WPF案例（－）模拟Windows7 Win+Tab切换

    一个使用Wpf模拟Windows7 Win+Tab页面切换的小程序，使用快捷键Ctrl+Down或Ctrl+Up在示例程序各个页面元素之间滑动导航，在本例中，使用Viewport2DVisual3D宿主二维控件，在这里为方便示例，二维控件仅简单的使用了一个Image，以下是界面缩略图，有兴趣的朋友可以下载源码

    在建立本示例中的三维场景时，使用了Viewport3D，PerspectiveCamera，AmbientLight，Viewport2DVisual3D，RotateTransform3D，TranslateTransform3D，ScaleTransform3D等元素，下面分别简单说明一下这些元素在三维场景中分别充当了什么角色

1.Viewport3D ：Viewport3D是一个2D可视化元素，它是在2D场景中封装3D元素的容器控件，具有两个重要的属性

   Camera 为3D场景指定观察者所处的位置

   Children 表示Viewport3D的所有3D子控件的集合类

2.PerspectiveCamera 表示透视投影摄像机，在本示例中使用它对3D场景进行透视投影

3.AmbientLight 灯光用来照亮3D场景

4.Viewport2DVisual3D 在3D场景中呈现可交互的2D控件，在本示例中就使用了6个Viewport2DVisual3D元素分别呈现了六幅Image

5.RotateTransform3D 对3D元素应用旋转，本示例中使用它对Viewport2DVisual3D进行Y轴45度旋转的模型变换

6.TranslateTransform3D 对3D元素应用平移，本示例中使用它对Viewport2DVisual3D分别进行X,Y,Z平移的模型变换

7.ScaleTransform3D 对3D元素应用拉伸缩放，本示例中使用它对Viewport2DVisual3D进行了X,Y的拉伸模型变换

以下为定义3D场景的XAML代码

3D场景 

  1    < Viewport3D   x:Name ="Viewport3D"  RenderOptions.EdgeMode ="Aliased"  ClipToBounds ="False"  

                               IsHitTestVisible ="False" >
  2               < Viewport3D.Camera >
  3                   < PerspectiveCamera  Position ="0,0,8"    />
  4               </ Viewport3D.Camera >
  5               < Viewport2DVisual3D  x:Name ="viewport2DVisual3D0"  Geometry =" {StaticResource geometry} "   

                                Material =" {StaticResource material} "   >
  6                   < Viewport2DVisual3D.Transform >
  7                       < Transform3DGroup >
  8                           < RotateTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0" >
  9                               < RotateTransform3D.Rotation >
 10                                   < AxisAngleRotation3D  Axis ="0,1,0"  Angle ="35" />
 11                               </ RotateTransform3D.Rotation >
 12                           </ RotateTransform3D >
 13                           < TranslateTransform3D  OffsetX ="0"  OffsetY ="0"  OffsetZ ="0" />
 14                           < ScaleTransform3D  CenterX ="0"  CenterY ="0"  

                                   CenterZ ="0"  ScaleX ="1.5"  ScaleY ="1"   />
 15                       </ Transform3DGroup >
 16                   </ Viewport2DVisual3D.Transform >
 17                   < Viewport2DVisual3D.Visual >
 18                       < Image  Source ="Images\051027nature01.jpg"  Stretch ="Fill"

                               HorizontalAlignment ="Stretch"  VerticalAlignment ="Stretch"   />
 19                   </ Viewport2DVisual3D.Visual >
 20               </ Viewport2DVisual3D >
 21               < Viewport2DVisual3D  x:Name ="viewport2DVisual3D1"  Geometry =" {StaticResource geometry} "  

                              Material =" {StaticResource material} " >
 22                   < Viewport2DVisual3D.Transform >
 23                       < Transform3DGroup >
 24                           < RotateTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0" >
 25                               < RotateTransform3D.Rotation >
 26                                   < AxisAngleRotation3D  Axis ="0,1,0"  Angle ="35" />
 27                               </ RotateTransform3D.Rotation >
 28                           </ RotateTransform3D >
 29                           < TranslateTransform3D  OffsetX ="-1"  OffsetY ="1"  OffsetZ ="-4" />
 30                           < ScaleTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0"  

                                   ScaleX ="1.5"  ScaleY ="1"   />
 31                       </ Transform3DGroup >
 32                   </ Viewport2DVisual3D.Transform >
 33                   < Viewport2DVisual3D.Visual >
 34                       < Image  Source ="Images\051027nature02.jpg"  Stretch ="Fill"  

                                      HorizontalAlignment ="Stretch"  VerticalAlignment ="Stretch"   />
 35                   </ Viewport2DVisual3D.Visual >
 36               </ Viewport2DVisual3D >
 37               < Viewport2DVisual3D  x:Name ="viewport2DVisual3D2"  Geometry =" {StaticResource geometry} "

