plan to address this in some future release.
setStyle()
, QApplication::styleSheet
, and Qt Style Sheets.
public final void setToolTip(java.lang.String arg__1)
Qt::WA_AlwaysShowToolTips
on the window, not on the widget with the tooltip. If you want to control a tooltip's behavior, you can intercept the event()
function and catch the QEvent::ToolTip
event (e.g., if you want to customize the area for which the tooltip should be shown).
QToolTip
, statusTip
, and whatsThis
.
public final void setUpdatesEnabled(boolean enable)
update()
and repaint()
has no effect if updates are disabled. setUpdatesEnabled()
is normally used to disable updates for a short period of time, for instance to avoid screen flicker during large changes. In Qt, widgets normally do not generate screen flicker, but on X11 the server might erase regions on the screen when widgets get hidden before they can be replaced by other widgets. Disabling updates solves this.
Example:
setUpdatesEnabled(false); bigVisualChanges(); setUpdatesEnabled(true);Disabling a widget implicitly disables all its children. Enabling respectively enables all child widgets unless they have been explicitly disabled. Re-enabling updates implicitly calls
update()
on the widget. paintEvent()
.
public final void setWhatsThis(java.lang.String arg__1)
QWhatsThis
, QWidget::toolTip
, and QWidget::statusTip
.
public final void setWindowFilePath(java.lang.String filePath)
QFileInfo::fileName()
[*], on Mac OS X, as per the Apple Human Interface Guidelines. QFileInfo::fileName()
[*] — QApplication::applicationName(), on Windows and X11 when QApplication::applicationName() is set.
If the window title is set at any point, then the window title takes precedence.
Additionally, on Mac OS X, this has an added benefit that it sets the proxy icon for the window, assuming that the file path exists.
If no file path is set, this function returns an empty string.
windowTitle
, and windowIcon
.
public final void setWindowFlags(Qt.WindowType[] type)
Qt::Dialog
) and zero or more hints to the window system (e.g. Qt::FramelessWindowHint
). If the widget had type Qt::Widget
or Qt::SubWindow
and becomes a window (Qt::Window
, Qt::Dialog
, etc.), it is put at position (0, 0) on the desktop. If the widget is a window and becomes a Qt::Widget
or Qt::SubWindow
, it is put at position (0, 0) relative to its parent widget.
Note: This function calls setParent()
when changing the flags for a window, causing the widget to be hidden. You must call show()
to make the widget visible again..
windowType()
, and Window Flags Example.
public final void setWindowFlags(Qt.WindowFlags type)
Qt::Dialog
) and zero or more hints to the window system (e.g. Qt::FramelessWindowHint
). If the widget had type Qt::Widget
or Qt::SubWindow
and becomes a window (Qt::Window
, Qt::Dialog
, etc.), it is put at position (0, 0) on the desktop. If the widget is a window and becomes a Qt::Widget
or Qt::SubWindow
, it is put at position (0, 0) relative to its parent widget.
Note: This function calls setParent()
when changing the flags for a window, causing the widget to be hidden. You must call show()
to make the widget visible again..
windowType()
, and Window Flags Example.
public final void setWindowIcon(QIcon icon)
windowIcon()
returns the application icon (QApplication::windowIcon()
). windowIconText
, and windowTitle
.
public final void setWindowIconText(java.lang.String arg__1)
windowIcon
, and windowTitle
.
public final void setWindowModality(Qt.WindowModality windowModality)
hide()
the widget first, then show()
it again. By default, this property is Qt::NonModal
.
isWindow()
, QWidget::modal
, and QDialog
.
public final void setWindowModified(boolean arg__1)
The window title must contain a "[*]" placeholder, which indicates where the '*' should appear. Normally, it should appear right after the file name (e.g., "document1.txt[*] - Text Editor"). If the window isn't modified, the placeholder is simply removed.
windowTitle
, Application Example, SDI Example, and MDI Example.
public final void setWindowOpacity(double level)
By default the value of this property is 1.0.
