WPF中的PathAnimation(路径动画)

                                   WPF中的PathAnimation(路径动画)
                                                               周银辉

在WPF中我们可以指定元素按照某一路径运动而形成动画,这称之为路径动画,在SDK中你会发现以[Type]AnimationUsingPath这种形式命名的类,它们就是用来创建路径动画的,其中[Type]表示一系列类型比如double,point等,这与DoubleAnimation等的命名方式一致。
为对路径动画有一个大体上的认识,你可以粘贴下面的代码到XamlPad:
<Window
    
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x
="http://schemas.microsoft.com/winfx/2006/xaml"
    
    x:Name
="Window"
    Title
="Window1"
    Width
="640" Height="480">

    
<Window.Resources>
        
<Storyboard x:Key="Timeline1" RepeatBehavior = "Forever" AutoReverse="True">
            
<DoubleAnimationUsingPath BeginTime="00:00:00" Duration="00:00:02" Storyboard.TargetName="button" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.X)" Source="X">
                
<DoubleAnimationUsingPath.PathGeometry>
                    
<PathGeometry Figures="M-68,149.00022 C-39.695816,109.3744 -17.383496,83.397528 39,74.000287 C73.433618,68.261356 91.198465,71.210009 125,89.000273 C157.86626,106.29829 181.01028,123.79991 204,155.00021 C213.7418,168.22121 224.03351,180.96708 234,194.00017 C246.07551,209.79121 257.36571,220.41957 275,231.00014 C285.57406,237.34456 295.83653,242.84775 307,248.00012 C317.8183,252.99318 324.46505,252.89547 337,252.00012 C362.92461,250.14836 384.46844,240.41978 404,225.00014"/>
                
</DoubleAnimationUsingPath.PathGeometry>
            
</DoubleAnimationUsingPath>
            
<DoubleAnimationUsingPath BeginTime="00:00:00" Duration="00:00:02" Storyboard.TargetName="button" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.Y)" Source="Y">
                
<DoubleAnimationUsingPath.PathGeometry>
                    
<PathGeometry Figures="M-68,149.00022 C-39.695816,109.3744 -17.383496,83.397528 39,74.000287 C73.433618,68.261356 91.198465,71.210009 125,89.000273 C157.86626,106.29829 181.01028,123.79991 204,155.00021 C213.7418,168.22121 224.03351,180.96708 234,194.00017 C246.07551,209.79121 257.36571,220.41957 275,231.00014 C285.57406,237.34456 295.83653,242.84775 307,248.00012 C317.8183,252.99318 324.46505,252.89547 337,252.00012 C362.92461,250.14836 384.46844,240.41978 404,225.00014"/>
                
</DoubleAnimationUsingPath.PathGeometry>
            
</DoubleAnimationUsingPath>
        
</Storyboard>
    
</Window.Resources>
    
<Window.Triggers>
        
<EventTrigger RoutedEvent="FrameworkElement.Loaded">
            
<BeginStoryboard Storyboard="{StaticResource Timeline1}"/>
        
</EventTrigger>
    
</Window.Triggers>

    
<Grid x:Name="LayoutRoot">
        
<Path Fill="#FFFFFFFF" Stretch="Fill" Stroke="#FF000000" Margin="63.5,128.847,87.5,133.025" Data="M64,207 C92.304184,167.37414 114.6165,141.39725 171,132 205.43362,126.26106 223.19847,129.20972 257,147 289.86626,164.29803 313.01028,181.79967 336,213 345.7418,226.22101 356.03351,238.96689 366,252 378.07551,267.79105 389.36571,278.41942 407,289 417.57406,295.34443 427.83653,300.84763 439,306 449.8183,310.99306 456.46505,310.89535 469,310 494.92461,308.14824 516.46844,298.41966&#xd;&#xa;536,283"/>
        
<Button RenderTransformOrigin="0.5,0.5" HorizontalAlignment="Left" Margin="82,30,0,0" x:Name="button" VerticalAlignment="Top" Width="100" Height="56" Content="Button">
            
<Button.RenderTransform>
                
<TransformGroup>
                    
<ScaleTransform ScaleX="1" ScaleY="1"/>
                    
<SkewTransform AngleX="0" AngleY="0"/>
                    
<RotateTransform Angle="0"/>
                    
<TranslateTransform X="0" Y="0"/>
                
</TransformGroup>
            
</Button.RenderTransform>
        
</Button>
    
</Grid>
</Window>

你可以得到如图所示的一个窗体:
pathAnimation1.png
窗体上的按钮沿着曲线来回的运动(按钮的中心始终与曲线相切)。


1,使用Microsoft Expression Blend工具为我们自动生成路径动画
打造路径动画的最简单的方式是使用 Microsoft Expression Blend工具来自动生成,当然这自然会失去灵活性。
第一步:创建动画对象(比如上图中的那个Button)
pathAnimation2.png
第二步:创建动画路径(比如一条曲线,一个圆)
pathAnimation3.png
记得将路径的逻辑树层次上调整得比刚才那个按钮低
pathAnimation4.png
第三步:将路径转化为MotionPath
选中逻辑树上的[Path]对象,单击菜单栏的Object,选择Path子项,在选择Convert To MotionPath,则会弹出如下窗口:pathAnimation5.png
其要求你选择MotionPath的目标,也就是路径动画的目标,我们这里选择我们的button按钮
单击OK,其会自动为你生成Timeline(此后的操作就与打造普通Timeline 的操作一样了,其实此时该路径动画已经生成,你可以单击Timeline录制旁边的“播放”按钮来观看效果了,或直接F5)


