I've been including a lot of source code examples in my blog lately and needed a good way to paste properly formatted code in blog posts. I write my posts in HTML and wanted a tool that was easy to use, simple to install, produced concise HTML, and worked well with Visual Studio 2008. I was aware of a handful of tools for this purpose but none of them were quite what I was looking for, so I wrote my own one evening. :)

Caveat: ConvertClipboardRtfToHtmlText is a simple utility written for my specific scenario. I'm releasing the tool and code here in case anyone wants to use it, enhance it, or whatever. I have NOT attempted to write a solid, general-purpose RTF-to-HTML converter. Instead, ConvertClipboardRtfToHtmlText assumes its input is in the exact format used by Visual Studio 2008 (and probably VS 2005).

Using ConvertClipboardRtfToHtmlText is simple:

  1. Copy code (C#, XAML, etc.) to clipboard from Visual Studio 2008
  2. Run ConvertClipboardRtfToHtmlText to convert the RTF representation of the code on the clipboard to HTML as text (there's no UI because the tool does the conversion and immediately exits)
  3. Paste the HTML code on the clipboard into your blog post, web page, etc.

I'm the first to acknowledge there's a lot of room for improvement in step #2. :) While the current implementation is good enough for my purposes, I encourage interested parties to consider turning this into a real application - maybe with a notify icon and a system-wide hotkey. If you do so, please let me know because I'd love to check it out!

The compiled tool and code are available in a ZIP file attached to this post. The complete source code is also available below. Naturally, I used ConvertClipboardRtfToHtmlText to post its own source code. :)

Enjoy!

Updated 2008-04-02: Minor changes to code and tool

 

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

// Convert Visual Studio 2008 RTF clipboard format into HTML by replacing the
// clipboard contents with its HTML representation in text format suitable for
// pasting into a web page or blog.
// USE: Copy to clipboard in VS, run this app (no UI), paste converted text
// NOTE: This is NOT a general-purpose RTF-to-HTML converter! It works well
// enough on the simple input I've tried, but may break for other input.
// TODO: Convert into a real application with a notify icon and hotkey.
namespace ConvertClipboardRtfToHtmlText
{
    static class ConvertClipboardRtfToHtmlText
    {
        private const string colorTbl = "\\colortbl;\r\n";
        private const string colorFieldTag = "cf";
        private const string tabExpansion = "    ";

        [STAThread]
        static void Main()
        {
            if (Clipboard.ContainsText(TextDataFormat.Rtf))
            {
                // Create color table, populate with default color
                List<Color> colors = new List<Color>();
                Color defaultColor = Color.FromArgb(0, 0, 0);
                colors.Add(defaultColor);

                // Get RTF
                string rtf = Clipboard.GetText(TextDataFormat.Rtf);

                // Parse color table
                int i = rtf.IndexOf(colorTbl);
                if (-1 != i)
                {
                    i += colorTbl.Length;
                    while ((i < rtf.Length) && ('}' != rtf[i]))
                    {
                        // Add color to color table
                        SkipExpectedText(rtf, ref i, "\\red");
                        byte red = (byte)ParseNumericField(rtf, ref i);
                        SkipExpectedText(rtf, ref i, "\\green");
                        byte green = (byte)ParseNumericField(rtf, ref i);
                        SkipExpectedText(rtf, ref i, "\\blue");
                        byte blue = (byte)ParseNumericField(rtf, ref i);
                        colors.Add(Color.FromArgb(red, green, blue));
                        SkipExpectedText(rtf, ref i, ";");
                    }
                }
                else
                {
                    throw new NotSupportedException("Missing/unknown colorTbl.");
                }

                // Find start of text and parse
                i = rtf.IndexOf("\\fs");
                if (-1 != i)
                {
                    // Skip font size tag
                    while ((i < rtf.Length) && (' ' != rtf[i]))
                    {
                        i++;
                    }
                    i++;

                    // Begin building HTML text
                    StringBuilder sb = new StringBuilder();
                    sb.AppendFormat("<pre><span style='color:#{0:x2}{1:x2}{2:x2}'>",
                        defaultColor.R, defaultColor.G, defaultColor.B);
                    while (i < rtf.Length)
                    {
                        if ('\\' == rtf[i])
                        {
                            // Parse escape code
                            i++;
                            if ((i < rtf.Length) &&
                                (('{' == rtf[i]) || ('}' == rtf[i]) || ('\\' == rtf[i])))
                            {
                                // Escaped '{' or '}' or '\'
                                sb.Append(rtf[i]);
                            }
                            else
                            {
                                // Parse tag
                                int tagEnd = rtf.IndexOf(' ', i);
                                if (-1 != tagEnd)
                                {
                                    if (rtf.Substring(i, tagEnd - i).StartsWith(colorFieldTag))
                                    {
                                        // Parse color field tag
                                        i += colorFieldTag.Length;
                                        int colorIndex = ParseNumericField(rtf, ref i);
                                        if ((colorIndex < 0) || (colors.Count <= colorIndex))
                                        {
                                            throw new NotSupportedException("Bad color index.");
                                        }

                                        // Change to new color
                                        sb.AppendFormat(
                                            "</span><span style='color:#{0:x2}{1:x2}{2:x2}'>",
                                            colors[colorIndex].R, colors[colorIndex].G,
                                            colors[colorIndex].B);
                                    }
                                    else if("tab" == rtf.Substring(i, tagEnd-i))
                                    {
                                        sb.Append(tabExpansion);
                                    }

                                    // Skip tag
                                    i = tagEnd;
                                }
                                else
                                {
                                    throw new NotSupportedException("Malformed tag.");
                                }
                            }
                        }
                        else if ('}' == rtf[i])
                        {
                            // Terminal curly; done
                            break;
                        }
                        else
                        {
                            // Normal character; HTML-escape '<', '>', and '&'
                            switch (rtf[i])
                            {
                                case '<':
                                    sb.Append("&lt;");
                                    break;
                                case '>':
                                    sb.Append("&gt;");
                                    break;
                                case '&':
                                    sb.Append("&amp;");
                                    break;
                                default:
                                    sb.Append(rtf[i]);
                                    break;
                            }
                        }
                        i++;
                    }

                    // Finish building HTML text
                    sb.Append("</span></pre>");

                    // Update the clipboard text
                    Clipboard.SetText(sb.ToString());
                }
                else
                {
                    throw new NotSupportedException("Missing text section.");
                }
            }
        }

        // Skip the specified text
        private static void SkipExpectedText(string s, ref int i, string text)
        {
            foreach (char c in text)
            {
                if ((s.Length <= i) || (c != s[i]))
                {
                    throw new NotSupportedException("Expected text missing.");
                }
                i++;
            }
        }

        // Parse a numeric field
        private static int ParseNumericField(string s, ref int i)
        {
            int value = 0;
            while ((i < s.Length) && char.IsDigit(s[i]))
            {
                value *= 10;
                value += s[i] - '0';
                i++;
            }
            return value;
        }
    }
}