• WPF数据视图

    将集合绑定到ItemsControl控件时，会不加通告的在后台创建数据视图——位于数据源和绑定的控件之间。数据视图是进入数据源的窗口，可以跟踪当前项，并且支持各种功能，如排序、过滤、分组。

    这些功能和数据对象本身是相互独立的，这意味着可在窗口的不同部分使用不同的方式绑定相同的数据。例如，可将同一个集合绑定到两个不同的列表，并对集合进行过滤以显示不同的记录。（来自于WPF编程宝典。我实测下来，绑定自同一个数据源的ItemsControl控件会共享一个View，当对该View进行筛选、排序时，会应用到所有绑定到该数据源的控件。）

    获取视图的方法：

    1. ListCollectionView? view = CollectionViewSource.GetDefaultView(filterListBox.ItemsSource) as ListCollectionView;
    2. ListCollectionView? view = CollectionViewSource.GetDefaultView(Orders) as ListCollectionView;

    可以看到，可以直接通过数据源来获取视图，这也表明，绑定到同一个数据源的控件会公用一个视图。

    视图有 MoveCurrentToPrevious()、MoveCurrentToNext() 方法，可以用于视图导航。

    1.     private void cmdPrev_Click(object sender, RoutedEventArgs e)
    2.     {
    3.         View?.MoveCurrentToPrevious();
    4.     }
    5.     private void cmdNext_Click(object sender, RoutedEventArgs e)
    6.     {
    7.         View?.MoveCurrentToNext();
    8.     }
    9.     private void view_CurrentChanged(object? sender, EventArgs e)
    10.     {
    11.         lblPosition.Text = "Record " + (View?.CurrentPosition + 1).ToString() + " of " + View?.Count.ToString();
    12.         cmdPrev.IsEnabled = View?.CurrentPosition > 0;
    13.         cmdNext.IsEnabled = View?.CurrentPosition < View?.Count - 1;
    14.     }

    视图排序

    1. View.SortDescriptions.Add(new SortDescription("Volume", ListSortDirection.Ascending));
    2. View.SortDescriptions.Add(new SortDescription("Price", ListSortDirection.Descending));

    视图分组

    1. "groupListBox" ItemsSource="{Binding Path=Orders}">
    2.     
    3.         
    4.             
    5.                 "{Binding Price}"> - "{Binding Volume}">
    6.             
    7.         
    8.     
    9.     
    10.         
    11.             
    12.                 
    13.                     "{Binding Path=Name}" FontWeight="Bold" Foreground="White" Background="LightGreen" Margin="0,5,0,0" Padding="3"/>
    14.                 
    15.             
    16.         
    17.     
    View.GroupDescriptions.Add(new PropertyGroupDescription("Volume"));

    视图过滤

    1. public class ProductByPriceFilterer
    2. {
    3.     public ProductByPriceFilterer(decimal minimumPrice)
    4.     {
    5.         MinimumPrice = minimumPrice;
    6.     }
    7.     public decimal MinimumPrice { get; set; }
    8.     public bool FilterItem(Object item)
    9.     {
    10.         Order? order = item as Order;
    11.         if (order != null)
    12.         {
    13.             return order.Price > MinimumPrice;
    14.         }
    15.         return false;
    16.     }
    17. }
    18. public partial class MainWindow : Window
    19. {
    20.     public MainWindow()
    21.     {
    22.         InitializeComponent();
    23.         View = (ListCollectionView)CollectionViewSource.GetDefaultView(Orders);
    24.         View.IsLiveFiltering = true;
    25.         View.LiveFilteringProperties.Add("Price");
    26.     }
    27.     public ObservableCollection Orders { get; set; } = new();
    28.     private ListCollectionView? View;
    29.     public decimal MinPrice { get; set; } = 200;
    30.     private ProductByPriceFilterer? filterer;
    31.     private void cmdFilter_Click(object sender, RoutedEventArgs e)
    32.     {
    33.         if (View != null)
    34.         {
    35.             filterer = new ProductByPriceFilterer(MinPrice);
    36.             View.Filter = new Predicate<object>(filterer.FilterItem);
    37.         }
    38.     }
    39.     private void cmdRemoveFilter_Click(object sender, RoutedEventArgs e)
    40.     {
    41.         if (View != null)
    42.         {
    43.             View.Filter = null;
    44.         }
    45.     }
    46. }

