Question

使用Visual Studio 2013，c＃

尝试在主页面上创建绑定到当前时间 - 在页面上每隔一次更改一次。（只是试着更好地理解绑定）

做了什么：

创建了一个实现INotifyPropertyChanged

的特殊类

using System.ComponentModel;
//this class must be used for binding changed time on main page
namespace Memo
{
//Implement INotifiyPropertyChanged 
//interface to subscribe for property change notifications
class DateTimeNow : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private string _currentDateTimeNow;

//simple prop
public string CurrentDateTimeNow
{
    get { return _currentDateTimeNow; }
    set
    {
        if (_currentDateTimeNow != value)
        {
            _currentDateTimeNow = value;
            RaisePropertyChanged("CurrentDateTimeNow");
        }
    }
}
//event
private void RaisePropertyChanged(string propertyName)
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}
}
}

在XAML中添加反映代码（mainPage.xaml）

TextBlock x:Name="currentTime" FontSize="25" Style="{StaticResource SubheaderTextBlockStyle}" Margin="20,10,0,0"
               Text="{Binding Path=CurrentDateTimeNow}"

添加一些代码（mainPage.xaml.cs）后

public MainPage()
{
    this.InitializeComponent();
    this.navigationHelper = new NavigationHelper(this);
    this.navigationHelper.LoadState += navigationHelper_LoadState;
    this.navigationHelper.SaveState += navigationHelper_SaveState;

    //add binding to main page
    //currentTime.DataContext = DateTime.Now;

    //initialize instances
    _dateTimeNow = new DateTimeNow();
    //get current time
    _dateTimeNow.CurrentDateTimeNow = DateTime.Now.ToString();
    //register event
    _dateTimeNow.PropertyChanged += _dateTimeNow_PropertyChanged;
    //move data to text block
    ShowCurrentTime(currentTime);
}

//move information from prop to the text block
private void ShowCurrentTime(TextBlock textBlock)
{
    textBlock.Text = _dateTimeNow.CurrentDateTimeNow;
}

//do on changes time
void _dateTimeNow_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
    ShowCurrentTime(currentTime);
}

结果得到的时间仅反映当前时刻 - 启动计划的时刻：

enter image description here

但每一秒都没有发生 - 时间不会更新。猜猜是因为我没有每秒都添加一些代码来更新属性 - 如果属性改变了 - 我的textBox信息将会更新。

问题 - 如何编码，该属性可以根据时间变化每秒更改？那么我为什么要问 - 无法在Windows应用商店中找到Timer。也许这是另一种方法吗？

Answer 1

使用DispatcherTimer：

public MainPage()
{
    this.InitializeComponent();
    ...

    var dateTimeNow = new DateTimeNow();
    DataContext = dateTimeNow;

    var timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
    timer.Tick += (o, e) => dateTimeNow.CurrentDateTimeNow = DateTime.Now.ToString();
    timer.Start();
}

另请注意，您不需要_dateTimeNow_PropertyChanged处理程序，因为TextBlock已由CurrentDateTimeNow绑定更新，前提是您已将MainPage的DataContext设置为DateTimeNow实例

如何在Windows应用商店应用中创建绑定

1 个答案: