refactor: move menu wheel trap helper

rust/spikes/leptos-tiptap-spike/src/editor_runtime/dom_events.rs

@@ -4,7 +4,7 @@
 //! 不处理编辑器状态、overlay 或命令分发。
 
 use wasm_bindgen::JsCast;
-use web_sys::{Element, EventTarget, Node};
+use web_sys::{Element, EventTarget, HtmlElement, Node, WheelEvent};
 
 pub(crate) fn target_element(target: EventTarget) -> Option<Element> {
     target.clone().dyn_into::<Element>().ok().or_else(|| {
@@ -21,3 +21,21 @@ pub(crate) fn event_target_matches_selector(target: Option<EventTarget>, selecto
         .and_then(|element| element.closest(selector).ok().flatten())
         .is_some()
 }
+
+pub(crate) fn current_target_html_element(event: &WheelEvent) -> Option<HtmlElement> {
+    event.current_target()?.dyn_into::<HtmlElement>().ok()
+}
+
+pub(crate) fn trap_scroll_inside_menu(event: &WheelEvent) {
+    event.prevent_default();
+    event.stop_propagation();
+
+    let Some(menu) = current_target_html_element(event) else {
+        return;
+    };
+
+    let current = f64::from(menu.scroll_top());
+    let max_scroll = f64::from((menu.scroll_height() - menu.client_height()).max(0));
+    let next = (current + event.delta_y()).clamp(0.0, max_scroll);
+    menu.set_scroll_top(next.round() as i32);
+}