This feature is available on Embedded Linux, Mac OS X, X11 platforms that support the Composite extension, and Windows 2000 and later.
This feature is not available on Windows CE.
Note that under X11 you need to have a composite manager running, and the X11 specific _NET_WM_WINDOW_OPACITY
atom needs to be supported by the window manager you are using.
Warning: Changing this property from opaque to transparent might issue a paint event that needs to be processed before the window is displayed correctly. This affects mainly the use of QPixmap::grabWindow()
. Also note that semi-transparent windows update and resize significantly slower than opaque windows.
setMask()
.
public final void setWindowRole(java.lang.String arg__1)
windowRole()
.
public final void setWindowState(Qt.WindowState[] state)
Qt::WindowState
: Qt::WindowMinimized
, Qt::WindowMaximized
, Qt::WindowFullScreen
, and Qt::WindowActive
. If the window is not visible (i.e. isVisible()
returns false), the window state will take effect when show()
is called. For visible windows, the change is immediate. For example, to toggle between full-screen and normal mode, use the following code:
w.setWindowState(w.windowState() ^ Qt.WindowFullScreen);In order to restore and activate a minimized window (while preserving its maximized and/or full-screen state), use the following:
w.setWindowState(w.windowState() & ~Qt.WindowMinimized | Qt.WindowActive);Calling this function will hide the widget. You must call
show()
to make the widget visible again. Note: On some window systems Qt::WindowActive
is not immediate, and may be ignored in certain cases.
When the window state changes, the widget receives a changeEvent()
of type QEvent::WindowStateChange
.
Qt::WindowState
, and windowState()
.
public final void setWindowState(Qt.WindowStates state)
Qt::WindowState
: Qt::WindowMinimized
, Qt::WindowMaximized
, Qt::WindowFullScreen
, and Qt::WindowActive
. If the window is not visible (i.e. isVisible()
returns false), the window state will take effect when show()
is called. For visible windows, the change is immediate. For example, to toggle between full-screen and normal mode, use the following code:
w.setWindowState(w.windowState() ^ Qt.WindowFullScreen);In order to restore and activate a minimized window (while preserving its maximized and/or full-screen state), use the following:
w.setWindowState(w.windowState() & ~Qt.WindowMinimized | Qt.WindowActive);Calling this function will hide the widget. You must call
show()
to make the widget visible again. Note: On some window systems Qt::WindowActive
is not immediate, and may be ignored in certain cases.
When the window state changes, the widget receives a changeEvent()
of type QEvent::WindowStateChange
.
Qt::WindowState
, and windowState()
.
public final void setWindowTitle(java.lang.String arg__1)
windowFilePath
. If neither of these is set, then the title is an empty string. If you use the windowModified
mechanism, the window title must contain a "[*]" placeholder, which indicates where the '*' should appear. Normally, it should appear right after the file name (e.g., "document1.txt[*] - Text Editor"). If the windowModified
property is false (the default), the placeholder is simply removed.
windowIcon
, windowIconText
, windowModified
, and windowFilePath
.
public final void show()
setVisible
(true). raise()
, showEvent()
, hide()
, setVisible()
, showMinimized()
, showMaximized()
, showNormal()
, and isVisible()
.
public final void showFullScreen()
Calling this function only affects windows
.
To return from full-screen mode, call showNormal()
.
Full-screen mode works fine under Windows, but has certain problems under X. These problems are due to limitations of the ICCCM protocol that specifies the communication between X11 clients and the window manager. ICCCM simply does not understand the concept of non-decorated full-screen windows. Therefore, the best we can do is to request a borderless window and place and resize it to fill the entire screen. Depending on the window manager, this may or may not work. The borderless window is requested using MOTIF hints, which are at least partially supported by virtually all modern window managers.
An alternative would be to bypass the window manager entirely and create a window with the Qt::X11BypassWindowManagerHint
flag. This has other severe problems though, like totally broken keyboard focus and very strange effects on desktop changes or when the user raises other windows.
