









Install-Package Microsoft.Xamls.Behavior.WPF
public class ListBoxSyncScrollBehavior : Behavior<ListBox> { static Dictionary<string, ScrollViewer> scrollViewerCache = new Dictionary<string, ScrollViewer>(); public ListBox SourceObj { get { return (ListBox)GetValue(SourceObjProperty); } set { SetValue(SourceObjProperty, value); } } // Using a DependencyProperty as the backing store for SourceObj. This enables animation, styling, binding, etc... public static readonly DependencyProperty SourceObjProperty = DependencyProperty.Register( nameof(SourceObj), typeof(ListBox), typeof(ListBoxSyncScrollBehavior), new PropertyMetadata(null)); protected override void OnAttached() { base.OnAttached(); AssociatedObject.Loaded += AssociatedObject_Loaded; AssociatedObject.Unloaded += AssociatedObject_Unloaded; } private void AssociatedObject_Unloaded(object sender, RoutedEventArgs e) { scrollViewerCache.Clear(); } private void AssociatedObject_Loaded(object sender, RoutedEventArgs e) { if (!scrollViewerCache.ContainsKey(AssociatedObject.Name)) { var scrollViewer = GetScrollViewer(AssociatedObject); if (scrollViewer != null) { scrollViewer.Name = AssociatedObject.Name; scrollViewerCache.Add(AssociatedObject.Name, scrollViewer); scrollViewer.ScrollChanged += ScrollViewer_ScrollChanged; } } } private void ScrollViewer_ScrollChanged(object sender, ScrollChangedEventArgs e) { var srcScrollViewer = sender as ScrollViewer; if (srcScrollViewer != null) { foreach (var de in scrollViewerCache) { if (de.Key != srcScrollViewer.Name) { var targetScrollViewer = scrollViewerCache[de.Key] as ScrollViewer; if (targetScrollViewer != null) { targetScrollViewer.ScrollToVerticalOffset(srcScrollViewer.VerticalOffset); targetScrollViewer.ScrollToHorizontalOffset(srcScrollViewer.HorizontalOffset); } } } } } protected override void OnDetaching() { base.OnDetaching(); } private ScrollViewer GetScrollViewer(DependencyObject dpObj) { int cnt = VisualTreeHelper.GetChildrenCount(dpObj); for (int i = 0; i < cnt; i++) { var obj = VisualTreeHelper.GetChild(dpObj, i); if (obj is ScrollViewer scrollViewer) { return scrollViewer; } var result = GetScrollViewer(obj) as ScrollViewer; if (result != null) { return result; } } return null; } }
//WPF <Window x:Class="WpfApp2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:behavior="http://schemas.microsoft.com/xaml/behaviors" xmlns:local="clr-namespace:WpfApp2" mc:Ignorable="d" Title="{Binding MainTitle}" WindowState="Maximized"> <Window.DataContext> <local:MainVM/> </Window.DataContext> <Window.Resources> <Style TargetType="TextBlock" x:Key="TbkStyle"> <Setter Property="FontSize" Value="30"/> <Style.Triggers> <Trigger Property="IsMouseOver" Value="True"> <Setter Property="Foreground" Value="Red"/> <Setter Property="FontWeight" Value="ExtraBold"/> </Trigger> </Style.Triggers> </Style> <DataTemplate DataType="{x:Type local:Book}" x:Key="BookDataTemplate"> <Grid MinHeight="150" Margin="10,50,10,50"> <Grid.Resources> <Style TargetType="TextBlock" BasedOn="{StaticResource TbkStyle}"/> </Grid.Resources> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition/> <RowDefinition/> <RowDefinition/> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <TextBlock Text="{Binding Id}" Grid.Row="0" Grid.Column="0"/> <TextBlock Text="{Binding Name}" Grid.Row="0" Grid.Column="1"/> <TextBlock Text="{Binding Author}" Grid.Row="0" Grid.Column="2"/> <TextBlock Text="{Binding