Question

我有一个如下图所示的列表视图。你可以看到我有一个名为时间的专栏。我想知道如何自动更新时间。

例如，飞行代码ABC123的时间应在1分钟后从3分钟变为4分钟。

Flight ListView

Answer 1

查看dispatch timer并每分钟执行一次记录更新

这就是我要做的事情

Answer 2

Big smart ViewModels, dumb Views, and any model, the best MVVM approach?包含WPF应用程序的代码，其中ViewModel（和绑定到它的View）由计时器更新。它是每1秒（1000毫秒）

Answer 3

编辑对每分钟使绑定失效的想法感到不满意（这可能完全没有根据，并且每分钟都无效，我不知道），所以来了使用直接设置内容的“更纯粹”实现，将原始内容保留以供参考：

你可以通过AttachedBehaviour来实现，下面应该可以让你开始：

public static class TimeAgoBehaviour {

    static Lazy<DispatcherTimer> LazyTimer = new Lazy<DispatcherTimer>(() => {
        DispatcherTimer timer = new DispatcherTimer { Interval = TimeSpan.FromMinutes(1) };
        timer.Start();
        return timer;
    });
    static ConcurrentDictionary<int, EventHandler> Events = new ConcurrentDictionary<int, EventHandler>();

    public static DateTime GetTimeAgo(ContentControl obj) {
        return (DateTime)obj.GetValue(TimeAgoProperty);
    }

    public static void SetTimeAgo(ContentControl obj, DependencyProperty value) {
        obj.SetValue(TimeAgoProperty, value);
    }

    public static readonly DependencyProperty TimeAgoProperty = DependencyProperty.RegisterAttached("TimeAgo",
        typeof(DateTime), typeof(TimeAgoBehaviour),
        new UIPropertyMetadata(DateTime.UtcNow, OnTimeAgoChanged));

    private static void OnTimeAgoChanged(object sender, DependencyPropertyChangedEventArgs e) {
        var newDate = (DateTime)e.NewValue;

        EventHandler oldEvent;
        if (Events.TryRemove(sender.GetHashCode(), out oldEvent)) {
            LazyTimer.Value.Tick -= oldEvent;
        }

        if (DateTime.MinValue == newDate) {
            return;
        }

        var doUpdate = new EventHandler((s, args) => {
            ContentControl control = sender as ContentControl;
            control.Content = TimeAgoConverter.GetTimeAgo(newDate);
        });

        doUpdate(sender, new EventArgs());

        Events.TryAdd(sender.GetHashCode(), doUpdate);
        LazyTimer.Value.Tick += doUpdate;
    }
}

的Xaml：

<Label local:TimeAgoBehaviour.TimeAgo="{Binding InitialisedDate}" />

以下是原始回复：

你可以通过AttachedBehaviour来实现，它会每分钟使绑定失效，导致它被重新评估，下面的工作，作为一个起点延伸到你需要的位置：

代码：

public static class PropertyToInvalidateBehaviour {

    static Lazy<DispatcherTimer> LazyTimer = new Lazy<DispatcherTimer>(() => {
        DispatcherTimer timer = new DispatcherTimer { Interval = TimeSpan.FromMinutes(1) };
        timer.Start();
        return timer;
    });
    static ConcurrentDictionary<int, EventHandler> Events = new ConcurrentDictionary<int, EventHandler>();

    public static DependencyProperty GetPropertyToInvalidate(DependencyObject obj) {
        return (DependencyProperty)obj.GetValue(PropertyToInvalidateProperty);
    }

    public static void SetPropertyToInvalidate(DependencyObject obj, DependencyProperty value) {
        obj.SetValue(PropertyToInvalidateProperty, value);
    }

    public static readonly DependencyProperty PropertyToInvalidateProperty = DependencyProperty.RegisterAttached("PropertyToInvalidate",
      typeof(DependencyProperty), typeof(PropertyToInvalidateBehaviour),
      new UIPropertyMetadata(null, OnPropertyToInvalidateChanged));

    private static void OnPropertyToInvalidateChanged(object sender, DependencyPropertyChangedEventArgs e) {
        var propertyToInvalidate = e.NewValue as DependencyProperty;

        EventHandler oldEvent;
        if (Events.TryRemove(e.Property.GetHashCode(), out oldEvent)) {
            LazyTimer.Value.Tick -= oldEvent;
        }

        if (null == propertyToInvalidate) {
            return;
        }

        var doUpdate = new EventHandler((s, args) => {
            BindingExpression binding = BindingOperations.GetBindingExpression(sender as DependencyObject, propertyToInvalidate);
            binding.UpdateTarget();
        });

        Events.TryAdd(e.Property.GetHashCode(), doUpdate);
        LazyTimer.Value.Tick += doUpdate;
    }
}

的Xaml：

<Label Content="{Binding Path=InitialisedDate, Converter={StaticResource cnvTimeAgo}}" local:PropertyToInvalidateBehaviour.PropertyToInvalidate="Label.Content" />`

C＃WPF Listview更新

3 个答案: