Creating a barcode is as simple as calling the classes static draw() method after including Image/Barcode.php.
The method has four parameters: The first is the string that shall be converted into barcode representation. The second parameter determines which driver/type should be used; it is one of: Code39, code128, ean13, int25, postnet or upca.
The case difference between Code39 and code128 has no reason and makes no sense, but is kept because of backward compatibility.
The third parameter of draw() determines the type of the image that is generated; one of jpg, png and gif.
By default, the image generated by the barcode driver is directly output to the browser. If you do not want this, pass false as fourth parameter and draw() will return the GD image resource object; allowing you to do further things with it.