How to convert a string to RTF in C#?

Question

Question

How do I convert the string "Européen" to the RTF-formatted string "Europ\'e9en"?

[TestMethod]
public void Convert_A_Word_To_Rtf()
{
    // Arrange
    string word = "Européen";
    string expected = "Europ\'e9en";
    string actual = string.Empty;

    // Act
    // actual = ... // How?

    // Assert
    Assert.AreEqual(expected, actual);
}

What I have found so far

RichTextBox

RichTextBox can be used for certain things. Example:

RichTextBox richTextBox = new RichTextBox();
richTextBox.Text = "Européen";
string rtfFormattedString = richTextBox.Rtf;

But then rtfFormattedString turns out to be the entire RTF-formatted document, not just the string "Europ\'e9en".

Stackoverflow

• Insert string with special characters into RTF
• How to output unicode string to RTF (using C#)
• Output RTF special characters to Unicode
• Convert Special Characters for RTF (iPhone)

Google

I've also found a bunch of other resources on the web, but nothing quite solved my problem.

Answer

Brad Christie's answer

Had to add Trim() to remove the preceeding space in result. Other than that, Brad Christie's solution seems to work.

I'll run with this solution for now even though I have a bad gut feeling since we have to SubString and Trim the heck out of RichTextBox to get a RTF-formatted string.

Test case:

[TestMethod]
public void Test_To_Verify_Brad_Christies_Stackoverflow_Answer()
{
        Assert.AreEqual(@"Europ\'e9en", "Européen".ConvertToRtf());
        Assert.AreEqual(@"d\'e9finitif", "définitif".ConvertToRtf());
        Assert.AreEqual(@"\'e0", "à".ConvertToRtf());
        Assert.AreEqual(@"H\'e4user", "Häuser".ConvertToRtf());
        Assert.AreEqual(@"T\'fcren", "Türen".ConvertToRtf());
        Assert.AreEqual(@"B\'f6den", "Böden".ConvertToRtf());
}

Logic as an extension method:

public static class StringExtensions
{
    public static string ConvertToRtf(this string value)
    {
        RichTextBox richTextBox = new RichTextBox();
        richTextBox.Text = value;
        int offset = richTextBox.Rtf.IndexOf(@"\f0\fs17") + 8; // offset = 118;
        int len = richTextBox.Rtf.LastIndexOf(@"\par") - offset;
        string result = richTextBox.Rtf.Substring(offset, len).Trim();
        return result;
    }
}

Answer 1

Doesn't RichTextBox always have the same header/footer? You could just read the content based on off-set location, and continue using it to parse. (I think? please correct me if I'm wrong)

There are libraries available, but I've never had good luck with them personally (though always just found another method before fully exhausting the possibilities). In addition, most of the better ones are usually include a nominal fee.

---

EDIT
Kind of a hack, but this should get you through what you need to get through (I hope):

RichTextBox rich = new RichTextBox();
Console.Write(rich.Rtf);

String[] words = { "Européen", "Apple", "Carrot", "Touché", "Résumé", "A Européen eating an apple while writing his Résumé, Touché!" };
foreach (String word in words)
{
    rich.Text = word;
    Int32 offset = rich.Rtf.IndexOf(@"\f0\fs17") + 8;
    Int32 len = rich.Rtf.LastIndexOf(@"\par") - offset;
    Console.WriteLine("{0,-15} : {1}", word, rich.Rtf.Substring(offset, len).Trim());
}

---

EDIT 2

The breakdown of the codes RTF control code are as follows:

• Header
  • \f0 - Use the 0-index font (first font in the list, which is typically Microsoft Sans Serif (noted in the font table in the header: {\fonttbl{\f0\fnil\fcharset0 Microsoft Sans Serif;}}))
  • \fs17 - Font formatting, specify the size is 17 (17 being in half-points)
• Footer
  • \par is specifying that it's the end of a paragraph.

Hopefully that clears some things up. ;-)

Answer 2

This is how I went:

private string ConvertString2RTF(string input)
{
    //first take care of special RTF chars
    StringBuilder backslashed = new StringBuilder(input);
    backslashed.Replace(@"\", @"\\");
    backslashed.Replace(@"{", @"\{");
    backslashed.Replace(@"}", @"\}");

    //then convert the string char by char
    StringBuilder sb = new StringBuilder();
    foreach (char character in backslashed.ToString())
    {
        if (character <= 0x7f)
            sb.Append(character);
        else
            sb.Append("\\u" + Convert.ToUInt32(character) + "?");
    }
    return sb.ToString();
}

I think using a RichTextBox is:
1) overkill
2) I don't like RichTextBox after spending days of trying to make it work with an RTF document created in Word.

