silverlight之任意UI元素上启用拖放功能

function dragDropEnable(element)
{
    //Attach three "private" event handlers contained inside this function
    element.AddEventListener("MouseLeftButtonDown",onMouseLeftButtonDown);
    element.AddEventListener("MouseMove",onMouseMove);
    element.AddEventListener("MouseLeftButtonUp",onMouseLeftButtonUp);

    var dragging=false;
    var lastPoint=null;

    function onMouseLeftButtonDown(sender,mouseEventArgs)
    {
        //Start the drag
        sender.CaptureMouse();
        lastPoint = mouseEventArgs.GetPosition(null);
        dragging=true;
    }
    
    function onMouseMove(sender,mouseEventArgs)
    {
        if(dragging)
        {
             //Move the element and remember this position for next time
             var point=mouseEventArgs.GetPosition(null);
             sender["Canvas.Left"]+=point.X-lastPoint.X;
             sender["Canvas.Top"]+=point.Y-lastPoint.Y;
             lastPoint=point;
        }
    }

    function onMouseLeftButtonUp(sender,mouseEventArgs)
    {
        //Here is the "drop" part of drag-and-drop
        sender.ReleaseMouseCapture();
        dragging=false;
    }
}

把这段js脚本放到任何项目中，它都不会与现有函数或全局变量冲突