Delphi 操作Windows系统睡眠

unit SystemCriticalU;

interface

uses

  Windows;

type

  TSystemCritical = class

  private

    FIsCritical: Boolean;

    procedure SetIsCritical(const Value: Boolean) ;

  protected

    procedure UpdateCritical(Value: Boolean) ; virtual;

  public

    constructor Create;

    property IsCritical: Boolean read FIsCritical write SetIsCritical;

  end;

var

  SystemCritical: TSystemCritical;

implementation

{ TSystemCritical }

// REF: http://msdn.microsoft.com/en-us/library/aa373208.aspx

type

  EXECUTION_STATE = DWORD;

   

const

  ES_SYSTEM_REQUIRED = $00000001;

  ES_DISPLAY_REQUIRED = $00000002;

  ES_USER_PRESENT = $00000004;

  ES_AWAYMODE_REQUIRED = $00000040;

  ES_CONTINUOUS = $80000000;

   

  KernelDLL = 'kernel32.dll';

{

  SetThreadExecutionState Function

  Enables an application to inform the system that it is in use,

  thereby preventing the system from entering sleep or turning off the

  display while the application is running.

}

procedure SetThreadExecutionState(ESFlags: EXECUTION_STATE);

  stdcall; external kernel32 name 'SetThreadExecutionState';

constructor TSystemCritical.Create;

begin

  inherited;

  FIsCritical := False;

end;

procedure TSystemCritical.SetIsCritical(const Value: Boolean) ;

begin

  if FIsCritical = Value then

    Exit;

  FIsCritical := Value;

  UpdateCritical(FIsCritical);

end;

procedure TSystemCritical.UpdateCritical(Value: Boolean) ;

begin

  if Value then

    // 防止睡眠空闲超时和关机。

    SetThreadExecutionState(ES_SYSTEM_REQUIRED or ES_CONTINUOUS)

  else

    //清除执行状态标志以禁用离开模式并允许

    // 系统空闲以正常睡眠

    SetThreadExecutionState(ES_CONTINUOUS);

end;

initialization

SystemCritical := TSystemCritical.Create;

finalization

SystemCritical.IsCritical := False;

SystemCritical.Free;

end.