WPF值在ValueConverter中为空

Question

我有一个WPF应用程序来显示一些LogMessage列表。 LogMessage类如下所示：

public class LogMessage
{
    public DateTime Timestamp { get; set; }
    public LogLevel LogLevel { get; set; }
    public string Message { get; set; }
}

我想使用此ValueConverter将LogLevel的值绑定到Foreground的{​​{1}}属性：

TextBlock

该视图看起来像这样：

[ValueConversion(typeof(LogLevel), typeof(Brush))]
public class LogLevelToColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var logLevel = (LogLevel)value;
        switch (logLevel)
        {
            case LogLevel.Info:
                return new SolidColorBrush(Colors.DarkGray);
            case LogLevel.Important:
                return new SolidColorBrush(Colors.Green);
            case LogLevel.Warning:
                return new SolidColorBrush(Colors.Orange);
            case LogLevel.Error:
                return new SolidColorBrush(Colors.Red);
            default:
                return new SolidColorBrush(Colors.DarkGray);
        }
    }

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

我的问题是我的值转换器中的<Window x:Class="TouchLogic.EcrServer.Wpf.Views.MainView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:TouchLogic.EcrServer.Wpf.ViewModels" mc:Ignorable="d" Title="MainView" Height="450" Width="800"> <Window.Resources> <local:LogLevelToColorConverter x:Key="LogLevelToColorConverter"/> </Window.Resources> <Grid Margin="8"> <Grid.RowDefinitions> <RowDefinition Height="*" /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition Width="*" /> <ColumnDefinition Width="140" /> </Grid.ColumnDefinitions> <ListBox Grid.Row="0" Grid.Column="0" ItemsSource="{Binding LogMessages}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <TextBlock Text="{Binding Timestamp}" Foreground="{Binding LogLevel, Converter={StaticResource LogLevelToColorConverter}}"/> <TextBlock Text="{Binding Message}" Foreground="{Binding LogLevel, Converter={StaticResource LogLevelToColorConverter}}"/> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Grid> </Window> 总是以value的形式出现，我不知道为什么。