QGraphicsProxyWidget¶

The QGraphicsProxyWidget class provides a proxy layer for embedding a QWidget in a QGraphicsScene . More…

Synopsis¶

Functions¶

def createProxyForChildWidget (child)
def setWidget (widget)
def subWidgetRect (widget)
def widget ()

Slots¶

def newProxyWidget (arg__1)

Detailed Description¶

QGraphicsProxyWidget embeds QWidget -based widgets, for example, a QPushButton , QFontComboBox , or even QFileDialog , into QGraphicsScene . It forwards events between the two objects and translates between QWidget ‘s integer-based geometry and QGraphicsWidget ‘s qreal-based geometry. QGraphicsProxyWidget supports all core features of QWidget , including tab focus, keyboard input, Drag & Drop, and popups. You can also embed complex widgets, e.g., widgets with subwidgets.

Example:

if __name__ == "__main__":

    app = QApplication([])
    tabWidget = QTabWidget()
    scene = QGraphicsScene()
    proxy = scene.addWidget(tabWidget)
    view = QGraphicsView(scene)
    view.show()
    sys.exit(app.exec())

QGraphicsProxyWidget takes care of automatically embedding popup children of embedded widgets through creating a child proxy for each popup. This means that when an embedded QComboBox shows its popup list, a new QGraphicsProxyWidget is created automatically, embedding the popup, and positioning it correctly. This only works if the popup is child of the embedded widget (for example setMenu() requires the QMenu instance to be child of the QToolButton ).

Embedding a Widget with QGraphicsProxyWidget¶

There are two ways to embed a widget using QGraphicsProxyWidget . The most common way is to pass a widget pointer to addWidget() together with any relevant WindowFlags . This function returns a pointer to a QGraphicsProxyWidget . You can then choose to reparent or position either the proxy, or the embedded widget itself.

For example, in the code snippet below, we embed a group box into the proxy:

groupBox = QGroupBox("Contact Details")
numberLabel = QLabel("Telephone number")
numberEdit = QLineEdit()
layout = QFormLayout()
layout.addRow(numberLabel, numberEdit)
groupBox.setLayout(layout)
scene = QGraphicsScene()
proxy = scene.addWidget(groupBox)
view = QGraphicsView(scene)
view.show()

The image below is the output obtained with its contents margin and contents rect labeled.

Alternatively, you can start by creating a new QGraphicsProxyWidget item, and then call setWidget() to embed a QWidget later. The widget() function returns a pointer to the embedded widget. QGraphicsProxyWidget shares ownership with QWidget , so if either of the two widgets are destroyed, the other widget will be automatically destroyed as well.

Synchronizing Widget States¶

QGraphicsProxyWidget keeps its state in sync with the embedded widget. For example, if the proxy is hidden or disabled, the embedded widget will be hidden or disabled as well, and vice versa. When the widget is embedded by calling addWidget(), QGraphicsProxyWidget copies the state from the widget into the proxy, and after that, the two will stay synchronized where possible. By default, when you embed a widget into a proxy, both the widget and the proxy will be visible because a QGraphicsWidget is visible when created (you do not have to call show() ). If you explicitly hide the embedded widget, the proxy will also become invisible.

Example:

scene = QGraphicsScene()
edit = QLineEdit()
proxy = scene.addWidget(edit)
edit.isVisible() # returns true
proxy.isVisible() # also returns true
edit.hide()
edit.isVisible() # returns false
proxy.isVisible() # also returns false

QGraphicsProxyWidget maintains symmetry for the following states:

QWidget state

QGraphicsProxyWidget state

Notes

enabled

QGraphicsProxyWidget::enabled

visible

QGraphicsProxyWidget::visible

The explicit state is also symmetric.

geometry

QGraphicsProxyWidget::geometry

Geometry is only guaranteed to be symmetric while the embedded widget is visible.

layoutDirection

QGraphicsProxyWidget::layoutDirection

style

QGraphicsProxyWidget::style

palette

QGraphicsProxyWidget::palette

font

QGraphicsProxyWidget::font

cursor

QGraphicsProxyWidget::cursor

The embedded widget overrides the proxy widget cursor. The proxy cursor changes depending on which embedded subwidget is currently under the mouse.

sizeHint()

sizeHint()

All size hint functionality from the embedded widget is forwarded by the proxy.

QWidget::getContentsMargins()

getContentsMargins()

Updated once by setWidget() .

windowTitle

QGraphicsProxyWidget::windowTitle

Updated once by setWidget() .

Note

QGraphicsScene keeps the embedded widget in a special state that prevents it from disturbing other widgets (both embedded and not embedded) while the widget is embedded. In this state, the widget may differ slightly in behavior from when it is not embedded.

Warning

This class is provided for convenience when bridging QWidgets and QGraphicsItems, it should not be used for high-performance scenarios. In particular, embedding widgets into a scene that is then displayed through a QGraphicsView that uses an OpenGL viewport will not work for all combinations.

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