Expose the number of X screen through the QXcbScreenFunctions

X screen corresponds to Qt virtual desktop, and RandR output
corresponds to QScreen. There can be more than one X screen,
so we need a way to get the number of X screen for QScreen,
in particular for the right implementation of some methods
in QX11Info.

Change-Id: Ib5e38703bf11ae08bb283f26a7b7b15f1a5e8671
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

5 files changed, 72 insertions, 1 deletions

diff --git a/src/platformheaders/xcbfunctions/qxcbscreenfunctions.h b/src/platformheaders/xcbfunctions/qxcbscreenfunctions.h
new file mode 100644
index 0000000000..7773c275b9
--- /dev/null
+++ b/src/platformheaders/xcbfunctions/qxcbscreenfunctions.h
@@ -0,0 +1,56 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QXCBSCREENFUNCTIONS_H
+#define QXCBSCREENFUNCTIONS_H
+
+#include <QtPlatformHeaders/QPlatformHeaderHelper>
+
+QT_BEGIN_NAMESPACE
+
+class QScreen;
+
+class QXcbScreenFunctions
+{
+public:
+    typedef bool (*VirtualDesktopNumber)(const QScreen *screen);
+    static const QByteArray virtualDesktopNumberIdentifier() { return QByteArrayLiteral("XcbVirtualDesktopNumber"); }
+    static int virtualDesktopNumber(const QScreen *screen)
+    {
+        return QPlatformHeaderHelper::callPlatformFunction<int, VirtualDesktopNumber, const QScreen *>(virtualDesktopNumberIdentifier(), screen);
+    }
+};
+
+QT_END_NAMESPACE
+
+#endif  /*QXCBSCREENFUNCTIONS_H*/
diff --git a/src/platformheaders/xcbfunctions/xcbfunctions.pri b/src/platformheaders/xcbfunctions/xcbfunctions.pri
index 7f611d80bd..3f2bcb2b34 100644
--- a/src/platformheaders/xcbfunctions/xcbfunctions.pri
+++ b/src/platformheaders/xcbfunctions/xcbfunctions.pri
@@ -1,3 +1,4 @@
 HEADERS += \
     $$PWD/qxcbwindowfunctions.h \
-    $$PWD/qxcbintegrationfunctions.h
+    $$PWD/qxcbintegrationfunctions.h \
+    $$PWD/qxcbscreenfunctions.h
diff --git a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
index f6bd878bde..96239a0f20 100644
--- a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
+++ b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
@@ -48,6 +48,7 @@
 
 #include <QtPlatformHeaders/qxcbwindowfunctions.h>
 #include <QtPlatformHeaders/qxcbintegrationfunctions.h>
+#include <QtPlatformHeaders/qxcbscreenfunctions.h>
 
 #ifndef QT_NO_DBUS
 #include "QtPlatformSupport/private/qdbusmenuconnection_p.h"
@@ -367,6 +368,10 @@ QFunctionPointer QXcbNativeInterface::platformFunction(const QByteArray &functio
     if (function == QXcbWindowFunctions::visualIdIdentifier()) {
         return QFunctionPointer(QXcbWindowFunctions::VisualId(QXcbWindow::visualIdStatic));
     }
+
+    if (function == QXcbScreenFunctions::virtualDesktopNumberIdentifier())
+        return QFunctionPointer(QXcbScreenFunctions::VirtualDesktopNumber(QXcbScreen::virtualDesktopNumberStatic));
+
     return Q_NULLPTR;
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index 28b1753712..1a90f824fc 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -438,6 +438,14 @@ void QXcbScreen::setOutput(xcb_randr_output_t outputId,
     // TODO: Send an event to the QScreen instance that the screen changed its name
 }
 
+int QXcbScreen::virtualDesktopNumberStatic(const QScreen *screen)
+{
+    if (screen && screen->handle())
+        return static_cast<const QXcbScreen *>(screen->handle())->screenNumber();
+
+    return 0;
+}
+
 /*!
     \brief handle the XCB screen change event and update properties
 
diff --git a/src/plugins/platforms/xcb/qxcbscreen.h b/src/plugins/platforms/xcb/qxcbscreen.h
index f4de2b9dfd..7376ddf35c 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.h
+++ b/src/plugins/platforms/xcb/qxcbscreen.h
@@ -133,6 +133,7 @@ public:
     bool isPrimary() const { return m_primary; }
 
     int screenNumber() const { return m_virtualDesktop->number(); }
+    static int virtualDesktopNumberStatic(const QScreen *screen);
 
     xcb_screen_t *screen() const { return m_virtualDesktop->screen(); }
     xcb_window_t root() const { return screen()->root; }