X11 window managers that follow modern post-ICCCM specifications support full-screen mode properly.
showNormal()
, showMaximized()
, show()
, hide()
, and isVisible()
.
public final void showMaximized()
Calling this function only affects windows
.
On X11, this function may not work properly with certain window managers. See Window Geometry for an explanation.
setWindowState()
, showNormal()
, showMinimized()
, show()
, hide()
, and isVisible()
.
public final void showMinimized()
Calling this function only affects windows
.
showNormal()
, showMaximized()
, show()
, hide()
, isVisible()
, and isMinimized()
.
public final void showNormal()
Calling this function only affects windows
.
setWindowState()
, showMinimized()
, showMaximized()
, show()
, hide()
, and isVisible()
.
public final QSize size()
resizeEvent()
) immediately. If the widget is not currently visible, it is guaranteed to receive an event before it is shown. The size is adjusted if it lies outside the range defined by minimumSize()
and maximumSize()
.
Warning: Calling resize()
or setGeometry()
inside resizeEvent()
can lead to infinite recursion.
Note that setting size to QSize
(0, 0) will cause the widget to not appear on screen. This also applies to windows.
pos
, geometry
, minimumSize
, maximumSize
, and resizeEvent()
.
public final QSize sizeIncrement()
sizeIncrement()
.width()
pixels horizontally and sizeIncrement
.height()
pixels vertically, with baseSize()
as the basis. Preferred widget sizes are 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 only affects windows.
Warning: The size increment has no effect under Windows, and may be disregarded by the window manager on X.
size
, minimumSize
, and maximumSize
.
public final QSizePolicy sizePolicy()
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 policy is Preferred/Preferred, which means that the widget can be freely resized, but prefers to be the size sizeHint()
returns. Button-like widgets set the size policy to specify that they may stretch horizontally, but are fixed vertically. The same applies to lineedit controls (such as QLineEdit
, QSpinBox
or an editable QComboBox
) and other horizontally orientated widgets (such as QProgressBar
). QToolButton
's are normally square, so they allow growth in both directions. Widgets that support different directions (such as QSlider
, QScrollBar
or QHeader) specify stretching in the respective direction only. Widgets that can provide scroll bars (usually subclasses of QScrollArea
) tend to specify that they can use additional space, and that they can make do with less than sizeHint()
.
sizeHint()
, QLayout
, QSizePolicy
, and updateGeometry()
.
public final void stackUnder(QWidget arg__1)
To make this work, the widget itself and w must be siblings.
raise()
, and lower()
.
public final java.lang.String statusTip()
toolTip
, and whatsThis
.
public final QStyle style()
public final java.lang.String styleSheet()
Note: Qt style sheets are currently not supported for QMacStyle (the default style on Mac OS X). We plan to address this in some future release.
setStyle()
, QApplication::styleSheet
, and Qt Style Sheets.
public final boolean testAttribute(Qt.WidgetAttribute arg__1)
setAttribute()
.
public final java.lang.String toolTip()
Qt::WA_AlwaysShowToolTips
on the window, not on the widget with the tooltip. If you want to control a tooltip's behavior, you can intercept the event()
function and catch the QEvent::ToolTip
event (e.g., if you want to customize the area for which the tooltip should be shown).
QToolTip
, statusTip
, and whatsThis
.
public final boolean underMouse()
This value is not updated properly during drag and drop operations.
enterEvent()
, and leaveEvent()
.
public final void unsetCursor()
list of predefined cursor objects
for a range of useful shapes. An editor widget might use an I-beam cursor:
setCursor(Qt.IBeamCursor);If no cursor has been set, or after a call to
unsetCursor()
, the parent's cursor is used. QApplication::setOverrideCursor()
.
public final void unsetLayoutDirection()
QApplication::layoutDirection
.
public final void unsetLocale()
If the widget displays dates or numbers, these should be formatted using the widget's locale.
