silverlight中用代码动态控制Storyboard(动画)属性的三种方法

先准备一个基本的xaml页面

 1<navigation:Page 
 2           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
 3           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
 4           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6           mc:Ignorable="d"
 7           xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
 8           x:Class="Projection.Test.TestPage"
 9           d:DesignWidth="640" d:DesignHeight="480"
10           Title="TestPage Page">
11    <navigation:Page.Resources>
12        
13        <Storyboard x:Name="storyTest">
14            
15            <!--绕y轴旋转，从0到360，再转到720度-->
16            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="img" Storyboard.TargetProperty="(UIElement.Projection).(PlaneProjection.RotationY)">
17                <EasingDoubleKeyFrame KeyTime="00:00:01" Value="360"/>
18                <EasingDoubleKeyFrame KeyTime="00:00:02" Value="720"/>
19            </DoubleAnimationUsingKeyFrames>
20            
21            <!--宽度按比例放大缩小，先放大到4位，再还原-->
22            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="img" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleX)">
23                <EasingDoubleKeyFrame KeyTime="00:00:01" Value="4"/>
24                <EasingDoubleKeyFrame KeyTime="00:00:02" Value="1"/>
25            </DoubleAnimationUsingKeyFrames>
26            
27            <!--高度按比例放大缩小，先放大到4位，再还原-->
28            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="img" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)">
29                <EasingDoubleKeyFrame KeyTime="00:00:01" Value="4"/>
30                <EasingDoubleKeyFrame KeyTime="00:00:02" Value="1"/>
31            </DoubleAnimationUsingKeyFrames>            
32            
33            <!--不透明度变化，从1到0.1，再还原为1-->
34            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="img" Storyboard.TargetProperty="(UIElement.Opacity)">
35                <EasingDoubleKeyFrame KeyTime="00:00:01" Value="0.1"/>
36                <EasingDoubleKeyFrame KeyTime="00:00:02" Value="1"/>
37            </DoubleAnimationUsingKeyFrames>
38        </Storyboard>
39        
40    </navigation:Page.Resources>
41    <Grid x:Name="LayoutRoot">
42
43        <Image x:Name="img" Source="/Projection;Component/img/img0.jpg" Width="100" HorizontalAlignment="Center" VerticalAlignment="Center" RenderTransformOrigin="0.5,0.5">
44            <Image.RenderTransform>
45                <TransformGroup>
46                    <ScaleTransform/>
47                    <SkewTransform/>
48                    <RotateTransform/>
49                    <TranslateTransform/>
50                </TransformGroup>
51            </Image.RenderTransform>
52            <Image.Projection>
53                <PlaneProjection/>
54            </Image.Projection>
55            <Image.Effect>
56                <DropShadowEffect/>
57            </Image.Effect>
58        </Image>
59
60    </Grid>
61</navigation:Page>

结构不复杂，里面就放了一张图片，同时预置了一个动画storyTest，里面把几种常见的动画形式都列在里面了，下面就来看看如何动态改变storyTest动画的属性(比如改变旋转的起始角度之类)

1.直接加x:Name，然后引用赋值

1 < DoubleAnimationUsingKeyFrames  BeginTime ="00:00:00"  Storyboard.TargetName ="img"  Storyboard.TargetProperty ="(UIElement.Projection).(PlaneProjection.RotationY)" >
2      < EasingDoubleKeyFrame  KeyTime ="00:00:01"  Value ="360"   x:Name ="yFrom" />
3      < EasingDoubleKeyFrame  KeyTime ="00:00:02"  Value ="720"   x:Name ="yTo" />
4 </ DoubleAnimationUsingKeyFrames >
5

注意高亮部分，然后象这样引用

System.Windows.Media.Animation.EasingDoubleKeyFrame yFrom  =   this .FindName( " yFrom " )  as  System.Windows.Media.Animation.EasingDoubleKeyFrame;

yFrom.Value  =   20 ;

这样我们就把00:00:01秒时角度由360改为20度了

2.利用StoryBoard的Children属性

 DoubleAnimationUsingKeyFrames _rotate  =  storyTest.Children[ 0 ]  as  DoubleAnimationUsingKeyFrames;
 _rotate.KeyFrames[ 0 ].Value  =   90 ; // 修改旋转角度的值
 _rotate.KeyFrames[ 1 ].Value  =   180 ;

 storyTest.RepeatBehavior  =  RepeatBehavior.Forever; // 指定为一直播放
  // this.storyTest.RepeatBehavior = new RepeatBehavior(2); // 播放2次

这样我们就把旋转的角度值从360,720改为90,180了

说明：StoryBoard的Children属性得到的是一个Timeline的集合，而DoubleAnimationUsingKeyFrames等这些基本的关键帧类型都是继承自Timeline，因此可以用as安全的把Timeline向下转化为DoubleAnimationUsingKeyFrames

3.动态添加/删除关键帧

当xaml中预定义的关键帧不满足要求时，这种方法就几乎成了唯一选择

storyTest.Children.Clear(); // 清除原来的动画设定，仅保留一个空壳           

DoubleAnimationUsingKeyFrames _new_rotate  =   new  DoubleAnimationUsingKeyFrames();

EasingDoubleKeyFrame _frame1  =   new  EasingDoubleKeyFrame();
_frame1.Value  =   180 ;
_frame1.KeyTime  =   new  TimeSpan( 0 ,  0 ,  0 ,  1 );

EasingDoubleKeyFrame _frame2  =   new  EasingDoubleKeyFrame();
_frame2.Value  =   0 ;
_frame2.KeyTime  =   new  TimeSpan( 0 ,  0 ,  0 ,  2 );


EasingDoubleKeyFrame _frame3  =   new  EasingDoubleKeyFrame();
_frame3.Value  =   90 ;
_frame3.KeyTime  =   new  TimeSpan( 0 ,  0 ,  0 ,  5 );

_new_rotate.KeyFrames.Add(_frame1);
_new_rotate.KeyFrames.Add(_frame2);
_new_rotate.KeyFrames.Add(_frame3);

storyTest.Children.Add(_new_rotate);

Storyboard.SetTarget(_new_rotate,  this .img);
Storyboard.SetTargetProperty(_new_rotate,  new  PropertyPath( " (UIElement.Projection).(PlaneProjection.RotationY) " ));

storyTest.AutoReverse  =   false ;

// storyTest.FillBehavior = FillBehavior.Stop; // 加入这一行后，不管AutoReverse设置为何值，都会回复原状            

storyTest.Begin();

在这里我们把原来storyTest中的动画设定全部清空 了，同时增加了一个三帧的动画

欢迎转载，但请注明来自菩提树下的杨过(http://yjmyzz.cnblogs.com/)