Mega Code Archive
How to implement the Pascal Delay function
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Title: How to implement the Pascal Delay-function
/ 1. Delay
procedure Delay(dwMilliseconds: Longint);
var
iStart, iStop: DWORD;
begin
iStart := GetTickCount;
repeat
iStop := GetTickCount;
Application.ProcessMessages;
Sleep(1); // addition from Christian Scheffler to avoid high CPU last
until (iStop - iStart) = dwMilliseconds;
end;
// 2. Delay: with API
procedure Delay(msecs: Longint);
var
targettime: Longint;
Msg: TMsg;
begin
targettime := GetTickCount + msecs;
while targettime GetTickCount do
if PeekMessage(Msg, 0, 0, 0, PM_REMOVE) then
begin
if Msg.message = WM_QUIT then
begin
PostQuitMessage(Msg.wParam);
Break;
end;
TranslateMessage(Msg);
DispatchMessage(Msg);
end;
end;
{
Note:
The elapsed time is stored as a DWORD value.
Therefore, the time will wrap around to zero if the system is
run continuously for 49.7 days.
}
// 3. Sleep
{
The Sleep function suspends the execution of the current
thread for a specified interval.
}
Sleep(dwMilliseconds: Word);
// 4. Combined Delay
{
Including the Sleep in the loop prevents the app from hogging
100% of the CPU for doing practically nothing but running around the loop.
}
procedure PauseFunc(delay: DWORD);
var
lTicks: DWORD;
begin
lTicks := GetTickCount + delay;
repeat
Sleep(100);
Application.ProcessMessages;
until (lTicks = GetTickCount) or Application.Terminated;
end;
// 5. more resource sparing:
procedure Delay(Milliseconds: Integer);
{by Hagen Reddmann}
var
Tick: DWORD;
Event: THandle;
begin
Event := CreateEvent(nil, False, False, nil);
try
Tick := GetTickCount + DWORD(Milliseconds);
while (Milliseconds 0) and
(MsgWaitForMultipleObjects(1, Event, False, Milliseconds,
QS_ALLINPUT) WAIT_TIMEOUT) do
begin
Application.ProcessMessages;
Milliseconds := Tick - GetTickCount;
end;
finally
CloseHandle(Event);
end;
end;
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