QDesignerPropertyEditorInterface Class

Detailed Description

QDesignerPropertyEditorInterface contains a collection of functions that is typically used to query the property editor for its current state, and several slots manipulating it's state. The interface also provide a signal, propertyChanged(), which is emitted whenever a property changes in the property editor. The signal's arguments are the property that changed and its new value.

For example, when implementing a custom widget plugin, you can connect the signal to a custom slot:

        QDesignerPropertyEditorInterface *propertyEditor = nullptr;
        propertyEditor = formEditor->propertyEditor();

        connect(propertyEditor, SIGNAL(propertyChanged(QString,QVariant)),
                this, SLOT(checkProperty(QString,QVariant)));

Then the custom slot can check if the new value is within the range we want when a specified property, belonging to a particular widget, changes:

        void checkProperty(QString property, QVariant value) {
            QDesignerPropertyEditorInterface *propertyEditor = nullptr;
            propertyEditor = formEditor->propertyEditor();

            QObject *object = propertyeditor->object();
            MyCustomWidget *widget = qobject_cast<MyCustomWidget>(object);

            if (widget && property == aProperty && value != expectedValue)
                {...}
        }

The QDesignerPropertyEditorInterface class is not intended to be instantiated directly. You can retrieve an interface to Qt Designer's property editor using the QDesignerFormEditorInterface::propertyEditor() function. A pointer to Qt Designer's current QDesignerFormEditorInterface object (formEditor in the examples above) is provided by the QDesignerCustomWidgetInterface::initialize() function's parameter. When implementing a custom widget plugin, you must subclass the QDesignerCustomWidgetInterface to expose your plugin to Qt Designer.

The functions accessing the property editor are the core() function that you can use to retrieve an interface to the form editor, the currentPropertyName() function that returns the name of the currently selected property in the property editor, the object() function that returns the currently selected object in Qt Designer's workspace, and the isReadOnly() function that returns true if the property editor is write proteced (otherwise false).

The slots manipulating the property editor's state are the setObject() slot that you can use to change the currently selected object in Qt Designer's workspace, the setPropertyValue() slot that changes the value of a given property and the setReadOnly() slot that control the write protection of the property editor.