c# - 动画后执行命令

Question

我在屏幕上收集了错误，每个错误一行。用户可以通过单击该行上的按钮来关闭任何错误消息。代码示例:

<UserControl>
    <ItemsControl ItemsSource="{Binding Errors}" >
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <Grid x:Name="grid" Height="20">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*"/>
                        <ColumnDefinition Width="Auto"/>
                    </Grid.ColumnDefinitions>
                    <TextBlock Text="{Binding ErrorText}"/>
                    <Button Grid.Column="1" Width="16" Height="16" Content="Close" Command="{Binding DataContext.RemoveErrorCommand, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" CommandParameter="{Binding CurrentError}">
                        <Button.Triggers>
                            <EventTrigger RoutedEvent="ButtonBase.Click">
                                <BeginStoryboard>
                                    <Storyboard TargetProperty="Height" TargetName="grid">
                                        <DoubleAnimation To="0" Duration="0:0:0.35"/>
                                    </Storyboard>
                                </BeginStoryboard>
                            </EventTrigger>
                        </Button.Triggers>
                    </Button>
                </Grid>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
</UserControl>

有什么问题:如您所见，我在 Storyboard 中添加了触发器以使其清晰可见，我想平滑地隐藏消息，并且仅在关闭消息之后才可以。因此，将是第一个 Storyboard ，然后执行命令。如何实现？请尽量减少代码隐藏。

Answer 1

您可以使用以下附加属性:

public static class StoryboardHelper
{
    public static readonly DependencyProperty CompletedCommandProperty = DependencyProperty.RegisterAttached("CompletedCommand", typeof(ICommand), typeof(StoryboardHelper), new PropertyMetadata(null, OnCompletedCommandChanged));
    public static readonly DependencyProperty CompletedCommandParameterProperty = DependencyProperty.RegisterAttached("CompletedCommandParameter", typeof(object), typeof(StoryboardHelper), new PropertyMetadata(null));

    public static void SetCompletedCommand(DependencyObject o, ICommand value)
    {
        o.SetValue(CompletedCommandProperty, value);
    }

    public static ICommand GetCompletedCommand(DependencyObject o)
    {
        return (ICommand)o.GetValue(CompletedCommandProperty);
    }

    public static void SetCompletedCommandParameter(DependencyObject o, object value)
    {
        o.SetValue(CompletedCommandParameterProperty, value);
    }

    public static object GetCompletedCommandParameter(DependencyObject o)
    {
        return o.GetValue(CompletedCommandParameterProperty);
    }

    private static void OnCompletedCommandChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        var sb = sender as Storyboard;

        if(sb != null)
        {
            sb.Completed += (a, b) =>
            {
                var command = GetCompletedCommand(sb);

                if (command != null)
                {
                    if (command.CanExecute(GetCompletedCommandParameter(sb)))
                    {
                        command.Execute(GetCompletedCommandParameter(sb));
                    }
                }
            };
        }
    }
}

并像这样使用它:

<Storyboard TargetProperty="Opacity" local:StoryboardHelper.CompletedCommand="{Binding Path=StoryCompletedCommand}">
    <DoubleAnimation From="0" To="1" Duration="0:0:5"/>
</Storyboard>

因此，该命令将在动画之后触发。