For a while now I’ve been toying with the idea of writing a C# editor (almost an IDE, but with only the features that I need). Clearly the hardest part of this task would be getting some form of edit control working.. the obvious choice for which is the
RichTextBox. Anyone who has tried using
RichTextBox in this situation will know that it has a number of flaws, the most serious being that it’s rather slow when trying to colourise the text.
I’ve long since given up on using
RichTextBox for a code editor, but while I was investigating its use I came across a number of ways to improve it’s functionality. I’ll present these here in a series of posts on the subject.. first up is how to speed up the control’s updating, as well as adding one little extra formatting option.
There are articles on this subject on the internet. The standard method seems to be to send a
WM_SETREDRAW message to prevent the control from being redrawn while updating. I had this implemented and running nicely when I came across another article showing that an extra speed increase can be gained by sending
EM_SETEVENTMASK to prevent the control from handling events. Here’s the code:
+ Code to help speed up
Although I’m using
HandleRef here, I have absolutely no idea if this is the correct usage (or even if it’s needed). Full code will be at the end of this posting. I have not fully tested these methods so I have no idea what the performance gains might be (if there are any). If anyone wants to try benchmarking, please let me know the results.
It always bothered me that the
SelectionAlignment property of
RichTextBox does not allow fully justified text. Especially since I know it’s possible with the richedit control that
RichTextBox wraps. Here’s some code that will replace
SelectionAlignment with something a little nicer for those that are writing word processors in C#:
+ Code to allow justified text in the
TextAlign enumeration contains
Justify. Again, this is mostly untested — it should work on any machine with the richedit 2.0 common control (I believe), but I offer no guarantees.
Here’s the full code for the
AdvRichTextBox control (plus the
I’ll add to this code in future posts and if anyone has any comments or suggestions (or even requests), feel free to ask them. Hope you found this useful.