当标签在WPF中更改值时,如何触发动画?

请检查下面的代码是否适用于您。对标签内容属性的任何更改都将设置动画。它是通过使用触发器和值转换器类来完成的,这个类将内容值转换为“真”或“假”,并设置触发器对这两个值做出反应。cnverter附加到标签的tag属性,该属性被弯折为数据上下文的name属性。另外,我还添加了一些动画到鼠标输入和离开事件中,这些事件非常简单,只使用XAML中的RouteRevents完成。

转换器:

public class TestConverter : IValueConverter
{
    private string  _originalValue = String.Empty;
    private bool    _previousValue = false;

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        _originalValue = (string)value;
        _previousValue = !_previousValue;
        return _previousValue.ToString();
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return _originalValue;
    }
}

数据上下文初始化:

label1.DataContext = new Test() { Name = DateTime.Now.ToString() };

XAML:

<Window.Resources>
    <local:TestConverter x:Key="TestConverter" />
</Window.Resources>
<Grid>
    <Label             
        Height="28" 
        HorizontalAlignment="Left" 
        Margin="132,96,0,0" 
        Name="label1" VerticalAlignment="Top" Width="120">

        <Label.Content>
            <Binding Path="Name"/>
        </Label.Content>
        <Label.Tag>
            <Binding Path="Name" Converter="{StaticResource TestConverter}"/>
        </Label.Tag>
        <Label.Background>
            <SolidColorBrush x:Name="animatedBrush1" Color="Yellow" />
        </Label.Background>
        <Label.Style>
            <Style TargetType="Label">
                <Style.Triggers>
                    <Trigger Property="Tag" Value="True">
                        <Trigger.EnterActions>
                            <BeginStoryboard>
                                <Storyboard AutoReverse="True">
                                    <!--<DoubleAnimation 
                                        Storyboard.TargetProperty="FontSize" To="20"/>-->
                                    <DoubleAnimation 
                                        Storyboard.TargetProperty="Opacity" To="0.0" AutoReverse="True"/>
                                </Storyboard>
                            </BeginStoryboard>
                        </Trigger.EnterActions>
                    </Trigger>
                    <Trigger Property="Tag" Value="False">
                        <Trigger.EnterActions>
                            <BeginStoryboard>
                                <Storyboard AutoReverse="True">
                                    <DoubleAnimation 
                                        Storyboard.TargetProperty="FontSize" To="20"/>
                                    <!--"<DoubleAnimation 
                                        Storyboard.TargetProperty="Opacity" To="0.0" AutoReverse="True"/>-->
                                </Storyboard>
                            </BeginStoryboard>
                        </Trigger.EnterActions>
                    </Trigger>
                </Style.Triggers>
            </Style>
        </Label.Style>
        <Label.Triggers>
            <EventTrigger RoutedEvent="Label.MouseEnter">
                <BeginStoryboard>
                    <Storyboard>
                        <ColorAnimation
                            Storyboard.TargetName="animatedBrush1"
                            Storyboard.TargetProperty="Color"
                            To="Blue" Duration="0:0:1" />
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
            <EventTrigger RoutedEvent="Label.MouseLeave">
                <BeginStoryboard>
                    <Storyboard>
                        <ColorAnimation
                            Storyboard.TargetName="animatedBrush1"
                            Storyboard.TargetProperty="Color"
                            To="Yellow" Duration="0:0:1" />
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </Label.Triggers>
    </Label>
</Grid>

希望这有帮助,问候

你不应该使用事件触发器吗? 你需要设置 NotifyOnTargetUpdated=True 在绑定中,但这在我的代码中有效。

<DataTemplate>
    <Border Name="templateBorder">
        <TextBlock Text="{Binding Path=Name, NotifyOnTargetUpdated=True}" />
    </Border>
    <DataTemplate.Triggers>
        <EventTrigger RoutedEvent="Binding.TargetUpdated">
            <BeginStoryboard>
                <Storyboard AutoReverse="True">
                    <DoubleAnimation Storyboard.TargetProperty="Opacity" 
                                     To=".1" Duration="0:0:.5" />
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </DataTemplate.Triggers>
</DataTemplate>

我喜欢谢尔盖·古本科的回答,但我想我应该提一下我有时会用到的另一种技巧。Serge的答案更接近您的“纯XAML”理想,因为它只有一个转换器,但是这个答案的代码更少,而且可读性更高。这里是:

将propertyChangedCallback添加到“name”属性中,然后从中启动情节提要:

DependencyProperty NameProperty = DependencyProperty.Register( ..., new UIElementMetadata
{
  PropertyChangedCallback = (obj, e) =>
  {
    storyBoard.Begin();
  }
});

如果在窗口首次加载时不希望闪烁,可以添加标志:

...
  PropertyChangedCallback = (obj, e) =>
  {
    if(_initialized)
      storyBoard.Begin();
  }
...

protected override void OnInitialized(...)
{
  _initialized = true;
}