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, 71 insertions, 0 deletions

diff --git a/src/gui/kernel/qguiapplication_platform.h b/src/gui/kernel/qguiapplication_platform.h
new file mode 100644
index 0000000000..66cdf10814
--- /dev/null
+++ b/src/gui/kernel/qguiapplication_platform.h
@@ -0,0 +1,71 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
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+** Licensees holding valid commercial Qt licenses may use this file in
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+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
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+****************************************************************************/
+
+#ifndef QGUIAPPLICATION_PLATFORM_H
+#define QGUIAPPLICATION_PLATFORM_H
+
+#include <QtGui/qtguiglobal.h>
+
+#include <QtCore/qnativeinterface.h>
+#include <QtGui/qguiapplication.h>
+
+#if QT_CONFIG(xcb)
+typedef struct _XDisplay Display;
+struct xcb_connection_t;
+#endif
+
+QT_BEGIN_NAMESPACE
+
+namespace QNativeInterface
+{
+
+#if QT_CONFIG(xcb) || defined(Q_CLANG_QDOC)
+struct Q_GUI_EXPORT QX11Application
+{
+    QT_DECLARE_NATIVE_INTERFACE(QX11Application, 1, QGuiApplication)
+    virtual Display *display() const = 0;
+    virtual xcb_connection_t *connection() const = 0;
+};
+#endif
+
+} // QNativeInterface
+
+QT_END_NAMESPACE
+
+#endif // QGUIAPPLICATION_PLATFORM_H