在Windows Phone 8.1中为分组的ListView实现LoadMore分页吗？

Question

是否可以将ListViewBase.LoadMoreItemsAsync方法应用于分组的ListView（CollectionViewSource）中的分页。 或者，也许您知道另一种方式，请告诉我。

Answer 1

您可以这样操作：在您的ListView上，使用以下代码添加“ Loaded”事件：

 private void LvPictures_OnLoaded(object sender, RoutedEventArgs e)
 {
     ScrollViewer viewer = GetScrollViewer(this.LvPictures);
     viewer.ViewChanged += LvPictures_ViewChanged;
 }


public static ScrollViewer GetScrollViewer(DependencyObject depObj)
      {
          if (depObj is ScrollViewer) return depObj as ScrollViewer;

          for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
          {
              var child = VisualTreeHelper.GetChild(depObj, i);

              var result = GetScrollViewer(child);
              if (result != null) return result;
          }
          return null;
      }

现在，您可以在ViewChangeEvent中指定何时要加载更多项目并实际执行此操作：

     private async void LvPictures_ViewChanged(object sender, ScrollViewerViewChangedEventArgs e)
      {
          ScrollViewer view = (ScrollViewer)sender;
          double progress = view.VerticalOffset / view.ScrollableHeight;
          if (progress > 0.8 & !_incallFilesList && NextPagePicturesAvailable)
          {
              _incallFilesList = true;
              GetNextPicturesPageAsync();
          }
          _incallFilesList = false;
      }