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Wait procedure
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| acUtils
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| procedure Wait(var WaitHandle: THandle; Timeout: DWord = 0);
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| The Wait procedure used to wait some time in that line of code which called Wait procedure, until the WaitHandle (system event) is signalled (StopWait procedure is called), OR the Timeout is expired. After calling the StopWait procedure, or expiration of the Timeout, the program will continue from the next line of your code.
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 The Wait and StopWait routines should be used instead "while something do Application.ProcessMessages;", to not utilize CPU time for long time, until some operation will be completed.
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| When Timeout parameter is set to 0, the function considering it as Timeout does not specified, so procedure will wait infinitely, until the WaitHandle is signalled (or StopWait procedure will be called).
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| TMyForm = class(TForm)
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| private
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| FWaitEvent: THandle;
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| public
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| procedure CallSomethingAndWait;
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| procedure DestroySomethingAndStopWait(Sender: TObject);
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| end;
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| procedure TMyForm.CallSomethingAndWait;
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| begin
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| // ...call something
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| Wait(FWaitEvent); // ...and wait result...
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| // next line will be executed after StopWait will be called OR the application will be terminated
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| end;
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| procedure TMyForm.DestroySomethingAndStopWait(Sender: TObject);
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| begin
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| // this code should be executed when the some long operation completed and the program should stop awaiting
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| StopWait(FWaitEvent);
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| end;
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| procedure Wait(var WaitHandle: THandle; Timeout: DWord {$IFDEF D4} = 0 {$ENDIF});
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| begin
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| if Timeout = 0 then Timeout := INFINITE;
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| WaitHandle := CreateEvent(nil, True, False, nil); // manual reset, start non-signaled
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| try
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| while not Application.Terminated and
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| (MsgWaitForMultipleObjects(1, WaitHandle, False, Timeout, QS_ALLINPUT) = WAIT_OBJECT_0 + 1) do
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| Application.ProcessMessages;
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| finally
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| CloseHandle(WaitHandle);
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| WaitHandle := INVALID_HANDLE_VALUE;
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| end;
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| end;
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| StopWait procedure.
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