How do I convert HTML to RTF (Rich Text) in .NET without paying for a component?

Question

Is there a free third-party or .NET class that will convert HTML to RTF (for use in a rich-text enabled Windows Forms control)?

The "free" requirement comes from the fact that I'm only working on a prototype and can just load the BrowserControl and just render HTML if need be (even if it is slow) and that Developer Express is going to be releasing their own such control soon-ish.

I don't want to learn to write RTF by hand, and I already know HTML, so I figure this is the quickest way to get some demonstrable code out the door quickly.

score 42 · Accepted Answer · answered Jan 31 '11 at 18:34

42

Actually there is a simple and free solution: use your browser, ok this is the trick I used:

var webBrowser = new WebBrowser();
webBrowser.CreateControl(); // only if needed
webBrowser.DocumentText = *yourhtmlstring*;
while (_webBrowser.DocumentText != *yourhtmlstring*)
    Application.DoEvents();
webBrowser.Document.ExecCommand("SelectAll", false, null);
webBrowser.Document.ExecCommand("Copy", false, null);
*yourRichTextControl*.Paste();

This could be slower than other methods but at least it's free and works!

answered Jan 31 '11 at 18:34

Spartaco

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This is a great solution. There will be a latency overhead, but I guess for large documents it will be reasonably fast, and the quality will be good. – Charles Stewart Jan 31 '11 at 18:41
1

Any way to save the images into the rich text box as well? – Landmine Jan 22 '14 at 21:14
Is there a way to convert to a specific version of RTF using this control? E.G. Convert to RTF 1.5 or 1.8, etc. – sager89 Sep 11 '14 at 15:55
4

Perhaps a better way to handle the wait for the browser control to load the HTML string is to use an event handler: `webBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowser_DocumentCompleted);` – rundavidrun Nov 25 '14 at 19:24
1

Is there a way of achieving the same using WebView control in windows phone 8.1? – Singhal2 Aug 01 '17 at 04:32
This works but is there a way to maintain coloring? The copied text maintains its fonts but not its colors – MattE Dec 18 '18 at 17:40

score 9 · Answer 2 · answered Apr 16 '09 at 03:03

9

Check out this CodeProject article on XHTML2RTF.

answered Apr 16 '09 at 03:03

Jonathan Parker

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Great for XHTML, but as one would guess from reading the name, doesn't work as well for non-XHTML/"vanilla HTML"... – sager89 Aug 29 '14 at 15:08
Awesome! Made an Console Application out of it. Needed to add [STAThread] in front of the consoles main method. – dforce Nov 03 '16 at 15:02

cjbarth · Answer 3 · 2012-05-06T20:06:13.137

5

Expanding on Spartaco's answer I implimented the following which works GREAT!

    Using reportWebBrowser As New WebBrowser
        reportWebBrowser.CreateControl()
        reportWebBrowser.DocumentText = sbHTMLDoc.ToString
        While reportWebBrowser.DocumentText <> sbHTMLDoc.ToString
            Application.DoEvents()
        End While
        reportWebBrowser.Document.ExecCommand("SelectAll", False, Nothing)
        reportWebBrowser.Document.ExecCommand("Copy", False, Nothing)

        Using reportRichTextBox As New RichTextBox
            reportRichTextBox.Paste()
            reportRichTextBox.SaveFile(DocumentFileName)
        End Using
    End Using

edited May 06 '12 at 20:06

answered Feb 17 '11 at 21:01

cjbarth

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Be sure to watch out for memory allocation problems if you're not calling `Dispose()` on those controls that you create all the time. – Seph May 06 '12 at 13:26
Thanks @Seph. I've modified the code to take that into account. – cjbarth May 06 '12 at 20:06

score 3 · Answer 4 · answered Sep 30 '08 at 21:11

It is not perfect of course, but here is the code I use to convert HTML to plain text.

