Question

无法弄清楚为什么这个计时器不显示信息。计时器被装配到TimeEntry中更新TextBlock的方法。绑定似乎不起作用，我不明白如何正确地做到这一点。我查看了MSDN网站。他们只给出了基础知识：还不够。

代码：

TimeEntry.xaml.cs ：

public partial class TimeEntry : UserControl
{
    public static readonly DependencyProperty timeSpentProperty =
       DependencyProperty.Register("timeSpent", typeof(TimeSpan),
       typeof(TimeEntry),
       new FrameworkPropertyMetadata(TimeSpan.Zero));

    #region Properties
    public TimeSpan timeSpent
    {
        get
        {
            return (TimeSpan)GetValue(TimeEntry.timeSpentProperty);
        }
        set
        {
            SetValue(TimeEntry.timeSpentProperty, value);
        }
    }
    #endregion

    static TimeEntry() { }

    public TimeEntry(int id)
    {
        DataContext = this;
        this.InitializeComponent();
        //code
    }
}

TimeEntry.xaml ：

<UserControl
    x:Class="ClockWatcher.TimeEntry"
    x:Name="UserControl">
    <Grid x:Name="LayoutRoot" HorizontalAlignment="Left"
        VerticalAlignment="Top" Width="{DynamicResource creationWidth}"
        Height="{DynamicResource creationHeight}">
        <TextBlock x:Name="timeSpentBlock"
            HorizontalAlignment="Left" TextWrapping="Wrap"
            Text="{Binding timeSpent, ElementName=UserControl}"
            VerticalAlignment="Top" Padding="{StaticResource labelPadding}"/>       
    </Grid>
</UserControl>

SessionManager.cs ：

    public class SessionManager : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        [NonSerialized]
        private Timer _timer;
        [NonSerialized]
        private Stopwatch _clockWatch;
        [NonSerialized]
        private DateTime _dtStartTime;
        private Session current_session;
        public string strStartTime
        {
            get
            {
                return _dtStartTime.ToString();
            }
            private set { }
        }

        public SessionManager()
        {
            _clockWatch = new Stopwatch();
            _timer = new Timer(1000);//one second
            _timer.Elapsed += clockWatch_Elapsed;
            _dtStartTime = DateTime.Now;
            CurrentSession = new Session();
        }

        /// <summary>
        /// Registered to Timer.Elapsed Event
        /// (See constructor)
        /// </summary>
        public void clockWatch_Elapsed(object sender, ElapsedEventArgs e)
        {
            if (CurrentSession != null)
            {
                //update the timespent variable of the current timeEntry
                if (CurrentSession.currentTimeEntry != null)
                {
                    CurrentSession.currentTimeEntry.timeSpent = _clockWatch.Elapsed;
                    calculateTotalTime();
                }
            }
        }
        private void OnPropertyChanged([CallerMemberName] string member_name = "")
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(member_name));
            }
        }
    }

Answer 1

你必须这样改变。因为你做错了路。

想一想，哪个属性必须更新。您想要的财产是timeSpent。然后，您的TimeEntry课程必须实施INotifyPropertyChanged活动。
timeSpent属性不需要依赖属性。因为您在“已过去”中手动分配了它事件
您的xaml必须与您的班级相关联。换句话说，你的身体（xaml）必须有灵魂（类实例）。
您已在步骤3中绑定模型。现在您可以像这样简单绑定。

步骤2的说明。（依赖属性）

您当前的使用情况为manually assignment。在您的情况下，不需要依赖属性

如果您想使用如下图像，您的属性timeSpent必须具有依赖属性。

定时器实现的数据绑定

1 个答案: