Question

I’m working on a WPF/XAML app using MVVM and have a collection of strings as a property on my viewmodel. I would like to concatenate the strings for display within a textblock or similar control. The strings should be concatenated using the text ” AND ” and the concatenation text should be styled using a bold font weight. The output would look something like this:

cat AND dog AND mouse AND rabbit

What is the best way to achieve my end result?

Answer 1

Since you can’t bind to the read-only TextBlock.Inlines property, I would suggest to create a derived TextBlock with a TextList property:

public class TextListBlock : TextBlock
{
    public static readonly DependencyProperty TextListProperty = DependencyProperty.Register(
        "TextList", typeof(IEnumerable<string>), typeof(TextListBlock),
        new PropertyMetadata((o, e) => ((TextListBlock)o).TextListChanged((IEnumerable<string>)e.NewValue)));

    public IEnumerable<string> TextList
    {
        get { return (IEnumerable<string>)GetValue(TextListProperty); }
        set { SetValue(TextListProperty, value); }
    }

    private void TextListChanged(IEnumerable<string> textList)
    {
        bool addSeparator = false;
        foreach (string text in textList)
        {
            if (addSeparator)
            {
                Inlines.Add(new Run(" AND ") { FontWeight = FontWeights.Bold });
            }

            Inlines.Add(new Run(text));
            addSeparator = true;
        }
    }
}