兼容Silverlight4的实用的Silverlight可拖放工具类源代码

开发日常的Silverlight应用程序时，常常要对一个域多个控件实现可拖放的MOUSE操作，在Silverlight中实现拖放的功能其实非常简单，但是为了提高程序功能代码的可复用性，程序员常常喜欢把常用的代码封装成一个工具类，例如Asp.net中常用SQLHelper类，用来操作数据库的，这里我们介绍的类是在Silverlight中实现拖动的工具类，它支持Silverlight2.0至Silverlight4.0的各个版本通用，好了话不多说，我们还是看代码吧：

public static class DragDrop

{

    private static bool IsDragging = false;

    private static Point curPoint;

    private const int MAX_ZINDEX = 99999;

    private const double CURRENT_OPACITY = 0.5;

    private static int lastZIndex;

    private static double lastOpacity;



    private static void sender_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)

    {

        UIElement uiElement = sender as UIElement;

        if (uiElement != null)

        {

            uiElement.CaptureMouse();

            lastZIndex = (int)uiElement.GetValue(Canvas.ZIndexProperty);

            uiElement.SetValue(Canvas.ZIndexProperty, MAX_ZINDEX);

            lastOpacity = uiElement.Opacity;

            uiElement.Opacity = CURRENT_OPACITY;

            IsDragging = true;

            curPoint = new Point(e.GetPosition(null).X, e.GetPosition(null).Y);

        }

    }



    private static void sender_MouseMove(object sender, MouseEventArgs e)

    {

        if (!IsDragging)

        {

            return;

        }



        UIElement uiElement = sender as UIElement;

        if (uiElement != null)

        {

            double currentLeft = (double)uiElement.GetValue(Canvas.LeftProperty);

            double currentTop = (double)uiElement.GetValue(Canvas.TopProperty);



            double newLeft = (double)currentLeft + e.GetPosition(null).X - curPoint.X;

            double newTop = (double)currentTop + e.GetPosition(null).Y - curPoint.Y;



            uiElement.SetValue(Canvas.LeftProperty, newLeft);

            uiElement.SetValue(Canvas.TopProperty, newTop);

            curPoint = new Point(e.GetPosition(null).X, e.GetPosition(null).Y);

        }

    }



    private static void sender_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)

    {

        UIElement uiElement = sender as UIElement;

        if (uiElement != null)

        {

            uiElement.ReleaseMouseCapture();

            IsDragging = false;

            uiElement.SetValue(Canvas.ZIndexProperty, lastZIndex);

            uiElement.Opacity = lastOpacity;

        }

    }



    public static void Load(UIElement sender)

    {

        sender.MouseLeftButtonDown += new MouseButtonEventHandler(sender_MouseLeftButtonDown);

        sender.MouseLeftButtonUp += new MouseButtonEventHandler(sender_MouseLeftButtonUp);

        sender.MouseMove += new MouseEventHandler(sender_MouseMove);

    }



    public static void UnLoad(UIElement sender)

    {

        sender.MouseLeftButtonDown -= new MouseButtonEventHandler(sender_MouseLeftButtonDown);

        sender.MouseLeftButtonUp -= new MouseButtonEventHandler(sender_MouseLeftButtonUp);

        sender.MouseMove -= new MouseEventHandler(sender_MouseMove);

    }

}



DragDrop工具类的使用方法：

DragDrop.Load(LayoutRoot);

DragDrop是一个静态类，使用起来非常简单，以上只要一行代码就可以实现对Grid控件的拖放操作了。

希望对大家有所帮助~！