如何用Double Animation替代Timer实现数值递增计数？

完全可以用DoubleAnimation替代DispatcherTimer实现从1开始的无限递增计数，不过DoubleAnimation默认是单次的数值过渡，要实现持续递增，需要在动画完成后动态更新参数并重复触发。

实现方案示例 #

XAML代码 #

保留Label控件，添加Storyboard管理动画：

<Window x:Class="MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" Loaded="MainWindow_Loaded">
    <Grid>
        <Label x:Name="myLabel" Content="0"/>
        <Storyboard x:Name="countStoryboard">
            <DoubleAnimation x:Name="countAnimation" 
                             Duration="0:0:1"
                             Completed="CountAnimation_Completed"/>
        </Storyboard>
    </Grid>
</Window>

VB.NET代码 #

通过动画的Completed事件持续更新数值，实现无限递增：

Class MainWindow
    Private currentCount As Double = 0

    Private Sub MainWindow_Loaded(sender As Object, e As RoutedEventArgs)
        StartCountAnimation()
    End Sub

    Private Sub StartCountAnimation()
        currentCount += 1
        countAnimation.From = currentCount - 1
        countAnimation.To = currentCount
        countStoryboard.Begin()
    End Sub

    Private Sub CountAnimation_Completed(sender As Object, e As EventArgs)
        myLabel.Content = currentCount.ToString()
        StartCountAnimation()
    End Sub
End Class

说明 #

• 每次动画完成后，将currentCount加1，把动画的起始值设为上一次计数、目标值设为新计数，再重启动画，以此实现每秒递增1的效果。
• 这种方式依托WPF动画系统处理计时，会自动与UI线程同步，相比DispatcherTimer能避免部分线程调度的潜在问题。

内容的提问来源于stack exchange，提问作者Danny Scofield