​delphi 识别图片流类型

//AValue 为图片文件流头两个字节

function GetImageExt(AValue: Cardinal): String;

begin

  case AValue of

    $4D42, $424D: Result := '.bmp';

    $D8FF, $FFD8: Result := '.jpg';

    $4947, $4749: Result := '.gif';

    $050A, $0A05: Result := '.pcx';

    $5089, $8950: Result := '.png';

    $4238, $3842: Result := '.psd';

    $A659, $59A6: Result := '.ras';

    $DA01, $01DA: Result := '.sgi';

    $4949: Result := '.tiff';

    else Result := '';

  end;

end;