（3）FluidMoveBehavior 之模仿 Windows Phone 开始菜单的 Tile 长按后排序

   这个工程和上一篇 （2）中介绍的排序大同小异，只是比上一篇交换复杂一点，不是通过单击进行交换，

而是拖动一个 Tile 到另一个 Tile 上时，判断两个 Tile 的中心距离是否符合条件来判断是否进行交换两个 Tile。

归根结底还是利用 FluidMoveBehavior 行为来使 Silverlight 的元素在重新定位时，产生动画效果。毕竟在

实际开发中，用户体验还是很重要的，生动的交互比生硬的交互会更让用户感到亲切。

   当然项目中也用到了视觉状态管理相关的技术，因为不是重点，这里不会过多的介绍。

   效果交互图：

 第一步：首先定义一个 UserControl 类，作为一个 Tile 控件，并且在 CodeBehind 页面中注册一个

  依赖属性 TileBackgroundProperty，用来设置 Tile 不同的背景，效果：

    给该 Tile 控件添加 3 种不同的视觉状态：NormalVisualState、CheckedVisualState、FloatVisualState，即

当长按选中时，为 CheckedVisualState 状态，并显示右上角的图片 “图钉”；其它 tile 状态为 FloatVisualState，

为了让不同的 tile 漂浮的方向和方式不同，提供 4 个 FloatVisualState 。

相应的 xaml :

    <Grid x:Name="LayoutRoot" Margin="10" Width="150" Height="150">
        <VisualStateManager.VisualStateGroups>
            <VisualStateGroup x:Name="VisualStateGroup">
                <VisualState x:Name="NormalVisualState"/>
                <VisualState x:Name="CheckedVisualState">
                    <Storyboard>
                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="Assets_thumb_png">
                            <DiscreteObjectKeyFrame KeyTime="0">
                                <DiscreteObjectKeyFrame.Value>
                                    <Visibility>Visible</Visibility>
                                </DiscreteObjectKeyFrame.Value>
                            </DiscreteObjectKeyFrame>
                        </ObjectAnimationUsingKeyFrames></Storyboard>
                </VisualState>    
                <VisualState x:Name="FloatVisualState1">
                    <Storyboard RepeatBehavior="Forever" AutoReverse="True">
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="-5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.6"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
                <VisualState x:Name="FloatVisualState2">
                    <Storyboard RepeatBehavior="Forever" AutoReverse="True">
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.6"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
                <VisualState x:Name="FloatVisualState3">
                    <Storyboard RepeatBehavior="Forever" AutoReverse="True">
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="-5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="-5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.6"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
                <VisualState x:Name="FloatVisualState4">
                    <Storyboard RepeatBehavior="Forever" AutoReverse="True">
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.9"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="0.9"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateX)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="-5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateY)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="-5"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:6" Value="5"/>
                        </DoubleAnimationUsingKeyFrames>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="grid">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1.5" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="0.6"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4.5" Value="0.6"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>     
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>

        <Grid x:Name="grid" Background="{StaticResource PhoneAccentBrush}" RenderTransformOrigin="0.5,0.5">
            <Grid.RenderTransform>
                <CompositeTransform/>
            </Grid.RenderTransform>
            <Image Source="{Binding TileBackground}" Stretch="Fill"/>
            <Image x:Name="Assets_thumb_png" Visibility="Collapsed" Margin="124,-16,-15,124" Source="Assets/thumb.png" Stretch="Fill"/>
        </Grid>        
    </Grid>

该自定义控件相应的 C#：

    public partial class TileControl : UserControl
    {
        public TileControl()
        {
            InitializeComponent();
            this.DataContext = this;
        }

        #region TileBackground (依赖属性)        
        /// <summary>
        /// Tile 的背景图片
        /// </summary>
        public string TileBackground
        {
            get 
            {
                return (string)GetValue(TileBackgroundProperty); 
            }
            set 
            { 
                SetValue(TileBackgroundProperty, value); 
            }
        }
        public static readonly DependencyProperty TileBackgroundProperty =
            DependencyProperty.Register("TileBackground", typeof(string), typeof(TileControl),
              new PropertyMetadata("/Assets/Tiles/FlipCycleTileMedium.png"));

