86 lines
3.0 KiB
C#
86 lines
3.0 KiB
C#
using Microsoft.Xaml.Behaviors;
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using SamplePre.Models;
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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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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namespace SamplePreSystem.UI.Behaviors
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{
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public class TreeViewDragBehavior :Behavior<TreeView>
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{
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// 拖拽起始点（用于判断是否是有效拖拽）
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private Point _dragStartPoint;
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protected override void OnAttached()
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{
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//记录鼠标按下时的坐标
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AssociatedObject.PreviewMouseLeftButtonDown += AssociatedObject_PreviewMouseLeftButtonDown;
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//处理TreeView的鼠标移动事件，触发拖拽
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AssociatedObject.PreviewMouseMove += AssociatedObject_PreviewMouseMove;
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}
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/// <summary>
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/// 处理TreeView的鼠标移动事件，触发拖拽
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/// </summary>
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/// <param name="sender"></param>
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/// <param name="e"></param>
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/// <exception cref="NotImplementedException"></exception>
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private void AssociatedObject_PreviewMouseMove(object sender, System.Windows.Input.MouseEventArgs e)
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{
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// 获取当前鼠标位置
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Point currentPoint = e.GetPosition(null);
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// 计算鼠标移动的距离（过滤掉微小移动，避免误触发拖拽）
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Vector dragVector = _dragStartPoint - currentPoint;
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// 如果鼠标左键按下，且移动距离超过阈值（系统默认的拖拽阈值），则开始拖拽
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if (e.LeftButton == MouseButtonState.Pressed &&
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(Math.Abs(dragVector.X) > SystemParameters.MinimumHorizontalDragDistance ||
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Math.Abs(dragVector.Y) > SystemParameters.MinimumVerticalDragDistance))
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{
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// 获取当前鼠标下的TreeViewItem
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var treeViewItem = FindVisualParent<TreeViewItem>(e.OriginalSource as DependencyObject);
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if (treeViewItem != null && treeViewItem.DataContext is TreeListItem dragItem)
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{
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// 开始拖拽，设置拖拽数据和拖拽效果
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DragDrop.DoDragDrop(treeViewItem, dragItem, DragDropEffects.Copy);
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}
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}
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}
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/// <summary>
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/// 查找可视化树中的父级控件（通用方法）
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/// </summary>
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private T FindVisualParent<T>(DependencyObject child) where T : DependencyObject
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{
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DependencyObject parentObject = VisualTreeHelper.GetParent(child);
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if (parentObject == null) return null;
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if (parentObject is T parent)
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return parent;
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else
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return FindVisualParent<T>(parentObject);
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}
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private void AssociatedObject_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
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{
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// 记录鼠标按下时的坐标
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_dragStartPoint = e.GetPosition(null);
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}
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}
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}
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