unit PowerButton;

interface

uses
 Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
  Menus, ShellApi, ExtCtrls,dialogs;

  

type
  TPowerButton = class(TComponent)
  private
    FHooked: Boolean;
    FOnPowerbuttonPress : TNotifyEvent;
    PPowerOffEnable:Boolean;
    function MessageHook(var Msg: TMessage): Boolean;
  protected
    procedure DoPowerbuttonPress; dynamic;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  published
    {events}
    property OnPowerbuttonPress: TNotifyEvent read FOnPowerbuttonPress write FOnPowerbuttonPress;
    {properties}
    property PowerOffEnable : boolean read PPowerOffEnable write PPowerOffEnable;

  end;

procedure Register;

implementation

const
  PBT_APMQUERYSUSPEND = 0; {Request for permission to suspend.}

procedure Register;
begin
  RegisterComponents('Zusätzlich', [TPowerButton]);
end;

constructor TPowerButton.create(AOwner : TComponent);
begin
  inherited Create(AOwner);
  FHooked := False;
  if not (csDesigning in ComponentState) then
  begin
    Application.HookMainWindow(MessageHook);
    FHooked := True;
  end;
end;

Procedure TPowerButton.DoPowerbuttonPress;
begin
  if Assigned(FOnPowerbuttonPress) then FOnPowerbuttonPress(Self);

end;

function TPowerButton.MessageHook(var Msg: TMessage): Boolean;
begin
  case msg.WParam of
    PWR_SUSPENDREQUEST: //win2000,XP
    begin
      if PPowerOffEnable = false then
      begin
        msg.Result := PWR_FAIL;
      end;
      DoPowerbuttonPress;
    end;

    PBT_APMQUERYSUSPEND: //win95,98
    begin
      if PPowerOffEnable = false then
      begin
        msg.Result := BROADCAST_QUERY_DENY;
      end;
      DoPowerbuttonPress;
    end;
  end;
end;

destructor TPowerButton.Destroy;
begin
  if FHooked then Application.UnhookMainWindow(MessageHook);
  inherited Destroy;
end;