QGraphicsProxyWidget

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

Inheritance diagram of PySide2.QtWidgets.QGraphicsProxyWidget

Synopsis

Functions

Slots

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:

import sys

QApplication app(sys.argv)

tabWidget = QTabWidget()

scene = QGraphicsScene()
proxy = scene.addWidget(tabWidget)

view = QGraphicsView(scene)
view.show()

return 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.

../../_images/qgraphicsproxywidget-embed.png

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

enabled

visible

visible

The explicit state is also symmetric.

geometry

geometry

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

layoutDirection

layoutDirection

style

style

palette

palette

font

font

cursor

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.

getContentsMargins()

getContentsMargins()

Updated once by setWidget() .

windowTitle

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.

class QGraphicsProxyWidget([parent=None[, wFlags=Qt.WindowFlags()]])
param parent

QGraphicsItem

param wFlags

WindowFlags

Constructs a new QGraphicsProxy widget. parent and wFlags are passed to QGraphicsItem ‘s constructor.

PySide2.QtWidgets.QGraphicsProxyWidget.createProxyForChildWidget(child)
Parameters

childQWidget

Return type

QGraphicsProxyWidget

Creates a proxy widget for the given child of the widget contained in this proxy.

This function makes it possible to acquire proxies for non top-level widgets. For instance, you can embed a dialog, and then transform only one of its widgets.

If the widget is already embedded, return the existing proxy widget.

PySide2.QtWidgets.QGraphicsProxyWidget.newProxyWidget(arg__1)
Parameters

arg__1QWidget

Return type

QGraphicsProxyWidget

Creates a proxy widget for the given child of the widget contained in this proxy.

You should not call this function directly; use createProxyForChildWidget() instead.

This function is a fake virtual slot that you can reimplement in your subclass in order to control how new proxy widgets are created. The default implementation returns a proxy created with the QGraphicsProxyWidget() constructor with this proxy widget as the parent.

PySide2.QtWidgets.QGraphicsProxyWidget.setWidget(widget)
Parameters

widgetQWidget

Embeds widget into this proxy widget. The embedded widget must reside exclusively either inside or outside of Graphics View. You cannot embed a widget as long as it is is visible elsewhere in the UI, at the same time.

widget must be a top-level widget whose parent is None .

When the widget is embedded, its state (e.g., visible, enabled, geometry, size hints) is copied into the proxy widget. If the embedded widget is explicitly hidden or disabled, the proxy widget will become explicitly hidden or disabled after embedding is complete. The class documentation has a full overview over the shared state.

QGraphicsProxyWidget ‘s window flags determine whether the widget, after embedding, will be given window decorations or not.

After this function returns, QGraphicsProxyWidget will keep its state synchronized with that of widget whenever possible.

If a widget is already embedded by this proxy when this function is called, that widget will first be automatically unembedded. Passing 0 for the widget argument will only unembed the widget, and the ownership of the currently embedded widget will be passed on to the caller. Every child widget that are embedded will also be embedded and their proxy widget destroyed.

Note that widgets with the WA_PaintOnScreen widget attribute set and widgets that wrap an external application or controller cannot be embedded. Examples are QGLWidget and QAxWidget.

See also

widget()

PySide2.QtWidgets.QGraphicsProxyWidget.subWidgetRect(widget)
Parameters

widgetQWidget

Return type

QRectF

Returns the rectangle for widget , which must be a descendant of widget() , or widget() itself, in this proxy item’s local coordinates.

If no widget is embedded, widget is None , or widget is not a descendant of the embedded widget, this function returns an empty QRectF .

See also

widget()

PySide2.QtWidgets.QGraphicsProxyWidget.widget()
Return type

QWidget

Returns a pointer to the embedded widget.

See also

setWidget()