Verwenden Sie Shape, um Animationsbeispielcode zu erstellen

相对于WPF/Silverlight，UWP的动画系统可以说有大幅提高，不过本文无意深入讨论这些动画API，本文将介绍使用Shape做一些进度、等待方面的动画，除此之外也会介绍一些相关技巧。

1. 使用StrokeDashOffset做等待提示动画

圆形的等待提示动画十分容易做，只要让它旋转就可以了：

但是圆形以外的形状就不容易做了，例如三角形，总不能让它单纯地旋转吧：

要解决这个问题可以使用StrokeDashOffset。StrokeDashOffset用于控制虚线边框的第一个短线相对于Shape开始点的位移，使用动画控制这个数值可以做出边框滚动的效果：

<Page.Resources><Storyboard x:Name="ProgressStoryboard"><DoubleAnimationUsingKeyFrames EnableDependentAnimation="True"                                       
Storyboard.TargetProperty="(Shape.StrokeDashOffset)"                                       
Storyboard.TargetName="triangle"><EasingDoubleKeyFrame KeyTime="0:1:0"                                  
Value="-500" /></DoubleAnimationUsingKeyFrames></Storyboard></Page.Resources><Grid Background="#FFCCCCCC"><Grid Height="100"          
HorizontalAlignment="Center"><StackPanel Orientation="Horizontal"                    
VerticalAlignment="Center"><TextBlock Text="L"                       
FontSize="55"                       
Margin="0,0,5,4" /><local:Triangle x:Name="triangle"                            
Height="40"                            
Width="40"                            
StrokeThickness="2"                            
Stroke="RoyalBlue"                            
StrokeDashArray="4.045 4.045"                            
StrokeDashOffset="0.05"                            
StrokeDashCap="Round" /><TextBlock Text="ading..."                       
FontSize="55"                       
Margin="5,0,0,4" /></StackPanel></Grid></Grid>

需要注意的是Shape的边长要正好能被StrokeDashArray中短线和缺口的和整除，即 满足边长 / StrokeThickness % Sum( StrokeDashArray ) = 0，这是因为在StrokeDashOffset=0的地方会截断短线，如下图所示：

另外注意的是边长的计算，如Rectangle，边长并不是(Height + Width) * 2，而是(Height - StrokeThickness) * 2 + (Width- StrokeThickness) * 2，如下图所示，边长应该从边框正中间开始计算：

有一些Shape的边长计算还会受到Stretch影响，如上一篇中自定义的Triangle：

<StackPanel Orientation="Horizontal" HorizontalAlignment="Center"><Grid Height="50"          
Width="50"><local:Triangle Stretch="Fill"                        
StrokeThickness="5"                        
Stroke="RoyalBlue" /></Grid><Grid Height="50"          
Width="50"          
Margin="10,0,0,0"><local:Triangle Stretch="None"                        
StrokeThickness="5"                        
Stroke="RoyalBlue" /></Grid></StackPanel>

2. 使用StrokeDashArray做进度提示动画

StrokeDashArray用于将Shape的边框变成虚线，StrokeDashArray的值是一个double类型的有序集合，里面的数值指定虚线中每一段以StrokeThickness为单位的长度。用StrokeDashArray做进度提示的基本做法就是将进度Progress通过Converter转换为分成两段的StrokeDashArray，第一段为实线，表示当前进度，第二段为空白。假设一个Shape的边长是100，当前进度为50，则将StrokeDashArray设置成{50，double.MaxValue}两段。

