向下滚动并更新 Listview C#

Question

我的 UWP 应用中有一个 ListView。

这是我的代码：

<ListView x:Name="viewMedias" SelectionMode="None" VirtualizingStackPanel.VirtualizationMode="Recycling" ScrollViewer.HorizontalScrollMode="Disabled" ScrollViewer.VerticalScrollMode="Auto">
        ......
</ListView>

现在，当这个 ListView 滚动到几乎结束时，我如何接收事件？我想更新 ItemsSource 以将新项目添加到 ListView 的底部。

Answer 1

欢迎来到 StackOverflow！ 您想要实现的称为增量加载。您不必自己实施它 - 只需检查现有的解决方案。 Windows 社区工具包 有IncrementalLoadingCollection 可以帮助您的助手。您可以在他们的示例应用程序中查看演示：Windows Community Toolkit Sample App in Windows Store（转到 helpers > Incremental Loading Collection）。以下是此应用程序的一些示例代码：

// Defines a data source whose data can be loaded incrementally.
using Microsoft.Toolkit.Uwp;

public class Person
{
    public string Name { get; set; }
}

public class PeopleSource : IIncrementalSource<Person>
{
    private readonly List<Person> _people;

    public PeopleSource()
    {
        // Creates an example collection.
        _people = new List<Person>();

        for (int i = 1; i <= 200; i++)
        {
            var p = new Person { Name = "Person " + i };
            _people.Add(p);
        }
    }

    public async Task<IEnumerable<Person>> GetPagedItemsAsync(int pageIndex, int pageSize)
    {
        // Gets items from the collection according to pageIndex and pageSize parameters.
        var result = (from p in _people
                      select p).Skip(pageIndex * pageSize).Take(pageSize);

        // Simulates a longer request...
        await Task.Delay(1000);

        return result;
    }
}

// IncrementalLoadingCollection can be bound to a GridView or a ListView. In this case it is a ListView called PeopleListView.

var collection = new IncrementalLoadingCollection<PeopleSource, Person>();

PeopleListView.ItemsSource = collection;

// Binds the collection to the page DataContext in order to use its IsLoading and HasMoreItems properties.
DataContext = collection;

// XAML UI Element
<TextBlock Text="{Binding IsLoading, Converter={StaticResource StringFormatConverter}, ConverterParameter='Is Loading: {0}'}" />
<TextBlock Text="{Binding HasMoreItems, Converter={StaticResource StringFormatConverter}, ConverterParameter='Has More Items: {0}'}" />