如何将项目位置限制在画布中?

好吧,

我编辑了这篇文章,因为我当时发布的代码与我现在要做的事情没有真正的联系,但问题是一样的。

当我谈到将对象限制在画布上时,它更像是一个鼠标剪辑,但是当我在许多线程上阅读时,这个功能在SL中并不存在。所以我在所有论坛中搜索了一下,得到了这个 link . 但我没能完全复制出来。以下是用于拖放事件的代码:

public class RoomImage : ContentControl
{
    public RoomImage()
    {
        DefaultStyleKey = typeof(RoomImage);
    }

    public static readonly DependencyProperty BackgroundImageProperty = DependencyProperty.Register("Source", typeof(ImageSource), typeof(RoomImage), null);
    public ImageSource BackgroundImage
    {
        get { return (ImageSource)GetValue(BackgroundImageProperty); }
        set { SetValue(BackgroundImageProperty, value); }
    }

    //Instance Drag variable

    private FrameworkElement _translateZone;
    bool _isDrag;
    Point StartingDragPoint;

    public double Top
    {
        get { return (double)GetValue(Canvas.TopProperty); }
        set { SetValue(Canvas.TopProperty, value); }
    }

    public double Left
    {
        get { return (double)GetValue(Canvas.LeftProperty); }
        set { SetValue(Canvas.LeftProperty, value); }
    }

    //Instance Drag events
    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();

        _translateZone = GetTemplateChild("PART_TranslateZone") as FrameworkElement;
        DefineDragEvents();
    }

    private void DefineDragEvents()
    {
        if (_translateZone != null)
        {
            _translateZone.MouseLeftButtonDown += new MouseButtonEventHandler(translateZone_MouseLeftButtonDown);
            _translateZone.MouseLeftButtonUp += new MouseButtonEventHandler(translateZone_MouseLeftButtonUp);
            _translateZone.MouseMove += new MouseEventHandler(translateZone_MouseMove);
        }
    }

    private void translateZone_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        _isDrag = true;

        //start the drag
        FrameworkElement DragBar = (FrameworkElement)sender;
        DragBar.CaptureMouse();

        // drag starting point
        StartingDragPoint = e.GetPosition(this);
    }

    private void translateZone_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        FrameworkElement translateZone = (FrameworkElement)sender;
        translateZone.ReleaseMouseCapture();

        _isDrag = false;
    }

    private void translateZone_MouseMove(object sender, MouseEventArgs e)
    {
        if (_isDrag)
        {
            UIElement ui = (UIElement)this.Parent;
            Point Point = e.GetPosition(ui);

            Move(Point.X - StartingDragPoint.X, Point.Y - StartingDragPoint.Y);
        }
    }

    public void Move(double left, double top)
    {
        Left = left;
        Top = top;
    }

}

如果有人能给我提供一些代码,或者我应该在哪里执行,那就太棒了!

谢谢你,伊菲斯门。