        #endregion                

        // 漂浮
        static Random rand = new Random();
        public void Float()
        {
            // 使 tile 进入不同的漂浮状态
            switch (rand.Next(5))
            {
                case 1:
                    VisualStateManager.GoToState(this, "FloatVisualState1", false);
                    break;
                case 2:
                    VisualStateManager.GoToState(this, "FloatVisualState2", false);
                    break;
                case 3:
                    VisualStateManager.GoToState(this, "FloatVisualState3", false);
                    break;
                case 4:
                    VisualStateManager.GoToState(this, "FloatVisualState4", false);
                    break;
                default: VisualStateManager.GoToState(this, "FloatVisualState3", false);
                    break;
            }
        }

        // 选中
        public void Checked()
        {
            VisualStateManager.GoToState(this, "CheckedVisualState", false);
        }

        // 恢复
        public void Reset()
        {
            VisualStateManager.GoToState(this, "NormalVisualState", false);
        }
    }

第二步：定义不同的 Tile 在重叠时，判断中心点的距离，是否小于 40px，如果是，则交换两个 Tile。

     如果 Tile 控件的 宽和 高设置为 150px，则各个控件的坐标为：

当拖动一个 Tile 到其它 Tile 上时，判断两个 Tile 的中心点坐标的距离：

第三步：在 MainPage 页面中，添加一个 Grid，分别放置各个自定义控件，并且每个自定义控件放在一个 Boder 里面，

    并且分别注册 Border 的长按事件 Hold 统一为 Border_Hold：

       <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Grid.Resources>
                <Style TargetType="Border">
                    <Setter Property="Background" Value="Transparent"/>
                </Style>
            </Grid.Resources>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <i:Interaction.Behaviors>
                <el:FluidMoveBehavior x:Name="fluidBehavior" AppliesTo="Children" Duration="00:00:01">
                    <el:FluidMoveBehavior.EaseY>
                        <QuinticEase EasingMode="EaseOut"/>
                    </el:FluidMoveBehavior.EaseY>
                    <el:FluidMoveBehavior.EaseX>
                        <QuinticEase EasingMode="EaseOut"/>
                    </el:FluidMoveBehavior.EaseX>
                </el:FluidMoveBehavior>
            </i:Interaction.Behaviors>
            <Border Hold="Border_Hold">
                <local:TileControl TileBackground="/Assets/Tiles/01.png"/>
            </Border>
            <Border Grid.Column="1" Hold="Border_Hold">
                <local:TileControl TileBackground="/Assets/Tiles/02.png"/>
            </Border>
            <Border  Grid.Row="1"  Hold="Border_Hold">
                <local:TileControl TileBackground="/Assets/Tiles/03.png"/>
            </Border>
            <Border Grid.Row="1" Grid.Column="1"  Hold="Border_Hold">
                <local:TileControl TileBackground="/Assets/Tiles/04.png"/>
            </Border>
            <Border Grid.Row="2"  Hold="Border_Hold">
                <local:TileControl TileBackground="/Assets/Tiles/05.png"/>
            </Border>
            <Border  Grid.Row="2" Grid.Column="1" Hold="Border_Hold">
                <local:TileControl TileBackground="/Assets/Tiles/06.png"/>
            </Border>
        </Grid>

第四步：在 MainPage 页面的 CodeBehind 中，定义一个类型为  Dictionary<Point, Border> 的泛型字典 dic，

     当页面加载完成时，初始化该字典：

       public MainPage()
        {
            InitializeComponent();
            this.Loaded += MainPage_Loaded;
        }

        void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            InitDic();
        }

        // Size : 资源素距离父元素左上角的距离
        Dictionary<Point, Border> dic = new Dictionary<Point, Border>();
        int childWidth;

        // 初始化一个字典集合，Key：border 元素的中心点坐标，value：border 自己
        void InitDic()
        {
            dic.Clear();

            foreach (var item in ContentPanel.Children)
            {
                childWidth = (int)item.DesiredSize.Width;

