判断是否有TrueType字体

function IsTrueTypeAvailable : bool;
var
 {$IFDEF WIN32}
  rs : TRasterizerStatus;
 {$ELSE}
  rs : TRasterizer_Status;
 {$ENDIF}
begin
  result := false;
  if not GetRasterizerCaps(rs, sizeof(rs)) then exit;
  if rs.WFlags and TT_AVAILABLE <> TT_AVAILABLE then exit;
  if rs.WFlags and TT_ENABLED <> TT_ENABLED then exit;
  result := true;
end;