procedure TForm1.SetFullScreen(SizeX,SizeY,Bits:longint);
var dmScreenSettings: DEVMODE;
begin
  ZeroMemory( @dmScreenSettings, sizeof( DEVMODE ) );
  dmScreenSettings.dmSize := sizeof( DEVMODE );
  dmScreenSettings.dmPelsWidth  := SizeX; // Width
  dmScreenSettings.dmPelsHeight := SizeY; // Height
  dmScreenSettings.dmFields     := DM_PELSWIDTH or DM_PELSHEIGHT; // Color Depth
  dmScreenSettings.dmBitsPerPel := Bits;
  ChangeDisplaySettings(dmScreenSettings, CDS_FULLSCREEN); // Switch To Fullscreen Mode

  Form1.WindowState := wsMaximized;
end;