做成动画如下图所示：

<Page.Resources><Style TargetType="TextBlock"><Setter Property="FontSize"                
Value="12" /></Style><local:ProgressToStrokeDashArrayConverter x:Key="ProgressToStrokeDashArrayConverter"                                              
TargetPath="{Binding ElementName=Triangle}" /><local:ProgressToStrokeDashArrayConverter2 x:Key="ProgressToStrokeDashArrayConverter2"                                               
TargetPath="{Binding ElementName=Triangle}" />
<toolkit:StringFormatConverter x:Key="StringFormatConverter" /><local:ProgressWrapper x:Name="ProgressWrapper" /><Storyboard x:Name="Storyboard1"><DoubleAnimation Duration="0:0:5"                         
To="100"                         
Storyboard.TargetProperty="Progress"                         
Storyboard.TargetName="ProgressWrapper"                         
EnableDependentAnimation="True" /></Storyboard></Page.Resources><Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"><Viewbox Height="150"><StackPanel Orientation="Horizontal"><Grid><local:Triangle Height="40"                                
Width="40"                                
StrokeThickness="2"                                
Stroke="DarkGray" /><local:Triangle x:Name="Triangle"                                
Height="40"                                
Width="40"                                
StrokeThickness="2"                                
Stroke="RoyalBlue"                                
StrokeDashArray="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource ProgressToStrokeDashArrayConverter}}" /><TextBlock Text="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource StringFormatConverter},ConverterParameter=&#39;{}{0:0}&#39;}"                           
HorizontalAlignment="Center"                           
VerticalAlignment="Center"                           
Margin="0,15,0,0" /></Grid><Grid Margin="20,0,0,0"><local:Triangle Height="40"                                
Width="40"                                
StrokeThickness="2"                                
Stroke="DarkGray" /><local:Triangle x:Name="Triangle2"                                
Height="40"                                
Width="40"                                
StrokeThickness="2"                                
Stroke="RoyalBlue"                               
StrokeDashArray="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource ProgressToStrokeDashArrayConverter2}}" /><TextBlock Text="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource StringFormatConverter},ConverterParameter=&#39;{}{0:0}&#39;}"                           
HorizontalAlignment="Center"                           
VerticalAlignment="Center"                           
Margin="0,15,0,0" /></Grid></StackPanel></Viewbox></Grid>

其中ProgressToStrokeDashArrayConverter和ProgressToStrokeDashArrayConverter2的代码如下：

public class ProgressToStrokeDashArrayConverter : DependencyObject, IValueConverter
{/// <summary>/// 获取或设置TargetPath的值/// </summary>  public Path TargetPath
    {
    get { return (Path)GetValue(TargetPathProperty);
     }
    set {
     SetValue(TargetPathProperty, value); 
    }
    }/// <summary>/// 标识 TargetPath 依赖属性。/// 
    </summary>public static readonly DependencyProperty TargetPathProperty =
        DependencyProperty.Register("TargetPath", typeof(Path), typeof(ProgressToStrokeDashArrayConverter), new PropertyMetadata(null));public virtual object Convert(object value, Type targetType, object parameter, string language)
    {
    if (value is double == false)return null;

        var progress = (double)value;if (TargetPath == null)return null;var totalLength = GetTotalLength();
        var firstSection = progress * totalLength / 100 / TargetPath.StrokeThickness;if (progress == 100)
            firstSection = Math.Ceiling(firstSection);var result = new DoubleCollection { 
            firstSection, double.MaxValue };return result;
    }public object ConvertBack(object value, Type targetType, object parameter, string language)
    {throw new NotImplementedException();
    }protected double GetTotalLength()
    {var geometry = TargetPath.Data as PathGeometry;
    if (geometry == null)
    return 0;
    if (geometry.Figures.Any() == false)return 0;
    var figure = geometry.Figures.FirstOrDefault();
    if (figure == null)
    return 0;
    var totalLength = 0d;
    var point = figure.StartPoint;
    foreach (var item in figure.Segments)
        {
        var segment = item as LineSegment;
        if (segment == null)
        return 0;

            totalLength += Math.Sqrt(Math.Pow(point.X - segment.Point.X, 2) + Math.Pow(point.Y - segment.Point.Y, 2));
            point = segment.Point;
        }

        totalLength += Math.Sqrt(Math.Pow(point.X - figure.StartPoint.X, 2) + Math.Pow(point.Y - figure.StartPoint.Y, 2));
        return totalLength;
    }
}
public class ProgressToStrokeDashArrayConverter2 : ProgressToStrokeDashArrayConverter
{
public override object Convert(object value, Type targetType, object parameter, string language)
    {
    if (value is double == false)return null;

