aHasCharsToEncode := False;
    for i := 1 to Length(s) do begin
        c := s[i];
        if (c = '%') or (c < ' ') then begin
            aHasCharsToEncode := True;
            break;
        end;
    end;
    if not aHasCharsToEncode then begin
        Result := s;
        exit;
    end;
    sb.Init;
    for i := 1 to Length(s) do begin
        c := s[i];
        if (c = '%') or (c < ' ') then begin
            sb.Add('%' + IntToHex(Ord(c), 2));
        end
        else begin
            sb.Add(c);
        end;
    end;
    Result := sb.Value;