I've been fiddling around, but can't seem to find a good documentation for it.
Can I make ZXing generate a CODE_128 barcode image? How?
If you are using ZXing.Net you can do it with the following snippet:
var content = "123456789012345678";
var writer = new BarcodeWriter
{
Format = BarcodeFormat.CODE_128
};
var bitmap = writer.Write(content);