Question

我创建了自己的CollectionView，支持我的要求分页。我创建了一个继承自CollectionView的版本，它在几乎所有场景中都可以正常运行。

现在，问题是当我 从列表中删除项目 时，它会按预期反映在用户界面中，但 中的项目视图未刷新 。我的意思是当我在视图中有5个项目时，如果我从列表中删除第4个项目，则第6个项目不会显示在页面上，现在只显示4个项目。

这是代码

PagingCollectionView.cs

public class PagingCollectionView : CollectionView
{
    private readonly IList _innerList;
    private readonly int _itemsPerPage;

    private int _currentPage = 1;

    public PagingCollectionView(IList innerList, int itemsPerPage)
        : base(innerList)
    {
        this._innerList = innerList;
        this._itemsPerPage = itemsPerPage;            
    }     

    public override int Count
    {
        get
        {
            if (this._currentPage < this.PageCount) // page 1..n-1
            {
                return this._itemsPerPage;
            }
            else // page n
            {
                var itemsLeft = this._innerList.Count % this._itemsPerPage;
                if (0 == itemsLeft)
                {
                    return this._itemsPerPage; // exactly itemsPerPage left
                }
                else
                {
                    // return the remaining items
                    return itemsLeft;
                }
            }
        }
    }      

    public int CurrentPage
    {
        get { return this._currentPage; }
        set
        {
            this._currentPage = value;
            this.OnPropertyChanged(new PropertyChangedEventArgs("CurrentPage"));
        }
    }

    public int ItemsPerPage { get { return this._itemsPerPage; } }

    public int PageCount
    {
        get
        {
            return (this._innerList.Count + this._itemsPerPage - 1)
                / this._itemsPerPage;
        }
    }

    private int EndIndex
    {
        get
        {
            var end = this._currentPage * this._itemsPerPage - 1;
            return (end > this._innerList.Count) ? this._innerList.Count : end;
        }
    }

    private int StartIndex
    {
        get { return (this._currentPage - 1) * this._itemsPerPage; }
    }

    public override object GetItemAt(int index)
    {
        var offset = index % (this._itemsPerPage);
        int iIndex = this.StartIndex + offset;

        if ((this._innerList != null) && (this._innerList.Count > 0) && (iIndex >= 0) && (iIndex <= this._innerList.Count))
            return this._innerList[iIndex];
        else
            return new object();
    }

    public void MoveToNextPage()
    {
        if (this._currentPage < this.PageCount)
        {
            this.CurrentPage += 1;
        }
        this.Refresh();
    }

    public void MoveToPreviousPage()
    {
        if (this._currentPage > 1)
        {
            this.CurrentPage -= 1;
        }
        this.Refresh();
    }

    public void MoveToPage(int pageno)
    {
        if (pageno > 0 && pageno <= this.PageCount)
        {
            this.CurrentPage = pageno;
        }
        this.Refresh();
    }

    public void RefreshCurrentPage()
    {
        this.Refresh();
    }
}

如何使用

MainWindow.xaml

<StackPanel>
    <ItemsControl ItemsSource="{Binding PagingSource}"/>         
    <Separator />
    <ItemsControl ItemsSource="{Binding List}" />
    <Button Width="150" Height="50" Click="Button_Click" Content="Remove an item from list" />

</StackPanel>

MainWindow.xaml.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        _list = new ObservableCollection<string> { "Item1", "Item2", "Item3", "Item4", "Item5", "Item6", "Item7" };            
        this.DataContext = this;
    }

    private ObservableCollection<string> _list;

    public ObservableCollection<string> List
    {
        get { return _list; }
        set { _list = value; }
    }

    private PagingCollectionView _pagingsource;      

    public PagingCollectionView PagingSource
    {
        get
        {
            _pagingsource = new PagingCollectionView(List, 5);                
            return _pagingsource;
        }
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        _list.RemoveAt(2);
    }
}

我已尝试过的内容：

当集合发生变化时，已经尝试刷新CollectionView。像这样的东西

    CollectionChanged += PagingCollectionView_CollectionChanged;         


    private void PagingCollectionView_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        Refresh();
    }

但结果是Stackoverflow Exception :(。

有关如何在此方案中刷新CollectionView的任何想法。

提前致谢。

Answer 1

在PagingCollectionView中添加它 - 您需要刷新集合：

＆＃13;

 protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs args)
        {
            base.OnCollectionChanged(args);
            switch (args.Action)
            {
                case NotifyCollectionChangedAction.Add:
                    
                    break;
                case NotifyCollectionChangedAction.Remove:
                    this.Refresh();
                    break;
                case NotifyCollectionChangedAction.Replace:
                    break;
                case NotifyCollectionChangedAction.Move:
                    break;
                case NotifyCollectionChangedAction.Reset:
                    break;
                default:
                    throw new ArgumentOutOfRangeException();
            }
        }

＆＃13;

如何在Collection Changed上手动刷新Custom CollectionView？

如何使用

我已尝试过的内容：

1 个答案: