Forward unhandled mouse wheel events to the parent widget

- All mouse wheel events are forwarded to Chromium.
- Forward unhandled wheel events by Chromium to the parent widget.
- Impersonated QSpontaneKeyEvent in Qt WebEngine to set
  spontaneous flag and forwarded the event as spontaneous.

Fixes: QTBUG-118398
Pick-to: 6.7 6.6 6.5
Change-Id: I4ec831b0077edc3d833fdd7ae8d31a5535b0c05b
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Michael Brüning <michael.bruning@qt.io>

3 files changed, 19 insertions, 4 deletions

diff --git a/src/core/render_widget_host_view_qt_delegate_item.cpp b/src/core/render_widget_host_view_qt_delegate_item.cpp
index 1ad664a1f..78ec06bb8 100644
--- a/src/core/render_widget_host_view_qt_delegate_item.cpp
+++ b/src/core/render_widget_host_view_qt_delegate_item.cpp
@@ -449,10 +449,8 @@ void RenderWidgetHostViewQtDelegateItem::updateAdapterClientIfNeeded(WebContents
 
 void RenderWidgetHostViewQtDelegateItem::unhandledWheelEvent(QWheelEvent *ev)
 {
-    if (QWindow *w = Window()) {
-        if (QWindow *p = w->parent())
-            qApp->sendEvent(p, ev);
-    }
+    if (m_widgetDelegate)
+        m_widgetDelegate->unhandledWheelEvent(ev);
 }
 
 } // namespace QtWebEngineCore
diff --git a/src/core/render_widget_host_view_qt_delegate_item.h b/src/core/render_widget_host_view_qt_delegate_item.h
index 082bd7791..55f243eab 100644
--- a/src/core/render_widget_host_view_qt_delegate_item.h
+++ b/src/core/render_widget_host_view_qt_delegate_item.h
@@ -35,6 +35,7 @@ public:
     virtual void Destroy() = 0;
     virtual void Resize(int, int) { }
     virtual QWindow *Window() { return nullptr; }
+    virtual void unhandledWheelEvent(QWheelEvent *) { }
 };
 
 // Useful information keyboard and mouse QEvent propagation.
diff --git a/src/webenginewidgets/api/qwebengineview.cpp b/src/webenginewidgets/api/qwebengineview.cpp
index 8d88726fa..65474506c 100644
--- a/src/webenginewidgets/api/qwebengineview.cpp
+++ b/src/webenginewidgets/api/qwebengineview.cpp
@@ -68,6 +68,14 @@
 #include <QThread>
 #endif
 
+QT_BEGIN_NAMESPACE
+class QSpontaneKeyEvent
+{
+public:
+    static inline void makeSpontaneous(QEvent *ev) { ev->setSpontaneous(); }
+};
+QT_END_NAMESPACE
+
 namespace QtWebEngineCore {
 class WebEngineQuickWidget : public QQuickWidget, public WidgetDelegate
 {
@@ -172,6 +180,14 @@ public:
             return root->windowHandle();
         return nullptr;
     }
+    void unhandledWheelEvent(QWheelEvent *ev) override
+    {
+        auto parentWidget = QQuickWidget::parentWidget();
+        if (parentWidget) {
+            QSpontaneKeyEvent::makeSpontaneous(ev);
+            qApp->notify(parentWidget, ev);
+        }
+    }
 
 protected:
     void closeEvent(QCloseEvent *event) override