QLocale
, and QLocale::setDefault()
.
public final void update()
This function does not cause an immediate repaint; instead it schedules a paint event for processing when Qt returns to the main event loop. This permits Qt to optimize for more speed and less flicker than a call to repaint()
does.
Calling update()
several times normally results in just one paintEvent()
call.
Qt normally erases the widget's area before the paintEvent()
call. If the Qt::WA_OpaquePaintEvent
widget attribute is set, the widget is responsible for painting all its pixels with an opaque color.
repaint()
, paintEvent()
, setUpdatesEnabled()
, and Analog Clock Example.
public final void update(QRect arg__1)
public final void update(QRegion arg__1)
public final void update(int x, int y, int w, int h)
public final void updateGeometry()
Call this function if the sizeHint()
or sizePolicy()
have changed.
For explicitly hidden widgets, updateGeometry()
is a no-op. The layout system will be notified as soon as the widget is shown.
protected final void updateMicroFocus()
QInputContext
.
public final boolean updatesEnabled()
update()
and repaint()
has no effect if updates are disabled. setUpdatesEnabled()
is normally used to disable updates for a short period of time, for instance to avoid screen flicker during large changes. In Qt, widgets normally do not generate screen flicker, but on X11 the server might erase regions on the screen when widgets get hidden before they can be replaced by other widgets. Disabling updates solves this.
Example:
setUpdatesEnabled(false); bigVisualChanges(); setUpdatesEnabled(true);Disabling a widget implicitly disables all its children. Enabling respectively enables all child widgets unless they have been explicitly disabled. Re-enabling updates implicitly calls
update()
on the widget. paintEvent()
.
public final QRegion visibleRegion()
For visible widgets, this is an approximation of the area not covered by other widgets; otherwise, this is an empty region.
The repaint()
function calls this function if necessary, so in general you do not need to call it.
public final java.lang.String whatsThis()
QWhatsThis
, QWidget::toolTip
, and QWidget::statusTip
.
public final int width()
QPixmap
and QWidget
). widthMM()
.
width
in interface QPaintDeviceInterface
public final int widthMM()
width()
.
widthMM
in interface QPaintDeviceInterface
public final long winId()
Portable in principle, but if you use it you are probably about to do something non-portable. Be careful.
Note: We recommend that you do not store this value as it is likely to change during run-time.
public final QWidget window()
If the widget is a window, the widget itself is returned.
Typical usage is changing the window title:
aWidget.window().setWindowTitle("New Window Title");
isWindow()
.
public final java.lang.String windowFilePath()
QFileInfo::fileName()
[*], on Mac OS X, as per the Apple Human Interface Guidelines. QFileInfo::fileName()
[*] — QApplication::applicationName(), on Windows and X11 when QApplication::applicationName() is set.
If the window title is set at any point, then the window title takes precedence.
Additionally, on Mac OS X, this has an added benefit that it sets the proxy icon for the window, assuming that the file path exists.
If no file path is set, this function returns an empty string.
windowTitle
, and windowIcon
.
public final Qt.WindowFlags windowFlags()
Qt::Dialog
) and zero or more hints to the window system (e.g. Qt::FramelessWindowHint
). If the widget had type Qt::Widget
or Qt::SubWindow
and becomes a window (Qt::Window
, Qt::Dialog
, etc.), it is put at position (0, 0) on the desktop. If the widget is a window and becomes a Qt::Widget
or Qt::SubWindow
, it is put at position (0, 0) relative to its parent widget.
Note: This function calls setParent()
when changing the flags for a window, causing the widget to be hidden. You must call show()
to make the widget visible again..
windowType()
, and Window Flags Example.
public final QIcon windowIcon()
windowIcon()
returns the application icon (QApplication::windowIcon()
). windowIconText
, and windowTitle
.
public final java.lang.String windowIconText()
windowIcon
, and windowTitle
.
public final Qt.WindowModality windowModality()
hide()
the widget first, then show()
it again. By default, this property is Qt::NonModal
.
isWindow()
, QWidget::modal
, and QDialog
.
public final double windowOpacity()
By default the value of this property is 1.0.
