在XAML中使用相同属性的MultiTriggers

Question

我实际上正在覆盖TextBox的默认ControlTemplate，为了完成我想要的操作，当TextBox失去焦点并且其文本为空时，我需要触发两个动画。为了做到这一点，我使用了一个MultiTrigger，有两个这样的条件：

(我将使用FontSize上的动画作为示例(

<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsFocused" Value="False"/>
<Condition Property="Text" Value="{x:Static sys:String.Empty}"/>
</MultiTrigger.Conditions>
<MultiTrigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation Storyboard.TargetName="Title" Storyboard.TargetProperty="FontSize" From="9" To="120" Duration="0:0:2">
<DoubleAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</MultiTrigger.EnterActions>
</MultiTrigger>

问题是，动画是在TextBox实例化时触发的，因为TextBox没有聚焦，而Text是空的。因此，我们可以说动画和MultiTrigger正在工作，但当我将TextBox聚焦一次(GotFocus重置FontSize(时，在LostFocus上不再触发动画。

但是如果我用这个替换整个MultiTrigger.EnterActions：

<MultiTrigger.Setters>
<Setter Property="Background" Value="Red"/>
</MultiTrigger.Setters>

一切都像符咒一样运转。我的意思是，背景一开始是红色的，GotFocus上是白色的，而LostFocus上又是红色的。

我可能误解了我们使用EnterActions的方式，但关于MultiTriggers的文档并不多。你知道为什么动画在第一次之后就不再触发了吗？

顺便问一下，有没有比Value="{x:Static sys:String.Empty}"更好的方法来检查Text属性是否为空？

编辑：在我的ControlTemplate.Triggers中，我已经使用了两个EventTriggers，一个路由到GotFocus事件，另一个路由至LostFocus事件。我在MSDN上看到EnterActions不适用于EventTrigger，所以我试图去掉我的EventTriggers，现在它可以工作了。

问题是，我使用了MultiTrigger，因为我需要检查LostFocus上的Text是否为空，但可能有办法将该条件放入EventTrigger中？

编辑#2：AS@Satish Pai问道，这是完整的ControlTemplate，我在其中用MutliTrigger替换了EventTriggers，因为正如我所说，它们似乎不兼容。

<ControlTemplate TargetType="{x:Type TextBox}">
<Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="14"/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<TextBlock x:Name="Title" Text="{TemplateBinding ToolTip}" Margin="8,14,0,0" Grid.Row="0" Grid.RowSpan="2" Foreground="{StaticResource TextBox.Static.Border}"></TextBlock>
<ScrollViewer x:Name="PART_ContentHost" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden" Grid.Row="1"/>
<Rectangle x:Name="UnfocusedUnderLine" Fill="{StaticResource TextBox.Static.Border}" Height="6" Margin="0,1,0,0" Grid.Row="2"/>
<Rectangle x:Name="UnderLine" Fill="{StaticResource TextBox.Focus.Border}" Height="6" Margin="0,1,0,0" Grid.Row="2" Width="0"/>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Opacity" TargetName="border" Value="0.56"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.MouseOver.Border}"/>
</Trigger>
<Trigger Property="IsKeyboardFocused" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.Focus.Border}"/>
</Trigger>
<MultiTrigger x:Name="FocusChanged">
<MultiTrigger.Conditions>
<Condition Property="IsFocused" Value="True"/>
</MultiTrigger.Conditions>
<MultiTrigger.EnterActions> <!--GotFocus-->
<BeginStoryboard>
<Storyboard>
<!--Change UnderLine Color-->
<DoubleAnimation Storyboard.TargetName="UnderLine" Storyboard.TargetProperty="Width" From="0" To="500" Duration="0:0:0.25">
<DoubleAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>

<!--Move Title Up-->
<ThicknessAnimation From="8,14,0,0" To="0,0,0,0" Duration="0:0:0.25" Storyboard.TargetName="Title" Storyboard.TargetProperty="Margin" AutoReverse="False" >
<ThicknessAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</ThicknessAnimation.EasingFunction>
</ThicknessAnimation>

