我是WPF的新手,正在尝试制作一个简单的应用程序,一个秒表。如果不进行数据绑定,它可以正常工作。以下是我的XAML代码:
<Window x:Class="StopWatch.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:s="clr-namespace:StopWatch"
Title="MainWindow" Height="318" Width="233">
<Window.Resources>
<s:StopWatchViewModel x:Key="swViewModel" x:Name="swViewModel"></s:StopWatchViewModel>
</Window.Resources>
<Grid DataContext="{StaticResource swViewModel}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="auto"/>
<RowDefinition Height="128*" />
</Grid.RowDefinitions>
<TextBlock Grid.Row="1" Height="49" HorizontalAlignment="Left" Margin="42,50,0,0" Name="txtTime" Text="{Binding Path=Message}" VerticalAlignment="Top" Width="147" FontSize="20" TextAlignment="Center" />
<Button Content="Start" Grid.Row="2" Height="23" HorizontalAlignment="Left" Margin="12,15,0,0" Name="startBtn" VerticalAlignment="Top" Width="58" Click="startBtn_Click" />
<Button Content="Stop" Grid.Row="2" Height="23" HorizontalAlignment="Left" Margin="76,15,0,0" Name="stopBtn" VerticalAlignment="Top" Width="58" Click="stopBtn_Click" />
<Button Content="Reset" Grid.Row="2" Height="23" HorizontalAlignment="Left" Margin="140,15,0,0" Name="resetBtn" VerticalAlignment="Top" Width="59"/>
</Grid>
这里是MainWindow中的代码
public partial class MainWindow : Window
{
private StopWatchViewModel stopwatch;
public MainWindow()
{
InitializeComponent();
stopwatch = new StopWatchViewModel();
}
private void startBtn_Click(object sender, RoutedEventArgs e)
{
stopwatch.Start();
}
private void stopBtn_Click(object sender, RoutedEventArgs e)
{
stopwatch.Stop();
}
}
以下是StopWatchViewModel.cs中的代码:
class StopWatchViewModel : INotifyPropertyChanged
{
private DispatcherTimer timer;
private Stopwatch stopwatch;
private string message;
public event PropertyChangedEventHandler PropertyChanged;
public string Message
{
get
{
return message;
}
set
{
if (message != value)
{
message = value;
OnPropertyChanged("Message");
}
}
}
public StopWatchViewModel()
{
timer = new DispatcherTimer();
stopwatch = new Stopwatch();
timer.Tick += new EventHandler(timer_Tick);
timer.Start();
stopwatch.Reset();
}
public void Start()
{
stopwatch.Start();
}
public void Stop()
{
stopwatch.Stop();
}
private void timer_Tick(object sender, EventArgs e)
{
Message = stopwatch.Elapsed.ToString(); // Doesn't work.
// Message = "hello"; does not work too!
}
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
我不知道我哪里出了错。
编辑: 我已经让它工作了。下面是可以供任何人参考的工作代码。
XAML,将原始代码更改为以下内容
<Window x:Class="StopWatch.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:s="clr-namespace:StopWatch"
Title="MainWindow" Height="318" Width="233">
<Grid> // partial code
在代码后面,基于Erno的建议更改构造函数。
public MainWindow()
{
InitializeComponent();
viewModel = new StopWatchViewModel();
this.DataContext = viewModel;
}
谢谢大家!