        var progress = (double)value;
        if (TargetPath == null)
        return null;
        var totalLength = GetTotalLength();
        totalLength = totalLength / TargetPath.StrokeThickness;
        var thirdSection = progress * totalLength / 100;
        if (progress == 100)
            thirdSection = Math.Ceiling(thirdSection);

        var secondSection = (totalLength - thirdSection) / 2;
        var result = new DoubleCollection { 0, secondSection, thirdSection, double.MaxValue };
        return result;
    }
}

由于代码只是用于演示，protected double GetTotalLength()写得比较将就。可以看到这两个Converter继承自DependencyObject，这是因为这里需要通过绑定为TargetPath赋值。

这里还有另一个类ProgressWrapper：

public class ProgressWrapper : DependencyObject
{/// <summary>/// 获取或设置Progress的值/// </summary>  public double Progress
    {get { return (double)GetValue(ProgressProperty); }set { SetValue(ProgressProperty, value); }
    }/// <summary>/// 标识 Progress 依赖属性。/// 
    </summary>public static readonly DependencyProperty ProgressProperty =
        DependencyProperty.Register("Progress", typeof(double), typeof(ProgressWrapper), new PropertyMetadata(0d));
}

因为这里没有可供Storyboard操作的double属性，所以用这个类充当Storyboard和StrokeDashArray的桥梁。UWPCommunityToolkit中也有一个差不多用法的类BindableValueHolder，这个类通用性比较强，可以参考它的用法。

3. 使用Behavior改进进度提示动画代码

只是做个动画而已，又是Converter，又是Wrapper，又是Binding，看起来十分复杂，如果Shape上面有Progress属性就方便多了。这时候首先会考虑附加属性，在XAML用法如下：

<UserControl.Resources>
  <Storyboard x:Name="Storyboard1"><DoubleAnimation Duration="0:0:5"                     
  To="100"                     
  Storyboard.TargetProperty="(local:PathExtention.Progress)"                     
  Storyboard.TargetName="Triangle" />
  </Storyboard></UserControl.Resources><Grid x:Name="LayoutRoot"      
  Background="White"><local:Triangle x:Name="Triangle"                    
  Height="40"                    
  local:PathExtention.Progress="0"                    
  Width="40"                    
  StrokeThickness="2"                    
  Stroke="RoyalBlue" ></local:Triangle></Grid>

但其实这是行不通的，XAML有一个存在了很久的限制：However, an existing limitation of the Windows Runtime XAML implementation is that you cannot animate a custom attached property.。这个限制决定了XAML不能对自定义附加属性做动画。不过，这个限制只限制了不能对自定义附加属性本身做动画，但对附加属性中的类的属性则可以，例如以下这种写法应该是行得通的：

<UserControl.Resources>
  <Storyboard x:Name="Storyboard1"><DoubleAnimation Duration="0:0:5"                     
  To="100"                     
  Storyboard.TargetProperty="(local:PathExtention.Progress)"                     
  Storyboard.TargetName="TrianglePathExtention" />
  </Storyboard></UserControl.Resources><Grid x:Name="LayoutRoot"      
  Background="White"><local:Triangle x:Name="Triangle"                    
  Height="40"                    
  Width="40"                    
  StrokeThickness="2"                    
  Stroke="RoyalBlue" >  <local:PathHelper><local:PathExtention x:Name="TrianglePathExtention"                             
  Progress="0" />  </local:PathHelper></local:Triangle></Grid>

更优雅的写法是利用XamlBehaviors，这篇文章很好地解释了XamlBehaviors的作用：

XAML Behaviors非常重要，因为它们提供了一种方法，让开发人员能够以一种简洁、可重复的方式轻松地向UI对象添加功能。
他们无需创建控件的子类或重复编写逻辑代码，只要简单地增加一个XAML代码片段。

