Using C#, how do I set tab positions in a multiline textbox?

Question

Is there a graceful way to set custom tab sizes/positions in a multiline textbox in C#?

Answer 1

You need to send the EM_SETTABSTOPS message, like this:

static class NativeMethods {
    [DllImport("user32.dll")]
    public static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, ref int lParam);
}
static void SetTabs(TextBox box) {
    //EM_SETTABSTOPS - http://msdn.microsoft.com/en-us/library/bb761663%28VS.85%29.aspx
    int lParam = 16;  //Set tab size to 4 spaces
    NativeMethods.SendMessage(box.Handle, 0x00CB, new IntPtr(1), ref lParam);
    box.Invalidate();
}

Answer 2

By "graceful," I mean really simple. What I ended up doing is switching the font to Courier New (Any fixed-width font would work.) and using spaces to fill in calculated tab stops with a for loop:

    for (n = sMsg.Length; n < maxLen; n++)
    {
       sMsg += " ";
    }