How to set the current screensaver - Delphi

The following code sets up your desired screensave then shows it. For actual use this code needs to be changed to suite your needs i.e. remove ShowMessage dialogs, change name of screensaver, change timeout value and remove actual testing section.

Tested under Windows XP but should work with earlier versions of Windows



program SetupDefaultScrnSaver;

uses
  Windows, SysUtils, Forms, Dialogs, Registry;

const
  { from Windows.pas }
  SPI_SETSCREENSAVEACTIVE = 17;
  SPIF_SENDWININICHANGE = 2;
  SPI_SETSCREENSAVETIMEOUT = 15;
  { from Messages.pas }
  WM_SYSCOMMAND       = $0112;

  { From Project JEDI JCL library
    http://www.delphi-jedi.org/Jedi:CODELIBJCL:22798 }
  function GetWindowsSysFolder: string;
    procedure StrResetLength(var S: AnsiString);
    begin
      SetLength(S, StrLen(PChar(S)));
    end;
  var
    Required: Cardinal;
  begin
    Result := '';
    Required := GetSystemDirectory(nil, 0);
    if Required <> 0 then
    begin
      SetLength(Result, Required);
      GetSystemDirectory(PChar(Result), Required);
      StrResetLength(Result) ;
    end;
  end;

  function SetScreenSave(const Name: string; Const TimeOut: Integer = 30):Boolean;
  const
    SixtySeconds = 60 ;
  var
    Reg:TRegistry ;
  begin
    if not FileExists(Name) then
    begin
      ShowMessage('ScreenSaver "' + Name + '" not located') ;
      exit ;
    end ;

    Reg := TRegistry.Create ;
    Reg.RootKey := HKEY_CURRENT_USER ;
    try
      with Reg do
      begin
        if OpenKey('Control Panel\Desktop',False) then
        begin
          WriteString('SCRNSAVE.EXE', Name) ;
          WriteString('ScreenSaverIsSecure','1') ;
          CloseKey ;
        end else
        begin
          Result := False ;
          exit ;
        end ;
      end ;
    finally
      Reg.Free ;
    end ;

    SystemParametersInfo(SPI_SETSCREENSAVEACTIVE,1,nil,SPIF_SENDWININICHANGE);
    SystemParametersInfo(SPI_SETSCREENSAVETIMEOUT,SixtySeconds * TimeOut,
      nil,SPIF_SENDWININICHANGE);
    Result := True ;
  end;

begin
  { -=CHANGE THE SCREENSAVER NAME TO ONE YOU WANT THE USER TO HAVE=- }
  if SetScreenSave(GetWindowsSysFolder + '\ss3dfo.scr') then  begin
    ShowMessage('Screensaver set, press OK to test (remember grace period)') ;
    PostMessage(GetDesktopWindow, WM_SYSCOMMAND, SC_SCREENSAVE, 0);
  end ;
end.