如何更改RichTextBox中指定行的格式

Question

I have a winforms RichTextBox containing lots of lines of text (eg 2 MB text files), and would like to programmatically change the formatting of specified lines, eg highlighting them.

How can I address the lines, rather than the characters? Is a RichTextBox even the best control for this sort of thing, or is there another alternative? I have tried the Infragistics UltraFormattedTextEditor, but it was at least a couple of orders of magnitude slower to display text, so no good for my longer files.

Thanks!

Answer 1

To access the lines on textbox controls you use the Lines property

richTextBox.Lines

From there you can iterate through the lines and work with the ones you want to change.

Edit: Agreed, I missed the highlight part (+1 for answering your own question). Including working code:

int lineCounter = 0;
foreach(string line in richTextBox1.Lines)
{
   //add conditional statement if not selecting all the lines
   richTextBox.Select(richTextBox.GetFirstCharIndexFromLine(lineCounter), line.Length);
   richTextBox.SelectionColor = Color.Red;
   lineCounter++;
}

Answer 2

OK, I'll document the solution I found: using richTextBox.Lines to get the lines as Luis says, then

richTextBox.GetFirstCharIndexFromLine(int line)
richTextBox.Select(int start, int length)

to select the relevant lines, then

richTextBox.SelectionColor...
richTextBox.SelectionBackground...

etc. etc. to format the lines.