Add native interface for X11 application, exposing display and connection

The major use-case of the now private QX11Info from Qt X11 Extras was
getting hold of the Xlib display and XCB connection, for example in KDE:

  https://lxr.kde.org/search?%21v=kf5-qt5&_filestring=&_string=QX11Info

A new native interface for QGuiApplication has now been added that
exposes these two properties, e.g.:

  if (auto *x11App = app.nativeInterface<QX11Application>())
      qDebug() << x11App->display() << x11App->connection();

To avoid type clashes one of the enum values of QXcbNativeInterface's
ResourceType had to be renamed.

Pick-to: 6.2
Task-number: QTBUG-93633
Change-Id: I2e366a2bb88bd3965ac6172ad000ae32209f43e7
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index e966d7962f..55a7c8027b 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -4208,8 +4208,22 @@ QInputDeviceManager *QGuiApplicationPrivate::inputDeviceManager()
     return m_inputDeviceManager;
 }
 
+/*!
+    \fn template <typename QNativeInterface> QNativeInterface *QGuiApplication::nativeInterface() const
+
+    Returns a native interface of the given type for the application.
+
+    This function provides access to platform specific functionality
+    of QGuiApplication, as defined in the QNativeInterface namespace:
+
+    \annotatedlist native-interfaces-qguiapplication
+
+    If the requested interface is not available a \nullptr is returned.
+ */
+
 void *QGuiApplication::resolveInterface(const char *name, int revision) const
 {
+    using namespace QNativeInterface;
     using namespace QNativeInterface::Private;
 
     auto *platformIntegration = QGuiApplicationPrivate::platformIntegration();
@@ -4218,6 +4232,9 @@ void *QGuiApplication::resolveInterface(const char *name, int revision) const
 #if defined(Q_OS_WIN)
     QT_NATIVE_INTERFACE_RETURN_IF(QWindowsApplication, platformIntegration);
 #endif
+#if QT_CONFIG(xcb)
+    QT_NATIVE_INTERFACE_RETURN_IF(QX11Application, platformNativeInterface());
+#endif
 
     return QCoreApplication::resolveInterface(name, revision);
 }