                                     Material =" {StaticResource material} " >
 38                   < Viewport2DVisual3D.Transform >
 39                       < Transform3DGroup >
 40                           < RotateTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0" >
 41                               < RotateTransform3D.Rotation >
 42                                   < AxisAngleRotation3D  Axis ="0,1,0"  Angle ="35" />
 43                               </ RotateTransform3D.Rotation >
 44                           </ RotateTransform3D >
 45                           < TranslateTransform3D  OffsetX ="-2"  OffsetY ="1.5"  OffsetZ ="-8" />
 46                           < ScaleTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0"

                                    ScaleX ="1.5"  ScaleY ="1"   />
 47                       </ Transform3DGroup >
 48                   </ Viewport2DVisual3D.Transform >
 49                   < Viewport2DVisual3D.Visual >
 50                       < Image  Source ="Images\11550549.jpg"  Stretch ="Fill"  

                                    HorizontalAlignment ="Stretch"  VerticalAlignment ="Stretch"   />
 51                   </ Viewport2DVisual3D.Visual >
 52               </ Viewport2DVisual3D >
 53               < Viewport2DVisual3D  x:Name ="viewport2DVisual3D3"  Geometry =" {StaticResource geometry} "  

                                Material =" {StaticResource material} " >
 54                   < Viewport2DVisual3D.Transform >
 55                       < Transform3DGroup >
 56                           < RotateTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0" >
 57                               < RotateTransform3D.Rotation >
 58                                   < AxisAngleRotation3D  Axis ="0,1,0"  Angle ="35" />
 59                               </ RotateTransform3D.Rotation >
 60                           </ RotateTransform3D >
 61                           < TranslateTransform3D  OffsetX ="-3"  OffsetY ="1.5"  OffsetZ ="-12" />
 62                           < ScaleTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0"  

                                      ScaleX ="1.5"  ScaleY ="1"   />
 63                       </ Transform3DGroup >
 64                   </ Viewport2DVisual3D.Transform >
 65                   < Viewport2DVisual3D.Visual >
 66                       < Image  Source ="Images\11550556.jpg"  Stretch ="Fill"  

                             HorizontalAlignment ="Stretch"  VerticalAlignment ="Stretch"   />
 67                   </ Viewport2DVisual3D.Visual >
 68               </ Viewport2DVisual3D >
 69               < Viewport2DVisual3D  x:Name ="viewport2DVisual3D4"  Geometry =" {StaticResource geometry} "

                                             Material =" {StaticResource material} " >
 70                   < Viewport2DVisual3D.Transform >
 71                       < Transform3DGroup >
 72                           < RotateTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0" >
 73                               < RotateTransform3D.Rotation >
 74                                   < AxisAngleRotation3D  Axis ="0,1,0"  Angle ="35" />
 75                               </ RotateTransform3D.Rotation >
 76                           </ RotateTransform3D >
 77                           < TranslateTransform3D  OffsetX ="-4"  OffsetY ="1.5"  OffsetZ ="-16" />
 78                           < ScaleTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0"

                                        ScaleX ="1.5"  ScaleY ="1"   />
 79                       </ Transform3DGroup >
 80                   </ Viewport2DVisual3D.Transform >
 81                   < Viewport2DVisual3D.Visual >
 82                       < Image  Source ="Images\11550560.jpg"  Stretch ="Fill"  

                                   HorizontalAlignment ="Stretch"  VerticalAlignment ="Stretch"   />
 83                   </ Viewport2DVisual3D.Visual >
 84               </ Viewport2DVisual3D >
 85               < Viewport2DVisual3D  x:Name ="viewport2DVisual3D5"  Geometry =" {StaticResource geometry} "  

                                      Material =" {StaticResource material} " >
 86                   < Viewport2DVisual3D.Transform >
 87                       < Transform3DGroup >
 88                           < RotateTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0" >
 89                               < RotateTransform3D.Rotation >
 90                                   < AxisAngleRotation3D  Axis ="0,1,0"  Angle ="35" />
 91                               </ RotateTransform3D.Rotation >
 92                           </ RotateTransform3D >
 93                           < TranslateTransform3D  OffsetX ="-5"  OffsetY ="1.5"  OffsetZ ="-20" />
 94                           < ScaleTransform3D  CenterX ="0"  CenterY ="0"  CenterZ ="0"

                                    ScaleX ="1.5"  ScaleY ="1"   />
 95                       </ Transform3DGroup >
 96                   </ Viewport2DVisual3D.Transform >
 97                   < Viewport2DVisual3D.Visual >
 98                       < Image  Source ="Images\051123Webshots05.jpg"  Stretch ="Fill"  

