| Home · All Classes · Modules |
The QGraphicsWidget class is the base class for all widget items in a QGraphicsScene. More...
Inherits QGraphicsObject and QGraphicsLayoutItem.
Inherited by QGraphicsProxyWidget and QGraphicsWebView.
The QGraphicsWidget class is the base class for all widget items in a QGraphicsScene.
QGraphicsWidget is an extended base item that provides extra functionality over QGraphicsItem. It is similar to QWidget in many ways:
Unlike QGraphicsItem, QGraphicsWidget is not an abstract class; you can create instances of a QGraphicsWidget without having to subclass it. This approach is useful for widgets that only serve the purpose of organizing child widgets into a layout.
QGraphicsWidget can be used as a base item for your own custom item if you require advanced input focus handling, e.g., tab focus and activation, or layouts.
Since QGraphicsWidget resembles QWidget and has similar API, it is easier to port a widget from QWidget to QGraphicsWidget, instead of QGraphicsItem.
Note: QWidget-based widgets can be directly embedded into a QGraphicsScene using QGraphicsProxyWidget.
Noticeable differences between QGraphicsWidget and QWidget are:
| QGraphicsWidget | QWidget |
|---|---|
| Coordinates and geometry are defined with qreals (doubles or floats, depending on the platform). | QWidget uses integer geometry (QPoint, QRect). |
| The widget is already visible by default; you do not have to call show() to display the widget. | QWidget is hidden by default until you call show(). |
| A subset of widget attributes are supported. | All widget attributes are supported. |
| A top-level item's style defaults to QGraphicsScene.style | A top-level widget's style defaults to QApplication.style |
| Graphics View provides a custom drag and drop framework, different from QWidget. | Standard drag and drop framework. |
| Widget items do not support modality. | Full modality support. |
QGraphicsWidget supports a subset of Qt's widget attributes, (Qt.WidgetAttribute), as shown in the table below. Any attributes not listed in this table are unsupported, or otherwise unused.
| Widget Attribute | Usage |
|---|---|
| Qt.WA_SetLayoutDirection | Set by setLayoutDirection(), cleared by unsetLayoutDirection(). You can test this attribute to check if the widget has been explicitly assigned a layoutDirection. If the attribute is not set, the layoutDirection() is inherited. |
| Qt.WA_RightToLeft | Toggled by setLayoutDirection(). Inherited from the parent/scene. If set, the widget's layout will order horizontally arranged widgets from right to left. |
| Qt.WA_SetStyle | Set and cleared by setStyle(). If this attribute is set, the widget has been explicitly assigned a style. If it is unset, the widget will use the scene's or the application's style. |
| Qt.WA_Resized | Set by setGeometry() and resize(). |
| Qt.WA_SetPalette | Set by setPalette(). |
| Qt.WA_SetFont | Set by setFont(). |
| Qt.WA_WindowPropagation | Enables propagation to window widgets. |
Although QGraphicsWidget inherits from both QObject and QGraphicsItem, you should use the functions provided by QGraphicsItem, not QObject, to manage the relationships between parent and child items. These functions control the stacking order of items as well as their ownership.
Note: The QObject.parent() should always return 0 for QGraphicsWidgets, but this policy is not strictly defined.
The parent argument, if not None, causes self to be owned by Qt instead of PyQt.
Constructs a QGraphicsWidget instance. The optional parent argument is passed to QGraphicsItem's constructor. The optional wFlags argument specifies the widget's window flags (e.g., whether the widget should be a window, a tool, a popup, etc).
Returns the (possibly empty) list of this widget's actions.
This function was introduced in Qt 4.5.
See also insertAction(), removeAction(), QWidget.actions(), QAction.associatedWidgets(), and QAction.associatedGraphicsWidgets().
Appends the action action to this widget's list of actions.
All QGraphicsWidgets have a list of QActions, 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 QGraphicsWidget should only have one of each action and adding an action it already has will not cause the same action to be in the widget twice.
This function was introduced in Qt 4.5.
See also removeAction(), insertAction(), actions(), and QWidget.addAction().
Appends the actions actions to this widget's list of actions.
This function was introduced in Qt 4.5.
See also removeAction(), QMenu, addAction(), and QWidget.addActions().
Adjusts the size of the widget to its effective preferred size hint.
This function is called implicitly when the item is shown for the first time.
See also effectiveSizeHint() and Qt.MinimumSize.
Reimplemented from QGraphicsItem.boundingRect().
This event handler can be reimplemented to handle state changes.
The state being changed in this event can be retrieved through event.
Change events include: QEvent.ActivationChange, QEvent.EnabledChange, QEvent.FontChange, QEvent.StyleChange, QEvent.PaletteChange, QEvent.ParentChange, QEvent.LayoutDirectionChange, and QEvent.ContentsRectChange.
