Best method for syntax highlighting

Hi,

You are doing it in the logical way, just like most people asking questions here about the subject; however IMO it is completely inappropriate for a range of reasons:

1. an RTB is a stupid control that doesn't scale well as it holds all the text as one large string, so it may or may not work well for 100 lines, it is bound to fail at serving you right for 10,000 lines of text. I did my own editor based on a Panel; that takes:
- keyboard and mouse handlers to do the editing myself;
- a Paint handler using Graphics.DrawString.

2. Regex is a powerful tool with big performance hits; I tend not to use it, except for offering complex search/replace capabilities in the hands of your apps' users. For maximum speed, code the search and replace stuff yourself, using string methods such as IndexOf and Contains.

3. Finally, my syntax colorizer is inside my Paint handler: it skips all the lines that are scrolled over, then parses just the 20 to 40 lines that are visible, and stops when it reaches the last visible line. In order to correctly skip the beginning of the text, my data structures are such that I keep a few flags for each line of text, related to opening and closing of multi-line comments; the idea is I can start parsing a (modified) line without the need to parse again all previous lines.


The net result is:
- I have an editor that works the way I like it;
- it syntax-colorizes instantaneously;
- when I select some text, it immediately highlights identical strings in the visible part of the text (something extremely useful Visual Studio doesn't do for me).

My advice to you, assuming you will want to keep the RTB, is to replace the Regex parts by string operations.

:)