要使用Behavior改进现有代码，只需实现一个PathProgressBehavior：

public class PathProgressBehavior : Behavior<UIElement>
{protected override void OnAttached()
    {base.OnAttached();UpdateStrokeDashArray();
    }/// <summary>/// 获取或设置Progress的值/// </summary>  public double Progress
    {get { return (double)GetValue(ProgressProperty); }set { SetValue(ProgressProperty, value); }
    }/*Progress DependencyProperty*/protected virtual void OnProgressChanged(double oldValue, double newValue)
    {UpdateStrokeDashArray();
    }protected virtual double GetTotalLength(Path path)
    {/*some code*/}private void UpdateStrokeDashArray()
    {
    var target = AssociatedObject as Path;if (target == null)return;double progress = Progress;
    //if (target.ActualHeight == 0 || target.ActualWidth == 0)//    
    return;
    if (target.StrokeThickness == 0)
    return;
    var totalLength = GetTotalLength(target);
    var firstSection = progress * totalLength / 100 / target.StrokeThickness;
    if (progress == 100)
            firstSection = Math.Ceiling(firstSection);
            var result = new DoubleCollection {
             firstSection, double.MaxValue 
             };
        target.StrokeDashArray = result;
    }
}

XAML中如下使用：

<UserControl.Resources>
  <Storyboard x:Name="Storyboard1"><DoubleAnimation Duration="0:0:5"                     
  To="100"                     
  Storyboard.TargetProperty="Progress"                     
  Storyboard.TargetName="PathProgressBehavior"                     
  EnableDependentAnimation="True"/>
  </Storyboard></UserControl.Resources><Grid x:Name="LayoutRoot"      
  Background="White">
  <local:Triangle x:Name="Triangle"                  
  Height="40"                  
  local:PathExtention.Progress="0"                  
  Width="40"                  
  StrokeThickness="2"                  
  Stroke="RoyalBlue" ><interactivity:Interaction.Behaviors>  
  <local:PathProgressBehavior x:Name="PathProgressBehavior" /></interactivity:Interaction.Behaviors>
  </local:Triangle></Grid>

这样看起来就清爽多了。

4. 模仿背景填充动画

先看看效果：

其实这篇文章里并不会讨论填充动画，不过首先声明做填充动画会更方便快捷，这一段只是深入学习过程中的产物，实用价值不高。
上图三角形的填充的效果只需要叠加两个同样大小的Shape，前面那个设置Stretch="Uniform"，再通过DoubleAnimation改变它的高度就可以了。文字也是相同的原理，叠加两个相同的TextBlock，将前面那个放在一个无边框的ScrollViewer里再去改变ScrollViewer的高度。