    完整代码文件：

    MainWindow.xaml

    1. "DataView.MainWindow"
    2.         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    3.         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    4.         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    5.         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    6.         xmlns:local="clr-namespace:DataView"
    7.         mc:Ignorable="d"
    8.         Title="MainWindow" Height="450" Width="800">
    9.     "myGrid">
    10.         
    11.             
    12.             
    13.         
    14.         
    15.             
    16.             
    17.             
    18.             "Auto"/>
    19.         
    20.  
    21.         "0" Grid.Column="0" >
    22.             "Horizontal">
    23.                 
    24.                 "lblPosition" VerticalAlignment="Center">
    25.                 
    26.             
    27.             "navigateListBox" DisplayMemberPath="Price" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Path=Orders}"/>
    28.         
    29.  
    30.         "0" Grid.Column="1" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
    31.             
    32.                 
    33.                     
    34.                     
    35.                 
    36.                 
    37.                     
    38.                     
    39.                 
    40.                 
    41.                 "0" Grid.Column="1" Text="{Binding Path=MinPrice}">
    42.                 
    43.                 
    44.             
    45.             "filterListBox" DisplayMemberPath="Price" ItemsSource="{Binding Path=Orders}"/>
    46.         
    47.  
    48.         "1" Grid.Column="0">
    49.             "groupListBox" ItemsSource="{Binding Path=Orders}">
    50.                 
    51.                     
    52.                         
    53.                             "{Binding Price}"> - "{Binding Volume}">
    54.                         
    55.                     
    56.                 
    57.                 
    58.                     
    59.                         
    60.                             
    61.                                 "{Binding Path=Name}" FontWeight="Bold" Foreground="White" Background="LightGreen" Margin="0,5,0,0" Padding="3"/>
    62.                             
    63.                         
    64.                     
    65.                 
    66.             
    67.         
    68.         
    69.         
    70.

