How to add TCPDF to Library to Magento 1

We can add a 3rd-party to library to Magento, for example TCPDF Show archive.org snapshot .

1. Download the library and unzip.
2. Place the unzip contents to /lib/Tcpdf/.
3. For autoloading by Magento, we need to change the main application class name to Mage standard (separated by underscore): <folder-name>_<original-class-name>; for TCPDF, we edit the file Tcpdf.php: the original class name is class TCPDF, we change it to class Tcpdf_Tcpdf.
   1. class Tcpdf_Tcpdf
   2. class Tcpdf_Tcpdf2DBarcode
4. No we can instantiate the class like this: $pdf = new Tcpdf_Tcpdf();