Fix handling of destroy-show and re-enable the zoom test for qmlpreview

Fixes: QTBUG-84059
Change-Id: Id70c043f96e9525a5a6053efbf99c5ea3408da65
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

4 files changed, 58 insertions, 8 deletions

diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index 12797c196b..9306d3351a 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -466,7 +466,9 @@ void QSGGuiThreadRenderLoop::releaseSwapchain(QQuickWindow *window)
     QQuickWindowPrivate *wd = QQuickWindowPrivate::get(window);
 
     // Unlike the threaded render loop, this one reuses the same rendercontext
-    // for all QQuickWindows for the entire lifetime of the render loop.
+    // for all QQuickWindows for the entire lifetime of the render loop. (and
+    // even if it wouldn't, special cases like destroy() - show() on the
+    // QQuickWindow still needed this)
     // Therefore the renderer, if there is one, needs to be notified about the
     // destruction of certain resources because they may be referenced from
     // per-rendercontext data structures.
@@ -489,10 +491,10 @@ bool QSGGuiThreadRenderLoop::eventFilter(QObject *watched, QEvent *event)
         // this is the proper time to tear down the swapchain (while the native window and surface are still around)
         if (static_cast<QPlatformSurfaceEvent *>(event)->surfaceEventType() == QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed) {
             QQuickWindow *w = qobject_cast<QQuickWindow *>(watched);
-            if (w) {
+            if (w)
                 releaseSwapchain(w);
-                w->removeEventFilter(this);
-            }
+            // keep this filter on the window - needed for uncommon but valid
+            // sequences of calls like window->destroy(); window->show();
         }
         break;
     default:
diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index 1318b2c034..76f65e5f85 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -1237,6 +1237,20 @@ void QSGThreadedRenderLoop::windowDestroyed(QQuickWindow *window)
 void QSGThreadedRenderLoop::releaseSwapchain(QQuickWindow *window)
 {
     QQuickWindowPrivate *wd = QQuickWindowPrivate::get(window);
+
+    // Counterintuitive, because this is not needed under normal circumstances
+    // due to the render loop using a dedicated rendercontext per thread, so
+    // per window. Problem is, there are cases like calling destroy(); show();
+    // on the QQuickWindow. (and we get here on SurfaceAboutToBeDestroyed, i.e.
+    // from destroy())
+    //
+    // That means recreating the native window and all the related graphics
+    // infrastructure, but the rendercontext stays around. So still have to
+    // notify the renderer to invalidate the relevant objects in the caches.
+    //
+    if (wd->renderer)
+        wd->renderer->invalidatePipelineCacheDependency(wd->rpDescForSwapchain);
+
     delete wd->rpDescForSwapchain;
     wd->rpDescForSwapchain = nullptr;
     delete wd->swapchain;
@@ -1419,8 +1433,9 @@ bool QSGThreadedRenderLoop::eventFilter(QObject *watched, QEvent *event)
                     w->thread->waitCondition.wait(&w->thread->mutex);
                     w->thread->mutex.unlock();
                 }
-                window->removeEventFilter(this);
             }
+            // keep this filter on the window - needed for uncommon but valid
+            // sequences of calls like window->destroy(); window->show();
         }
         break;
     default:
diff --git a/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp b/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp
index f3e5850edc..eb6ee09479 100644
--- a/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp
+++ b/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp
@@ -311,9 +311,6 @@ static void verifyZoomFactor(const QQmlDebugProcess *process, float factor)
 
 void tst_QQmlPreview::zoom()
 {
-    // ### Qt 6
-    QSKIP("Crashes with dev, not clear why. TBD.");
-
     const QString file("zoom.qml");
     QCOMPARE(startQmlProcess(file), ConnectSuccess);
     QVERIFY(m_client);
diff --git a/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp b/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
index 9b88946090..b2ff74b631 100644
--- a/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
+++ b/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
@@ -390,6 +390,7 @@ private slots:
     void constantUpdatesOnWindow();
     void mouseFiltering();
     void headless();
+    void destroyShowWithoutHide();
     void noUpdateWhenNothingChanges();
 
     void touchEvent_basic();
@@ -1624,6 +1625,41 @@ void tst_qquickwindow::headless()
              qPrintable(errorMessage));
 }
 
+void tst_qquickwindow::destroyShowWithoutHide()
+{
+    // this is a variation of the headless case, to test if the more aggressive
+    // destroy(); show(); sequence survives.
+
+    QQmlEngine engine;
+    QQmlComponent component(&engine);
+    component.loadUrl(testFileUrl("Headless.qml"));
+    QObject *created = component.create();
+    QScopedPointer<QObject> cleanup(created);
+
+    QQuickWindow *window = qobject_cast<QQuickWindow*>(created);
+    QVERIFY(window);
+    window->setTitle(QTest::currentTestFunction());
+    window->show();
+
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+    QVERIFY(window->isSceneGraphInitialized());
+
+    QImage originalContent = window->grabWindow();
+
+    window->destroy();
+    QVERIFY(!window->handle());
+
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+
+    QVERIFY(window->isSceneGraphInitialized());
+
+    QImage newContent = window->grabWindow();
+    QString errorMessage;
+    QVERIFY2(QQuickVisualTestUtil::compareImages(newContent, originalContent, &errorMessage),
+             qPrintable(errorMessage));
+}
+
 void tst_qquickwindow::noUpdateWhenNothingChanges()
 {
     QQuickWindow window;