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 Window);

            if (isCapture)

            {

                DrawRectangle(sender); //这里隐藏与不隐藏时差别很大,特别是鼠标的最后位置与开始位置的相对位移为负时,特征更加明显。

            }

        }

        static void WindowOnMouseUp(object sender, MouseButtonEventArgs args)

        {

            isCapture = false;

            DrawRectangle(sender);

        }

        static void DrawRectangle(object sender)

        {

            #region DoStartEndPointPlace

            Point tmpPoint = startPoint;

            if (endPoint.X < startPoint.X)

            {

                startPoint.X = endPoint.X;

                endPoint.X = tmpPoint.X;

            }

            if (endPoint.Y < startPoint.Y)

            {

                startPoint.Y = endPoint.Y;

                endPoint.Y = tmpPoint.Y;

            }

            #endregion DoStartEndPointPlace

            Window win = sender as Window;

            Rectangle rect = new Rectangle();

            rect.Stroke = Brushes.Black;

            rect.Fill = Brushes.SkyBlue;

            rect.HorizontalAlignment = HorizontalAlignment.Left;

            rect.VerticalAlignment = VerticalAlignment.Center;

            rect.Height = Math.Abs(endPoint.Y - startPoint.Y);

            rect.Width = Math.Abs(endPoint.X - startPoint.X);

            Canvas canvas = new Canvas();

            Canvas.SetLeft(rect, startPoint.X);

            Canvas.SetTop(rect, startPoint.Y);

            canvas.Children.Add(rect);

            win.Content = canvas;

        }

    }

}