Make QWasmScreen::allWindows return all (wasm) windows

It seems that findChildren does not return every window if called
at an inconvenient time.

This causes not all windows to be returned, and later the
QWasmCompositor will not detect a valid window to compose,
and therefor goes to disabled.

Fixes: QTBUG-132414
Pick-to: 6.9
Change-Id: I6c872071751d5a2fbdeea36fb8f4c7e9677fd7d0
Reviewed-by: Morten Johan Sørvig <[email protected]>

2 files changed, 18 insertions, 13 deletions

diff --git a/src/plugins/platforms/wasm/qwasmscreen.cpp b/src/plugins/platforms/wasm/qwasmscreen.cpp
index 1ec7d758395..badc5468c8b 100644
--- a/src/plugins/platforms/wasm/qwasmscreen.cpp
+++ b/src/plugins/platforms/wasm/qwasmscreen.cpp
@@ -330,21 +330,26 @@ QWasmWindowTreeNode *QWasmScreen::parentNode()
     return nullptr;
 }
 
-QList<QWasmWindow *> QWasmScreen::allWindows()
+QList<QWasmWindow *> QWasmScreen::allWindows() const
 {
-    QList<QWasmWindow *> windows;
-    for (auto *child : childStack()) {
-        const QWindowList list = child->window()->findChildren<QWindow *>(Qt::FindChildrenRecursively);
-        for (auto child : list) {
-            auto handle = child->handle();
-            if (handle) {
-                auto wnd = static_cast<QWasmWindow *>(handle);
-                windows.push_back(wnd);
-            }
+    QList<QWasmWindow *> currentChildren;
+    QList<QWasmWindow *> result;
+
+    for (auto *w : childStack())
+        currentChildren << w;
+
+    while (!currentChildren.empty()) {
+        result << currentChildren;
+
+        QList<QWasmWindow *> toIterate;
+        currentChildren.swap(toIterate);
+
+        for (auto child : toIterate) {
+            for (auto *w : child->childStack())
+                currentChildren << w;
         }
-        windows.push_back(child);
     }
-    return windows;
+    return result;
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/wasm/qwasmscreen.h b/src/plugins/platforms/wasm/qwasmscreen.h
index cf9916b9075..66e7e39d008 100644
--- a/src/plugins/platforms/wasm/qwasmscreen.h
+++ b/src/plugins/platforms/wasm/qwasmscreen.h
@@ -43,7 +43,7 @@ public:
     QWasmCompositor *compositor();
     QWasmDeadKeySupport *deadKeySupport() { return m_deadKeySupport.get(); }
 
-    QList<QWasmWindow *> allWindows();
+    QList<QWasmWindow *> allWindows() const;
 
     QRect geometry() const override;
     int depth() const override;