WPF拖動繪製

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Shapes;
using System.Windows.Media;

namespace BrawDraw.Com.HandleAnEvent
{
    class HandleAnEvent
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            Window win = new Window();
            win.Title = "Handle An Event";
            win.MouseDown += WindowOnMouseDown;
            win.MouseMove += WindowOnMouseMove;
            win.MouseUp += WindowOnMouseUp;

            app.Run(win);
        }

        static Point startPoint;
        static Point endPoint;
        static bool isCapture = false;

        static void WindowOnMouseDown(object sender, MouseButtonEventArgs args)
        {
            Window win = sender as Window;
            startPoint = args.GetPosition(win);
            isCapture = true;
        }

        static void WindowOnMouseMove(object sender, MouseEventArgs args)
        {
            endPoint = args.GetPosition(sender as Wi</