This feature is available on Embedded Linux, Mac OS X, X11 platforms that support the Composite extension, and Windows 2000 and later.
This feature is not available on Windows CE.
Note that under X11 you need to have a composite manager running, and the X11 specific _NET_WM_WINDOW_OPACITY
atom needs to be supported by the window manager you are using.
Warning: Changing this property from opaque to transparent might issue a paint event that needs to be processed before the window is displayed correctly. This affects mainly the use of QPixmap::grabWindow()
. Also note that semi-transparent windows update and resize significantly slower than opaque windows.
setMask()
.
public final java.lang.String windowRole()
setWindowRole()
, windowIcon
, and windowTitle
.
public final Qt.WindowStates windowState()
Qt::WindowState
: Qt::WindowMinimized
, Qt::WindowMaximized
, Qt::WindowFullScreen
, and Qt::WindowActive
. Qt::WindowState
, and setWindowState()
.
public final java.lang.String windowTitle()
windowFilePath
. If neither of these is set, then the title is an empty string. If you use the windowModified
mechanism, the window title must contain a "[*]" placeholder, which indicates where the '*' should appear. Normally, it should appear right after the file name (e.g., "document1.txt[*] - Text Editor"). If the windowModified
property is false (the default), the placeholder is simply removed.
windowIcon
, windowIconText
, windowModified
, and windowFilePath
.
public final Qt.WindowType windowType()
windowFlags()
& Qt::WindowType_Mask
. windowFlags
.
public final int x()
frameGeometry
, y
, and pos
.
public final int y()
frameGeometry
, x
, and pos
.
protected void actionEvent(QActionEvent arg__1)
addAction()
, insertAction()
, removeAction()
, actions()
, and QActionEvent
.
protected void changeEvent(QEvent arg__1)
The state being changed in this event can be retrieved through event event.
Change events include: QEvent::ToolBarChange
, QEvent::ActivationChange
, QEvent::EnabledChange
, QEvent::FontChange
, QEvent::StyleChange
, QEvent::PaletteChange
, QEvent::WindowTitleChange
, QEvent::IconTextChange
, QEvent::ModifiedChange
, QEvent::MouseTrackingChange
, QEvent::ParentChange
, QEvent::WindowStateChange
, QEvent::LanguageChange
, QEvent::LocaleChange
, QEvent::LayoutDirectionChange
.
protected void closeEvent(QCloseEvent arg__1)
By default, the event is accepted and the widget is closed. You can reimplement this function to change the way the widget responds to window close requests. For example, you can prevent the window from closing by calling ignore()
on all events.
Main window applications typically use reimplementations of this function to check whether the user's work has been saved and ask for permission before closing. For example, the Application Example uses a helper function to determine whether or not to close the window: Missing snippet: mainwindows/application/mainwindow.cpp. Missing snippet: mainwindows/application/mainwindow.cpp.
event()
, hide()
, close()
, QCloseEvent
, and Application Example.
protected void contextMenuEvent(QContextMenuEvent arg__1)
The handler is called when the widget's contextMenuPolicy
is Qt::DefaultContextMenu
.
The default implementation ignores the context event. See the QContextMenuEvent
documentation for more details.
event()
, QContextMenuEvent
, and customContextMenuRequested()
.
protected void dragEnterEvent(QDragEnterEvent arg__1)
If the event is ignored, the widget won't receive any drag move events
.
See the Drag-and-drop documentation for an overview of how to provide drag-and-drop in your application.
QDrag
, and QDragEnterEvent
.
protected void dragLeaveEvent(QDragLeaveEvent arg__1)
See the Drag-and-drop documentation for an overview of how to provide drag-and-drop in your application.
QDrag
, and QDragLeaveEvent
.
protected void dragMoveEvent(QDragMoveEvent arg__1)
See the Drag-and-drop documentation for an overview of how to provide drag-and-drop in your application.