2,使用代码来打造更灵活的路径动画
我更喜欢使用手写代码的方式来做更多的事情,这让事情变得更容易控制,同时也更具有灵活性。
以DoubleAnimationUsingPath为例,我们逐步讲解一下如何使用代码来打造上面的示例。
为了让对象沿着曲线运动,我们通过改变一个TranslateTransform的X与Y值来做到,并将该TranslateTransform指定给按钮的RenderTransform。
假设我们动画中的路径(也就是示例中的那条曲线)为path1,动画的对象为border1,如果你有过编写WPF动画代码的经验,那么你可以很轻松地编写出以下代码:

            DoubleAnimationUsingPath animationX = new DoubleAnimationUsingPath();
            animationX.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationX.Source 
= PathAnimationSource.X;
            animationX.Duration 
= new Duration(TimeSpan.FromSeconds(2));

            DoubleAnimationUsingPath animationY 
= new DoubleAnimationUsingPath();
            animationY.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationY.Source 
= PathAnimationSource.Y;
            animationY.Duration 
= animationX.Duration;
其中
animationX.PathGeometry = this.path1.Data.GetFlattenedPathGeometry();
指定了我们的animationX所遵照的路径为path1
animationX.Source = PathAnimationSource.X;
指定了animationX将遵照路径的X值的变化而变化,其中PathAnimationSource枚举存在三个值,分别是X,Y与Angle,在沿着路径旋转的动画中将会用到Angle值。
将代码补充完整后如下:
           TranslateTransform translate = new TranslateTransform();
            
this.border1.RenderTransform = translate;

            NameScope.SetNameScope(
thisnew NameScope());
            
this.RegisterName("translate", translate);

            DoubleAnimationUsingPath animationX 
= new DoubleAnimationUsingPath();
            animationX.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationX.Source 
= PathAnimationSource.X;
            animationX.Duration 
= new Duration(TimeSpan.FromSeconds(2));

            DoubleAnimationUsingPath animationY 
= new DoubleAnimationUsingPath();
            animationY.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationY.Source 
= PathAnimationSource.Y;
            animationY.Duration 
= animationX.Duration;


            Storyboard story 
= new Storyboard();
            story.RepeatBehavior 
= RepeatBehavior.Forever;
            story.AutoReverse 
= true;
            story.Children.Add(animationX);
            story.Children.Add(animationY);
            Storyboard.SetTargetName(animationX, 
"translate");
            Storyboard.SetTargetName(animationY, 
"translate");
            Storyboard.SetTargetProperty(animationX, 
new PropertyPath(TranslateTransform.XProperty));
            Storyboard.SetTargetProperty(animationY, 
new PropertyPath(TranslateTransform.YProperty));

            story.Begin(
this);
到此为止,我们可以说已经打造了一个路径动画,效果如下图
pathAnimation6.png
但不难发现,图中方块运动的路径与曲线并为完全重合,而是存在X与Y方向上的平移。这是一个很让人头疼的问题,但是我发现,只要在动画播放之前,将方块的中心位置设置为与动画所在容器的(0,0)位置向重合,那么该问题就可以被避免。
修改后的代码:
            Canvas.SetTop(this.border1, -this.border1.ActualHeight / 2);
            Canvas.SetLeft(
this.border1, -this.border1.ActualWidth / 2
);

            TranslateTransform translate 
= new TranslateTransform();
            
this.border1.RenderTransform = translate;

            NameScope.SetNameScope(
thisnew NameScope());
            
this.RegisterName("translate", translate);

            DoubleAnimationUsingPath animationX 
= new DoubleAnimationUsingPath();
            animationX.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationX.Source 
= PathAnimationSource.X;
            animationX.Duration 
= new Duration(TimeSpan.FromSeconds(2));

            DoubleAnimationUsingPath animationY 
= new DoubleAnimationUsingPath();
            animationY.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationY.Source 
= PathAnimationSource.Y;
            animationY.Duration 
= animationX.Duration;


