Comment by dfox

Do not do this unless you do not have any other choice. Preferrably use whatever native barcode support of the printer involved, if it does not have that, just generate the barcode as vector image or bitmap with a resolution that is a integer fraction of the printers resolution. Generating correct Code128 as a SVG is about the same amount of work as generating the correct input for some sort of barcode font (the hard part is determining the switches between character sets, not generating bars from bytes).