/// <summary> /// 列表滚动 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void HomePage_ViewChanged(object sender, ScrollViewerViewChangedEventArgs e) { if (_scrollView.VerticalOffset > 220) { if (_itemsPanel != null) { _viewModel.Title = HomeHelper.DateStringFormat((listStories.Items[_itemsPanel.FirstVisibleIndex] as Story).Date); } } else { _viewModel.Title = "首页"; } }
/// <summary> /// /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void Page_Loaded(object sender, RoutedEventArgs e) { List <ScrollViewer> list = new List <ScrollViewer>(); HomeHelper.FindChildren <ScrollViewer>(list, listStories); //先找到ScrollViewer 注册ViewChanged事件 if (list.Count > 0) { _scrollView = list[0]; _scrollView.ViewChanged += HomePage_ViewChanged; } List <ItemsStackPanel> list2 = new List <ItemsStackPanel>(); HomeHelper.FindChildren <ItemsStackPanel>(list2, listStories); //找到ItemStackPanel 它包含FirstVisibleIndex属性 if (list.Count > 0) { _itemsPanel = list2[0]; } }