<!--Decrease Title Size-->
<DoubleAnimation Storyboard.TargetName="Title"
Storyboard.TargetProperty="FontSize"
From="12"
To="9"
Duration="0:0:0.25">
<DoubleAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</MultiTrigger.EnterActions>
<MultiTrigger.ExitActions>  <!--LostFocus-->
<BeginStoryboard>
<Storyboard>

<!--Change UnderLine Color-->
<DoubleAnimation Storyboard.TargetName="UnderLine"
Storyboard.TargetProperty="Width"
From="500"
To="0"
Duration="0:0:0.2">
<DoubleAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</MultiTrigger.ExitActions>
</MultiTrigger>
<MultiTrigger x:Name="LostFocusAndEmptyText">
<MultiTrigger.Conditions>
<Condition Property="Text" Value="{x:Static sys:String.Empty}"/>
</MultiTrigger.Conditions>
<MultiTrigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<!--Move Title Down-->
<ThicknessAnimation From="0,0,0,0" To="8,14,0,0" Duration="0:0:0.2" Storyboard.TargetName="Title" Storyboard.TargetProperty="Margin" AutoReverse="False" >
<ThicknessAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</ThicknessAnimation.EasingFunction>
</ThicknessAnimation>
<!--Increase Title Size-->
<DoubleAnimation Storyboard.TargetName="Title"
Storyboard.TargetProperty="FontSize"
From="9"
To="12"
Duration="0:0:0.2">
<DoubleAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</MultiTrigger.EnterActions>
</MultiTrigger>
<!--LostFocusWithEmptyText-->
</ControlTemplate.Triggers>
</ControlTemplate>

问题是，两个MultiTiggers都引用了相同的IsFocused属性，它们不想一起工作。如果我删除LostFocusAndEmptyText触发器，它会起作用，但我确实需要区分使用空文本和不使用空文本的情况。

关于如何实现这一目标，有什么建议吗？

Answer 1

检查您的TiTle TextBlock初始化状态。边距="；0,0,0,0"；FontSize="；9〃；

<TextBlock x:Name="Title" Text="{TemplateBinding ToolTip}" FontSize="9" Margin="0,0,0,0" Grid.Row="0" Grid.RowSpan="2" 

使用Animation的属性"FillBehavior"设置为"；停止"；。和在EventTrigger中删除动画的属性"From"。祝你好运

<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Opacity" TargetName="border" Value="0.56"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.MouseOver.Border}"/>
</Trigger>
<Trigger Property="IsKeyboardFocused" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.Focus.Border}"/>
</Trigger>
<EventTrigger RoutedEvent="GotFocus">
<BeginStoryboard>
<Storyboard>
<ThicknessAnimation To="0,0,0,0" Duration="0:0:0.25"
Storyboard.TargetName="Title" FillBehavior="Stop" 
Storyboard.TargetProperty="Margin" AutoReverse="False" >
<ThicknessAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</ThicknessAnimation.EasingFunction>
</ThicknessAnimation>
<DoubleAnimation Storyboard.TargetName="Title"
Storyboard.TargetProperty="FontSize" FillBehavior="Stop" 
To="9"
Duration="0:0:0.25">
<DoubleAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
<MultiTrigger x:Name="LostFocusAndEmptyText">
<MultiTrigger.Conditions>
<Condition Property="Text" Value="{x:Static sys:String.Empty}"/>
<Condition Property="IsFocused" Value="False"/>
</MultiTrigger.Conditions>
<Setter TargetName="Title"  Property="FontSize"  Value="12"/>
<Setter TargetName="Title"  Property="Margin"  Value="8,14,0,0"/>
<MultiTrigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<ThicknessAnimation From="0,0,0,0" To="8,14,0,0" Duration="0:0:0.25" 
FillBehavior="Stop"
Storyboard.TargetName="Title" Storyboard.TargetProperty="Margin" 
AutoReverse="False" >
<ThicknessAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</ThicknessAnimation.EasingFunction>
</ThicknessAnimation>
<DoubleAnimation Storyboard.TargetName="Title"
Storyboard.TargetProperty="FontSize"
FillBehavior="Stop"
To="12" From="9"
Duration="0:0:0.2">
<DoubleAnimation.EasingFunction>
<QuinticEase EasingMode="EaseInOut"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</MultiTrigger.EnterActions>
</MultiTrigger>                        
</ControlTemplate.Triggers>