                                 HorizontalAlignment ="Stretch"  VerticalAlignment ="Stretch"   />
 99                   </ Viewport2DVisual3D.Visual >
100               </ Viewport2DVisual3D >
101               < ModelVisual3D >
102                   < ModelVisual3D.Content >
103                       < AmbientLight  Color ="White"   />
104                   </ ModelVisual3D.Content >
105               </ ModelVisual3D >
106  </ Viewport3D >

   通过以上的XAML语言定义了一个静态的3D场景，以下的代码实现将此3D场景支持动画效果，即模仿Windows7的Win+Tab切换特效

C#动画

  1           public   void  MoveCurrentToNext()
  2          {
  3               // 向前移动，取Viewport3D的第一个Viewport2DVisual3为当前Viewport2DVisual3D
  4              var current  =   this .Viewport3D.Children[ 0 ];
  5              var child1  =   this .Viewport3D.Children[ 1 ];
  6              var child2  =   this .Viewport3D.Children[ 2 ];
  7              var child3  =   this .Viewport3D.Children[ 3 ];
  8              var child4  =   this .Viewport3D.Children[ 4 ];
  9              var child5  =   this .Viewport3D.Children[ 5 ];
 10 
 11 
 12               this .Viewport3D.Children.RemoveAt( 0 );
 13               this .Viewport3D.Children.Insert( 5 , current);
 14 
 15              var translate  =  (current.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                         as  TranslateTransform3D;
 16 
 17               // 对每个Viewport2DVisual3D元素应用平移动画
 18              AnimationVisualElement((current  as  Viewport2DVisual3D).Visual 

                                                   as  FrameworkElement, . 3 );
 19              AnimationVisualElement(translate,  true ,  - 5.0 ,  1.5 ,  - 20.0 );
 20 
 21              translate  =  (child1.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                     as  TranslateTransform3D;
 22              AnimationVisualElement(translate,  true , . 0 , . 0 , . 0 );
 23 
 24              translate  =  (child2.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                        as  TranslateTransform3D;
 25              AnimationVisualElement(translate,  true ,  - 1.0 ,  1.0 ,  - 4.0 );
 26 
 27              translate  =  (child3.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                        as  TranslateTransform3D;
 28              AnimationVisualElement(translate,  true ,  - 2.0 ,  1.5 ,  - 8.0 );
 29 
 30              translate  =  (child4.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                        as  TranslateTransform3D;
 31              AnimationVisualElement(translate,  true ,  - 3.0 ,  1.5 ,  - 12.0 );
 32 
 33              translate  =  (child5.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                        as  TranslateTransform3D;
 34              AnimationVisualElement(translate,  true ,  - 4.0 ,  1.5 ,  - 16.0 );
 35 
 36          }
 37 
 38           public   void  MoveCurrentToPrevious()
 39          {
 40               // 向后移动，取Viewport3D的最后一个Viewport2DVisual3D当前Viewport2DVisual3D
 41              var current  =   this .Viewport3D.Children[ 5 ];
 42              var child1  =   this .Viewport3D.Children[ 0 ];
 43              var child2  =   this .Viewport3D.Children[ 1 ];
 44              var child3  =   this .Viewport3D.Children[ 2 ];
 45              var child4  =   this .Viewport3D.Children[ 3 ];
 46              var child5  =   this .Viewport3D.Children[ 4 ];
 47 
 48               this .Viewport3D.Children.RemoveAt( 5 );
 49               this .Viewport3D.Children.Insert( 0 , current);
 50 
 51              var translate  =  (current.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                            as  TranslateTransform3D;
 52 
 53              AnimationVisualElement(translate,  false ,  0.0 ,  0.0 ,  0.0 );
 55 
 56              translate  =  (child1.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                       as  TranslateTransform3D;
 57              AnimationVisualElement(translate,  false ,  - 1.0 ,  1.0 ,  - 4.0 );
 58 
 59              translate  =  (child2.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                       as  TranslateTransform3D;
 60              AnimationVisualElement(translate,  false ,  - 2.0 ,  1.5 ,  - 8.0 );
 61 
 62              translate  =  (child3.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                         as  TranslateTransform3D;
 63              AnimationVisualElement(translate,  false ,  - 3.0 ,  1.5 ,  - 12.0 );
 64 
 65              translate  =  (child4.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                        as  TranslateTransform3D;
 66              AnimationVisualElement(translate,  false ,  - 4.0 ,  1.5 ,  - 16.0 );
 67 
 68              translate  =  (child5.Transform  as  Transform3DGroup).Children[ 1 ] 

