Have you ever had the desire to convert some RTF text into HTML? Probably not. But if you do, then you are in luck! I recently had the need to do this conversion and after some searching found out a way to do it by enhancing a sample distributed in the MSDN library. The sample is called: XAML to HTML Conversion Demo.
The sample has code which converts HTML to and from a XAML Flow Document. But this doesn’t make things easier until you realize that there is a way to convert RTF to XAML easily. The key is to use System.Windows.Controls.RichTextBox which can load RTF from a stream and save it as XAML. This conversion is shown below:
private static string ConvertRtfToXaml(string rtfText)
{
var richTextBox = new RichTextBox();
if (string.IsNullOrEmpty(rtfText)) return "";
var textRange = new TextRange(richTextBox.Document.ContentStart, richTextBox.Document.ContentEnd);
using (var rtfMemoryStream = new MemoryStream())
{
using (var rtfStreamWriter = new StreamWriter(rtfMemoryStream))
{
rtfStreamWriter.Write(rtfText);
rtfStreamWriter.Flush();
rtfMemoryStream.Seek(0, SeekOrigin.Begin);
textRange.Load(rtfMemoryStream, DataFormats.Rtf);
}
}
using (var rtfMemoryStream = new MemoryStream())
{
textRange = new TextRange(richTextBox.Document.ContentStart, richTextBox.Document.ContentEnd);
textRange.Save(rtfMemoryStream, DataFormats.Xaml);
rtfMemoryStream.Seek(0, SeekOrigin.Begin);
using (var rtfStreamReader = new StreamReader(rtfMemoryStream))
{
return rtfStreamReader.ReadToEnd();
}
}
}
With this code we have all we need to convert RTF to HTML. I modified the sample to add this RTF To XAML conversation and then I run that XAML through HTML converter which results in the HTML text. I added an interface to these conversion utilities and converted the sample into a library so that I would be able to use it from other projects. Here is the interface:
public interface IMarkupConverter
{
string ConvertXamlToHtml(string xamlText);
string ConvertHtmlToXaml(string htmlText);
string ConvertRtfToHtml(string rtfText);
}
public class MarkupConverter : IMarkupConverter
{
public string ConvertXamlToHtml(string xamlText)
{
return HtmlFromXamlConverter.ConvertXamlToHtml(xamlText, false);
}
public string ConvertHtmlToXaml(string htmlText)
{
return HtmlToXamlConverter.ConvertHtmlToXaml(htmlText, true);
}
public string ConvertRtfToHtml(string rtfText)
{
return RtfToHtmlConverter.ConvertRtfToHtml(rtfText);
}
}
With this I am now able to convert from RTF to HTML. However, there is one catch – the conversion uses the RichTextBox WPF control which requires a single threaded apartment (STA). Therefore in order to run your code that calls the ConvertRtfToHtml function, it must also be running in a STA. If you can’t have your program run in a STA then you must create a new STA thread to run the conversion. Like this:
MarkupConverter markupConverter = new MarkupConverter();
private string ConvertRtfToHtml(string rtfText)
{
var thread = new Thread(ConvertRtfInSTAThread);
var threadData = new ConvertRtfThreadData { RtfText = rtfText };
thread.SetApartmentState(ApartmentState.STA);
thread.Start(threadData);
thread.Join();
return threadData.HtmlText;
}
private void ConvertRtfInSTAThread(object rtf)
{
var threadData = rtf as ConvertRtfThreadData;
threadData.HtmlText = markupConverter.ConvertRtfToHtml(threadData.RtfText);
}
private class ConvertRtfThreadData
{
public string RtfText { get; set; }
public string HtmlText { get; set; }
}
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Hi Matthew,
First of all, my appreciation for your excellent code on converting between rtf and htm.
