Sorting lines in winforms richtextbox preserving RTF formatting

Question

Is there any way to sort lines in winforms richtextbox preserving RTF formatting?

var lines = edit.Lines.OrderBy(s => s);
edit.Lines = lines.ToArray();

do the job fine, but, obviously, loosing any RTF formatting.

I have slightly changed the snippet of TaW: 1. Adding "unique" might break the very first line formatting 2. Besides "\par" tag there is also "\pard"

Here is a snippet (thanks again to TaW!):

private void cmdSort_Click(object sender, EventArgs e)
    {
        const string PARD = "\\pard";
        var pard = Guid.NewGuid().ToString();

        var pos1 = edit.Rtf.IndexOf(PARD, StringComparison.Ordinal) + PARD.Length;
        if (pos1 < 0) return;
        var header = edit.Rtf.Substring(0, pos1);
        var body = edit.Rtf.Substring(pos1);
        body = body.Replace("\\pard", pard);
        var lines = body.Split(new[] { "\\par" }, StringSplitOptions.None);
        var lastFormat = "";
        var sb = new StringBuilder();
        var rtfLines = new SortedList<string, string>();
        foreach (var line in lines)
        {
            var ln = line.Replace(pard, "\\pard");
            var temp = ln.Replace("\r\n", "").Trim();
            if (temp.Length > 0 && temp[0] != '\\')
            {
                rtfLines.Add(temp.Trim(), lastFormat + " " + ln);
            }
            else
            {
                var pos2 = temp.IndexOf(' ');
                if (pos2 < 0)
                {
                    rtfLines.Add(temp.Trim(), ln);
                }
                else
                {
                    rtfLines.Add(temp.Substring(pos2).Trim(), ln);
                    lastFormat = temp.Substring(0, pos2);
                }
            }
        }
        foreach (var key in rtfLines.Keys.Where(key => key != "}"))
        {
            sb.Append(rtfLines[key] + "\\par");
        }
        edit.Rtf = header + sb;
    }

Answer 1

Here is a code snippet that seems to work if the file has neither images nor tables embedded..

It uses two RTF boxes. In my tests they sorted alright and kept all formatting intact.

    private void button4_Click(object sender, EventArgs e)
    {
        string unique = Guid.NewGuid().ToString() ; 

        richTextBox1.SelectionStart = 0;
        richTextBox1.SelectionLength = 0;
        richTextBox1.SelectedText = unique;
        int pos1 = richTextBox1.Rtf.IndexOf(unique);

        if (pos1 >= 0)
        {
            string header = richTextBox1.Rtf.Substring(0, pos1);
            string header1 = "";
            string header2 = "";
            int pos0 = header.LastIndexOf('}') + 1;
            if (pos0 > 1) { header1 = header.Substring(0, pos0); header2 = header.Substring(pos0); }
            // after the header comes a string of formats to start the document
            string[] formats = header2.Split('\\');
            string firstFormat = "";
            string lastFormat = "";
            // we extract a few important character formats (bold, italic, underline, font, color)
            // to keep with the first line which will be sorted away
            // the lastFormat variable holds the last formatting encountered
            // so we can add it to all lines without formatting
            // (and of course we are really talking about paragraphs)
            foreach (string fmt in formats)  
                if (fmt[0]=='b' ||  ("cfiu".IndexOf(fmt[0]) >= 0 && fmt.Substring(0,2)!="uc") ) 
                      lastFormat += "\\" + fmt; else firstFormat += "\\" + fmt;
            // add the rest to the header
            header = header1 + firstFormat;
            // now we remove our marker from the body and split it into paragraphs
            string body = richTextBox1.Rtf.Substring(pos1);
            string[] lines = body.Replace(unique, "").Split(new string[] { "\\par" }, StringSplitOptions.None);

            StringBuilder sb = new StringBuilder();
            // the soteredlist will contain the unformatted text as key and the formatted one as valaue
            SortedList<string, string> rtfLines = new SortedList<string, string>();
            foreach (string line in lines)
                {
                    // cleanup
                    string line_ = line.Replace("\r\n", "").Trim();
                    if (line_[0] != '\\' ) rtfLines.Add(line_, lastFormat + " " + line);
                    else
                    {
                        int pos2 = line_.IndexOf(' ');
                        if (pos2 < 0) rtfLines.Add(line_, line);
                        else
                        {
                            rtfLines.Add(line_.Substring(pos2).Trim(), line);
                            lastFormat = line_.Substring(0, pos2);
                        }
                    }

                }
            foreach (string key in rtfLines.Keys) if (key != "}") sb.Append(rtfLines[key] + "\\par");
            richTextBox2.Rtf = header + sb.ToString();
        }

Of course this is really q&d and not ready for serious production; but it looks like a start.

EDIT 2: I changed the code to fix a bug with the first line's format and added some comments. This should work a lot better, but is still a hack that must be adapted to the real input files..

Answer 2

RichTextBox has a property Rtf that would keep RTF formatting.

[BrowsableAttribute(false)]
public string Rtf { get; set; }