在WPF中的Window.Resources中声明时,EventTrigger不起作用

发布时间：2020-12-14 04:38:14 所属栏目：Windows 来源：网络整理

导读：我是 WPF的新手,所以我可能会遗漏一些必要的东西,但我已经尝试并试图找出以下现象的解释,但无济于事. 基本上,以下代码工作(显示动画)： Window.Resources Storyboard x:Key="LoadStoryBoard"AutoReverse="True"RepeatBehavior="Forever" DoubleAnimationUsin

我是 WPF的新手,所以我可能会遗漏一些必要的东西,但我已经尝试并试图找出以下现象的解释,但无济于事.
基本上,以下代码工作(显示动画)：

<Window.Resources>
    <Storyboard x:Key="LoadStoryBoard"
AutoReverse="True"
RepeatBehavior="Forever">
        <DoubleAnimationUsingKeyFrames Storyboard.TargetName="button1" 
                Storyboard.TargetProperty="(Button.Opacity)">
            <EasingDoubleKeyFrame KeyTime="0:0:0.7" Value="0.4" />
        </DoubleAnimationUsingKeyFrames>
    </Storyboard>
</Window.Resources>
...
<Button x:Name="button1" Grid.Column="0" Grid.Row="1" Style="{StaticResource Load}">
<Button.Triggers>
    <EventTrigger RoutedEvent="Loaded">
                <BeginStoryboard Storyboard="{StaticResource LoadStoryBoard}" />
            </EventTrigger>
</Button.Triggers>
</Button>

但是,当我尝试将eventrigger置于下面的Load Style中时,动画将不再出现：

<Window.Resources>
    <Storyboard x:Key="LoadStoryBoard"
AutoReverse="True"
RepeatBehavior="Forever">
        <DoubleAnimationUsingKeyFrames Storyboard.TargetName="button1" 
                Storyboard.TargetProperty="(Button.Opacity)">
            <EasingDoubleKeyFrame KeyTime="0:0:0.7" Value="0.4" />
        </DoubleAnimationUsingKeyFrames>
    </Storyboard>
</Window.Resources>
...
<Style x:Key="Load" TargetType="Button">
...
<Style.Triggers>
    ...
    <EventTrigger RoutedEvent="Loaded">
                <BeginStoryboard Storyboard="{StaticResource LoadStoryBoard}" />
            </EventTrigger>
</Style.Triggers>
</Style>

解决方法

在触发器的样式中不能使用具有TargetName的对象,这样的动画.为此,将它们放在触发器模板< ControlTemplate.Triggers>中.引自 link：

TargetName is not intended for use within the Triggers collection of a Style. A style does not have a namescope,so it does not make sense to refer to elements by name there. But a template (either DataTemplate or ControlTemplate) does have a namescope.

以下作品：

<Window.Resources>
    <Storyboard x:Key="LoadStoryBoard" AutoReverse="True" RepeatBehavior="Forever">
        <DoubleAnimationUsingKeyFrames Storyboard.TargetName="button1" Storyboard.TargetProperty="(Button.Opacity)">
            <EasingDoubleKeyFrame KeyTime="0:0:0.7" Value="0.4" />
        </DoubleAnimationUsingKeyFrames>
    </Storyboard>       

    <Style x:Key="ButtonStyle" TargetType="{x:Type Button}">
        <Setter Property="Background" Value="Green" />
        <Setter Property="Foreground" Value="White" />
        <Setter Property="FontSize" Value="14" />
        <Setter Property="FocusVisualStyle" Value="{x:Null}" />
        <Setter Property="SnapsToDevicePixels" Value="True" />

        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Button}">
                    <Border x:Name="button1" CornerRadius="0" Background="{TemplateBinding Background}">
                        <Grid>
                            <ContentPresenter x:Name="MyContentPresenter" Content="{TemplateBinding Content}" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,0" />                                
                        </Grid>
                    </Border>

                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouSEOver" Value="True">
                            <Setter Property="Background" Value="Orange" />
                        </Trigger>

                        <EventTrigger RoutedEvent="Button.Loaded">
                            <BeginStoryboard Storyboard="{StaticResource LoadStoryBoard}" />
                        </EventTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>

<Grid>
    <Button Name="TestButton" Style="{StaticResource ButtonStyle}" Width="100" Height="30" Content="Test" Grid.Column="0" Grid.Row="1" />
</Grid>

请注意,现在Border中指定的模板中的TargetName：< Border x：Name =“button1”... />.

注意：或者,您可以删除Storyboard.TargetName,因为它不支持触发样式.

（编辑：李大同）

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