protected async override void OnNavigatedTo(NavigationEventArgs e)
        {
            var json        = e.Parameter as string;
            var paihangdata = Class.data.DataContractJsonDeSerialize <YueKuPage.ViewMode.PaiHang>(json);

            title.Text  = paihangdata.rankname;
            listmanager = new SongDataList(paihangdata.rankid);
            SongLoadProgress.IsActive = true;
            await listmanager.LoadPage();

            SongListView.ItemsSource       = listmanager.list;
            SongListView.SelectionMode     = ListViewSelectionMode.Single;
            SongListView.SelectionChanged += SongListView_SelectionChanged;
            SongLoadProgress.IsActive      = false;
        }
        private void ScrollViewer_ViewChanged(object sender, ScrollViewerViewChangedEventArgs e)
        {
            var sv_SP = sender as ScrollViewer;

            if (sv_SP.VerticalOffset == sv_SP.ScrollableHeight)
            {
                lock (o)
                {
                    if (!SongLoadProgress.IsActive)
                    {
                        SongLoadProgress.IsActive = true;
                        Task.Factory.StartNew(async() =>
                        {
                            await this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, async() =>
                            {
                                await listmanager.LoadPage();
                                SongLoadProgress.IsActive = false;
                            });
                        });
                    }
                }
            }
        }