This method is also a Qt slot with the C++ signature bool close().
Call this function to close the widget.
Returns true if the widget was closed; otherwise returns false. This slot will first send a QCloseEvent to the widget, which may or may not accept the event. If the event was ignored, nothing happens. If the event was accepted, it will hide() the widget.
If the widget has the Qt.WA_DeleteOnClose attribute set it will be deleted.
This event handler, for event, can be reimplemented in a subclass to receive widget close events. The default implementation accepts the event.
See also close() and QCloseEvent.
Reimplemented from QObject.event().
Handles the event. QGraphicsWidget handles the following events:
| Polish | Delivered to the widget some time after it has been shown. |
| GraphicsSceneMove | Delivered to the widget after its local position has changed. |
| GraphicsSceneResize | Delivered to the widget after its size has changed. |
| Show | Delivered to the widget before it has been shown. |
| Hide | Delivered to the widget after it has been hidden. |
| PaletteChange | Delivered to the widget after its palette has changed. |
| FontChange | Delivered to the widget after its font has changed. |
| EnabledChange | Delivered to the widget after its enabled state has changed. |
| StyleChange | Delivered to the widget after its style has changed. |
| LayoutDirectionChange | Delivered to the widget after its layout direction has changed. |
| ContentsRectChange | Delivered to the widget after its contents margins/ contents rect has changed. |
Reimplemented from QGraphicsItem.focusInEvent().
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; returns false otherwise. If next is true, this function searches forward; if next is false, it searches backward.
Sometimes, you will want to reimplement this function to provide special focus handling for your widget and its subwidgets. For example, a web browser might reimplement it to move its current active link forward or backward, and call the base implementation 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 gain control of focus traversal for all child widgets.
See also focusPolicy().
Reimplemented from QGraphicsItem.focusOutEvent().
If this widget, a child or descendant of this widget currently has input focus, this function will return a pointer to that widget. If no descendant widget has input focus, 0 is returned.
See also QGraphicsItem.focusItem() and QWidget.focusWidget().
Reimplemented from QGraphicsLayoutItem.getContentsMargins().
Gets the widget's contents margins. The margins are stored in left, top, right and bottom, as pointers to qreals. Each argument can be omitted by passing 0.
See also setContentsMargins().
Gets the widget's window frame margins. The margins are stored in left, top, right and bottom as pointers to qreals. Each argument can be omitted by passing 0.
See also setWindowFrameMargins() and windowFrameRect().
This event handler, for event, can be reimplemented in a subclass to receive notifications for QEvent.GrabKeyboard events.
See also grabKeyboard() and grabMouse().
This event handler, for event, can be reimplemented in a subclass to receive notifications for QEvent.GrabMouse events.
See also grabMouse() and grabKeyboard().
Adds a shortcut to Qt's shortcut system that watches for the given key sequence in the given context. If the context is 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. For widgets that are not part of a window (i.e., top-level widgets and their children), Qt.WindowShortcut shortcuts apply to the scene.
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 QActions with the shortcut key sequences you require (if you also want equivalent menu options and toolbar buttons), or create QShortcuts 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.
This function was introduced in Qt 4.5.
See also releaseShortcut(), setShortcutEnabled(), and QWidget.grabShortcut().
This event handler, for Hide events, is delivered after the widget has been hidden, for example, setVisible(false) has been called for the widget or one of its ancestors when the widget was previously shown.
You can reimplement this event handler to detect when your widget is hidden. Calling QEvent.accept() or QEvent.ignore() on event has no effect.
See also showEvent(), QWidget.hideEvent(), and ItemVisibleChange.
Reimplemented from QGraphicsItem.hoverLeaveEvent().
Reimplemented from QGraphicsItem.hoverMoveEvent().
Populates a style option object for this widget based on its current state, and stores the output in option. The default implementation populates option with the following properties.
| Style Option Property | Value |
|---|---|
| state & QStyle.State_Enabled | Corresponds to QGraphicsItem.isEnabled(). |
| state & QStyle.State_HasFocus | Corresponds to QGraphicsItem.hasFocus(). |
| state & QStyle.State_MouseOver | Corresponds to QGraphicsItem.isUnderMouse(). |
| direction | Corresponds to QGraphicsWidget.layoutDirection(). |
| rect | Corresponds to QGraphicsWidget.rect().toRect(). |
| palette | Corresponds to QGraphicsWidget.palette(). |
| fontMetrics | Corresponds to QFontMetrics(QGraphicsWidget.font()). |
Subclasses of QGraphicsWidget should call the base implementation, and then test the type of option using qstyleoption_cast<>() or test QStyleOption.Type before storing widget-specific options.
