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QGraphicsProxyWidget ClassThe QGraphicsProxyWidget class provides a proxy layer for embedding a QWidget in a QGraphicsScene. More... #include <QGraphicsProxyWidget>Inherits: QGraphicsWidget. Inherited by: This class was introduced in Qt 4.4. Public Types
Public Functions
Reimplemented Public Functions
Static Public Members
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Reimplemented Protected Functions
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Additional Inherited Members
Detailed DescriptionThe QGraphicsProxyWidget class provides a proxy layer for embedding a QWidget in a QGraphicsScene. 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: int main(int argc, char **argv) { QApplication app(argc, argv); QTabWidget *tabWidget = new QTabWidget; QGraphicsScene scene; QGraphicsProxyWidget *proxy = scene.addWidget(tabWidget); QGraphicsView view(&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 QToolButton::setMenu() requires the QMenu instance to be child of the QToolButton). Embedding a Widget with QGraphicsProxyWidgetThere are two ways to embed a widget using QGraphicsProxyWidget. The most common way is to pass a widget pointer to QGraphicsScene::addWidget() together with any relevant Qt::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: QGroupBox *groupBox = new QGroupBox("Contact Details"); QLabel *numberLabel = new QLabel("Telephone number"); QLineEdit *numberEdit = new QLineEdit; QFormLayout *layout = new QFormLayout; layout->addRow(numberLabel, numberEdit); groupBox->setLayout(layout); QGraphicsScene scene; QGraphicsProxyWidget *proxy = scene.addWidget(groupBox); QGraphicsView view(&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 StatesQGraphicsProxyWidget 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: QGraphicsScene scene; QLineEdit *edit = new QLineEdit; QGraphicsProxyWidget *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:
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. See also QGraphicsScene::addWidget() and QGraphicsWidget. Member Function Documentation
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