Delphi Timer: Time before next event

Question

Is it possible to determine when a TTimer in Delphi will trigger? I know how to calculate this based upon the timer\'s last run and the timers interval. Unfortunately, the

Answer 1

There's absolutely no way to query a Windows timer for information of this nature. You will simply have to keep track of this yourself.

I would do this by wrapping up the TTimer with composition and not inheritance. You can then be sure that you will capture all modifications to the timer state.

Answer 2

In this case I recommend you switch from a TTimer which uses Windows timers, to a thread based TTimer-style component. Then you can query the time until the next event.

Alternative; If you want a simple ugly hack, then change your Timer interval to 1 second instead of 120 seconds, and do a countdown yourself:

   const
     CounterPreset = 120;

   ...

   procedure TForm1.FormCreate(Sender:TObject);
   begin
      FCounter := CounterPreset;
      Timer1.Interval := 1000;
      Timer1.Enabled := true;
   end;

   procedure TForm1.Timer1Timer(Sender);
   begin
           Dec(FCounter);
           if (FCounter<=0) then
           begin
              DoRealTimerCodeHere;
              FCounter := CounterPreset;
           end;
   end;

   function  TForm1.TimeLeft:Integer;
   begin
         result := FCounter;
   end;

This will be inaccurate subject to the limitations of the WM_TIMER message, documented only vaguely at MSDN here. Real experience shows that WM_TIMER should only be used for things that don't need to happen at all, and should be used as a convenience, not as a hard-timing system.