Now, heres the query – Is it possible to keep the ‘tracked changes’ formatting intact while this conversion occurs. If we use the code (http://code.msdn.microsoft.com/Converting-between-RTF-and-aaa02a6e) to perform converstion, the tracked changes in the rtf example below are lost :
rtf1sste16000ansideflang1033ftnbjuc1deff0
{fonttbl{f0 fnil fcharset0 Arial;}}
{colortbl ;red255green255blue255 ;red0green0blue0 ;}
{stylesheet{f0fs24 Normal;}{cs1 Default Paragraph Font;}}
{*revtbl{Unknown;}{atiwari1;}}
paperw12240paperh15840margl1800margr1800margt1440margb1440headery720footery720nogrowautofitdeftab720formshadefet4aendnotesaftnnrlcpgbrdrheadpgbrdrfoot
sectdpgwsxn12240pghsxn15840marglsxn1800margrsxn1800margtsxn1440margbsxn1440headery720footery720sbkpagepgncontpgndec
plainplainf0fs24pardplainf0fs24plainlang1033hichf0dbchf0lochf0fs20 This is my plainlang1033hichf0dbchf0lochf0fs20revisedrevauth1revdttm651739769 Secondplainlang1033hichf0dbchf0lochf0fs20deletedrevauthdel1revdttmdel651739769
firstplainlang1033hichf0dbchf0lochf0fs20 line of text.par
}
(you can open the above .rtf in word and check out).
Thanks
Ashutosh
The support for RTF I am using it limited by the WPF RichText box control. That control does not seem to support the revision tags so my sample also doesn’t support those tags.
Hi..
Excellent to see your code.
I am getting an error at this line
var richTextBox = new RichTextBox();
{“The calling thread must be STA, because many UI components require this.”}
at System.Windows.Input.InputManager..ctor()
at System.Windows.Input.InputManager.GetCurrentInputManagerImpl()
at System.Windows.Input.KeyboardNavigation..ctor()
at System.Windows.FrameworkElement.FrameworkServices..ctor()
at System.Windows.FrameworkElement.EnsureFrameworkServices()
at System.Windows.FrameworkElement..ctor()
at System.Windows.Controls.Control..ctor()
at System.Windows.Controls.Primitives.TextBoxBase..ctor()
at System.Windows.Controls.RichTextBox..ctor(FlowDocument document)
at System.Windows.Controls.RichTextBox..ctor()
at MarkupConverter.HtmlToRtfConverter.ConvertXamlToRtf(String xamlText) in C:\Users\smurugesan\Downloads\MarkupConverter\MarkupConverter\HtmlToRtfConverter.cs:line 22
at MarkupConverter.HtmlToRtfConverter.ConvertHtmlToRtf(String htmlText) in C:\Users\smurugesan\Downloads\MarkupConverter\MarkupConverter\HtmlToRtfConverter.cs:line 17
at WebApplication1._Default.btnConvert_Click(Object sender, EventArgs e) in c:\users\smurugesan\documents\visual studio 2010\Projects\ConversionHTMLtoRTF\WebApplication1\Default.aspx.cs:line 25
at System.Web.UI.WebControls.Button.OnClick(EventArgs e)
at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)
at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
Can you please clarify this..
I am implementing your code at the web site. i.e Using your .dll in the web application.
but your code works fine at the windows side.
Did you follow the instructions at the end of the post where I show how to run the conversion inside of an STA thread? You will need to do this for the conversion to work inside of a website.
where to write this code
You can copy and paste the code that I show at the end of the blog post where you want to perform the conversion.
Hello, did you tried this using images? i’m not able to see it…
Hey Marco,
I don’t think this works with images. I haven’t had a chance to dig deeper to see if it is possible using this method.
Thanks for the code.
I tried implementing this using STA. I am calling this function from SSRS.
Visual Studio crashes when I try to run SSRS with RTF to Html conversion.
Do you know of any such problem?
I have not heard of such a problem. Can you show me the code you are using to launch the thread and the code to run the conversion?
hi mr. mat,
i don’t know c#, would u write ur code as a vb.net function(s) with a rtf stream as input & html stream as output, please?
thanks in advance.
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i am implementing your code in web site .i want to convert html to rtf but there is STA thread exception occured.Can u tell me where in which class i have to write STA Thread Code