如何对 ObservableCollection 进行分页？

发布于 2024-07-10 16:27:54 字数 193 浏览 6 评论 0原文

我有一个列表框，里面有太多项目，并且 UI 变得越来越慢（虚拟化已打开，等等）。因此，我正在考虑仅显示前 20 个项目并允许用户浏览结果集（即 ObservableCollection）。

有人知道 ObservableCollection 是否存在分页机制吗？有人以前这样做过吗？

谢谢！

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春风十里 2024-07-17 16:27:55

此功能在 ObservableCollection 基类中不能直接使用。您可以扩展 ObservableCollection 并创建一个自定义集合来执行此操作。您需要将原始 Collection 隐藏在这个新类中，并根据 FromIndex 和 ToIndex 动态地将项目范围添加到该类中。重写InsertItem 和RemoveItem。我在下面给出了一个未经测试的版本。但请将此视为伪代码。

 //This class represents a single Page collection, but have the entire items available in the originalCollection
public class PaginatedObservableCollection : ObservableCollection<object>
{
    private ObservableCollection<object> originalCollection;

    public int CurrentPage { get; set; }
    public int CountPerPage { get; set; }

    protected override void InsertItem(int index, object item)
    {
        //Check if the Index is with in the current Page then add to the collection as bellow. And add to the originalCollection also
        base.InsertItem(index, item);
    }

    protected override void RemoveItem(int index)
    {
        //Check if the Index is with in the current Page range then remove from the collection as bellow. And remove from the originalCollection also
        base.RemoveItem(index);
    }
}

更新：我在这里有一篇关于此主题的博客文章 - http://jobijoy .blogspot.com/2008/12/pagination-observablecollection.html 并将源代码上传到 Codeplex 。

This facility is not directly available in the base ObservableCollecton class. You can extend the ObservableCollection and create a custom Collection which does this. You need to hide the original Collection inside this new class and based on a FromIndex and ToIndex give dynamically add the range of items to the class. Override InsertItem and RemoveItem. I am giving a not-tested version bellow. But please take this as just pseudo code.

 //This class represents a single Page collection, but have the entire items available in the originalCollection
public class PaginatedObservableCollection : ObservableCollection<object>
{
    private ObservableCollection<object> originalCollection;

    public int CurrentPage { get; set; }
    public int CountPerPage { get; set; }

    protected override void InsertItem(int index, object item)
    {
        //Check if the Index is with in the current Page then add to the collection as bellow. And add to the originalCollection also
        base.InsertItem(index, item);
    }

    protected override void RemoveItem(int index)
    {
        //Check if the Index is with in the current Page range then remove from the collection as bellow. And remove from the originalCollection also
        base.RemoveItem(index);
    }
}

UPDATE: I have a blog post about this topic on here - http://jobijoy.blogspot.com/2008/12/paginated-observablecollection.html and the source code is uploaded to Codeplex.

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