wayland: Mark Xwayland windows ready for painting when mapped

This makes the logic that determines when Xwayland windows can be marked
as ready for painting more robust.

At the moment, we call setReadyForPainting() when the surface is damaged,
but we want Toplevel stop managing damages.

src/unmanaged.cpp

@@ -21,6 +21,10 @@
 
 #include <xcb/shape.h>
 
+#include <KWaylandServer/surface_interface.h>
+
+using namespace KWaylandServer;
+
 namespace KWin
 {
 
@@ -34,13 +38,36 @@ const NET::WindowTypes SUPPORTED_UNMANAGED_WINDOW_TYPES_MASK = NET::NormalMask |
 Unmanaged::Unmanaged()
     : Toplevel()
 {
-    QTimer::singleShot(50, this, &Unmanaged::setReadyForPainting);
+    switch (kwinApp()->operationMode()) {
+    case Application::OperationModeXwayland:
+        if (surface()) {
+            associate();
+        } else {
+            connect(this, &Toplevel::surfaceChanged, this, &Unmanaged::associate);
+        }
+        break;
+    case Application::OperationModeX11:
+        // It's probably not ready for painting yet, show it after synthetic 50ms delay.
+        QTimer::singleShot(50, this, &Unmanaged::setReadyForPainting);
+        break;
+    case Application::OperationModeWaylandOnly:
+        Q_UNREACHABLE();
+    }
 }
 
 Unmanaged::~Unmanaged()
 {
 }
 
+void Unmanaged::associate()
+{
+    if (surface()->isMapped()) {
+        setReadyForPainting();
+    } else {
+        connect(surface(), &SurfaceInterface::mapped, this, &Unmanaged::setReadyForPainting);
+    }
+}
+
 bool Unmanaged::track(xcb_window_t w)
 {
     XServerGrabber xserverGrabber;

src/unmanaged.h

@@ -48,6 +48,7 @@ private:
     // handlers for X11 events
     void configureNotifyEvent(xcb_configure_notify_event_t *e);
     QWindow *findInternalWindow() const;
+    void associate();
     bool m_outline = false;
     bool m_scheduledRelease = false;
 };

src/xwaylandclient.cpp

@@ -9,9 +9,37 @@
 
 #include "xwaylandclient.h"
 
+#include <KWaylandServer/surface_interface.h>
+
+using namespace KWaylandServer;
+
 namespace KWin
 {
 
+XwaylandClient::XwaylandClient()
+{
+    if (surface()) {
+        associate();
+    } else {
+        connect(this, &Toplevel::surfaceChanged, this, &XwaylandClient::associate);
+    }
+}
+
+void XwaylandClient::associate()
+{
+    if (surface()->isMapped()) {
+        initialize();
+    } else {
+        connect(surface(), &SurfaceInterface::mapped, this, &XwaylandClient::initialize);
+    }
+}
+
+void XwaylandClient::initialize()
+{
+    setReadyForPainting();
+    setupWindowManagementInterface();
+}
+
 bool XwaylandClient::wantsSyncCounter() const
 {
     // When the frame window is resized, the attached buffer will be destroyed by

src/xwaylandclient.h

@@ -22,7 +22,13 @@ class XwaylandClient : public X11Client
     Q_OBJECT
 
 public:
+    explicit XwaylandClient();
+
     bool wantsSyncCounter() const override;
+
+private:
+    void associate();
+    void initialize();
 };
 
 } // namespace KWin