QDrag
, and QDragMoveEvent
.
protected void dropEvent(QDropEvent arg__1)
See the Drag-and-drop documentation for an overview of how to provide drag-and-drop in your application.
QDrag
, and QDropEvent
.
protected void enterEvent(QEvent arg__1)
An event is sent to the widget when the mouse cursor enters the widget.
leaveEvent()
, mouseMoveEvent()
, and event()
.
protected void focusInEvent(QFocusEvent arg__1)
A widget normally must setFocusPolicy()
to something other than Qt::NoFocus
in order to receive focus events. (Note that the application programmer can call setFocus()
on any widget, even those that do not normally accept focus.)
The default implementation updates the widget (except for windows that do not specify a focusPolicy()
).
focusOutEvent()
, setFocusPolicy()
, keyPressEvent()
, keyReleaseEvent()
, event()
, and QFocusEvent
.
protected boolean focusNextPrevChild(boolean next)
If next is true, this function searches forward, if next is false, it searches backward.
Sometimes, you will want to reimplement this function. For example, a web browser might reimplement it to move its "current active link" forward or backward, and call focusNextPrevChild()
only when it reaches the last or first link on the "page".
Child widgets call focusNextPrevChild()
on their parent widgets, but only the window that contains the child widgets decides where to redirect focus. By reimplementing this function for an object, you thus gain control of focus traversal for all child widgets.
focusNextChild()
, and focusPreviousChild()
.
protected void focusOutEvent(QFocusEvent arg__1)
A widget normally must setFocusPolicy()
to something other than Qt::NoFocus
in order to receive focus events. (Note that the application programmer can call setFocus()
on any widget, even those that do not normally accept focus.)
The default implementation updates the widget (except for windows that do not specify a focusPolicy()
).
focusInEvent()
, setFocusPolicy()
, keyPressEvent()
, keyReleaseEvent()
, event()
, and QFocusEvent
.
public int heightForWidth(int arg__1)
If this widget has a layout, the default implementation returns the layout's preferred height. if there is no layout, the default implementation returns -1 indicating that the preferred height does not depend on the width.
protected void hideEvent(QHideEvent arg__1)
Hide events are sent to widgets immediately after they have been hidden.
Note: A widget receives spontaneous show and hide events when its mapping status is changed by the window system, e.g. a spontaneous hide event when the user minimizes the window, and a spontaneous show event when the window is restored again. After receiving a spontaneous hide event, a widget is still considered visible in the sense of isVisible()
.
visible
, event()
, and QHideEvent
.
protected void inputMethodEvent(QInputMethodEvent arg__1)
Note that when creating custom text editing widgets, the Qt::WA_InputMethodEnabled
window attribute must be set explicitly (using the setAttribute()
function) in order to receive input method events.
The default implementation calls event->ignore()
, which rejects the Input Method event. See the QInputMethodEvent
documentation for more details.
event()
, and QInputMethodEvent
.
public java.lang.Object inputMethodQuery(Qt.InputMethodQuery arg__1)
query specifies which property is queried.
inputMethodEvent()
, QInputMethodEvent
, and QInputContext
.
protected void keyPressEvent(QKeyEvent arg__1)
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 call the base class implementation if you do not act upon the key.
The default implementation closes popup widgets if the user presses Esc. Otherwise the event is ignored, so that the widget's parent can interpret it.
Note that QKeyEvent
starts with isAccepted()
== true, so you do not need to call QKeyEvent::accept()
- just do not call the base class implementation if you act upon the key.
keyReleaseEvent()
, setFocusPolicy()
, focusInEvent()
, focusOutEvent()
, event()
, QKeyEvent
, and Tetrix Example.
protected void keyReleaseEvent(QKeyEvent arg__1)
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 call the base class implementation if you do not act upon the key.
The default implementation ignores the event, so that the widget's parent can interpret it.