(I was not the original author, I adapted it from code found on the web)

public static string ConvertHtmlToText(string source) {

            string result;

            // Remove HTML Development formatting
            // Replace line breaks with space
            // because browsers inserts space
            result = source.Replace("\r", " ");
            // Replace line breaks with space
            // because browsers inserts space
            result = result.Replace("\n", " ");
            // Remove step-formatting
            result = result.Replace("\t", string.Empty);
            // Remove repeating speces becuase browsers ignore them
            result = System.Text.RegularExpressions.Regex.Replace(result,
                                                                  @"( )+", " ");

            // Remove the header (prepare first by clearing attributes)
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*head([^>])*>", "<head>",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"(<( )*(/)( )*head( )*>)", "</head>",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(<head>).*(</head>)", string.Empty,
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            // remove all scripts (prepare first by clearing attributes)
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*script([^>])*>", "<script>",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"(<( )*(/)( )*script( )*>)", "</script>",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            //result = System.Text.RegularExpressions.Regex.Replace(result, 
            //         @"(<script>)([^(<script>\.</script>)])*(</script>)",
            //         string.Empty, 
            //         System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"(<script>).*(</script>)", string.Empty,
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            // remove all styles (prepare first by clearing attributes)
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*style([^>])*>", "<style>",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"(<( )*(/)( )*style( )*>)", "</style>",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(<style>).*(</style>)", string.Empty,
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            // insert tabs in spaces of <td> tags
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*td([^>])*>", "\t",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            // insert line breaks in places of <BR> and <LI> tags
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*br( )*>", "\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*li( )*>", "\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            // insert line paragraphs (double line breaks) in place
            // if <P>, <DIV> and <TR> tags
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*div([^>])*>", "\r\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*tr([^>])*>", "\r\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<( )*p([^>])*>", "\r\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            // Remove remaining tags like <a>, links, images,
            // comments etc - anything thats enclosed inside < >
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<[^>]*>", string.Empty,
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            // replace special characters:
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&nbsp;", " ",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&bull;", " * ",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&lsaquo;", "<",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&rsaquo;", ">",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&trade;", "(tm)",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&frasl;", "/",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"<", "<",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @">", ">",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&copy;", "(c)",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&reg;", "(r)",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            // Remove all others. More can be added, see
            // http://hotwired.lycos.com/webmonkey/reference/special_characters/
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     @"&(.{2,6});", string.Empty,
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);


            // make line breaking consistent
            result = result.Replace("\n", "\r");

            // Remove extra line breaks and tabs:
            // replace over 2 breaks with 2 and over 4 tabs with 4. 
            // Prepare first to remove any whitespaces inbetween
            // the escaped characters and remove redundant tabs inbetween linebreaks
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(\r)( )+(\r)", "\r\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(\t)( )+(\t)", "\t\t",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(\t)( )+(\r)", "\t\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(\r)( )+(\t)", "\r\t",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            // Remove redundant tabs
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(\r)(\t)+(\r)", "\r\r",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            // Remove multible tabs followind a linebreak with just one tab
            result = System.Text.RegularExpressions.Regex.Replace(result,
                     "(\r)(\t)+", "\r\t",
                     System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            // Initial replacement target string for linebreaks
            string breaks = "\r\r\r";
            // Initial replacement target string for tabs
            string tabs = "\t\t\t\t\t";
            for (int index = 0; index < result.Length; index++) {
                result = result.Replace(breaks, "\r\r");
                result = result.Replace(tabs, "\t\t\t\t");
                breaks = breaks + "\r";
                tabs = tabs + "\t";
            }

            // Thats it.
            return result;

    }

Downvoted for the reasons so eloquently explained here: http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 — Duncan Bayne, Jun 30 '11 at 07:26
Ironically it is for nearly the same reasons XSLT can be error prone. HTML is messy. And is seldom a proper XML document ready for transformation. I suspect a proper solution would incorporate a little regex to get the doc clean enough for a proper XSLT transformation. — Menefee, Jun 23 '12 at 03:47

score 2 · Answer 5 · answered Jun 24 '19 at 09:35

I recommend a console tool named Pandoc. It is not a component, it is rather huge conversion pack. I am using it to convert between HTML and LaTeX. It is just awesome.

The full list of supported formats you can find on the program page.

In order to convert an HTML document to RTF format you write on the console:

pandoc filename.html -f html -t rtf -s -o filename.rtf

score 1 · Answer 6 · answered Sep 30 '08 at 08:10

1

Maybe what you need is a control to edit the HTML?

answered Sep 30 '08 at 08:10

GvS

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How do I convert HTML to RTF (Rich Text) in .NET without paying for a component?

6 Answers6

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