How to create a TListBox with coloured entries

Problem/Question/Abstract:

I add protocol messages into a listbox, simple lines of text like "success" and "failed". Now I want to have a different background color for every item. For example the "failed" ones in red and the "successed" in green. How to achieve this?

Answer:

Put a TListBox on a form, call it ListBox1, set its style to "lbOwnerDrawFixed" and implement the following event:

procedure TForm1.ListBox1DrawItem(Control: TWinControl; Index: Integer;
  Rect: TRect; State: TOwnerDrawState);
var
  Flags: Longint;
begin
  with ListBox1 do
  begin
    { If the item is not selected, then...}
    if not (odSelected in State) then
      with Canvas.Brush do
      begin
        { Choose the appropriate color}
        case Index of
          0: Color := clBlue;
          1: Color := clRed;
          2: Color := clGreen;
        end;
      end;
    { Draw the colored rectangle.}
    ListBox1.Canvas.FillRect(Rect);
    if Index < Items.Count then
    begin
      Flags := DrawTextBiDiModeFlags(DT_SINGLELINE or DT_VCENTER or DT_NOPREFIX);
      if not UseRightToLeftAlignment then
        Inc(Rect.Left, 2)
      else
        Dec(Rect.Right, 2);
      DrawText(Canvas.Handle, PChar(Items[Index]), Length(Items[Index]), Rect, Flags);
    end;
  end;
end;