Answer 3

I found a nice solution that actually uses the RichTextBox itself to do the conversion:

private static string FormatAsRTF(string DirtyText)
{
    System.Windows.Forms.RichTextBox rtf = new System.Windows.Forms.RichTextBox();
    rtf.Text = DirtyText;
    return rtf.Rtf;
}

http://www.baltimoreconsulting.com/blog/development/easily-convert-a-string-to-rtf-in-net/

Answer 4

I know it has been a while, hope this helps..

This code is working for me after trying every conversion code I could put my hands on:

titleText and contentText are simple text filled in a regular TextBox

var rtb = new RichTextBox();
rtb.AppendText(titleText)
rtb.AppendText(Environment.NewLine);
rtb.AppendText(contentText)

rtb.Refresh();

rtb.rtf now holds the rtf text.

The following code will save the rtf text and allow you to open the file, edit it and than load it back into a RichTextBox back again:

rtb.SaveFile(path, RichTextBoxStreamType.RichText);

Answer 5

Below is an ugly example of converting a string to an RTF string:

class Program
{
    static RichTextBox generalRTF = new RichTextBox();

    static void Main()
    {
        string foo = @"Européen";
        string output = ToRtf(foo);
        Trace.WriteLine(output);
    }

    private static string ToRtf(string foo)
    {
        string bar = string.Format("!!@@!!{0}!!@@!!", foo);
        generalRTF.Text = bar;
        int pos1 = generalRTF.Rtf.IndexOf("!!@@!!");
        int pos2 = generalRTF.Rtf.LastIndexOf("!!@@!!");
        if (pos1 != -1 && pos2 != -1 && pos2 > pos1 + "!!@@!!".Length)
        {
            pos1 += "!!@@!!".Length;
            return generalRTF.Rtf.Substring(pos1, pos2 - pos1);
        }
        throw new Exception("Not sure how this happened...");
    }
}

Answer 6

Here's improved @Vladislav Zalesak's answer:

public static string ConvertToRtf(string text)
{
    // using default template from wiki
    StringBuilder sb = new StringBuilder(@"{\rtf1\ansi\ansicpg1250\deff0{\fonttbl\f0\fswiss Helvetica;}\f0\pard ");
    foreach (char character in text)
    {
        if (character <= 0x7f)
        {
            // escaping rtf characters
            switch (character)
            {
                case '\\':
                case '{':
                case '}':
                    sb.Append('\\');
                    break;
                case '\r':
                    sb.Append("\\par");
                    break;
            }

            sb.Append(character);
        }
        // converting special characters
        else
        {
            sb.Append("\\u" + Convert.ToUInt32(character) + "?");
        }
    }
    sb.Append("}");
    return sb.ToString();
}

Answer 7

Not the most elegant, but quite optimal and fast method:

public static string PlainTextToRtf(string plainText)
{
    if (string.IsNullOrEmpty(plainText))
        return "";

    string escapedPlainText = plainText.Replace(@"\", @"\\").Replace("{", @"\{").Replace("}", @"\}");
    escapedPlainText = EncodeCharacters(escapedPlainText);

    string rtf = @"{\rtf1\ansi\ansicpg1250\deff0{\fonttbl\f0\fswiss Helvetica;}\f0\pard ";
    rtf += escapedPlainText.Replace(Environment.NewLine, "\\par\r\n ") + ;
    rtf += " }";
    return rtf;
}

.

Encode characters (Polish ones) method:

private static string EncodeCharacters(string text)
{
    if (string.IsNullOrEmpty(text))
        return "";

    return text
        .Replace("ą", @"\'b9")
        .Replace("ć", @"\'e6")
        .Replace("ę", @"\'ea")
        .Replace("ł", @"\'b3")
        .Replace("ń", @"\'f1")
        .Replace("ó", @"\'f3")
        .Replace("ś", @"\'9c")
        .Replace("ź", @"\'9f")
        .Replace("ż", @"\'bf")
        .Replace("Ą", @"\'a5")
        .Replace("Ć", @"\'c6")
        .Replace("Ę", @"\'ca")
        .Replace("Ł", @"\'a3")
        .Replace("Ń", @"\'d1")
        .Replace("Ó", @"\'d3")
        .Replace("Ś", @"\'8c")
        .Replace("Ź", @"\'8f")
        .Replace("Ż", @"\'af");
}

Answer 8

private static string ConvertToRtf(string text)
{
    // Create a regular expression pattern to match non-ASCII characters
    string pattern = "[^\x00-\x7F]";
    // Use Regex.Replace to escape non-ASCII characters
    return Regex.Replace(text, pattern, m => m.Value[0] > 255 ? @"\u" + ((int)m.Value[0]).ToString() + "?" : @"\'" + ((int)m.Value[0]).ToString("X2").ToLowerInvariant());
}