For example:
void MyGroupBoxWidget.initStyleOption(QStyleOption *option) const { QGraphicsWidget.initStyleOption(option); if (QStyleOptionGroupBox *box = qstyleoption_cast<QStyleOptionGroupBox *>(option)) { // Add group box specific state. box->flat = isFlat(); ... } }
See also QStyleOption.initFrom().
Inserts the action action to this widget's list of actions, before the action before. It appends the action if before is 0 or before is not a valid action for this widget.
A QGraphicsWidget should only have one of each action.
This function was introduced in Qt 4.5.
See also removeAction(), addAction(), QMenu, actions(), and QWidget.insertActions().
Inserts the actions actions to this widget's list of actions, before the action before. It appends the action if before is 0 or before is not a valid action for this widget.
A QGraphicsWidget can have at most one of each action.
This function was introduced in Qt 4.5.
See also removeAction(), QMenu, insertAction(), and QWidget.insertActions().
Returns true if this widget's window is in the active window, or if the widget does not have a window but is in an active scene (i.e., a scene that currently has focus).
The active window is the window that either contains a child widget that currently has input focus, or that itself has input focus.
See also QGraphicsScene.activeWindow(), QGraphicsScene.setActiveWindow(), and isActive().
Reimplemented from QGraphicsItem.itemChange().
QGraphicsWidget uses the base implementation of this function to catch and deliver events related to state changes in the item. Because of this, it is very important that subclasses call the base implementation.
change specifies the type of change, and value is the new value.
For example, QGraphicsWidget uses ItemVisibleChange to deliver Show and Hide events, ItemPositionHasChanged to deliver Move events, and ItemParentChange both to deliver ParentChange events, and for managing the focus chain.
QGraphicsWidget enables the ItemSendsGeometryChanges flag by default in order to track position changes.
See also QGraphicsItem.itemChange().
This event handler, for GraphicsSceneMove events, is delivered after the widget has moved (e.g., its local position has changed).
This event is only delivered when the item is moved locally. Calling setTransform() or moving any of the item's ancestors does not affect the item's local position.
You can reimplement this event handler to detect when your widget has moved. Calling QEvent.accept() or QEvent.ignore() on event has no effect.
See also ItemPositionChange and ItemPositionHasChanged.
Reimplemented from QGraphicsItem.paint().
This virtual function is called by QGraphicsScene to draw the window frame for windows using painter, option, and widget, in local coordinates. The base implementation uses the current style to render the frame and title bar.
You can reimplement this function in a subclass of QGraphicsWidget to provide custom rendering of the widget's window frame.
See also QGraphicsItem.paint().
This event is delivered to the item by the scene at some point after it has been constructed, but before it is shown or otherwise accessed through the scene. You can use this event handler to do last-minute initializations of the widget which require the item to be fully constructed.
The base implementation does nothing.
Returns the item's local rect as a QRectF. This function is equivalent to QRectF(QPointF(), size()).
See also setGeometry() and resize().
Removes the shortcut with the given id from Qt's shortcut system. The widget will no longer receive 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.
This function was introduced in Qt 4.5.
See also grabShortcut(), setShortcutEnabled(), and QWidget.releaseShortcut().
Removes the action action from this widget's list of actions.
This function was introduced in Qt 4.5.
See also insertAction(), actions(), insertAction(), and QWidget.removeAction().
This event handler, for GraphicsSceneResize events, is delivered after the widget has been resized (i.e., its local size has changed). event contains both the old and the new size.
This event is only delivered when the widget is resized locally; calling setTransform() on the widget or any of its ancestors or view, does not affect the widget's local size.
You can reimplement this event handler to detect when your widget has been resized. Calling QEvent.accept() or QEvent.ignore() on event has no effect.
See also geometry() and setGeometry().
Reimplemented from QGraphicsItem.sceneEvent().
QGraphicsWidget's implementation of sceneEvent() simply passes event to QGraphicsWidget.event(). You can handle all events for your widget in event() or in any of the convenience functions; you should not have to reimplement this function in a subclass of QGraphicsWidget.
See also QGraphicsItem.sceneEvent().
If on is true, this function enables attribute; otherwise attribute is disabled.
See the class documentation for QGraphicsWidget for a complete list of which attributes are supported, and what they are for.
See also testAttribute() and QWidget.setAttribute().
Sets the widget's contents margins to left, top, right and bottom.
Contents margins are used by the assigned layout to define the placement of subwidgets and layouts. Margins are particularly useful for widgets that constrain subwidgets to only a section of its own geometry. For example, a group box with a layout will place subwidgets inside its frame, but below the title.
Changing a widget's contents margins will always trigger an update(), and any assigned layout will be activated automatically. The widget will then receive a ContentsRectChange event.
See also getContentsMargins() and setGeometry().
