122 lines
3.7 KiB
C#
122 lines
3.7 KiB
C#
using System;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Input;
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using System.Windows.Media;
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using System.Windows.Threading;
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namespace OrderSupportTicket.Behaviors;
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/// <summary>
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/// 仅承载视图交互：列表点击命令、消息列表滚动到底部。
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/// </summary>
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public static class ListBoxInteractionBehavior
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{
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public static readonly DependencyProperty SelectedItemCommandProperty =
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DependencyProperty.RegisterAttached(
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"SelectedItemCommand",
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typeof(ICommand),
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typeof(ListBoxInteractionBehavior),
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new PropertyMetadata(null, OnSelectedItemCommandChanged));
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public static readonly DependencyProperty ScrollVersionProperty =
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DependencyProperty.RegisterAttached(
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"ScrollVersion",
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typeof(int),
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typeof(ListBoxInteractionBehavior),
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new PropertyMetadata(0, OnScrollVersionChanged));
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public static void SetSelectedItemCommand(DependencyObject element, ICommand value)
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{
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element.SetValue(SelectedItemCommandProperty, value);
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}
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public static ICommand GetSelectedItemCommand(DependencyObject element)
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{
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return (ICommand)element.GetValue(SelectedItemCommandProperty);
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}
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public static void SetScrollVersion(DependencyObject element, int value)
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{
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element.SetValue(ScrollVersionProperty, value);
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}
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public static int GetScrollVersion(DependencyObject element)
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{
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return (int)element.GetValue(ScrollVersionProperty);
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}
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private static void OnSelectedItemCommandChanged(
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DependencyObject d,
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DependencyPropertyChangedEventArgs e)
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{
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if (!(d is ListBox listBox))
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return;
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listBox.PreviewMouseLeftButtonUp -= OnPreviewMouseLeftButtonUp;
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listBox.PreviewKeyUp -= OnPreviewKeyUp;
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if (e.NewValue is ICommand)
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{
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listBox.PreviewMouseLeftButtonUp += OnPreviewMouseLeftButtonUp;
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listBox.PreviewKeyUp += OnPreviewKeyUp;
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}
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}
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private static void OnPreviewMouseLeftButtonUp(
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object sender,
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MouseButtonEventArgs e)
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{
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ExecuteForSelectedItem(sender as ListBox);
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}
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private static void OnPreviewKeyUp(object sender, KeyEventArgs e)
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{
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if (e.Key != Key.Enter && e.Key != Key.Space)
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return;
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ExecuteForSelectedItem(sender as ListBox);
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}
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private static void ExecuteForSelectedItem(ListBox listBox)
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{
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if (listBox == null || listBox.SelectedItem == null)
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return;
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var command = GetSelectedItemCommand(listBox);
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if (command != null && command.CanExecute(listBox.SelectedItem))
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command.Execute(listBox.SelectedItem);
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}
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private static void OnScrollVersionChanged(
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DependencyObject d,
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DependencyPropertyChangedEventArgs e)
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{
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if (!(d is ListBox listBox))
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return;
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listBox.Dispatcher.BeginInvoke(
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new Action(() =>
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{
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var scrollViewer = FindVisualChild<ScrollViewer>(listBox);
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if (scrollViewer != null)
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scrollViewer.ScrollToEnd();
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}),
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DispatcherPriority.Background);
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}
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private static T FindVisualChild<T>(DependencyObject parent)
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where T : DependencyObject
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{
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if (parent == null)
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return null;
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for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
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{
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var child = VisualTreeHelper.GetChild(parent, i);
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if (child is T match)
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return match;
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var nested = FindVisualChild<T>(child);
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if (nested != null)
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return nested;
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}
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return null;
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}
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}
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