                                                        as  TranslateTransform3D;
 69              AnimationVisualElement(translate,  false ,  - 5.0 ,  1.5 ,  - 20.0 );
 70          }
 71           private   void  AnimationVisualElement(FrameworkElement element,  double  duration)
 72          {
 73               if  (element  ==   null )
 74                   return ;
 75               // 对Visual元素的Visibility应用动画
 76              ObjectAnimationUsingKeyFrames objectAnimation  =   new  ObjectAnimationUsingKeyFrames();
 77              objectAnimation.KeyFrames.Add(

                   new  DiscreteObjectKeyFrame(Visibility.Collapsed, KeyTime.FromPercent(. 0 )));
 78              objectAnimation.KeyFrames.Add(

                   new  DiscreteObjectKeyFrame(Visibility.Visible, KeyTime.FromPercent( 1 )));
 79              objectAnimation.Duration  =  TimeSpan.FromSeconds(duration);
 80              objectAnimation.FillBehavior  =  FillBehavior.Stop;
 81              element.BeginAnimation(FrameworkElement.VisibilityProperty, objectAnimation);
 82 
 83          }
 84           private   void  AnimationVisualElement(TranslateTransform3D translate,  bool  forward, 

                                                  double  targetX,  double  targetY,  double  targetZ)
 85          {
 86              Duration duration  =   new  Duration(TimeSpan.FromSeconds(. 4 ));
 87               // 对TranslateTransform3D的X偏移量应用动画
 88              DoubleAnimation animationX  =   new  DoubleAnimation();
 89              animationX.To  =  targetX;
 90              animationX.Duration  =  duration;
 91              animationX.AccelerationRatio  =  forward  ?   0  :  1 ;
 92              animationX.DecelerationRatio  =  forward  ?   1  :  0 ;
 93              translate.BeginAnimation(TranslateTransform3D.OffsetXProperty, animationX);
 94               // 对TranslateTransform3D的Y偏移量应用动画
 95              DoubleAnimation animationY  =   new  DoubleAnimation();
 96              animationX.To  =  targetY;
 97              animationX.AccelerationRatio  =  forward  ?   0.7  :  0.3 ;
 98              animationX.DecelerationRatio  =  forward  ?   0.3  :  0.7 ;
 99              animationX.Duration  =  duration;
100              translate.BeginAnimation(TranslateTransform3D.OffsetYProperty, animationX);
101               // 对TranslateTransform3D的Z偏移量应用动画
102              DoubleAnimation animationZ  =   new  DoubleAnimation();
103              animationZ.To  =  targetZ;
104              animationZ.AccelerationRatio  =  forward  ?   0.3  :  0.7 ;
105              animationZ.DecelerationRatio  =  forward  ?   0.7  :  0.3 ;
106              animationZ.Duration  =  duration;
107              translate.BeginAnimation(TranslateTransform3D.OffsetZProperty, animationZ);
108          }

     在以上代码中主要实现了对ViewPort3D的6个子Viewport2DVisual3D分别应用TranslateTransform3D的平移动画，TranslateTransform3D具有三个跟位置有关的属性，分别表示X轴偏移量OffsetX,Y轴偏移量OffsetY，以及Z轴偏移量OffsetZ

    由于OffsetX，OffsetY，OffsetY在TranslateTransform3D中被定义为Double类型的依赖项属性，因此可以使用DoubleAnimation对属性的目标值定义动画效果，最后通过TranslateTransform3D的BeginAnimation方法分别对OffsetX，OffsetY，OffsetY属性应用动画

    最后定义快捷键事件，按下Ctrl+Down组合键，图片向前滑动，按下Ctrl+Up组合键，图片向后滑动

定义快捷键 

 1    private   void  Window_KeyDown( object  sender, KeyEventArgs e)
 2          {
 3               if  (e.KeyStates  ==  Keyboard.GetKeyStates(Key.Down)  &&  
 4                          Keyboard.Modifiers  ==  ModifierKeys.Control)
 5              {
 6                   // 向前移动Visual元素
 7                   this .MoveCurrentToNext();
 8              }
 9               else   if  (e.KeyStates  ==  Keyboard.GetKeyStates(Key.Up)  &&  
10                         Keyboard.Modifiers  ==  ModifierKeys.Control)
11              {
12                   // 向后移动Visual元素
13                   this .MoveCurrentToPrevious();
14              }
15               else   if  (e.KeyStates  ==  Keyboard.GetKeyStates(Key.Escape))
16              {
17                   // 注销
18                  Application.Current.Shutdown();
19              }
20          }

    注：在本示例中连续使用了6个Viewport2DVisual3D三维元素，并且在每个Viewport2DVisual3D元素的Visual上宿主一个二维的Image控件，对于本示例，为优化性能，应尽可能的减少Viewport2DVisual3D的数目，在这里一个好的方法是使用三维元素ModelVisual3D来代替Viewport2DVisual3D，将六幅图片分别定义成Material，再将Material应用到六个对应的GeometryModel3D三维模型中，最后使用Model3DGroup将六个GeometryModel3D三维模型打包作为ModelVisual3D的Content属性值，因此只需要一个ModelVisual3D就可实现相同的功能并能优化了性能