Embedded hyperlinks in WPF and localization

Question

I have a TextBlock in a WPF application where I'd like to show the user a message similar to:

Retry or go back.

I can accomplish this by doing:

<TextBlock>
    <Hyperlink Command="{Binding RetryCommand}">
        <Run Text="Retry" />
    </Hyperlink>
    <Run Text=" or " />
    <Hyperlink Command="{Binding GoBackCommand}">
        <Run Text="go back." />
    </Hyperlink>
</TextBlock>

However, this solution is not very friendly to localization; it is particularly problematic in the case where sentences require rearranging in the process of localization. I would much prefer to be able to specify something like "[Retry]({0}) or [go back.]({1})." in a resx file and dynamically insert the hyperlinks into the localized string. Is there a clean and simple way to go about doing this?

In another application, we used a surprisingly complex solution involving extending the TextBlock class and dynamically constructing the Inlines property, but it seemed like a lot of code for what should be a common problem.

Related questions: Is adding strings with placeholders (`{0}`) into resources a good idea?, How to embed links in localized text

Answer 1

So I guess one solution would be a custom control. However, I was able to use a IMultiValueConverter to get the job done.

public class TextBlockFormatToHyperlinkConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (values.Length >= 3)
        {
            var tblk = values[0] as TextBlock;
            var format = values[1] as string;
            var tokens = Tokenizer.ParseTokens(format);
            int hyperLinkIndex = 0;
            for (int i = 2; i < values.Length; i++)
            {
                var token = tokens.FirstOrDefault((p) => string.Equals(p.Value as string, "{" + hyperLinkIndex + "}"));
                if (token != null)
                {
                    token.Value = values[i];
                }
                hyperLinkIndex++;
            }

            tblk.Inlines.Clear();
            foreach (var token in tokens)
            {
                if (token.Value is Hyperlink)
                    tblk.Inlines.Add((Hyperlink)token.Value);
                else
                    tblk.Inlines.Add(new Run(token.Value as string));
            }

            return tblk;
        }
        return null;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }

    private class Token
    {
        public object Value { get; set; }
        public Token(object value)
        {
            Value = value;
        }
    }
    private class HyperlinkToken : Token
    {
        public HyperlinkToken(object value) : base(value) { }
    }

    private static class Tokenizer
    {
        public static List<Token> ParseTokens(string format)
        {
            var tokens = new List<Token>();
            var strings = Regex.Split(format, @"({\d+})");
            foreach (var str in strings)
            {
                if (Regex.IsMatch(str, @"({\d+})"))
                {
                    tokens.Add(new HyperlinkToken(str));
                }
                else
                {
                    tokens.Add(new Token(str));
                }
            }
            return tokens;
        }
    }
}

And then in the XAML I used it like this:

<TextBlock x:Name="tblk_LogFileLink" TextWrapping="Wrap">
    <TextBlock.Tag>
        <MultiBinding Converter="{StaticResource TextBlockFormatToHyperlinkConverter}">
            <Binding x:Name="textblock" ElementName="tblk_LogFileLink"/>
            <Binding x:Name="formatString" Source="Click to open the {0}."/>
            <Binding x:Name="firstHyperlink">
                <Binding.Source>
                    <Hyperlink NavigateUri="{Binding LogPath}">
                        <Run Text="{x:Static localization:Resources.LBL_LOG_FILE}"/>
                    </Hyperlink>
                </Binding.Source>
            </Binding>
        </MultiBinding>
    </TextBlock.Tag>
</TextBlock>

You could add several hyperlinks to the MultiBinding if your string format required more.

This allowed me to localize the entire string while still providing the hyperlink text.