<Page.Resources><Style TargetType="TextBlock"><Setter Property="FontSize"               
Value="12" /></Style><local:ProgressToHeightConverter x:Key="ProgressToHeightConverter"                                     
TargetContentControl="{Binding ElementName=ContentControl}" /><local:ReverseProgressToHeightConverter x:Key="ReverseProgressToHeightConverter"                                           
TargetContentControl="{Binding ElementName=ContentControl2}" /><toolkit:StringFormatConverter x:Key="StringFormatConverter" /><local:ProgressWrapper x:Name="ProgressWrapper" /><Storyboard x:Name="Storyboard1"><DoubleAnimation Duration="0:0:5"                         
To="100"                         
Storyboard.TargetProperty="Progress"                         
Storyboard.TargetName="ProgressWrapper"                         
EnableDependentAnimation="True" /></Storyboard></Page.Resources><Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"><Grid><local:Triangle Height="40"                        
Width="40"                        
StrokeThickness="2"                        
Fill="LightGray" /><local:Triangle  Height="40"                         
Width="40"                         
Stretch="Fill"                         
StrokeThickness="2"                         
Stroke="RoyalBlue" /><ContentControl x:Name="ContentControl"                       
 VerticalAlignment="Bottom"                       
 HorizontalAlignment="Center"                        
 Height="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource ProgressToHeightConverter}}"><local:Triangle x:Name="Triangle3"                            Height="40"                            
 Width="40"                            
 StrokeThickness="2"                            
 Fill="RoyalBlue"                            
 Stretch="Uniform"                            
 VerticalAlignment="Bottom" /></ContentControl><TextBlock Text="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource StringFormatConverter},ConverterParameter=&#39;{}{0:0}&#39;}"                   
 HorizontalAlignment="Center"                   
 VerticalAlignment="Center"                   
 Margin="0,12,0,0"                   
 Foreground="White" /><ContentControl x:Name="ContentControl2"                        
 Height="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource ReverseProgressToHeightConverter}}"                        
 VerticalAlignment="Top"                        
 HorizontalAlignment="Center"><ScrollViewer BorderThickness="0"                          
 Padding="0,0,0,0"                          
 VerticalScrollBarVisibility="Disabled"                          
 HorizontalScrollBarVisibility="Disabled"                          
 VerticalAlignment="Top"                          
 Height="40"><Grid  Height="40"><TextBlock Text="{Binding Progress,Source={StaticResource ProgressWrapper},Converter={StaticResource StringFormatConverter},ConverterParameter=&#39;{}{0:0}&#39;}"                               
 HorizontalAlignment="Center"                               
 VerticalAlignment="Center"                               
 Margin="0,12,0,0" /></Grid></ScrollViewer></ContentControl></Grid></Grid>

ProgressToHeightConverter和ReverseProgressToHeightConverter的代码如下：

public class ProgressToHeightConverter : DependencyObject, IValueConverter
{/// <summary>/// 获取或设置TargetContentControl的值/// </summary>  public ContentControl TargetContentControl
    {
    get { 
    return (ContentControl)GetValue(TargetContentControlProperty); 
    }
    set { 
    SetValue(TargetContentControlProperty, value); 
    }
    }/// <summary>/// 标识 TargetContentControl 依赖属性。///
     </summary>public static readonly DependencyProperty TargetContentControlProperty =
        DependencyProperty.Register("TargetContentControl", typeof(ContentControl), typeof(ProgressToHeightConverter), new PropertyMetadata(null));
        public object Convert(object value, Type targetType, object parameter, string language)
    {
    if (value is double == false)
    return 0d;

        var progress = (double)value;
        if (TargetContentControl == null)
        return 0d;
        var element = TargetContentControl.Content as FrameworkElement;
        if (element == null)
        return 0d;return element.Height * progress / 100;
    }public object ConvertBack(object value, Type targetType, object parameter, string language)
    {throw new NotImplementedException();
    }

      
}public class ReverseProgressToHeightConverter : DependencyObject, IValueConverter
{/// <summary>/// 获取或设置TargetContentControl的值/// </summary>  
public ContentControl TargetContentControl
    {
    get { 
    return (ContentControl)GetValue(TargetContentControlProperty);
     }
    set { 
    SetValue(TargetContentControlProperty, value); 
    }
    }/// <summary>/// 标识 TargetContentControl 依赖属性。/// 
    </summary>public static readonly DependencyProperty TargetContentControlProperty =
        DependencyProperty.Register("TargetContentControl", typeof(ContentControl), typeof(ReverseProgressToHeightConverter), new PropertyMetadata(null));
        public object Convert(object value, Type targetType, object parameter, string language)
    {
    if (value is double == false)
    return double.NaN;

        var progress = (double)value;if (TargetContentControl == null)return double.NaN;
        var element = TargetContentControl.Content as FrameworkElement;
        if (element == null)return double.NaN;
        return element.Height * (100 - progress) / 100;
    }
    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
    throw new NotImplementedException();
    }
}

