代码之家 › 专栏 › 技术社区 › iLemming

绑定到DateTime.Now。更新值

binding wpf

iLemming · 技术社区 · 15 年前

嗯,我需要绑定DateTime。现在到一个TextBlock,我用了:

 Text="{Binding Source={x:Static System:DateTime.Now},StringFormat='HH:mm:ss tt'}"

现在,如何强制更新?它得到的时候,控制加载,不会更新它。。。

4 回复 | 直到 15 年前

myermian 13 年前

编辑(我没有说明他想自动更新):

这里是 a link 使用INotifyPropertyChanged以便自动更新的“Ticker”类。以下是网站的代码:

namespace TheJoyOfCode.WpfExample
{
    public class Ticker : INotifyPropertyChanged
    {
        public Ticker()
        {
            Timer timer = new Timer();
            timer.Interval = 1000; // 1 second updates
            timer.Elapsed += timer_Elapsed;
            timer.Start();
        }

        public DateTime Now
        {
            get { return DateTime.Now; }
        }

        void timer_Elapsed(object sender, ElapsedEventArgs e)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs("Now"));
        }

        public event PropertyChangedEventHandler PropertyChanged;
    }
}


<Page.Resources>
   <src:Ticker x:Key="ticker" />
</Page.Resources>

<TextBox Text="{Binding Source={StaticResource ticker}, Path=Now, Mode=OneWay}"/>

声明:

xmlns:sys="clr-namespace:System;assembly=mscorlib"

现在这将起作用:

<TextBox Text="{Binding Source={StaticResource ticker}, Path=Now, Mode=OneWay}"/>

aloisdg 11 年前

对于Windows Phone,可以使用以下代码段

public Timer()
{
    DispatcherTimer timer = new DispatcherTimer();
    timer.Interval = TimeSpan.FromSeconds(1); // 1 second updates
    timer.Tick += timer_Tick;
    timer.Start();
}

public DateTime Now
{
    get { return DateTime.Now; }
}

void timer_Tick(object sender, EventArgs e)
{
    if (PropertyChanged != null)
        PropertyChanged(this, new PropertyChangedEventArgs("Now"));
}

public event PropertyChangedEventHandler PropertyChanged;

SLaks 15 年前

你需要做一个定时器,每秒钟更新一次文本框。

Maksim Satsikau 7 年前

实际上,这样做的“规范”方法是设置一个dispatcher

    <Storyboard x:Key="clockStory" Duration="0:0:2" RepeatBehavior="Forever">
        <StringAnimationUsingKeyFrames
            Storyboard.TargetName="clock"
            Storyboard.TargetProperty="(Label.Tag)">
            <DiscreteStringKeyFrame KeyTime="0:0:0" Value="Let's force binding" />
            <DiscreteStringKeyFrame KeyTime="0:0:1" Value="..to change back and forth" />
        </StringAnimationUsingKeyFrames>
    </Storyboard>
</Window.Resources>

<Window.Triggers>
    <EventTrigger RoutedEvent="FrameworkElement.Loaded">
        <BeginStoryboard Storyboard="{StaticResource clockStory}"/>
    </EventTrigger>
</Window.Triggers>

<Grid>
    <Label x:Name="clock" Content="{Binding ElementName=clock, Path=Tag, Converter={StaticResource conv}}"/>
</Grid>

..转换器如下

public class AnythingToCurrentTimeConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return DateTime.Now.ToString("HH:mm:ss");
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}