QCocoaDrag: reset the stored NSView when it gets destroyed

QCocoaDrag stores the last NSView that received an input event, which becomes a dangling pointer when the NSView gets destroyed. Inform the QCocoaDrag when NSView's destructor runs, so that it can reset the pointer (and reset the NSEvent pointer as well) when the destroyed NSView is the stored one. With this change alone we'd end up triggering the Q_ASSERT later on in QCocoaDrag::drag, as m_lastEvent is now nil so the NSWindow will be nil as well. QCocoaDrag::drag cannot do anything useful if m_lastEvent is nil, so exit early. Pick-to: 6.8 6.5 Fixes: QTBUG-116554 Change-Id: I5949d728d05adcf3d4a32c91f7e181393bef0422 Reviewed-by: Tor Arne Vestbø <[email protected]>
qt · Nov 8, 2024 · 720ce9b · 720ce9b
1 parent 6661b95
commit 720ce9b
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Showing 3 changed files with 19 additions and 1 deletion.
diff --git a/src/plugins/platforms/cocoa/qcocoadrag.h b/src/plugins/platforms/cocoa/qcocoadrag.h
@@ -36,6 +36,7 @@ class QCocoaDrag : public QPlatformDrag
     * event and view when handling an event in QNSView
     */
     void setLastInputEvent(NSEvent *event, NSView *view);
+    void viewDestroyed(NSView *view);
 
     void setAcceptedAction(Qt::DropAction act);
     void exitDragLoop();

diff --git a/src/plugins/platforms/cocoa/qcocoadrag.mm b/src/plugins/platforms/cocoa/qcocoadrag.mm
@@ -38,6 +38,17 @@
     m_lastView = view;
 }
 
+void QCocoaDrag::viewDestroyed(NSView *view)
+{
+    if (view == m_lastView) {
+        if (m_lastEvent.window.contentView == view) {
+            [m_lastEvent release];
+            m_lastEvent = nil;
+        }
+        m_lastView = nil;
+    }
+}
+
 QMimeData *QCocoaDrag::dragMimeData()
 {
     if (m_drag)
@@ -95,9 +106,11 @@
 
 Qt::DropAction QCocoaDrag::drag(QDrag *o)
 {
-    m_drag = o;
     m_executed_drop_action = Qt::IgnoreAction;
+    if (!m_lastEvent)
+        return m_executed_drop_action;
 
+    m_drag = o;
     QMacPasteboard dragBoard(CFStringRef(NSPasteboardNameDrag), QUtiMimeConverter::HandlerScopeFlag::DnD);
     m_drag->mimeData()->setData("application/x-qt-mime-type-name"_L1, QByteArray("dummy"));
     dragBoard.setMimeData(m_drag->mimeData(), QMacPasteboard::LazyRequest);

diff --git a/src/plugins/platforms/cocoa/qnsview.mm b/src/plugins/platforms/cocoa/qnsview.mm
@@ -173,6 +173,10 @@ - (void)dealloc
     [[NSNotificationCenter defaultCenter] removeObserver:self];
     [m_mouseMoveHelper release];
 
+    // FIXME: Replace with __weak or someting equivalent
+    QCocoaDrag* nativeDrag = QCocoaIntegration::instance()->drag();
+    nativeDrag->viewDestroyed(self);
+
     [super dealloc];
 }