在WPF数据网格中突出显示单元格时看不到任何文本

Question

I am writing a quick and dirty WPF application as a complete WPF novice. I have a simple datagrid:

<DataGrid ItemsSource="{Binding Path=BetterFoods}" Grid.Row="1" Grid.Column="0" AutoGenerateColumns="True" Loaded="DataGrid_Loaded">
    <DataGrid.Resources>
        <local:ValueColorConverter x:Key="colorconverter"/>
        <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="#FF0033"/>
    </DataGrid.Resources>
    <DataGrid.CellStyle>
        <Style TargetType="DataGridCell">
            <Setter Property="Background" Value="{Binding RelativeSource={RelativeSource Self}, Path=Content.Text, Converter={StaticResource colorconverter}}"/>
        </Style>
   </DataGrid.CellStyle>
</DataGrid>

The datagrid is coloured by a simple IValueConverter , which is virtually identical to loads of examples from tutorials and Stack Overflow:

class ValueColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value == null)
        {
            return Brushes.Beige;
        }
        else if (value is string)
        {
            string str = ((string)value).Trim();
            if (str.Equals(string.Empty))
            {
                return Brushes.Beige;
            }
            else if (str.Equals("0"))
            {
                return Brushes.LightYellow;
            }
        }

        return System.Windows.DependencyProperty.UnsetValue;
    }

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

The IValueConverter works exactly like it should, but it introduces a strange side effect: selecting a row makes all values in its cells disappear . The values are still there, since changing selection or double-clicking a cell makes them visible again (see .gif below).

This is obviously unfortunate, since one usually highlights a row to have a closer look at its data.

What is causing this behaviour and how do I fix it?

Answer 1

Add a resource (SystemColors.HighlightTextBrushKey) that changes the text brush to something darker so you can actually see the text:

<DataGrid ItemsSource="{Binding Path=BetterFoods}" Grid.Row="1" Grid.Column="0" AutoGenerateColumns="True">
    <DataGrid.Resources>
        <local:ValueColorConverter x:Key="colorconverter"/>
        <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="#FF0033"/>
        <!-- ADDED: -->
        <SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="Black"/>
    </DataGrid.Resources>
    <DataGrid.CellStyle>
        <Style TargetType="DataGridCell">
            <Setter Property="Background" Value="{Binding RelativeSource={RelativeSource Self}, Path=Content.Text, Converter={StaticResource colorconverter}}"/>
        </Style>
    </DataGrid.CellStyle>
</DataGrid>