didStartUserGesture method
route 路由目标页面 previousRoute 目标页面的上一个页面
Implementation
// 滑动手势开始
@override
void didStartUserGesture(Route route, Route? previousRoute) {
super.didStartUserGesture(route, previousRoute);
DStackNavigatorObserver.instance!
.setGesturingRouteName(route.settings.name);
}