Note that QKeyEvent
starts with isAccepted()
== true, so you do not need to call QKeyEvent::accept()
- just do not call the base class implementation if you act upon the key.
keyPressEvent()
, QKeyEvent::ignore()
, setFocusPolicy()
, focusInEvent()
, focusOutEvent()
, event()
, and QKeyEvent
.
protected void languageChange()
protected void leaveEvent(QEvent arg__1)
A leave event is sent to the widget when the mouse cursor leaves the widget.
enterEvent()
, mouseMoveEvent()
, and event()
.
public int metric(QPaintDevice.PaintDeviceMetric arg__1)
PaintDeviceMetric
.
metric
in interface QPaintDeviceInterface
public QSize minimumSizeHint()
The default implementation of minimumSizeHint()
returns an invalid size if there is no layout for this widget, and returns the layout's minimum size otherwise. Most built-in widgets reimplement minimumSizeHint()
.
QLayout
will never resize a widget to a size smaller than the minimum size hint unless minimumSize()
is set or the size policy is set to QSizePolicy::Ignore
. If minimumSize()
is set, the minimum size hint will be ignored.
QSize::isValid()
, resize()
, setMinimumSize()
, and sizePolicy()
.
protected void mouseDoubleClickEvent(QMouseEvent arg__1)
The default implementation generates a normal mouse press event.
Note that the widgets gets a mousePressEvent()
and a mouseReleaseEvent()
before the mouseDoubleClickEvent()
.
mousePressEvent()
, mouseReleaseEvent()
, mouseMoveEvent()
, event()
, and QMouseEvent
.
protected void mouseMoveEvent(QMouseEvent arg__1)
If mouse tracking is switched off, mouse move events only occur if a mouse button is pressed while the mouse is being moved. If mouse tracking is switched on, mouse move events occur even if no mouse button is pressed.
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's hand shakes. This is a feature of the underlying window system, not Qt.
setMouseTracking()
, mousePressEvent()
, mouseReleaseEvent()
, mouseDoubleClickEvent()
, event()
, QMouseEvent
, and Scribble Example.
protected void mousePressEvent(QMouseEvent arg__1)
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.
mouseReleaseEvent()
, mouseDoubleClickEvent()
, mouseMoveEvent()
, event()
, QMouseEvent
, and Scribble Example.
protected void mouseReleaseEvent(QMouseEvent arg__1)
mousePressEvent()
, mouseDoubleClickEvent()
, mouseMoveEvent()
, event()
, QMouseEvent
, and Scribble Example.
protected void moveEvent(QMoveEvent arg__1)
The old position is accessible through QMoveEvent::oldPos()
.
resizeEvent()
, event()
, move()
, and QMoveEvent
.
public QPaintEngine paintEngine()
paintEngine
in interface QPaintDeviceInterface
protected void paintEvent(QPaintEvent arg__1)
A paint event is a request to repaint all or part of the widget. It can happen as a result of repaint()
or update()
, or because the widget was obscured and has now been uncovered, or for many other reasons.
Many widgets can simply repaint their entire surface when asked to, but some slow widgets need to optimize by painting only the requested region: QPaintEvent::region()
. This speed optimization does not change the result, as painting is clipped to that region during event processing. QListView
and QTableView
do this, for example.
Qt also tries to speed up painting by merging multiple paint events into one. When update()
is called several times or the window system sends several paint events, Qt merges these events into one event with a larger region (see QRegion::united()
). repaint()
does not permit this optimization, so we suggest using update()
whenever possible.
When the paint event occurs, the update region has normally been erased, so that you're painting on the widget's background.
The background can be set using setBackgroundRole()
and setPalette()
.
From Qt 4.0, QWidget
automatically double-buffers its painting, so there's no need to write double-buffering code in paintEvent()
to avoid flicker.
