正在尝试从usercontrol更改主窗口的DataContext

Question

在初始化主窗口时，我将DataContext设置为usercontrol，在这个usercontrol上，我有一个事件，假设将主窗口的DataContext更改为另一个usercontrol，但什么也没发生。

以下是主窗口的xaml：

</Window.Resources>
<Grid>
<ContentControl Content="{Binding}" Width="auto" Height="auto" />
</Grid>

这是主窗口的C#：

public MainWindow()
{
InitializeComponent();
DataContext = new LogInViewModel();
}

这里是LogInUserControl:的xaml

<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<StackPanel Grid.Column="1" Grid.Row="1">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Width="250">
<StackPanel Width="125">
<TextBlock Text="Email:" Margin="5,0,5,0" Width="auto"/>
</StackPanel>
<StackPanel Width="125">
<TextBlock Text="Password:" Margin="5,0,0,0" Width="auto"/>
</StackPanel>
</StackPanel>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
<TextBox Margin="5,0,5,0" HorizontalAlignment="Center" Height="23" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
<PasswordBox Margin="0,0,0,5" HorizontalAlignment="Center" Height="23" VerticalAlignment="Top" Width="120"/>
</StackPanel>
<Button Content="Log In" Margin="0,0,0,5" HorizontalAlignment="Center" VerticalAlignment="Top" Width="75"/>
</StackPanel>
<Grid Grid.Column="1" Grid.Row="1">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
<TextBlock Text="don't have account yet ?" HorizontalAlignment="Center" VerticalAlignment="Bottom" Margin="5"/>
<TextBlock Name="TBSignUp" Text="Sign Up" HorizontalAlignment="Center" VerticalAlignment="Bottom" Margin="5" PreviewMouseLeftButtonDown="TextBlock_PreviewMouseLeftButtonDown" PreviewMouseLeftButtonUp="TextBlock_PreviewMouseLeftButtonUp" Foreground="#FF0B36F5"/>
</StackPanel>
</Grid>
</Grid>

这里是LogInUserControl:的C#

public partial class LogInView : UserControl
{
string BlackForeground = "#FF000000" ;
string OriginalForeground = "#FF0B36F5";
public LogInView()
{
InitializeComponent();
}
private void TextBlock_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
TBSignUp.Foreground = new SolidColorBrush((Color)ColorConverter.ConvertFromString(OriginalForeground));
DataContext = new RegisterView();
}
private void TextBlock_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
TBSignUp.Foreground = new SolidColorBrush((Color)ColorConverter.ConvertFromString(BlackForeground));
}
}

Answer 1

在WPF中，您可以从任何位置获得shell(第一个(窗口：

System.Windows.Window shell = System.Windows.Application.Current.MainWindow;

或

Application.Current.Windows[0];

但如果需要，我建议通过推荐。

看看MVVM模式，您需要在视图模型类中实现属性更改通知来绑定属性。

Answer 2

您需要在App.xaml.cs上设置它。

应用程序.xaml.cs:

public class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
MainWindow window=new MainWindow();
LogInViewModel vm=new LogInViewModel(); // You need to set DataContext...
window.DataContext=vm; // ...before showing up the window.
window.Show();
}
}

在我从研究中发现的ViewModel模式中，用法在DataContext之前，在Show();之后。

我希望这能解决你的问题。