CategoryName}" Grid.Row="1" Grid.Column="0"/> <TextBlock Text="{Binding Comment}" Grid.Row="1" Grid.Column="1"/> <TextBlock Text="{Binding Content}" Grid.Row="1" Grid.Column="2"/> <TextBlock Text="{Binding Summary}" Grid.Row="2" Grid.Column="0"/> <TextBlock Text="{Binding Title}" Grid.Row="2" Grid.Column="1"/> <TextBlock Text="{Binding Topic}" Grid.Row="2" Grid.Column="2"/> <TextBlock Text="{Binding ISBN}" Grid.Row="3" Grid.Column="0" Grid.ColumnSpan="3"/> </Grid> </DataTemplate> </Window.Resources> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <!--<ItemsControl Grid.Column="0" BorderBrush="LightBlue" BorderThickness="5" ItemsSource="{Binding BksCollection}" VirtualizingPanel.IsVirtualizing="True" VirtualizingPanel.VirtualizationMode="Recycling" VirtualizingPanel.CacheLengthUnit="Item" VirtualizingPanel.CacheLength="5,5"> <ItemsControl.Template> <ControlTemplate TargetType="ItemsControl"> <Border> <ScrollViewer> <ItemsPresenter/> </ScrollViewer> </Border> </ControlTemplate> </ItemsControl.Template> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <VirtualizingStackPanel IsItemsHost="True"/> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> <ItemsControl.ItemTemplate> <StaticResource ResourceKey="BookDataTemplate"/> </ItemsControl.ItemTemplate> </ItemsControl>--> <ListBox Grid.Column="0" x:Name="lbx1" BorderBrush="LightCyan" BorderThickness="5" ItemsSource="{Binding BksCollection}" VirtualizingPanel.IsVirtualizing="True" VirtualizingPanel.VirtualizationMode="Recycling" VirtualizingPanel.CacheLength="5,5" VirtualizingPanel.CacheLengthUnit="Item" ItemTemplate="{StaticResource BookDataTemplate}" > <behavior:Interaction.Behaviors> <local:ListBoxSyncScrollBehavior SourceObj="{Binding ElementName=lbx1}"/> </behavior:Interaction.Behaviors> </ListBox> <ListBox Grid.Column="1" x:Name="lbx2" BorderBrush="LightCyan" BorderThickness="5" ItemsSource="{Binding BksCollection}" VirtualizingPanel.IsVirtualizing="True" VirtualizingPanel.VirtualizationMode="Recycling" VirtualizingPanel.CacheLength="5,5" VirtualizingPanel.CacheLengthUnit="Item" ItemTemplate="{StaticResource BookDataTemplate}"> <behavior:Interaction.Behaviors> <local:ListBoxSyncScrollBehavior SourceObj="{Binding ElementName=lbx2}"/> </behavior:Interaction.Behaviors> </ListBox> </Grid> </Window> //cs using System.Collections; using System.Collections.ObjectModel; using System.ComponentModel; using System.Net.Http; using System.Runtime.CompilerServices; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; using Microsoft.Xaml.Behaviors; using Newtonsoft.Json; namespace WpfApp2 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } } public class MainVM : INotifyPropertyChanged { private static HttpClient client = new HttpClient() { Timeout = TimeSpan.FromHours(1) }; private string url = "http://localhost:5000/api/book/getbooks/"; private bool isLoading = false; public MainVM() { if (!DesignerProperties.GetIsInDesignMode(new DependencyObject())) { _ = LoadDataAsync(1000000); } } private async Task LoadDataAsync(int cnt = 1000000) { if (isLoading) { return; } isLoading = true; try { MainTitle = $"{DateTime.Now},loading..."; string jsonStr = await client.GetStringAsync($"{url}{cnt}"); List<Book> bks = JsonConvert.DeserializeObject<List<Book>>(jsonStr); if (bks != null && bks.Any()) { BksCollection = new ObservableCollection<Book>(bks); MainTitle = $"{DateTime.Now},loaded {BksCollection.Count} items,FirstId:{BksCollection.FirstOrDefault()?.Id}," + $"LastId:{BksCollection.LastOrDefault()?.Id}"; System.Diagnostics.Debug.WriteLine(MainTitle); } } catch (Exception ex) { MessageBox.Show(ex?.Message); } finally { isLoading = false; } } private ObservableCollection<Book> bksCollection; public ObservableCollection<Book> BksCollection { get { return bksCollection; } set { if (value != bksCollection) { bksCollection = value; OnPropertyChanged(); } } } private string mainTitle = $"{DateTime.Now}"; public string MainTitle { get { return mainTitle; } set { if (value != mainTitle) { mainTitle = value; OnPropertyChanged(); } } } public event PropertyChangedEventHandler? PropertyChanged; private void OnPropertyChanged([CallerMemberName] string propName = "") { var handler = Volatile.Read(ref PropertyChanged); if (handler == null) { return; } handler(this, new PropertyChangedEventArgs(propName)); } } public class Book { public long Id { get; set; } public string Name { get; set; } public string Author { get; set; } public string CategoryName { get; set; } public string Comment { get; set; } public string Content { get; set; } public string ISBN { get; set; } public string Summary { get; set; } public string Title { get; set; } public string Topic { get; set; } } public class ListBoxSyncScrollBehavior : Behavior<ListBox> { static Dictionary<string, ScrollViewer> scrollViewerCache = new Dictionary<string, ScrollViewer>(); public ListBox SourceObj { get { return (ListBox)GetValue(SourceObjProperty); } set { SetValue(SourceObjProperty, value); } } // Using a DependencyProperty as the backing store for SourceObj. This enables animation, styling, binding, etc... public static readonly DependencyProperty SourceObjProperty = DependencyProperty.Register( nameof(SourceObj), typeof(ListBox), typeof(ListBoxSyncScrollBehavior), new PropertyMetadata(null)); protected override void OnAttached() { base.OnAttached(); AssociatedObject.Loaded += AssociatedObject_Loaded; AssociatedObject.Unloaded += AssociatedObject_Unloaded; } private void AssociatedObject_Unloaded(object sender, RoutedEventArgs e) { scrollViewerCache.Clear(); } private void AssociatedObject_Loaded(object sender, RoutedEventArgs e) { if (!scrollViewerCache.ContainsKey(AssociatedObject.Name)) { var scrollViewer = GetScrollViewer(AssociatedObject); if (scrollViewer != null) { scrollViewer.Name = AssociatedObject.Name; scrollViewerCache.Add(AssociatedObject.Name, scrollViewer); scrollViewer.ScrollChanged += ScrollViewer_ScrollChanged; } } } private void ScrollViewer_ScrollChanged(object sender, ScrollChangedEventArgs e) { var srcScrollViewer = sender as ScrollViewer; if (srcScrollViewer != null) { foreach (var de in scrollViewerCache) { if (de.Key != srcScrollViewer.Name) { var targetScrollViewer = scrollViewerCache[de.Key] as ScrollViewer; if (targetScrollViewer != null) { targetScrollViewer.ScrollToVerticalOffset(srcScrollViewer.VerticalOffset); targetScrollViewer.ScrollToHorizontalOffset(srcScrollViewer.HorizontalOffset); } } } } } protected override void OnDetaching() { base.OnDetaching(); } private ScrollViewer GetScrollViewer(DependencyObject dpObj) { int cnt = VisualTreeHelper.GetChildrenCount(dpObj); for (int i = 0; i < cnt; i++) { var obj = VisualTreeHelper.GetChild(dpObj, i); if (obj is ScrollViewer scrollViewer) { return scrollViewer; } var result = GetScrollViewer(obj) as ScrollViewer; if (result != null) { return result; } } return null; } } }



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