isTopPage method
组件当前页面当前是否栈顶
Implementation
bool isTopPage(BuildContext context) {
final state = context.findRootAncestorStateOfType<BaseStatePage>();
if (state != null) return state.isTopPage;
final stateless =
context.findAncestorWidgetOfExactType<BaseStatelessPage>();
if (stateless != null) return stateless.isTopPage;
return false;
}