WaylandBackend becomes a KWin Singleton

The backend gets created by Workspace, but only if the environment
variable WAYLAND_DISPLAY is set.

Because of that the egl wayland backend does no longer create the
backend, but uses the already created one.

egl_wayland_backend.cpp

@@ -40,15 +40,19 @@ EglWaylandBackend::EglWaylandBackend()
     , OpenGLBackend()
     , m_context(EGL_NO_CONTEXT)
     , m_bufferAge(0)
-    , m_wayland(new Wayland::WaylandBackend)
+    , m_wayland(Wayland::WaylandBackend::self())
     , m_overlay(NULL)
 {
+    if (!m_wayland) {
+        setFailed("Wayland Backend has not been created");
+        return;
+    }
     qDebug() << "Connected to Wayland display?" << (m_wayland->display() ? "yes" : "no" );
     if (!m_wayland->display()) {
         setFailed("Could not connect to Wayland compositor");
         return;
     }
-    connect(m_wayland.data(), SIGNAL(shellSurfaceSizeChanged(QSize)), SLOT(overlaySizeChanged(QSize)));
+    connect(m_wayland, SIGNAL(shellSurfaceSizeChanged(QSize)), SLOT(overlaySizeChanged(QSize)));
     initializeEgl();
     init();
     // Egl is always direct rendering

egl_wayland_backend.h

@@ -85,7 +85,7 @@ private:
     EGLSurface m_surface;
     EGLContext m_context;
     int m_bufferAge;
-    QScopedPointer<Wayland::WaylandBackend> m_wayland;
+    Wayland::WaylandBackend *m_wayland;
     wl_egl_window *m_overlay;
     QScopedPointer<Shm> m_shm;
     friend class EglWaylandTexture;

wayland_backend.cpp

@@ -20,7 +20,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // own
 #include "wayland_backend.h"
 // KWin
-#include <kwinglobals.h>
 #include "cursor.h"
 // Qt
 #include <QDebug>
@@ -338,7 +337,10 @@ X11CursorTracker::X11CursorTracker(wl_pointer *pointer, WaylandBackend *backend,
 
 X11CursorTracker::~X11CursorTracker()
 {
-    Cursor::self()->stopCursorTracking();
+    if (Cursor::self()) {
+        // Cursor might have been destroyed before Wayland backend gets destroyed
+        Cursor::self()->stopCursorTracking();
+    }
     if (m_cursor) {
         wl_surface_destroy(m_cursor);
     }
@@ -519,8 +521,20 @@ void WaylandSeat::resetCursor()
     }
 }
 
-WaylandBackend::WaylandBackend()
-    : QObject(NULL)
+WaylandBackend *WaylandBackend::s_self = 0;
+WaylandBackend *WaylandBackend::create(QObject *parent)
+{
+    Q_ASSERT(!s_self);
+    const QByteArray display = qgetenv("WAYLAND_DISPLAY");
+    if (display.isEmpty()) {
+        return NULL;
+    }
+    s_self = new WaylandBackend(parent);
+    return s_self;
+}
+
+WaylandBackend::WaylandBackend(QObject *parent)
+    : QObject(parent)
     , m_display(wl_display_connect(NULL))
     , m_registry(wl_display_get_registry(m_display))
     , m_compositor(NULL)
@@ -562,6 +576,7 @@ WaylandBackend::~WaylandBackend()
         wl_display_disconnect(m_display);
     }
     qDebug() << "Destroyed Wayland display";
+    s_self = NULL;
 }
 
 void WaylandBackend::readEvents()

wayland_backend.h

@@ -19,6 +19,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 #ifndef KWIN_WAYLAND_BACKEND_H
 #define KWIN_WAYLAND_BACKEND_H
+// KWin
+#include <kwinglobals.h>
 // Qt
 #include <QHash>
 #include <QObject>
@@ -126,7 +128,6 @@ class WaylandBackend : public QObject
 {
     Q_OBJECT
 public:
-    WaylandBackend();
     virtual ~WaylandBackend();
     wl_display *display();
     wl_registry *registry();
@@ -159,6 +160,8 @@ private:
     QSize m_shellSurfaceSize;
     QScopedPointer<WaylandSeat> m_seat;
     QScopedPointer<ShmPool> m_shm;
+
+    KWIN_SINGLETON(WaylandBackend)
 };
 
 inline

workspace.cpp

@@ -58,6 +58,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "unmanaged.h"
 #include "useractions.h"
 #include "virtualdesktops.h"
+#include <config-workspace.h>
+#ifdef WAYLAND_FOUND
+#include "wayland_backend.h"
+#endif
 #include "xcbutils.h"
 #include "main.h"
 // KDE
@@ -168,6 +172,11 @@ Workspace::Workspace(bool restore)
     // first initialize the extensions
     Xcb::Extensions::self();
 
+    // start the Wayland Backend - will only be created if WAYLAND_DISPLAY is present
+#ifdef WAYLAND_FOUND
+    Wayland::WaylandBackend::create(this);
+#endif
+
     // start the cursor support
     Cursor::create(this);