UWP Listview變得非常緩慢，而綁定海量數據

Question

我想使用ObservableCollection將數據綁定到listview。

我的XAML是這樣

<ScrollViewer x:Name="svListEarthquakes" Grid.Row="2" Grid.ColumnSpan="4" ViewChanged="svListEarthquakes_ViewChanged"> 
      <ListView x:Name="listEarthquakes" IsItemClickEnabled="True" SelectionMode="Single" ItemsSource="{x:Bind ObsList}" ItemClick="listEarthquakes_ItemClick"> 
       <ListView.ItemContainerStyle> 
        <Style TargetType="ListViewItem"> 
         <Setter Property="HorizontalContentAlignment" Value="Stretch"></Setter> 
         <Setter Property="BorderBrush" Value="LightGray"></Setter> 
         <Setter Property="BorderThickness" Value="0,0,0,1"></Setter> 
        </Style> 
       </ListView.ItemContainerStyle> 
       <ListView.ItemTemplate> 
        <DataTemplate> 
         <Grid> 
          <Grid.ColumnDefinitions> 
           <ColumnDefinition Width="*"/> 
           <ColumnDefinition Width="2*"/> 
           <ColumnDefinition Width="*"/> 
           <ColumnDefinition Width="*"/> 
           <ColumnDefinition Width="*"/> 
           <ColumnDefinition Width="2*"/> 
          </Grid.ColumnDefinitions> 
          <TextBlock Grid.Column="0" TextWrapping="WrapWholeWords" Text="{Binding properties.mag}" VerticalAlignment="Center" HorizontalAlignment="Center"/> 
          <TextBlock Grid.Column="1" TextWrapping="WrapWholeWords" Text="{Binding Path=properties.time,Converter={StaticResource cvtDate}}" VerticalAlignment="Center" HorizontalAlignment="Center"/> 
          <TextBlock Grid.Column="2" TextWrapping="WrapWholeWords" Text="{Binding geometry.coordinates[0]}" VerticalAlignment="Center" HorizontalAlignment="Center"/> 
          <TextBlock Grid.Column="3" TextWrapping="WrapWholeWords" Text="{Binding geometry.coordinates[1]}" VerticalAlignment="Center" HorizontalAlignment="Center"/> 
          <TextBlock Grid.Column="4" TextWrapping="WrapWholeWords" Text="{Binding geometry.coordinates[2]}" VerticalAlignment="Center" HorizontalAlignment="Center"/> 
          <TextBlock Grid.Column="5" TextWrapping="WrapWholeWords" Text="{Binding properties.place}" VerticalAlignment="Center" HorizontalAlignment="Center"/> 
         </Grid> 
        </DataTemplate> 
       </ListView.ItemTemplate> 
      </ListView> 
     </ScrollViewer> 

和C＃代碼

private async Task DisplayDataAsync() 
     { 
      Debug.WriteLine("BeginRequest " + DateTime.Now); 

      var repsonse = (Application.Current as App).gEarthquakesGeoJson = await HttpEarthquakes.GetdEarthquakesGeoJsonAsync<EarthquakesModel>(strRequestUrl); 
      if (repsonse.metadata.status == 200) 
      { 
       Debug.WriteLine("EndRequest " + DateTime.Now); 
       Debug.WriteLine("BeginxBind " + DateTime.Now); 
       Debug.WriteLine("Count " + repsonse.metadata.count); 
       ObsList.Clear(); 
       if (repsonse.metadata.count > 0) 
       { 
        //List<FeaturesItem> fis = new List<FeaturesItem>(); 
        foreach (FeaturesItem em in repsonse.features) 
        { 
         FeaturesItem fi = new FeaturesItem 
         { 
          type = em.type, 
          properties = em.properties, 
          geometry = em.geometry, 
          id = em.id 
         }; 
         ObsList.Add(fi); 
        } 

        //listEarthquakes.ItemsSource = ObsList; 
        Debug.WriteLine("EndxBind " + DateTime.Now); 
       } 
       else 
       { 
        //No Data 

       } 
      } 
      else 
      { 
       //Net Error 

      } 
     } 

注： GetdEarthquakesGeoJsonAsync（）返回的所有數據。

例如：

的BeginRequest 2017年8月17日下午5點38分二十秒

EndRequest 2017年8月17日下午5點38分21秒

BeginxBind 2017年8月17日5 ：38：21 PM

計數1798

EndxBind 2017年8月17日下午5點38分21秒

我使用Debug.WriteLine打印時間，發現web請求和響應時間很短，而ObsList.Add（fi），也需要一些時間。

但是我的軟件在滾動時非常慢。

那麼如何改進呢，非常感謝。

Answer 1

1. 在ListView刪除ScrollViewer。它會禁用ListView虛擬化。 ListView有它自己的ScrollViewer。
2. 啓用虛擬化技術ListView

閱讀有關虛擬化的位置：https://docs.microsoft.com/en-us/windows/uwp/debug-test-perf/optimize-gridview-and-listview