[wayland] Handle damage events from SurfaceInterface

On Wayland we get the damage from the SurfaceInterface instead of
using a damage handle. This change ensures that the damage handle
interaction is only used on platform X11, while on Wayland we get
the damage from the SurfaceInterface directly.

client.cpp

@@ -2455,6 +2455,15 @@ void Client::setDecoratedClient(QPointer< Decoration::DecoratedClientImpl > clie
     m_decoratedClient = client;
 }
 
+void Client::addDamage(const QRegion &damage)
+{
+    if (!ready_for_painting) { // avoid "setReadyForPainting()" function calling overhead
+        if (syncRequest.counter == XCB_NONE)   // cannot detect complete redraw, consider done now
+            setReadyForPainting();
+    }
+    Toplevel::addDamage(damage);
+}
+
 } // namespace
 
 #include "client.moc"

client.h

@@ -740,6 +740,7 @@ private:
 protected:
     virtual void debug(QDebug& stream) const;
     virtual bool shouldUnredirect() const;
+    void addDamage(const QRegion &damage) override;
 
 private Q_SLOTS:
     void delayedSetShortcut();

composite.cpp

@@ -898,8 +898,10 @@ bool Toplevel::setupCompositing()
     if (damage_handle != XCB_NONE)
         return false;
 
-    damage_handle = xcb_generate_id(connection());
-    xcb_damage_create(connection(), damage_handle, frameId(), XCB_DAMAGE_REPORT_LEVEL_NON_EMPTY);
+    if (kwinApp()->operationMode() == Application::OperationModeX11) {
+        damage_handle = xcb_generate_id(connection());
+        xcb_damage_create(connection(), damage_handle, frameId(), XCB_DAMAGE_REPORT_LEVEL_NON_EMPTY);
+    }
 
     damage_region = QRegion(0, 0, width(), height());
     effect_window = new EffectWindowImpl(this);
@@ -920,7 +922,7 @@ bool Toplevel::setupCompositing()
 
 void Toplevel::finishCompositing(ReleaseReason releaseReason)
 {
-    if (damage_handle == XCB_NONE)
+    if (kwinApp()->operationMode() == Application::OperationModeX11 && damage_handle == XCB_NONE)
         return;
     Compositor::self()->checkUnredirect(true);
     if (effect_window->window() == this) { // otherwise it's already passed to Deleted, don't free data
@@ -928,7 +930,8 @@ void Toplevel::finishCompositing(ReleaseReason releaseReason)
         delete effect_window;
     }
 
-    if (releaseReason != ReleaseReason::Destroyed) {
+    if (kwinApp()->operationMode() == Application::OperationModeX11 &&
+            releaseReason != ReleaseReason::Destroyed) {
         xcb_damage_destroy(connection(), damage_handle);
     }
 
@@ -981,6 +984,11 @@ bool Toplevel::resetAndFetchDamage()
     if (!m_isDamaged)
         return false;
 
+    if (kwinApp()->operationMode() != Application::OperationModeX11) {
+        m_isDamaged = false;
+        return true;
+    }
+
     xcb_connection_t *conn = connection();
 
     // Create a new region and copy the damage region to it,

toplevel.cpp

@@ -31,6 +31,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "shadow.h"
 #include "xcbutils.h"
 
+#if HAVE_WAYLAND
+#include <KWayland/Server/surface_interface.h>
+#endif
+
 #include <QDebug>
 
 namespace KWin
@@ -474,6 +478,31 @@ void Toplevel::sendKeybordKeyEvent(uint32_t key, InputRedirection::KeyboardKeySt
     Q_UNUSED(state)
 }
 
+#if HAVE_WAYLAND
+void Toplevel::setSurface(KWayland::Server::SurfaceInterface *surface)
+{
+    if (m_surface == surface) {
+        return;
+    }
+    using namespace KWayland::Server;
+    if (m_surface) {
+        disconnect(m_surface, &SurfaceInterface::damaged, this, &Toplevel::addDamage);
+    }
+    m_surface = surface;
+    connect(m_surface, &SurfaceInterface::damaged, this, &Toplevel::addDamage);
+}
+#endif
+
+void Toplevel::addDamage(const QRegion &damage)
+{
+    m_isDamaged = true;
+    damage_region += damage;
+    repaints_region += damage;
+    for (const QRect &r : damage.rects()) {
+        emit damaged(this, r);
+    }
+}
+
 } // namespace
 
 #include "toplevel.moc"

toplevel.h

@@ -441,6 +441,7 @@ protected:
     virtual void clientMessageEvent(xcb_client_message_event_t *e);
     void discardWindowPixmap();
     void addDamageFull();
+    virtual void addDamage(const QRegion &damage);
     Xcb::Property fetchWmClientLeader() const;
     void readWmClientLeader(Xcb::Property &p);
     void getWmClientLeader();
@@ -740,11 +741,6 @@ inline KWayland::Server::SurfaceInterface *Toplevel::surface() const
 {
     return m_surface;
 }
-
-inline void Toplevel::setSurface(KWayland::Server::SurfaceInterface *surface)
-{
-    m_surface = surface;
-}
 #endif
 
 template <class T, class U>