wpf拖拽封装类

<UserControl x:Class="WpfApplication1.DragItem"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" MouseDown="UserControl_MouseDown_1">
    <Grid Background="#FF191919" HorizontalAlignment="Center" VerticalAlignment="Center">
        <Label  Content="项目文字" Foreground="White" FontSize="16" Width="450" Height="36" VerticalContentAlignment="Center" BorderThickness="2" BorderBrush="#FF424242"/>
    </Grid>
</UserControl>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
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;

namespace WpfApplication1
{
    /// <summary>
    /// DragItem.xaml 的交互逻辑
    /// </summary>
    public partial class DragItem : UserControl
    {
        public static Point dragDownMousePoint;
        public static Point dragDownControlPoint;

        public DragItem()
        {
            InitializeComponent();
        }

        public DragItem(string content)
        {
            InitializeComponent();
            this.Content.Content = content;   
        }

        private void mouseMove(object sender, MouseEventArgs e)
        {
            Window w = Window.GetWindow(this);
            Point p = e.GetPosition(w);

            double moveX = p.X - dragDownMousePoint.X;
            double moveY = p.Y - dragDownMousePoint.Y;

            Point targetPoint = new Point(dragDownControlPoint.X + moveX, dragDownControlPoint.Y + moveY);
            if (double.IsNaN(dragDownControlPoint.X))
            {
                targetPoint.X = moveX;
            }
            if (double.IsNaN(dragDownControlPoint.Y))
            {
                targetPoint.Y = moveY;
            }

            Canvas parent = (Canvas)this.Parent;

            if (targetPoint.X < 0)
            {
                Canvas.SetLeft(this, 0);
            }
            else if (targetPoint.X + this.ActualWidth > parent.ActualWidth)
            {
                Canvas.SetLeft(this, parent.ActualWidth - this.ActualWidth);
            }
            else
            {
                Canvas.SetLeft(this, targetPoint.X);
            }

            if (targetPoint.Y< 0)
            {
                Canvas.SetTop(this, 0);
            }
            else if (targetPoint.Y + this.ActualHeight > parent.ActualHeight)
            {
                Canvas.SetTop(this, parent.ActualHeight - this.ActualHeight);
            }
            else
            {
                Canvas.SetTop(this, targetPoint.Y);
            }
            Console.WriteLine(targetPoint.X + this.ActualWidth + "    " + parent.ActualWidth);
        }

        private void mouseUp(object sender, MouseEventArgs e)
        {
            Mouse.RemoveMouseMoveHandler(Window.GetWindow(this), mouseMove);
            Mouse.RemoveMouseUpHandler(Window.GetWindow(this), mouseUp);
            Mouse.Capture(null);
        }

        private void UserControl_MouseDown_1(object sender, MouseButtonEventArgs e)
        {
            Point p = e.GetPosition(Window.GetWindow(this));
            dragDownMousePoint = p;
            dragDownControlPoint = new Point(Canvas.GetLeft(this), Canvas.GetTop(this));

            Mouse.AddMouseMoveHandler(Window.GetWindow(this), mouseMove);
            Mouse.AddMouseUpHandler(Window.GetWindow(this), mouseUp);
            Mouse.Capture(this);
        }

        private void Label_Loaded_1(object sender, RoutedEventArgs e)
        {

        }
    }
}