            Storyboard story 
= new Storyboard();
            story.RepeatBehavior 
= RepeatBehavior.Forever;
            story.AutoReverse 
= true;
            story.Children.Add(animationX);
            story.Children.Add(animationY);
            Storyboard.SetTargetName(animationX, 
"translate");
            Storyboard.SetTargetName(animationY, 
"translate");
            Storyboard.SetTargetProperty(animationX, 
new PropertyPath(TranslateTransform.XProperty));
            Storyboard.SetTargetProperty(animationY, 
new PropertyPath(TranslateTransform.YProperty));

            story.Begin(
this);
然后,运行效果如下:
pathAnimation7.png


刚才已经提到,PathAnimationSource枚举拥有第三个值Angle,它是用来使我们的动画对象沿着路径旋转的,旋转对象与移动类似,但需要注意的是:
(1)旋转时对象的中心点始终与路径相切,那么你需要注意旋转时对象的中心在哪,比如上面的方块的中心点在其长宽的50%处,那么我们设置其RenderTransformOrigin为(0.5,0.5)
this.border1.RenderTransformOrigin = new Point(0.50.5);
(2)如果我们在旋转的同时在进行其他动作,比如平移,那么我们需要注意动作叠加的顺序,先旋转再平移与先平移再旋转的效果是不同的(你可以参考WPF中的MatrixTransform ),这在编码时体现在向TransformGroup中添加元素时的顺序
            TranslateTransform translate = new TranslateTransform();
            RotateTransform rotate 
= new RotateTransform();
            TransformGroup group 
= new TransformGroup();
            group.Children.Add(rotate);
//先旋转
            group.Children.Add(translate);//再平移
            this.border1.RenderTransform = group;
补充完整后的代码:
            Canvas.SetTop(this.border1, -this.border1.ActualHeight / 2);
            Canvas.SetLeft(
this.border1, -this.border1.ActualWidth / 2);

            
this.border1.RenderTransformOrigin = new Point(0.50.5);
        
            TranslateTransform translate 
= new TranslateTransform();
            RotateTransform rotate 
= new RotateTransform();
            TransformGroup group 
= new TransformGroup();
            group.Children.Add(rotate);
//先旋转
            group.Children.Add(translate);//再平移
            this.border1.RenderTransform = group;

            NameScope.SetNameScope(
thisnew NameScope());
            
this.RegisterName("translate", translate);
            
this.RegisterName("rotate", rotate);

            DoubleAnimationUsingPath animationX 
= new DoubleAnimationUsingPath();
            animationX.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationX.Source 
= PathAnimationSource.X;
            animationX.Duration 
= new Duration(TimeSpan.FromSeconds(2));

            DoubleAnimationUsingPath animationY 
= new DoubleAnimationUsingPath();
            animationY.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationY.Source 
= PathAnimationSource.Y;
            animationY.Duration 
= animationX.Duration;

            DoubleAnimationUsingPath animationAngle 
= new DoubleAnimationUsingPath();
            animationAngle.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            animationAngle.Source 
= PathAnimationSource.Angle;
            animationAngle.Duration 
= animationX.Duration;

            Storyboard story 
= new Storyboard();
            story.RepeatBehavior 
= RepeatBehavior.Forever;
            story.AutoReverse 
= true;
            story.Children.Add(animationX);
            story.Children.Add(animationY);
            story.Children.Add(animationAngle);
            Storyboard.SetTargetName(animationX, 
"translate");
            Storyboard.SetTargetName(animationY, 
"translate");
            Storyboard.SetTargetName(animationAngle, 
"rotate");
            Storyboard.SetTargetProperty(animationX, 
new PropertyPath(TranslateTransform.XProperty));
            Storyboard.SetTargetProperty(animationY, 
new PropertyPath(TranslateTransform.YProperty));
            Storyboard.SetTargetProperty(animationAngle, 
new PropertyPath(RotateTransform.AngleProperty));

            story.Begin(
this);

效果图如下:
pathAnimation8.png


关于路径动画,先介绍到这里,不过其实实现上面的的动画更为常用的方式是使用MatrixAnimationUsingPath,可以参考以下代码:

            Canvas.SetLeft(this.border1, -this.border1.ActualWidth / 2);
            Canvas.SetTop(
this.border1, -this.border1.ActualHeight / 2);
            
this.border1.RenderTransformOrigin = new Point(0.50.5);

            MatrixTransform matrix 
= new MatrixTransform();
            
this.border1.RenderTransform = matrix;

            NameScope.SetNameScope(
thisnew NameScope());
            
this.RegisterName("matrix", matrix);

            MatrixAnimationUsingPath matrixAnimation 
= new MatrixAnimationUsingPath();
            matrixAnimation.PathGeometry 
= this.path1.Data.GetFlattenedPathGeometry();
            matrixAnimation.Duration 
= new Duration(TimeSpan.FromSeconds(2));
            matrixAnimation.RepeatBehavior 
= RepeatBehavior.Forever;
            matrixAnimation.AutoReverse 
= true;
            matrixAnimation.IsOffsetCumulative 
= !matrixAnimation.AutoReverse;
            matrixAnimation.DoesRotateWithTangent 
= true;//旋转


            Storyboard story 
= new Storyboard();
            story.Children.Add(matrixAnimation);
            Storyboard.SetTargetName(matrixAnimation, 
"matrix");
            Storyboard.SetTargetProperty(matrixAnimation, 
new PropertyPath(MatrixTransform.MatrixProperty));
            story.Begin(
this);


下载Demo:https://files.cnblogs.com/zhouyinhui/PathAnimationDemo.rar


 

 

 

 


 

posted @ 2007-07-31 17:11  周银辉  阅读(18355)  评论(12编辑  收藏  举报