go-tinyqr

This is an experimental QR code generator that aims to be as small as possible. It is based on go-qrcode by Tom Harwood.

In order to reduce the size, I mostly removed options:

• go-tinyqr always uses byte encoding. That's what you want most of the time anyway.
• go-tinyqr always uses the medium error correction level.
• go-tinyqr always uses mask pattern 0.

Fixing all of these options leads to slightly worse results, but massivly simplifies the code. For example, it allows to hardcode the complete format info.

Still, generating QR codes stays complex. I had hoped that I can reduce this down to a small library that can just be copied to a new project. But it is still ~1000 loc.

I did not remove support for different versions (sizes). Concentrating on a single version would have similar benefits to the other optimizations in terms of size, but I feel that the loss of flexibility would be much more relevant in this case.

Reduction in code size

| file | old | new | diff | | ---------- | ---: | --: | ---: | | gf.go | 92 | 83 | -10% | | ecc.go | 177 | 102 | -42% | | bitset.go | 174 | 22 | -87% | | version.go | 2927 | 416 | -86% | | render.go | 439 | 147 | -67% | | qrcode.go | 649 | 119 | -82% | | total | 4528 | 902 | -80% |

This table compares b6ab6a4 (old) and f88a46e (new). The numbers were measured using sloc. In cases where I combined files I added up the line counts of the old files.

The biggest single change is that I was able to remove ~2000 lines of version information for error correction levels that I didn't use.

Links

• ISO/IEC 18004:2006
• Nayuki: Creating a QR Code step by step
• Thonky's QR Code tutorial