    MainWindow.xaml.cs

    1. using System;
    2. using System.Collections.Generic;
    3. using System.Collections.ObjectModel;
    4. using System.ComponentModel;
    5. using System.Globalization;
    6. using System.Runtime.CompilerServices;
    7. using System.Windows;
    8. using System.Windows.Controls;
    9. using System.Windows.Data;
    10.  
    11. namespace DataView;
    12.  
    13. public class ViewModelBase : INotifyPropertyChanged
    14. {
    15.     public event PropertyChangedEventHandler? PropertyChanged;
    16.     protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
    17.     {
    18.         PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    19.     }
    20.     protected virtual bool SetProperty<T>(ref T member, T value, [CallerMemberName] string? propertyName = null)
    21.     {
    22.         if (EqualityComparer.Default.Equals(member, value))
    23.         {
    24.             return false;
    25.         }
    26.         member = value;
    27.         OnPropertyChanged(propertyName);
    28.         return true;
    29.     }
    30. }
    31. public class Order : ViewModelBase
    32. {
    33.     public decimal price = 0;
    34.     public decimal Price { get => price; set => SetProperty(ref price, value); }
    35.     public int volume = 0;
    36.     public int Volume { get => volume; set => SetProperty(ref volume, value); }
    37.  
    38.     public DateTime orderDate = DateTime.Now;
    39.     public DateTime OrderDate { get => orderDate; set => SetProperty(ref orderDate, value); }
    40.  
    41.     public string image = string.Empty;
    42.     public string Image { get => image; set => SetProperty(ref image, value); }
    43. }
    44. public class ProductByPriceFilterer
    45. {
    46.     public ProductByPriceFilterer(decimal minimumPrice)
    47.     {
    48.         MinimumPrice = minimumPrice;
    49.     }
    50.     public decimal MinimumPrice { get; set; }
    51.     public bool FilterItem(Object item)
    52.     {
    53.         Order? order = item as Order;
    54.         if (order != null)
    55.         {
    56.             return order.Price > MinimumPrice;
    57.         }
    58.         return false;
    59.     }
    60. }
    61. public class PriceRangeProductGrouper : IValueConverter
    62. {
    63.     public int GroupInterval { get; set; }
    64.     public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    65.     {
    66.         decimal price = (decimal)value;
    67.         if (price < GroupInterval)
    68.         {
    69.             return string.Format("Less than {0:C}", GroupInterval);
    70.         }
    71.         else
    72.         {
    73.             int interval = (int)price / GroupInterval;
    74.             int lowerLimit = interval * GroupInterval;
    75.             int upperLimit = (interval + 1) * GroupInterval;
    76.             return string.Format("{0:C} to {1:C}", lowerLimit, upperLimit);
    77.         }
    78.     }
    79.     public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    80.     {
    81.         throw new NotSupportedException("This converter is for grouping only.");
    82.     }
    83. }
    84. public partial class MainWindow : Window
    85. {
    86.     public MainWindow()
    87.     {
    88.         InitializeComponent();
    89.         myGrid.DataContext = this;
    90.  
    91.         InitOrders();
    92.         InitView();
    93.     }
    94.     public void InitOrders()
    95.     {
    96.         Order order1 = new Order();
    97.         Order order2 = new Order();
    98.         Order order3 = new Order();
    99.         Order order4 = new Order();
    100.  
    101.         order1.Price = 100;
    102.         order1.Volume = 100;
    103.         order1.Image = "image1.gif";
    104.  
    105.         order2.Price = 1000;
    106.         order2.Volume = 100;
    107.         order2.Image = "image2.gif";
    108.  
    109.         order3.Price = 10000;
    110.         order3.Volume = 10000;
    111.         order3.Image = "image3.gif";
    112.  
    113.         order4.Price = 100000;
    114.         order4.Volume = 10000;
    115.         order4.Image = "image4.gif";
    116.  
    117.         Orders.Add(order1);
    118.         Orders.Add(order2);
    119.         Orders.Add(order3);
    120.         Orders.Add(order4);
    121.     }
    122.     private void InitView()
    123.     {
    124.         View = (ListCollectionView)CollectionViewSource.GetDefaultView(Orders);
    125.         if(View != null)
    126.         {
    127.             View.CurrentChanged += new EventHandler(view_CurrentChanged);
    128.             View.SortDescriptions.Add(new SortDescription("Volume", ListSortDirection.Ascending));
    129.             View.SortDescriptions.Add(new SortDescription("Price", ListSortDirection.Descending));
    130.             View.GroupDescriptions.Add(new PropertyGroupDescription("Volume"));
    131.             View.IsLiveFiltering = true;
    132.             View.LiveFilteringProperties.Add("Price");
    133.         }
    134.     }
    135.     public ObservableCollection Orders { get; set; } = new();
    136.     private ListCollectionView? View;
    137.     private void cmdPrev_Click(object sender, RoutedEventArgs e)
    138.     {
    139.  
    140.         View?.MoveCurrentToPrevious();
    141.     }
    142.     private void cmdNext_Click(object sender, RoutedEventArgs e)
    143.     {
    144.         View?.MoveCurrentToNext();
    145.     }
    146.     private void view_CurrentChanged(object? sender, EventArgs e)
    147.     {
    148.         lblPosition.Text = "Record " + (View?.CurrentPosition + 1).ToString() + " of " + View?.Count.ToString();
    149.         cmdPrev.IsEnabled = View?.CurrentPosition > 0;
    150.         cmdNext.IsEnabled = View?.CurrentPosition < View?.Count - 1;
    151.     }
    152.  
    153.     public decimal MinPrice { get; set; } = 200;
    154.     private ProductByPriceFilterer? filterer;
    155.     private void cmdFilter_Click(object sender, RoutedEventArgs e)
    156.     {
    157.         if (View != null)
    158.         {
    159.             filterer = new ProductByPriceFilterer(MinPrice);
    160.             View.Filter = new Predicate<object>(filterer.FilterItem);
    161.         }
    162.     }
    163.     private void cmdRemoveFilter_Click(object sender, RoutedEventArgs e)
    164.     {
    165.         if (View != null)
    166.         {
    167.             View.Filter = null;
    168.         }
    169.     }
    170.  
    171.     private void IncreaseButton_Click(object sender, RoutedEventArgs e)
    172.     {
    173.         foreach(var order in Orders)
    174.         {
    175.             order.Price *= 10;
    176.         }
    177.     }
    178.     private void DecreaseButton_Click(object sender, RoutedEventArgs e)
    179.     {
    180.         foreach (var order in Orders)
    181.         {
    182.             order.Price /= 10;
    183.         }
    184.     }
    185. }

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  • 原文地址：https://blog.csdn.net/xunmeng2002/article/details/132617593