add scroll logics to mac

engine/src/shell/platform/unity/darwin/macos/uiwidgets_panel.h

 
   void VSyncCallback(intptr_t baton);
 
+  void SetEventLocationFromCursorPosition(UIWidgetsPointerEvent* event_data);
+
+
+  void OnScroll(float x, float y, float px, float py);
 
   void OnMouseDown(float x, float y, int button);
 
   void SendMouseUp(float x, float y);
 
   void SendMouseLeave();
+
+  void SendScroll(float delta_x, float delta_y, float px, float py);
 
   void SetEventPhaseFromCursorButtonState(UIWidgetsPointerEvent* event_data);
 

engine/src/shell/platform/unity/darwin/macos/uiwidgets_panel.mm

   SendPointerEventWithData(event);
 }
 
+void UIWidgetsPanel::SendScroll(float delta_x, float delta_y, float px, float py) {
+  UIWidgetsPointerEvent event = {};
+ // TODO: this is a native method, use unity position instead.
+  event.x = px;
+  event.y = py;
+  SetEventPhaseFromCursorButtonState(&event);
+  event.signal_kind = UIWidgetsPointerSignalKind::kUIWidgetsPointerSignalKindScroll;
+  // TODO: See if this can be queried from the OS; this value is chosen
+  // arbitrarily to get something that feels reasonable.
+  const int kScrollOffsetMultiplier = 20;
+  event.scroll_delta_x = delta_x * kScrollOffsetMultiplier;
+  event.scroll_delta_y = delta_y * kScrollOffsetMultiplier;
+  SendPointerEventWithData(event);
+}
+
 void UIWidgetsPanel::SendPointerEventWithData(
     const UIWidgetsPointerEvent& event_data) {
   MouseState mouse_state = GetMouseState();
   }
 }
 
-
+  }
+}
+
+void UIWidgetsPanel::OnScroll(float x, float y, float px, float py) {
+  if (process_events_) {
+    SendScroll(x, y, px, py);
   }
 }
 
 
   //_Wait
   panel->ProcessMessages();
+}
+
+UIWIDGETS_API(void)
+UIWidgetsPanel_onScroll(UIWidgetsPanel* panel, float x, float y, float px, float py) {
+  panel->OnScroll(x, y, px, py);
 }
 
 }  // namespace uiwidgets