Client: Don't send fake SurfaceCreated/Destroyed events

QPlatformSurface relates to the platform window, not the wl_surface.
The events are already emitted by QPlatformWindow on create/destroy.

To preserve compatibility for a previous KDE version it was faked to
emit the events when the wl_surface is created/hidden to keep behavior.
This is no longer necessary, and it has caused multiple errors, the latest
being a crash when switching between sub-menus with the Sway compositor.

[ChangeLog][QPA plugin] QWaylandWindow no longer sends fake SurfaceCreated/Destroyed events.
Use expose events to be notified when a Wayland surface appears.

Task-number: QTBUG-76324
Fixes: QTBUG-81952
Pick-to: 5.15
Change-Id: I2f003bc9da85f032a0053677fd281152099fc9eb
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: David Edmundson <davidedmundson@kde.org>

3 files changed, 8 insertions, 11 deletions

diff --git a/examples/wayland/custom-extension/client-common/customextension.cpp b/examples/wayland/custom-extension/client-common/customextension.cpp
index aa0cb58a4..8b77c061a 100644
--- a/examples/wayland/custom-extension/client-common/customextension.cpp
+++ b/examples/wayland/custom-extension/client-common/customextension.cpp
@@ -81,8 +81,11 @@ QWindow *CustomExtension::windowForSurface(struct ::wl_surface *surface)
 
 bool CustomExtension::eventFilter(QObject *object, QEvent *event)
 {
-    if (event->type() == QEvent::PlatformSurface
-            && static_cast<QPlatformSurfaceEvent*>(event)->surfaceEventType() == QPlatformSurfaceEvent::SurfaceCreated) {
+    if (event->type() == QEvent::Expose) {
+        auto *exposeEvent = static_cast<QExposeEvent *>(event);
+        if (exposeEvent->region().isNull())
+            return false;
+
         QWindow *window = qobject_cast<QWindow*>(object);
         Q_ASSERT(window);
         window->removeEventFilter(this);
diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index 8cc26d71c..523bdc732 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -91,7 +91,7 @@ QWaylandWindow::~QWaylandWindow()
     delete mWindowDecoration;
 
     if (mSurface)
-        reset(false);
+        reset();
 
     const QWindow *parent = window();
     const auto tlw = QGuiApplication::topLevelWindows();
@@ -118,8 +118,6 @@ void QWaylandWindow::initWindow()
 
     if (!mSurface) {
         initializeWlSurface();
-        QPlatformSurfaceEvent e(QPlatformSurfaceEvent::SurfaceCreated);
-        QGuiApplication::sendEvent(window(), &e);
     }
 
     if (shouldCreateSubSurface()) {
@@ -234,12 +232,8 @@ bool QWaylandWindow::shouldCreateSubSurface() const
     return QPlatformWindow::parent() != nullptr;
 }
 
-void QWaylandWindow::reset(bool sendDestroyEvent)
+void QWaylandWindow::reset()
 {
-    if (mSurface && sendDestroyEvent) {
-        QPlatformSurfaceEvent e(QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed);
-        QGuiApplication::sendEvent(window(), &e);
-    }
     delete mShellSurface;
     mShellSurface = nullptr;
     delete mSubSurfaceWindow;
diff --git a/src/client/qwaylandwindow_p.h b/src/client/qwaylandwindow_p.h
index c0328996d..6ad63d354 100644
--- a/src/client/qwaylandwindow_p.h
+++ b/src/client/qwaylandwindow_p.h
@@ -260,7 +260,7 @@ private:
     void initializeWlSurface();
     bool shouldCreateShellSurface() const;
     bool shouldCreateSubSurface() const;
-    void reset(bool sendDestroyEvent = true);
+    void reset();
     void sendExposeEvent(const QRect &rect);
     static void closePopups(QWaylandWindow *parent);
     QPlatformScreen *calculateScreenFromSurfaceEvents() const;