Ross Levis Wrote: >>I have found TTimer to work down to about 8 to 10ms as a minimum, >>definately well less than 55ms.
The standard TTimer can only be guaranteed to be accurate to 55 milliseconds as it utilises the PC's clock timer. You may get better results but it will depend upon the PC. For greater accuracy you can use the Windows API's QueryPerformanceCounter which can be accurate to 1,193,180 counts per second on a Pentium and above but will definitely give you millisecond accuracy on Win98 and above. I posted an article here http://www.delphi3000.com/articles/article_1347.asp some time back which simplifies the API usage by providing a Delphi interface to utilise for performance logging code. It works with Delphi 3, 4 & 5 and although not tested should work with later versions too. Code from the article as follows: --------------------------------- The following unit implements a HighResTimer object to simplify use of the WinAPI QueryPerformanceCounter and QueryPerformanceFrequency High resolution counter functions. This can then be extended to provide WriteToFile, LogToDB functionality etc... Just add to your uses clause then create an instance of THighResTimer whenever you need it. Note: Contains IFDEFs to handle the change to TLargeInteger in Delphi versions 3, 4 & 5+ unit HighResTimer; {********************************************************************* ********************************************************************** * Comments: Provides an object to access Window's high resolution performance * timer mechanism. * Notes: The accuracy provided by the functions Now and Time are * limited to 55ms as they use the PC's clock timer. The * Window's API gives access to a hardware based high * resolution performance timer that counts 1,193,180 times * per second (at least it does on WinNT with a Pentium) to * retrieve more accurate timings. * * Help: The HighResTimer once created just needs to be started * before performing an action then stopped once the * actions been performed. The time taken can be retrieved * as a TDateTime by calling the Time property or as an * integer by calling the Ticks property. * Example: * var * MyHighResTimer: THighResTimer; * i, j: Integer; * begin * MyHighResTimer := THighResTimer.Create; * try * MyHighResTimer.Start; * for i := 0 to 1000 do * begin * j := i; * end; * MyHighResTimer.Stop; * ShowMessage(Format('Operation took Time:%8.8f * Ticks:%d',[FHighResTimer.Time, * FHighResTimer.Ticks])); * finally * MyHighResTimer.Free; * end; * end; * * ********************************************************************** **********************************************************************} interface uses Windows; type THighResTimer = Class(TObject) private FStartCount: TLargeInteger; FStopCount: TLargeInteger; FTicks: Cardinal; FTime: TDateTime; function GetTicks: Cardinal; function GetTime: TDateTime; public constructor Create; virtual; destructor Destroy; override; procedure Start; virtual; procedure Stop; virtual; property Ticks: Cardinal read GetTicks; property Time: TDateTime read GetTime; end; const TICK_MILLISECOND = 1000; DATE_TIME_MILLISECOND = 0.00001; var GHighResFrequency: TLargeInteger; implementation { THighResTimer } constructor THighResTimer.Create; begin inherited Create; {$IFDEF VER130} FStartCount := 0; FStopCount := 0; {$ELSE} FStartCount.QuadPart := 0; FStopCount.QuadPart := 0; {$ENDIF} end; destructor THighResTimer.Destroy; begin {} inherited; end; { Note: The use of cardinal means this can only cope with a maximum 49 day gap} function THighResTimer.GetTicks: Cardinal; var countTaken: TLargeInteger; countTicks: Double; begin {$IFDEF VER130} countTaken := FStopCount - FStartCount; { Use double, instead of integer division to arrive at an equal value as in GetTime, below} countTicks := (countTaken / GHighResFrequency) * TICK_MILLISECOND; {$ELSE} countTaken.QuadPart := FStopCount.QuadPart - FStartCount.QuadPart; countTicks := (countTaken.QuadPart / GHighResFrequency.QuadPart) * TICK_MILLISECOND; {$ENDIF} Result := Round(countTicks); end; function THighResTimer.GetTime: TDateTime; var countTaken: Double; begin {$IFDEF VER130} countTaken := FStopCount - FStartCount; Result := (countTaken / GHighResFrequency) * DATE_TIME_MILLISECOND; {$ELSE} countTaken := FStopCount.QuadPart - FStartCount.QuadPart; Result := (countTaken / GHighResFrequency.QuadPart) * DATE_TIME_MILLISECOND; {$ENDIF} end; procedure THighResTimer.Start; begin QueryPerformanceCounter(FStartCount); FStopCount := FStartCount; end; procedure THighResTimer.Stop; begin QueryPerformanceCounter(FStopCount); end; initialization QueryPerformanceFrequency(GHighResFrequency); end. Michael Darling Senior Solutions Developer ROOM Solutions Ltd mailto:[EMAIL PROTECTED] -----Original Message----- From: Ross Levis [mailto:[EMAIL PROTECTED] Sent: 31 March 2006 08:22 To: Borland's Delphi Discussion List Subject: Re: More accurate timers I have found TTimer to work down to about 8 to 10ms as a minimum, definately well less than 55ms. Ross. ----- Original Message ----- From: "John Dammeyer" <[EMAIL PROTECTED]> To: "'Borland's Delphi Discussion List'" <[email protected]> Sent: Friday, March 31, 2006 4:13 PM Subject: More accurate timers Hi all, The standard Delphi TTimer appears to be fairly useful since it allows time delays in 1mS steps but apparently resolves to a 55mS granularity. A while back I tried a timer I found on the WEB but couldn't get it to work with Delphi-5. If you are using a better timer, which one and what sort of issues are there with them? 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