C# RichTextBox colors only the text between the first tags

Question

2.00/5 (1 vote)

See more:

Hello, I found a way how to color the text between tags in RichTextBox using C# WPF, but the problem is that it colors the text only once, no matter how many times the tag is found.

I'll post my code here, would anyone tell me what's wrong with it? Thanks!

In my Window_Loaded function:

TextRange textRange = new TextRange(lesson_content.Document.ContentStart, lesson_content.Document.ContentEnd);

string[] tags = new string[2];
tags[0] = "t";
tags[1] = "blue";


foreach (string tag in tags)
{
   if (tag == "t")
   {
   string s = ExtractString(textRange.Text, tag);

   Regex reg = new Regex(s, RegexOptions.Compiled | RegexOptions.IgnoreCase);

   TextPointer start = lesson_content.Document.ContentStart;
   while (start != null && start.CompareTo(lesson_content.Document.ContentEnd) < 0)
   {
      if start.GetPointerContext(LogicalDirection.Forward)==TextPointerContext.Text)
      {
         var match = reg.Match(start.GetTextInRun(LogicalDirection.Forward));
         var textrange = new TextRange(start.GetPositionAtOffset(match.Index,    LogicalDirection.Forward), start.GetPositionAtOffset(match.Index + match.Length, LogicalDirection.Backward));

         textrange.ApplyPropertyValue(TextElement.ForegroundProperty, new  SolidColorBrush(Colors.Blue));
      }
      start = start.GetNextContextPosition(LogicalDirection.Forward);
    }
}

ExtractString Function:

string ExtractString(string s, string tag)
{
   string startTag = "<" + tag + ">";
   int startIndex = s.IndexOf(startTag) + startTag.Length;
   int endIndex = s.IndexOf(", startIndex);

   return s.Substring(startIndex, endIndex - startIndex);
}

I tried to put two <t> tags, but it only colors the text between the first ones.

Posted 14-Jul-11 3:23am

George Findulov

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Answer 1 · 2011-07-14T08:39:00

Not clear what you mean by "tag". Hope you don't mix up HTML with Rich Text. Not quite clear what you want to do and why. I only want to note that if you continue coding in this way, it well lead you nowhere.

Assignment of tag can be written like this: string[] tags = new string[] {"t", "blue"}. What you do is not well maintainable. What if you want to add one more tag? You will need to change two places in code, otherwise tags[2] will cause exception.

You use "t" in two different places. What if you change the tag? Are you going to find all places where you use it? By that reasons, you should never use immediate constants at all (except of few such as 0, 1, null). Not even ""; use string.Empty instead.

Expressions like startTag = "<" + tag + ">" are bad. Did you know that strings are immutable? Avoid repeated concatenation. Use string.Format("<{0}>", tag); in other cases use System.Text.StringBuilder. You tend to use ad-hoc coding and accidental complexity. Try to get rid of it.

—SA