WPF 拖拽功能

using System;
using System.Collections.Generic;
using System.Linq;
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 System.Data;

namespace WpfApplication1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
Point startPoint;
ListBoxItem contact;

public MainWindow()
{
InitializeComponent();
}

private static T FindAnchestor<T>(DependencyObject current) where T : DependencyObject
{
do
{
if (current is T)
{
return (T)current;
}
current = VisualTreeHelper.GetParent(current);
}
while (current != null);

return null;
}

private void listView1_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
startPoint = e.GetPosition(null);
}

private void listView1_PreviewMouseMove(object sender, MouseEventArgs e)
{
Point mousPos = e.GetPosition(null);
Vector diff = startPoint - mousPos;

if ((e.LeftButton == MouseButtonState.Pressed) && (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance) && (Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
{
ListViewItem listViewItem = FindAnchestor<ListViewItem>((DependencyObject)e.OriginalSource);
if (listViewItem == null) { return; }

ListView listView = sender as ListView;
contact = (ListViewItem)listView.ItemContainerGenerator.ItemFromContainer(listViewItem);
DataObject dataObject = new DataObject("MyFormat", contact);
DragDrop.DoDragDrop(listViewItem, dataObject, DragDropEffects.Move);
}
}

private void canvas1_Drop(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent("MyFormat"))
{
contact = e.Data.GetData("MyFormat") as ListBoxItem;
Canvas CanvasView = sender as Canvas;
this.listView1.Items.Remove(contact);
CanvasView.Children.Add(contact);
}
}

private void canvas1_DragEnter(object sender, DragEventArgs e)
{
if (!(e.Data.GetDataPresent("contact")) || (sender == e.Source))
{
e.Effects = DragDropEffects.None;
}
}
}
}