Color TextBlock depending on enum value

Question

I'm working on WPF with a MvvM model.

I have a view containing Texblocks. It display information about ID (from a document and from a database) :

<GroupBox Grid.Row="1" Grid.Column="0" Header="ID Informations">
    <StackPanel Orientation="Vertical">
        <TextBlock Text="DataBase surname: "/>
        <TextBlock Text="{Binding Model.Db_SURNAME}" FontWeight="Bold"/>
        <TextBlock Text="Document surname: "/>
        <TextBlock Text="{Binding Model.Dc_SURNAME}" FontWeight="Bold"/>
        <TextBlock Text="DataBase forename: "/>
        <TextBlock Text="{Binding Model.Db_FORENAME}" FontWeight="Bold"/>
        <TextBlock Text="Document forename: "/>
        <TextBlock Text="{Binding Model.Dc_FORENAME}" FontWeight="Bold"/>
    </StackPanel>
</GroupBox>

I have an enum containing an error code :

[Flags]
public enum errorID
{
    OK = 1<<0,
    SURNAME_DIFF = 1 << 1,
    FORENAME_DIFF = 1 << 2
}

And my model is wrote like this :

private String _db_SURNAME;
public String Db_SURNAME
{
    get { return _db_SURNAME; }
    set { SetProperty(ref _db_SURNAME, value); }
}
[...]

private errorID _errorID;
public errorID ErrorID
{
    get { return _errorID; }
    set { SetProperty(ref _errorID, value); }
}

I want that both of my textblocks displaying Model.Db_SURNAME and Model.Dc_SURNAME are colored in red when ErrorID.HasFlag(errorID.SURNAME_DIFF ). And also for Forname.

How can I do ?

Answer 1

Use a converter that converts your enum to a color like following:

public class ErrorIdColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if(!(value is errorID))
             throw new ArgumentException("value not of type errorID");
        if(!(parameteris errorID))
             throw new ArgumentException("parameter not of type errorID");

        errorID error = (errorID)value;
        errorID flag = (errorID)parameter;

        if (error.HasFlag(flag))
        {
            return Brushes.Red;
        }
        ...

        return Brushes.Black;
}

public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
   ....
}

}

Then you can bind the Foreground Color to your enum using the converter:

<TextBlock Text="{Binding Model.Db_SURNAME}" FontWeight="Bold" Foreground={Binding Model.errorId, Converter={StaticRessource errorIDColorConverter}, ConverterParameter={StaticRessource errorID.SURNAME_DIFF}}/>