c# - UWP Listview在绑定(bind)海量数据时变得很慢

Question

我正在尝试使用 ObservableCollection 将数据绑定(bind)到 ListView 。

我的 XAML 是这样的

<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# 代码

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() 返回所有数据。

例如:

开始请求 2017 年 8 月 17 日下午 5:38:20

结束请求 2017 年 8 月 17 日下午 5:38:21

BeginxBind 2017 年 8 月 17 日下午 5:38:21

计数 1798

EndxBind 2017 年 8 月 17 日下午 5:38:21

我用Debug.WriteLine打印时间，发现web请求和响应时间很短，而ObsList.Add(fi)，也需要一点点时间。

但是我的软件在向下滚动时非常慢。

那么如何改进呢，非常感谢。

Answer 1

删除 ScrollViewer超过 ListView .它禁用 ListView虚拟化。 ListView有自己的ScrollViewer .

启用虚拟化到 ListView

在此处阅读有关虚拟化的信息:https://docs.microsoft.com/en-us/windows/uwp/debug-test-perf/optimize-gridview-and-listview