再提醒一次，实际上老老实实做填充动画好像更方便些。

5. 将动画应用到Button的ControlTemplate

同样的技术，配合ControlTemplate可以制作很有趣的按钮：

PointerEntered时，按钮的边框从进入点向反方向延伸。PointerExited时，边框从反方向向移出点消退。要做到这点需要在PointerEntered时改变边框的方向，使用了ChangeAngleToEnterPointerBehavior：

public class ChangeAngleToEnterPointerBehavior : Behavior<Ellipse>
{protected override void OnAttached()
    {base.OnAttached();
        AssociatedObject.PointerEntered += OnAssociatedObjectPointerEntered;
        AssociatedObject.PointerExited += OnAssociatedObjectPointerExited;
    }protected override void OnDetaching()
    {base.OnDetaching();
        AssociatedObject.PointerEntered -= OnAssociatedObjectPointerEntered;
        AssociatedObject.PointerExited -= OnAssociatedObjectPointerExited;
    }private void OnAssociatedObjectPointerExited(object sender, PointerRoutedEventArgs e)
    {UpdateAngle(e);
    }private void OnAssociatedObjectPointerEntered(object sender, PointerRoutedEventArgs e)
    {UpdateAngle(e);
    }private void UpdateAngle(PointerRoutedEventArgs e)
    {if (AssociatedObject == null || AssociatedObject.StrokeThickness == 0)return;

        AssociatedObject.RenderTransformOrigin = new Point(0.5, 0.5);var rotateTransform = AssociatedObject.RenderTransform as RotateTransform;if (rotateTransform == null)
        {
            rotateTransform = new RotateTransform();
            AssociatedObject.RenderTransform = rotateTransform;
        }var point = e.GetCurrentPoint(AssociatedObject.Parent as UIElement).Position;var centerPoint = new Point(AssociatedObject.ActualWidth / 2, AssociatedObject.ActualHeight / 2);var angleOfLine = Math.Atan2(point.Y - centerPoint.Y, point.X - centerPoint.X) * 180 / Math.PI;
        rotateTransform.Angle = angleOfLine + 180;
    }
}

这个类命名不是很好，不过将就一下吧。

为了做出边框延伸的效果，另外需要一个类EllipseProgressBehavior：

public class EllipseProgressBehavior : Behavior<Ellipse>
{/// <summary>/// 获取或设置Progress的值/// </summary>  
public double Progress
    {
    get { 
    return (double)GetValue(ProgressProperty); 
    }
    set { 
    SetValue(ProgressProperty, value); 
    }
    }/// <summary>/// 标识 Progress 依赖属性。/// </summary>
    public static readonly DependencyProperty ProgressProperty =
        DependencyProperty.Register("Progress", typeof(double), typeof(EllipseProgressBehavior), new PropertyMetadata(0d, OnProgressChanged));
        private static void OnProgressChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
    {
    var target = obj as EllipseProgressBehavior;
    double oldValue = (double)args.OldValue;
    double newValue = (double)args.NewValue;if (oldValue != newValue)
            target.OnProgressChanged(oldValue, newValue);
    }
    protected virtual void OnProgressChanged(double oldValue, double newValue)
    {UpdateStrokeDashArray();
    }protected virtual double GetTotalLength()
    {if (AssociatedObject == null)return 0;
    return (AssociatedObject.ActualHeight - AssociatedObject.StrokeThickness) * Math.PI;
    }private void UpdateStrokeDashArray()
    {if (AssociatedObject == null || AssociatedObject.StrokeThickness == 0)
    return;
    //if (target.ActualHeight == 0 || target.ActualWidth == 0)//    
    return;var totalLength = GetTotalLength();
        totalLength = totalLength / AssociatedObject.StrokeThickness;
        var thirdSection = Progress * totalLength / 100;
        var secondSection = (totalLength - thirdSection) / 2;
        var result = new DoubleCollection { 0, secondSection, thirdSection, double.MaxValue };
        AssociatedObject.StrokeDashArray = result;
    }

