求解释代码，越详细越好

    public MyCanvas()
        {
            InitializeComponent();
            this.Loaded += new RoutedEventHandler(MyCanvas_Loaded);

            this.scrollViewer.AddHandler(Image.MouseMoveEvent, new MouseEventHandler(newImage_MouseMove), true);


        }


        /// <summary>
        /// 用于在画布上拖动控件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void newImage_MouseMove(object sender, MouseEventArgs e)
        {


            if (MouseButtonState.Pressed != Mouse.LeftButton)
            {
                return;
            }

            MyImage image = e.Source as MyImage;
            if (image == null)
            {
                return;
            }

            isImagerDrag = true;
            moveImage = image;

            CurrentSelectMyImage = image;
            NotifyPropertyChanged("CurrentSelectMyImage");
            //此方法的第一个参数位置是需要拖动的数据的内容
            //DragDropEffects.Move实现的是拖放的效果。Move 将拖动源的数据移动到放置的目标
            DragDrop.DoDragDrop(image, new DataObject("aa"), DragDropEffects.Move);
        }

        void MyCanvas_Loaded(object sender, RoutedEventArgs e)
        {
            //页面加载时，网格画布处于中间位置
            scrollViewer.ScrollToVerticalOffset(1600);
            scrollViewer.ScrollToHorizontalOffset(800);
        }

        List<MyImage> images = new List<MyImage>();
        private void canvas_Drop(object sender, DragEventArgs e)
        {

            isImagerDrag = false;

            //验证拖入的是计算器传入的 new DataObject(image)
            ImageAndTextDecorator sourceIamge = e.Data.GetData(typeof(ImageAndTextDecorator)) as ImageAndTextDecorator;
            if (sourceIamge == null)
            {
                return;
            }
            //位置计算
            Point newLocation;
            if (calculateLocation(e, out newLocation) == false)
            {
                return;
            }
            if (!(e.OriginalSource is Border))
            {
                return;
            }

            MyImage newImage = new MyImage();
            newImage.Source = sourceIamge.ImageSource;
            newImage.Width = newImage.Height = 39 + 39 + 39 + 1 + 1;//三个格子加两条边框
            newImage.SetValue(Canvas.LeftProperty, newLocation.Y - 40);
            newImage.SetValue(Canvas.TopProperty, newLocation.X - 40);
            canvas.Children.Add(newImage);
            newImage.Drop += new DragEventHandler(newImage_Drop);

            images.Add(newImage);
            //    System.Diagnostics.Trace.WriteLine(e.OriginalSource);

            if (border != null)
            {
                border.SetValue(Canvas.LeftProperty, 3.0);
                border.SetValue(Canvas.TopProperty, 3.0);
                border.Visibility = Visibility.Hidden;
            }
        }

        //需要画线的控件组
        List<LineControlBoth> lineControlBoth_List = new List<LineControlBoth>();
        //将树控件拖放画布上的图像上
        void newImage_Drop(object sender, DragEventArgs e)
        {

            //验证拖入的是计算器传入的 new DataObject(image)
            TextBlock txt = (TextBlock)e.Data.GetData(typeof(TextBlock));
            if (txt == null)
            {
                return;
            }
            Point pos = e.GetPosition(canvas);
            HitTestResult result = VisualTreeHelper.HitTest(canvas, pos);
            if (result == null) return;

            MyImage item = Uitls.FindVisualParent<MyImage>(result.VisualHit);
            if (item == null)
            {
                return;
            }
            lineControlBoth_List.Add(new LineControlBoth() { SourceControl = txt, TargetControl = item });



        }
        Grid root2 = null;


        Border border = null;

        private bool calculateLocation(DragEventArgs e, out Point pointLocation)
        {
            pointLocation = new Point();
            //鼠标在画布中的位置
            Point pos = e.GetPosition(canvas);
            //是否在允许拖放的位置上，上下左右各有42PX为不可用区域
            if (pos.X <= 42)
            {
                return false;
            }
            if (pos.Y <= 42)
            {
                return false;
            }
            if (pos.X >= 1600 - 42)
            {
                return false;
            }
            if (pos.Y >= 3200 - 42)
            {
                return false;
            }

           //是否在允许拖放的位置上，滚动scrollViewer对可用区域有影响，比如各边的方框里有一部份在可示区域内
            double scrollTop = this.scrollViewer.VerticalOffset;
            double scrollLeft = this.scrollViewer.HorizontalOffset;
            if (pos.X - scrollLeft < 42)
            {
                return false;
            }
            if (pos.Y - scrollTop < 42)
            {
                return false;
            }
            if (scrollViewer.ActualWidth - (pos.X - scrollLeft) < 42)
            {
                return false;
            }
            if (scrollViewer.ActualHeight - (pos.Y - scrollTop) < 42)
            {
                return false;
            }



            //计算顶点
            int x = (int)pos.X % 40;
            int y = (int)pos.Y % 40;
            // double top = pos.X+(x>=20?40-x:-x) + 1.0;
            //    double left = pos.Y+(y>=20?40-y:-y) + 1.0;
            double top = pos.X - x + 2.0;
            double left = pos.Y - y + 2.0;
            pointLocation.X = left;
            pointLocation.Y = top;
            return true;

        }

        bool isImagerDrag = false;
        MyImage moveImage = null; --------------------编程问答-------------------- 除 --------------------编程问答-------------------- 好长的代码啊，帮你顶下 --------------------编程问答-------------------- //构造函数
public MyCanvas()
        {
            //调用设计器生成的代码初始化组件
            InitializeComponent();
            //注册窗体载入时的事件处理MyCanvas_Loaded
            this.Loaded += new RoutedEventHandler(MyCanvas_Loaded);
            //向scrollViewer控件的注册鼠标移动时的事件处理newImage_MouseMove
            this.scrollViewer.AddHandler(Image.MouseMoveEvent, new MouseEventHandler(newImage_MouseMove), true);

           --------------------编程问答-------------------- 这个真蛋疼啊，解释一些特定的地方还有人有时间，全丢出来，╮(╯▽╰)╭

补充：.NET技术 ,  C#