Note: Under X11 it is possible to toggle the global double buffering by calling qt_x11_set_global_double_buffer(). Example usage:
... extern void qt_x11_set_global_double_buffer(bool); qt_x11_set_global_double_buffer(false); ...Note: In general, one should refrain from calling
update()
or repaint()
inside of paintEvent()
. For example, calling update()
or repaint()
on children inside a paintEvent()
results in undefined behavior; the child may or may not get a paint event. event()
, repaint()
, update()
, QPainter
, QPixmap
, QPaintEvent
, and Analog Clock Example.
protected void resizeEvent(QResizeEvent arg__1)
resizeEvent()
is called, the widget already has its new geometry. The old size is accessible through QResizeEvent::oldSize()
. The widget will be erased and receive a paint event immediately after processing the resize event. No drawing need be (or should be) done inside this handler.
moveEvent()
, event()
, resize()
, QResizeEvent
, paintEvent()
, and Scribble Example.
public void setVisible(boolean visible)
setVisible
(true) or show()
sets the widget to visible status if all its parent widgets up to the window are visible. If an ancestor is not visible, the widget won't become visible until all its ancestors are shown. If its size or position has changed, Qt guarantees that a widget gets move and resize events just before it is shown. If the widget has not been resized yet, Qt will adjust the widget's size to a useful default using adjustSize()
. Calling setVisible
(false) or hide()
hides a widget explicitly. An explicitly hidden widget will never become visible, even if all its ancestors become visible, unless you show it.
A widget receives show and hide events when its visibility status changes. Between a hide and a show event, there is no need to waste CPU cycles preparing or displaying information to the user. A video application, for example, might simply stop generating new frames.
A widget that happens to be obscured by other windows on the screen is considered to be visible. The same applies to iconified windows and windows that exist on another virtual desktop (on platforms that support this concept). A widget receives spontaneous show and hide events when its mapping status is changed by the window system, e.g. a spontaneous hide event when the user minimizes the window, and a spontaneous show event when the window is restored again.
You almost never have to reimplement the setVisible()
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 the Polish event delivered to the event()
function.
show()
, hide()
, isHidden()
, isVisibleTo()
, isMinimized()
, showEvent()
, and hideEvent()
.
protected void showEvent(QShowEvent arg__1)
Non-spontaneous show events are sent to widgets immediately before they are shown. The spontaneous show events of windows are delivered afterwards.
Note: A widget receives spontaneous show and hide events when its mapping status is changed by the window system, e.g. a spontaneous hide event when the user minimizes the window, and a spontaneous show event when the window is restored again. After receiving a spontaneous hide event, a widget is still considered visible in the sense of isVisible()
.
visible
, event()
, and QShowEvent
.
public QSize sizeHint()
The default implementation of sizeHint()
returns an invalid size if there is no layout for this widget, and returns the layout's preferred size otherwise.
QSize::isValid()
, minimumSizeHint()
, sizePolicy()
, setMinimumSize()
, and updateGeometry()
.
protected void tabletEvent(QTabletEvent arg__1)
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.
QTabletEvent::ignore()
, QTabletEvent::accept()
, event()
, and QTabletEvent
.
protected void wheelEvent(QWheelEvent arg__1)
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.
QWheelEvent::ignore()
, QWheelEvent::accept()
, event()
, and QWheelEvent
.
public static QWidget keyboardGrabber()
If no widget in this application is currently grabbing the keyboard, 0 is returned.
grabMouse()
, and mouseGrabber()
.
public static QWidget mouseGrabber()
If no widget in this application is currently grabbing the mouse, 0 is returned.
grabMouse()
, and keyboardGrabber()
.
public static void setTabOrder(QWidget arg__1, QWidget arg__2)
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 dnot like this:
// WRONG 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 dIf first or second has a focus proxy,
setTabOrder()
correctly substitutes the proxy. setFocusPolicy()
, setFocusProxy()
, and Keyboard Focus.
public static QWidget fromNativePointer(QNativePointer nativePointer)
public final QContentsMargins getContentsMargins()
public final void setContentsMargins(QContentsMargins margins)
Changing the margins will trigger a resizeEvent().
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