Routed Input Enents（1）译

wpf程序展示了鼠标捕捉和许多鼠标事件。

效果图如下：左键可以画圆，右键可以拖动，滚轮可以改变颜色

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;

namespace WpfApplication4
{
    /// <summary>
    /// Window1.xaml 的交互逻辑
    /// </summary>
    public partial class Window1 : Window
    {
       
        //绘图相关的字段
        bool isDrawing;
        Ellipse elips;
        Point ptCenter;
        //拖拽相关的字段
        bool isDragging;
        FrameworkElement elDragging;
        Point ptMouseStart, ptElementStart;
        public Window1()
        {
            InitializeComponent();
            Title = "draw circles";

        
           
        }
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new Window1());
        }

        protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonDown(e);
            if (isDragging)
                return;
            //创建一个新的ellipse对象，并加入canvas中

            ptCenter = e.GetPosition(canv);
            label1.Content ="根据鼠标左键点击获得"+ ptCenter.X.ToString() +"//" +ptCenter.Y.ToString();
            elips = new Ellipse();
            elips.Stroke = SystemColors.WindowBrush;
            elips.StrokeThickness = 1;
            elips.Width = 10;
            elips.Height =10;
            canv.Children.Add(elips);
            Canvas.SetLeft(elips,ptCenter.X);
            Canvas.SetTop(elips,ptCenter.Y);

            CaptureMouse();
            isDrawing = true;
        }

        protected override void OnMouseRightButtonDown(MouseButtonEventArgs e)
        {
            base.OnMouseRightButtonDown(e);
            if (isDrawing)
            {
                return;
            }
            ptMouseStart = e.GetPosition(canv);
            label2.Content = "根据鼠标右键获取鼠标初始值" + ptMouseStart.X.ToString() + "//" + ptMouseStart.Y;
            elDragging = canv.InputHitTest(ptMouseStart) as FrameworkElement;
            if (elDragging != null)
            {
                ptElementStart = new Point(Canvas.GetLeft(elDragging),Canvas.GetTop(elDragging));
               // label3.Content = "获取元素的初始位置" + ptElementStart.X + "//" + ptElementStart.Y;
                label3.Content = "获取元素的初始位置" + Canvas.GetLeft(elDragging).ToString() + "//" + Canvas.GetTop(elDragging).ToString();
                isDragging = true;
            }
        }

        protected override void OnMouseDown(MouseButtonEventArgs e)
        {
            base.OnMouseDown(e);
            if (e.ChangedButton == MouseButton.Middle)
            {
                Shape shape = canv.InputHitTest(e.GetPosition(canv)) as Shape;
                if (shape != null)
                {
                    shape.Fill=(shape.Fill==Brushes.Red?Brushes.Transparent:Brushes.Red);
                }
            }
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);
            Point ptMouse = e.GetPosition(canv);
            //改变椭圆的位置和尺寸

            if (isDrawing)
            {
                double dRadius = Math.Sqrt(Math.Pow(ptCenter.X-ptMouse.X,2)+Math.Pow(ptCenter.Y-ptMouse.Y,2));
                Canvas.SetLeft(elips,ptCenter.X-dRadius);
                Canvas.SetTop(elips,ptCenter.Y-dRadius);
                elips.Width = 2 * dRadius;
                elips.Height = 2 * dRadius;

               

            }
            else if (isDragging)
            {
                Canvas.SetLeft(elDragging,ptElementStart.X+ptMouse.X- ptMouseStart.X);

                Canvas.SetTop(elDragging,ptElementStart.Y+ptMouse.Y-ptElementStart.Y);
                label4.Content = ptElementStart.Y.ToString() +"//"+ ptMouse.Y.ToString() +"//"+ ptElementStart.Y.ToString();
            }
        }

        protected override void OnMouseUp(MouseButtonEventArgs e)
        {
            base.OnMouseUp(e);
            //结束绘图操作
            if (isDrawing && e.ChangedButton == MouseButton.Left)
            {
                elips.Stroke = Brushes.Blue;
                elips.StrokeThickness = 2;// Math.Min(24,elips.Width/2);
                elips.Fill = Brushes.Red;
                isDrawing = false;
                ReleaseMouseCapture();
            }
            // 结束捕捉操作
            else if (isDragging && e.ChangedButton == MouseButton.Right)
            {
                isDragging = false;

            }
        }
        protected override void OnTextInput(TextCompositionEventArgs e)
        {
            base.OnTextInput(e);
            //接下escape，结束绘图或拖拽
            if(e.Text.IndexOf('\x1B')!=-1)
            {
                if (isDrawing)
                    ReleaseMouseCapture();
                else if (isDragging)
                {
                    Canvas.SetLeft(elDragging,ptElementStart.X);
                    Canvas.SetTop(elDragging,ptElementStart.Y);
                    isDragging = false;
                }
            }
        }
        protected override void OnLostMouseCapture(MouseEventArgs e)
        {
            base.OnLostMouseCapture(e);

            //不正常结束绘图，将此ellipse从孩子中删除

            if (isDrawing)
            {
                canv.Children.Remove(elips);
                isDrawing = false;
            }
        }
        

     
    }
}