Help with RTB Highlighting

Question

Hi!

I made a highlight script that checks the text and highlights matched words:
    foreach (Match keyWordMatch in keyWords.Matches(txtIzvor.Text))
                        {

                            txtIzvor.Select(keyWordMatch.Index, keyWordMatch.Length);
                            txtIzvor.SelectionColor = System.Drawing.Color.Blue;
                            txtIzvor.SelectionStart = selPos;

                            txtIzvor.SelectionLength = 0;


                        }
but I have one problem: this check is ok but on every text changed event it checks all of the text so it bugs.
I used this script on document load. Can anybody help me make this script work for only the
line you are writing in
example:
if you write in line 1 it only checks line 1

Thanks!

Stefan · Answer

Try messing around with the selection start and length to check only one line. To stop the flashing do this: 1. Add using System.Runtime.InteropServices; to your namespaces. 2. At the top of the class add [DllImport(user32.dll)] 3. Under that add public static extern bool LockWindowUpdate(IntPtr hWndLock); 4. Put the foreach loop you are using inside a try block. Instead of using a catch block use a finally block. 5. Right before the foreach loop add LockWindowUpdate(richtextbox1.Handle); 6. Inside the finally block add LockWindowUpdate(IntPtr.zero); This allows you to lock the rich text box's update thus stopping the flashing. I used this for a html editor I wrote and it worked well. It won't do much for performance however since your still selecting all the text. I suggest you just play around with the selection start and length values.

blagoje ivanovic · Answer

Thanks for your reply. That's the problem. For each change of color or something it runs text_changed event and it flashes and the process comes to 99. So basically for every word it highlights it runs a text_changed event which checks the whole text again. I think it would be much easier for the processor if it checked only the current line.

Stefan · Answer

Sorry for the late reply I've been really busy. You'll probably have to mess around with the selection start and length properties. Maybe you could store the previous start and length of the selection then set the current selection to right after that. When I asked what you meant by it bugs I meant what exactly is the problem. I'm guessing that when the document length starts getting longer the rich text box starts to flash. Is this what's happening? If so I can tell you how to fix that which is a lot easier than trying to select only the current line. Please post back if the flashing is the issue. If not post back and I'll try to help with selecting only the current line. Until then I'll keep looking for a better solution.

blagoje ivanovic · Answer

Can anybody help please?

blagoje ivanovic · Answer

Well didn't you read the whole post? I said that on every text_changed event (in RTB txtIzvor) it checks the whole text so it takes a lot if you have a lot of text. I want it to check only the line you're writing in.

Stefan · Answer

What do you mean it bugs?