                Border border = item as Border;
                int row = Grid.GetRow(border);
                int col = Grid.GetColumn(border);
                Point position = new Point(col * childWidth + childWidth / 2, row * childWidth + childWidth / 2);
                border.Tag = position;

                dic.Add(position, border);

                Debug.WriteLine("point-  x:" + (col * childWidth + childWidth / 2) + "  y:" + (row * childWidth + childWidth / 2));
            }
        }

在 Border 的 Border_Hold 方法中，添加逻辑，用来处理各个 Tile 的视图状态，并且注册 ManipulationDelta 和 MouseLeftButtonUp 事件：

       Border borderTemp;
        CompositeTransform transformTemp;
        private void Border_Hold(object sender, System.Windows.Input.GestureEventArgs e)
        {
            e.Handled = true;

            borderTemp = sender as Border;

            // 注册 tile 右上角“图钉”图片的单击事件
            (borderTemp.Child as TileControl).Assets_thumb_png.Tap += Assets_thumb_png_Tap;

            transformTemp = new CompositeTransform();

            transformTemp.TranslateX = x;
            transformTemp.TranslateY = y;

            borderTemp.RenderTransform = transformTemp;

            // 拖动 border 时，改变它的坐标
            borderTemp.ManipulationDelta += borderTemp_ManipulationDelta;

            // 当手指离开 border 时，判断各个 tile 中心点的距离
            borderTemp.MouseLeftButtonUp += borderTemp_MouseLeftButtonUp;

            if (borderTemp.Child != null)
            {
                foreach (var item in ContentPanel.Children)
                {
                    Border border = item as Border;
                    if (border.Child != null)
                    {
                        TileControl tile = border.Child as TileControl;
                        // 被选中的 tile 进入 CheckedVisualState 视图状态，其余的进入 FloatVisualState 视图状态
                        if (tile == (borderTemp.Child as TileControl))
                        {
                            tile.Checked();                            
                            border.IsHitTestVisible = true;
                        }
                        else
                        {
                            tile.Float();
                            // 当处于漂浮状态时，不再接收“单击”等屏幕事件
                            border.IsHitTestVisible = false;
                        }
                    }
                }
            }
        }

当手指离开选择的 Tile 时，判断各个 Tile 的中心点的距离，从而判断是否具备交换两个 Tile 的条件：

        void borderTemp_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            e.Handled = true;

            DateTime timeStart = DateTime.Now;

            Debug.WriteLine("Translation.X: " + transformTemp.TranslateX);
            Debug.WriteLine("Translation.Y: " + transformTemp.TranslateY);

            Point pointSource = (Point)borderTemp.Tag;

            Point point = new Point(transformTemp.TranslateX + pointSource.X, transformTemp.TranslateY + pointSource.Y);

            bool IsSwaped = false;

            // 当手指离开屏幕时，判断选中的 tile 的中心点和其它中心点的直线距离，
            // 如果距离小于 40px，则两个 tile 互换 //换
            foreach (Point position in dic.Keys)
            {
                Border border2 = dic[position];
                if (borderTemp != border2)
                {
                    x = (int)(point.X - position.X);
                    y = (int)(point.Y - position.Y);

                   // 计算两个 Tile 中心点的直线距离                  
                   int distance = (int)Math.Sqrt(x * x + y * y);

                    if (distance < 40)
                    {
                        // 交换两个 tile 的位置
                        SwapBorder(borderTemp, border2);
                        IsSwaped = true;
                        break;
                    }
                }
            }

            Debug.WriteLine(DateTime.Now - timeStart);

            if (!IsSwaped)
            {
                transformTemp.TranslateX = 0;
                transformTemp.TranslateY = 0;
            }
        }

   重要代码粘贴到上面了，具体代码可以下载工程。至此有关 FluidMoveBehavior 行为的三篇文章暂时写完了。

   这个demo 运行的交互很简单，但是算法上还是颇费周折，想了几种实现方式，最终采用了上面的方式，重点时间

都花费在了数学计算上了。不过 demo 的代码还是比较粗糙，性能也没有优化，只是实现了大概的交互。

工程源码下载