The format on the printer for each character stores bits in a column-major format, while most raster formats are row-major, so I wrote a quick converter to rotate the bits. The non-printable 7 pixels at the bottom of the images are ignored by the printer. Note that wider characters have a two-pixel dead-zone on the right.

These pictures show how the glpyhs (grey) are laid out in the available print area (unused print area in white), in the available memory (unused memory in red).

Since the characters would be surrounded by too much whitespace in the “Font A” (12×24) representation, I settled on printing in “Font B” (9×17), leaving a one-pixel space underneath, and to the right of each character.

ESC/POS fonts are submitted in a 24 pixel tall format regardless of print area.

ESC/POS supports a fixed 12×24 or a smaller 9×17 font.

Unifont contains characters that are 8 or 16 pixels wide, that cover the entire Unicode Basic Multilingual Plane (BMP), at 16 characters tall.

So the first issue to solve was to do with font sizes: I decided to start with the GNU Unifont project, because it ships fixed-width binary fonts in a text format that can be parsed without a font library, is freely licensed, and has excellent coverage. These next sections go through some of the things I had to write to get it all working. I then modified this to print arbitrary UTF-8 text with a local bitmap font. $connector = new FilePrintConnector('php://stdout') $text = file_get_contents('php://stdin') I started by making a new standalone test script, which converts text input into ESC/POS using a cut-down version of the escpos-php printer driver. So, I decided to try to get this working on an Epson TM-T20 variant which has no CJK fonts. On some printers, there are native commands to print Japanese, but for a driver project, we need something with broad compatibility. However, if you attempt to send an example string like “日本語” to escpos-php currently, the driver will substitute it with “?”, since it doesn’t know how to convert them to ESC/POS. The escpos-php driver will automatically map a lot of western scripts to these code pages. Mapping arbitrary text to something understood by these printers is a huge challenge. Instead, they still use a series of legacy code pages to represent non-ASCII text. Programmers usually deal with text in UTF-8, but receipt printers don’t. I previously wrote a bit about printing individual bitmaps for each character, where here I am aiming to print entire scripts. I have recently been looking for a way to add support for these on receipt printers that have no native ability to render them, and thought I would write a bit about some progress so far. I develop a printer driver for ESC/POS receipt printers, and we regularly get feature requests for encoding text in the Chinese, Japanese and Korean languages (“CJK”).

Epson thermal printer font