How to show line numbers for every 10 lines?

Question

The SynEdit control has an event OnGutterGetText. I would like to use this to make the gutter only display every 10th line number (also line 1 and currently selected line). The same way that the Delphi (XE7) IDE works. How do I determine whether to show the line or not using this event?

Answer 1

The question transpires to be nothing to do with the edit control in reality. You simply want to know if a is an exact multiple of b. That is so if the remainder of a divided by b is zero. And the remainder operator in Delphi is mod.

if a mod b = 0 then

Now, in your case you want

if LineNum mod 10 = 0 then

This assumes that LineNum is one based. If it is zero based then you need

if (LineNum + 1) mod 10 = 0 then