The layout argument has it's ownership transferred to Qt.
If enabled is true, auto repeat of the shortcut with the given id is enabled; otherwise it is disabled.
This function was introduced in Qt 4.5.
See also grabShortcut(), releaseShortcut(), and QWidget.setShortcutAutoRepeat().
If enabled is true, the shortcut with the given id is enabled; otherwise the shortcut is disabled.
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.
This function was introduced in Qt 4.5.
See also grabShortcut(), releaseShortcut(), and QWidget.setShortcutEnabled().
Sets the widget's style to style. QGraphicsWidget does not take ownership of style.
If no style is assigned, or style is 0, the widget will use QGraphicsScene.style() (if this has been set). Otherwise the widget will use QApplication.style().
This function sets the Qt.WA_SetStyle attribute if style is not 0; otherwise it clears the attribute.
See also style().
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.
Note that since the tab order of the second widget is changed, you should order a chain like this:
setTabOrder(a, b); // a to b setTabOrder(b, c); // a to b to c setTabOrder(c, d); // a to b to c to d
not like this:
// 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 d
If first is 0, this indicates that second should be the first widget to receive input focus should the scene gain Tab focus (i.e., the user hits Tab so that focus passes into the scene). If second is 0, this indicates that first should be the first widget to gain focus if the scene gained BackTab focus.
By default, tab order is defined implicitly using widget creation order.
See also focusPolicy and Keyboard Focus.
Sets the widget's window frame margins to left, top, right and bottom. The default frame margins are provided by the style, and they depend on the current window flags.
If you would like to draw your own window decoration, you can set your own frame margins to override the default margins.
See also unsetWindowFrameMargins(), getWindowFrameMargins(), and windowFrameRect().
Reimplemented from QGraphicsItem.shape().
This event handler, for Show events, is delivered before the widget has been shown, for example, setVisible(true) has been called for the widget or one of its ancestors when the widget was previously hidden.
You can reimplement this event handler to detect when your widget is shown. Calling QEvent.accept() or QEvent.ignore() on event has no effect.
See also hideEvent(), QWidget.showEvent(), and ItemVisibleChange.
Reimplemented from QGraphicsLayoutItem.sizeHint().
Returns a pointer to the widget's style. If this widget does not have any explicitly assigned style, the scene's style is returned instead. In turn, if the scene does not have any assigned style, this function returns QApplication.style().
See also setStyle().
Returns true if attribute is enabled for this widget; otherwise, returns false.
See also setAttribute().
Reimplemented from QGraphicsItem.type().
This event handler, for event, can be reimplemented in a subclass to receive notifications for QEvent.UngrabKeyboard events.
See also ungrabKeyboard() and ungrabMouse().
This event handler, for event, can be reimplemented in a subclass to receive notifications for QEvent.UngrabMouse events.
See also ungrabMouse() and ungrabKeyboard().
Resets the window frame margins to the default value, provided by the style.
See also setWindowFrameMargins(), getWindowFrameMargins(), and windowFrameRect().
Reimplemented from QGraphicsLayoutItem.updateGeometry().
If this widget is currently managed by a layout, this function notifies the layout that the widget's size hints have changed and the layout may need to resize and reposition the widget accordingly.
Call this function if the widget's sizeHint() has changed.
See also QGraphicsLayout.invalidate().
This event handler, for event, receives events for the window frame if this widget is a window. Its base implementation provides support for default window frame interaction such as moving, resizing, etc.
You can reimplement this handler in a subclass of QGraphicsWidget to provide your own custom window frame interaction support.
Returns true if event has been recognized and processed; otherwise, returns false.
See also event().
Returns the widget's geometry in parent coordinates including any window frame.
See also windowFrameRect(), getWindowFrameMargins(), and setWindowFrameMargins().
Returns the widget's local rect including any window frame.
See also windowFrameGeometry(), getWindowFrameMargins(), and setWindowFrameMargins().
Returns the window frame section at position pos, or Qt.NoSection if there is no window frame section at this position.
This function is used in QGraphicsWidget's base implementation for window frame interaction.
You can reimplement this function if you want to customize how a window can be interactively moved or resized. For instance, if you only want to allow a window to be resized by the bottom right corner, you can reimplement this function to return Qt.NoSection for all sections except Qt.BottomRightSection.
This function was introduced in Qt 4.4.
See also windowFrameEvent(), paintWindowFrame(), and windowFrameGeometry().
Returns the widgets window type.
See also windowFlags(), isWindow(), and isPanel().
This is the default overload of this signal.
This signal gets emitted whenever the geometry is changed in setGeometry().
| PyQt 4.10.1 for MacOS | Copyright © Riverbank Computing Ltd and Nokia 2012 | Qt 4.8.4 |