Eigene Timer Komponente aus der MMSystem

[Zacherl]

Hi,

ich habe versucht eine eigene Timer Komponente zu basteln, die den MultiMedia Timer aus der Unit MMSystem verwendet ... Leider kommt es immer wieder zu AccessViolations.

Kann mir da jemand helfen:

Delphi-Quellcode:

unit SystemTimer;

interface 

uses
  Windows, SysUtils, MMSystem, Classes, SyncObjs;

type
  TSystemTimer = class(TObject)
    private
      TimerID: Longword;
      FOnTimer: TNotifyEvent;
      FInterval: integer;
      procedure SetInterval(Value: integer);
      function GetInterval: integer;
    public
      procedure StartTimer;
      procedure StopTimer;
      constructor Create;
      destructor Destroy; override;
    published
      property Interval: integer read GetInterval write SetInterval;
      property OnTimer: TNotifyEvent read FOnTimer write FOnTimer;
  end;

implementation

var
  Timers: TList;
  IDs: TStringList;
  CS: TCriticalSection;

procedure TSystemTimer.SetInterval(Value: integer);
begin
  FInterval := Value;
end;

function TSystemTimer.GetInterval: integer;
begin
  Result := FInterval;
end;

procedure TimerCallback(uTimerID, uMessage: UINT; dwUser, dw1, dw2: DWORD) stdcall;
begin
  CS.Enter;
  if assigned(TSystemTimer(Timers[IDs.IndexOf(IntToStr(uTimerID))]).OnTimer) then
    TSystemTimer(Timers[IDs.IndexOf(IntToStr(uTimerID))]).OnTimer(TSystemTimer(Timers[IDs.IndexOf(IntToStr(uTimerID))]));
  CS.Leave;
end;

constructor TSystemTimer.Create;
begin
  inherited Create;
end;

destructor TSystemTimer.Destroy;
begin
  inherited Destroy;
end;

procedure TSystemTimer.StartTimer;
begin
  Timers.Add(Pointer(Self));
  TimerID := timeSetEvent(FInterval, 0, TimerCallback, 0, TIME_PERIODIC);
  IDs.Add(IntToStr(TimerID));
end;

procedure TSystemTimer.StopTimer;
begin
  timeKillEvent(TimerID);
  Timers.Delete(IDs.IndexOf(IntToStr(TimerID)));
  IDs.Delete(IDs.IndexOf(IntToStr(TimerID)));
end;

initialization
  IDs := TStringList.Create;
  Timers := TList.Create;
  CS := TCriticalSection.Create;

finalization
  Timers.Free;
  IDs.Free;
  CS.Free;

end.

Florian