C＃WPF触发器文本框从代码更新

Question

我有这个文本框：

<TextBlock x:Name="StatusTextBlock" Foreground="Black">
            <TextBlock.Triggers>
                <EventTrigger RoutedEvent="Binding.TargetUpdated">
                    <EventTrigger.Actions>
                        <BeginStoryboard>
                            <Storyboard Duration="0:0:4" >
                                <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(TextBlock.Foreground).(SolidColorBrush.Color)"
                                  Storyboard.TargetName="StatusTextBlock"
                                  AutoReverse="False">
                                    <ColorAnimationUsingKeyFrames.KeyFrames>
                                        <DiscreteColorKeyFrame KeyTime="0:0:0" Value="Black"/>
                                        <DiscreteColorKeyFrame KeyTime="0:0:0.5" Value="DarkGray"/>
                                        <DiscreteColorKeyFrame KeyTime="0:0:1" Value="Black"/>
                                        <DiscreteColorKeyFrame KeyTime="0:0:1.5" Value="DarkGray"/>
                                        <DiscreteColorKeyFrame KeyTime="0:0:2" Value="Black"/>
                                        <DiscreteColorKeyFrame KeyTime="0:0:2.5" Value="DarkGray"/>
                                        <DiscreteColorKeyFrame KeyTime="0:0:3" Value="Black"/>
                                    </ColorAnimationUsingKeyFrames.KeyFrames>
                                </ColorAnimationUsingKeyFrames>
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger.Actions>
                </EventTrigger>
            </TextBlock.Triggers>
        </TextBlock>

现在在我的代码背后，我想触发一个方法内的更新：

public void UpdateStatusBlock(string text)
    {
        StatusTextBlock.Text = text;
        // How can i trigger the animation in here
    }

如何触发动画？

Answer 1

为了使其工作，您必须将TextBlox.Text属性绑定到实现INotifyPropertyChanged的某些对象。 为什么？ 因为您定义了仅在“ Binding.TargetUpdated”时触发的触发器。

这里看起来像：

public partial class MainWindow : Window
    {       
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = new SampleViewModel();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            SampleViewModel vm = (SampleViewModel) this.DataContext;
            vm.SampleText = DateTime.Now.Ticks.ToString();
        }
    }

public class SampleViewModel : INotifyPropertyChanged
    {
        private string _sampleText;

        public string SampleText
        {
            get { return _sampleText; }
            set
            {
                _sampleText = value;
                OnPropertyChanged();
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;        
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

最后，您必须将Text属性绑定到视图模型的“ SampleText”属性。

 <TextBlock x:Name="StatusTextBlock" Foreground="Black" Text="{Binding SampleText,NotifyOnTargetUpdated=True}">

请注意，还必须定义NotifyOnTargetUpdated，因为它指示是否引发TargetUpdated事件。