Silverlight 2完美征程学习笔记

拖拽效果分为3个步骤

1. 按下鼠标，触发MouseLeftButtonDown事件，选择要拖动的对象
2. 移动鼠标，触发MouseMove事件，移动选择的对象
3. 放开鼠标，触发MouseLeftButtonUp事件，停止捕捉事件

页面代码：

<UserControl x:Class="SilverlightStuding.MouseDrag"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Width="400" Height="300"><Canvas><StackPanel MouseLeftButtonDown="StackPanel_MouseLeftButtonDown" MouseMove="StackPanel_MouseMove" MouseLeftButtonUp="StackPanel_MouseLeftButtonUp" Canvas.Left="50" Canvas.Top="50" Width="200" Height="80"><Border BorderThickness="3" BorderBrush="Red"><StackPanel Orientation="Horizontal" VerticalAlignment="Center" HorizontalAlignment="Center"><Image Source="drag.png"/><TextBlock Text="Drag Me" VerticalAlignment="Center" Margin="10"></TextBlock></StackPanel></Border></StackPanel><TextBlock Text="" x:Name="txtStatus" Canvas.Top="200" Canvas.Left="60"></TextBlock></Canvas>
</UserControl>

开始拖放操作，实现MouseLeftButtonDown事件的处理

        private void StackPanel_MouseLeftButtonDown(object sender, MouseButtonEventArgs e){FrameworkElement element = sender as FrameworkElement;mousePosition = e.GetPosition(null);trackingMouseMove = true;if(null!=element){element.CaptureMouse();element.Cursor = Cursors.Hand;}txtStatus.Text = "MouseLeftButtonDown";}

移动对象，实现 MouseMove事件处理程序，计算元素的位置并更新，同时更新鼠标的位置

        private void StackPanel_MouseMove(object sender, MouseEventArgs e){FrameworkElement element = sender as FrameworkElement;if(trackingMouseMove){double deltaV = e.GetPosition(null).Y - mousePosition.Y;double deltaH = e.GetPosition(null).X - mousePosition.X;double newTop = deltaV + (double) element.GetValue(Canvas.TopProperty);double newLeft = deltaH + (double) element.GetValue(Canvas.LeftProperty);element.SetValue(Canvas.TopProperty, newTop);element.SetValue(Canvas.LeftProperty, newLeft);mousePosition = e.GetPosition(null);}txtStatus.Text = "Mouse Moving ……";}

完成拖放操作，释放鼠标，实现MouseLeftButtonUp事件处理程序

        private void StackPanel_MouseLeftButtonUp(object sender, MouseButtonEventArgs e){FrameworkElement element = sender as FrameworkElement;trackingMouseMove = false;element.ReleaseMouseCapture();mousePosition.X = mousePosition.Y = 0;element.Cursor = null;txtStatus.Text = "ReleaseMouse";}