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>

3 files changed, 14 insertions, 0 deletions

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; }