c# - WPF 在 X 秒后淡出状态栏文本？

Question

我正在尝试想出一种不显眼的方式来向用户显示小错误消息。所以我在我的表单中添加了一个状态栏，

    <StatusBar Margin="0,288,0,0" Name="statusBar" Height="23" VerticalAlignment="Bottom">
        <TextBlock Name="statusText">Ready.</TextBlock>
    </StatusBar>

然后当他们点击“添加”按钮时，它应该做一些事情，或者显示一条错误消息:

private void DownloadButton_Click(object sender, RoutedEventArgs e)
{
    addressBar.Focus();
    var url = addressBar.Text.Trim();
    if (string.IsNullOrEmpty(url))
    {
        statusText.Text = "Nothing to add.";
        return;
    }
    if (!url.Contains('.'))
    {
        statusText.Text = "Invalid URL format.";
        return;
    }
    if (!Regex.IsMatch(url, @"^\w://")) url = "http://" + url;
    addressBar.Text = "";

但该消息在应用程序的整个生命周期内一直存在...我想我应该在大约 5 秒后重置它...我如何设置计时器来执行此操作？

奖励:我如何在这样做时给它一个漂亮的淡出效果？

---

我创建了一个System.Timers.Timer，

    private Timer _resetStatusTimer = new Timer(5000);

    void _resetStatusTimer_Elapsed(object sender, ElapsedEventArgs e)
    {
        statusText.Text = "Ready";
    }

但是 Elapsed 事件运行在与 UI 不同的线程上，它不喜欢这样……我该如何解决这个问题？

Answer 1

您可以使用 Storyboard 来实现这个目的。

<Storyboard x:Key="Storyboard1">
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="statusBarItem">
            <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
            <EasingDoubleKeyFrame KeyTime="0:0:0.5" Value="1"/>
            <EasingDoubleKeyFrame KeyTime="0:0:3" Value="1"/>
            <EasingDoubleKeyFrame KeyTime="0:0:4" Value="0"/>
        </DoubleAnimationUsingKeyFrames>
    </Storyboard>

当必须显示消息时，您只需以编程方式调用 StoryBoard 的 Begin 方法或插入一个触发器，如下所示。

<Window.Triggers>
    <EventTrigger RoutedEvent="TextBoxBase.TextChanged" SourceName="textBox">
        <BeginStoryboard Storyboard="{StaticResource Storyboard1}"/>
    </EventTrigger>
</Window.Triggers>

编辑:另一种选择是这样做:

<TextBlock Name="statusText" Text="{Binding Path=StatusBarText, NotifyOnTargetUpdated=True}">
        <TextBlock.Triggers>
            <EventTrigger RoutedEvent="Binding.TargetUpdated">
                <BeginStoryboard>
                    <Storyboard>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:0.25" Value="1"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:4" Value="1"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:5" Value="0"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </TextBlock.Triggers>

然后在这种情况下创建一个名为 StatusBarText 的 DependencyProperty，实现如下:

public string StatusBarText
    {
        get { return (string)GetValue(StatusBarTextProperty); }
        set { SetValue(StatusBarTextProperty, value); }
    }

    // Using a DependencyProperty as the backing store for StatusBarText.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty StatusBarTextProperty =
        DependencyProperty.Register("StatusBarText", typeof(string), typeof(MyOwnerClass), new UIPropertyMetadata(""));

希望这对您有所帮助。