wpf - 如何对 WPF DataGrid 进行分页？

Question

如何在 wpf 中设置分页DataGrid？

Answer 1

上面的代码项目文章非常适合使用 ADO 表完成此操作。虽然对于大多数应用程序来说，它可能工作得很好，而且很容易理解，但也有一种更“类似于 WPF zen”的方式来做到这一点，那就是使用 CollectionViews。与上面的示例相比，使用 CollectionView 的优势在于，它在您放入网格中的数据方面更加通用（并不是说您不能使该示例更通用），并且非常适合使用通用的 WPF 数据绑定模型。如果您需要，它为您提供了一个支持常见操作（如排序、分组等）的地方。

我整理了一个非常简短的示例，说明绑定到 .NET 4.0 DataGrid 控件的几乎无法正常工作的 PagingCollectionView。尽管该示例本身非常简单，但它至少向您展示了如何开始，因为您有一个围绕实际数据集合的代理，您可以在该代理上执行诸如 MoveToNextPage 和 MoveToPreviousPage 之类的简单操作。

这是 Window 事件处理和 PagingCollectionView 的 C#：

using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using System.Windows.Data;

namespace GridPagingExample
{
    public partial class MainWindow : Window
    {
        private readonly PagingCollectionView _cview;

        public MainWindow()
        {
            InitializeComponent();
            this._cview = new PagingCollectionView(
                new List<object>
                {
                    new { Animal = "Lion", Eats = "Tiger" },
                    new { Animal = "Tiger", Eats =  "Bear" },
                    new { Animal = "Bear", Eats = "Oh my" },
                    new { Animal = "Wait", Eats = "Oh my isn't an animal" },
                    new { Animal = "Oh well", Eats = "Who is counting anyway" },
                    new { Animal = "Need better content", Eats = "For posting on stackoverflow" }
                },
                2
            );
            this.DataContext = this._cview;
        }

        private void OnNextClicked(object sender, RoutedEventArgs e)
        {
            this._cview.MoveToNextPage();
        }

        private void OnPreviousClicked(object sender, RoutedEventArgs e)
        {
            this._cview.MoveToPreviousPage();
        }
    }

    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._innerList.Count == 0) return 0;
                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); 
            return this._innerList[this.StartIndex + offset];
        }

        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();
        }
    }
}

这是窗口的 XAML：

<Window x:Class="GridPagingExample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <StackPanel Orientation="Horizontal" Grid.Row="0">
            <Label Grid.Row="0" Margin="2">
                <Label.Content>
                    <Binding Path="CurrentPage">
                        <Binding.StringFormat>Current Page: {0}</Binding.StringFormat>
                    </Binding>
                </Label.Content>
            </Label>
            <Button Content="Next" Click="OnNextClicked" Margin="2"/>
            <Button Content="Previous" Click="OnPreviousClicked" Margin="2"/>
        </StackPanel>
        <DataGrid ItemsSource="{Binding}" Grid.Row="1">
            <DataGrid.Columns>
                <DataGridTextColumn Header="Animal" Width="*" Binding="{Binding Animal}"/>
                <DataGridTextColumn Header="Eats" Width="*" Binding="{Binding Eats}"/>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

您可以构建此 CollectionView 以支持更多功能，一些微不足道的功能，如 MoveToLastPage 和 MoveToFirstPage，以及一些需要更多考虑您希望它如何表现的功能，例如排序。希望它是有帮助的。