}

套用到ControlTemplate如下：

<ControlTemplate TargetType="Button"><Grid x:Name="RootGrid"><VisualStateManager.VisualStateGroups><VisualStateGroup x:Name="CommonStates"><VisualStateGroup.Transitions><VisualTransition GeneratedDuration="0:0:1"                                      
To="Normal"><Storyboard><DoubleAnimationUsingKeyFrames EnableDependentAnimation="True"                                                           
Storyboard.TargetProperty="(local:EllipseProgressBehavior.Progress)"                                                           
Storyboard.TargetName="EllipseProgressBehavior"><EasingDoubleKeyFrame KeyTime="0:0:1"                                                      
Value="0"><EasingDoubleKeyFrame.EasingFunction><QuinticEase EasingMode="EaseOut" /></EasingDoubleKeyFrame.EasingFunction></EasingDoubleKeyFrame></DoubleAnimationUsingKeyFrames></Storyboard></VisualTransition><VisualTransition GeneratedDuration="0:0:1"                                     
To="PointerOver"><Storyboard><DoubleAnimationUsingKeyFrames EnableDependentAnimation="True"                                                           
Storyboard.TargetProperty="(local:EllipseProgressBehavior.Progress)"                                                           
Storyboard.TargetName="EllipseProgressBehavior"><EasingDoubleKeyFrame KeyTime="0:0:1"                                                      
Value="100"><EasingDoubleKeyFrame.EasingFunction><QuinticEase EasingMode="EaseOut" /></EasingDoubleKeyFrame.EasingFunction></EasingDoubleKeyFrame></DoubleAnimationUsingKeyFrames></Storyboard></VisualTransition></VisualStateGroup.Transitions><VisualState x:Name="Normal"><Storyboard><PointerUpThemeAnimation Storyboard.TargetName="RootGrid" /></Storyboard></VisualState><VisualState x:Name="PointerOver"><Storyboard><PointerUpThemeAnimation Storyboard.TargetName="RootGrid" /></Storyboard><VisualState.Setters><Setter Target="EllipseProgressBehavior.(local:EllipseProgressBehavior.Progress)"                               
 Value="100" /></VisualState.Setters></VisualState><VisualState x:Name="Pressed"><Storyboard><PointerDownThemeAnimation Storyboard.TargetName="RootGrid" /></Storyboard></VisualState><VisualState x:Name="Disabled" /></VisualStateGroup></VisualStateManager.VisualStateGroups><ContentPresenter x:Name="ContentPresenter"                          
AutomationProperties.AccessibilityView="Raw"                          
ContentTemplate="{TemplateBinding ContentTemplate}"                          
ContentTransitions="{TemplateBinding ContentTransitions}"                          
Content="{TemplateBinding Content}"                          
HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"                          
Padding="{TemplateBinding Padding}"                         
 VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" /><Ellipse Fill="Transparent"                 Stroke="{TemplateBinding BorderBrush}"                 StrokeThickness="2"><interactivity:Interaction.Behaviors><local:ChangeAngleToEnterPointerBehavior /><local:EllipseProgressBehavior x:Name="EllipseProgressBehavior" /></interactivity:Interaction.Behaviors></Ellipse></Grid></ControlTemplate>

注意：我没有鼓励任何人自定义按钮外观的意思，能用系统自带的动画或样式就尽量用系统自带的，没有设计师的情况下
又想UI做得与众不同通常会做得很难看。想要UI好看，合理的布局、合理的颜色、合理的图片就足够了。

6. 结语

在学习Shape的过程中觉得好玩就做了很多尝试，因为以前工作中做过不少等待、进度的动画，所以这次就试着做出本文的动画。
XAML的传统动画并没有提供太多功能，主要是ColorAnimation、DoubleAnimation、PointAnimation三种，不过靠Binding和Converter可以弥补这方面的不足，实现很多需要的功能。
本文的一些动画效果参考了SVG的动画。话说回来，Windows 10 1703新增了SvgImageSource，不过看起来只是简单地将SVG翻译成对应的Shape，然后用Shape呈现，不少高级特性都不支持（如下图阴影的滤镜），用法如下：

<Image><Image.Source><SvgImageSource UriSource="feoffset_1.svg" /></Image.Source></Image>

SvgImageSource：

原本的Svg：

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