How to append \line into RTF using RichTextBox control

Question

When using the Microsoft RichTextBox control it is possible to add new lines like this...

richtextbox.AppendText(System.Environment.NewLine); // appends \r\n

However, if you now view the generated rtf the \\r\\n characters are converted to \\par not \\line

How do I insert a \\line control code into the generated RTF?

Hacks like inserting a token at the end of the string and then replacing it after the fact, so something like this:

string text = "my text";
text = text.Replace("||" "|"); // replace any '|' chars with a double '||' so they aren't confused in the output.
text = text.Replace("\r\n", "_|0|_"); // replace \r\n with a placeholder of |0|

richtextbox.AppendText(text);

string rtf = richtextbox.Rtf;
rtf.Replace("_|0|_", "\\line"); // replace placeholder with \line
rtf.Replace("||", "|"); // set back any || chars to |

This almost worked, it breaks down if you have to support right to left text as the right to left control sequence always ends up in the middle of the placeholder.

public void AppendNewLine()
{
    Keys[] keys = new Keys[] {Keys.Shift, Keys.Return};
    SendKeys(keys);
}

private void SendKeys(Keys[] keys)
{
    foreach(Keys key in keys)
    {
        SendKeyDown(key);
    }
}

private void SendKeyDown(Keys key)
{
    user32.SendMessage(this.Handle, Messages.WM_KEYDOWN, (int)key, 0);
}

private void SendKeyUp(Keys key)
{
    user32.SendMessage(this.Handle, Messages.WM_KEYUP, (int)key, 0);
}

This also ends up being converted to a \\par

Is there a way to post a messaged directly to the msftedit control to insert a control character?

I am totally stumped, any ideas guys? Thanks for your help!

Answer 1

Adding a Unicode "Line Separator" (U+2028) does work as far as my testing showed:

private void Form_Load(object sender, EventArgs e)
{
    richText.AppendText("Hello, World!\u2028");
    richText.AppendText("Hello, World!\u2028");
    string rtf = richText.Rtf;
    richText.AppendText(rtf);
}

When I run the program, I get:

Hello, World!
Hello, World!
{\rtf1\ansi\ansicpg1252\deff0\deflang1031{\fonttbl{\f0\fnil\fcharset0 Courier New;}}
{\colortbl ;\red255\green255\blue255;}
\viewkind4\uc1\pard\cf1\f0\fs17 Hello, World!\line Hello, World!\line\par
}

It did add \\line instead of \\par .

Answer 2

Since you want to use a different RTF code, I think you may need to forget about the simplistic AppendText() method and manipulate the .Rtf property of your RichTextBox directly instead. Here is a sample (tested) to demonstrate:

RichTextBox rtb = new RichTextBox();
//this just gets the textbox to populate its Rtf property... may not be necessary in typical usage
rtb.AppendText("blah");
rtb.Clear();

string rtf = rtb.Rtf;

//exclude the final } and anything after it so we can use Append instead of Insert
StringBuilder richText = new StringBuilder(rtf, 0, rtf.LastIndexOf('}'), rtf.Length /* this capacity should be selected for the specific application */);

for (int i = 0; i < 5; i++)
{
    string lineText = "example text" + i;
    richText.Append(lineText);
    //add a \line and CRLF to separate this line of text from the next one
    richText.AppendLine(@"\line");
}

//Add back the final } and newline
richText.AppendLine("}");


System.Diagnostics.Debug.WriteLine("Original RTF data:");
System.Diagnostics.Debug.WriteLine(rtf);

System.Diagnostics.Debug.WriteLine("New Data:");
System.Diagnostics.Debug.WriteLine(richText.ToString());


//Write the RTF data back into the RichTextBox.
//WARNING - .NET will reformat the data to its liking at this point, removing
//any unused colors from the color table and simplifying/standardizing the RTF.
rtb.Rtf = richText.ToString();

//Print out the resulting Rtf data after .NET (potentially) reformats it
System.Diagnostics.Debug.WriteLine("Resulting Data:");
System.Diagnostics.Debug.WriteLine(rtb.Rtf);

Output:

Original RTF data:

{\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fnil\fcharset0 Microsoft Sans Serif;}}
\viewkind4\uc1\pard\f0\fs17\par
}

New RTF Data:

{\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fnil\fcharset0 Microsoft Sans Serif;}}
\viewkind4\uc1\pard\f0\fs17\par
example text0\line
example text1\line
example text2\line
example text3\line
example text4\line
}

Resulting RTF Data:

{\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fnil\fcharset0 Microsoft Sans Serif;}}
\viewkind4\uc1\pard\f0\fs17\par
example text0\line example text1\line example text2\line example text3\line example text4\par
}

Answer 3

if you are using paragraphs to write to richtextbox you can use the LineBreak() same code shown below

Paragraph myParagraph = new Paragraph();
FlowDocument myFlowDocument = new FlowDocument();

// Add some Bold text to the paragraph
myParagraph.Inlines.Add(new Bold(new Run(@"Test Description:")));
myParagraph.Inlines.Add(new LineBreak()); // to add a new line use LineBreak()
myParagraph.Inlines.Add(new Run("my text"));
myFlowDocument.Blocks.Add(myParagraph);
myrichtextboxcontrolid.Document = myFlowDocument;

Hope this helps!