QR code encoding — PNG, SVG, and ASCII output
(scm qr) is a pure-Scheme QR-code encoder (ISO/IEC 18004). qr-encode builds a QR matrix from a string; render it to PNG, SVG, or ASCII, or inspect the matrix directly. It supports versions 1–40 and error-correction levels L/M/Q/H.
(import (scm qr) (scm png))
(define m (qr-encode "https://example.org")) ;; a QR matrix
(write-png-file "qr.png" (qr->png m)) ;; PNG file
(qr->svg m 4 4) ;; => SVG string
(display (qr->ascii m)) ;; print to the terminalPass an error-correction level as a trailing argument to qr-encode ('L, 'M, 'Q, 'H; default 'M). The matrix accessors (qr-matrix-size, qr-matrix-ref, qr-matrix-version, …) expose the raw modules.
10 bindings
Syntax: (qr->ascii matrix) Library: (scm qr) Description: Renders a qr-matrix using two-character cells suitable for terminal preview. Each module becomes ' ' (light) or '##' (dark). Adds a 1-module quiet zone. Example: (display (qr->ascii (qr-encode "hi")))
Syntax: (qr->png matrix [module-px [quiet-modules]]) Library: (scm qr) Description: Renders a qr-matrix as an 8-bit grayscale PNG bytevector. module-px is the side length in pixels of one module (default 8). quiet-modules is the border width in modules (default 4, per spec). Example: (write-png-file "qr.png" (qr->png (qr-encode "hello")))
Syntax: (qr->svg matrix [module-px [quiet-modules]]) Library: (scm qr) Description: Renders a qr-matrix as an SVG string. module-px sets the width/height attribute scale (default 8 px per module). quiet-modules is the border in modules (default 4). Example: (display (qr->svg (qr-encode "hi")))
Syntax: (qr-encode data [ec-level [version]]) Library: (scm qr) Description: Encodes data as a QR code and returns a qr-matrix record. data may be a string (encoded as UTF-8) or a bytevector. ec-level defaults to 'M and must be one of 'L 'M 'Q 'H. version defaults to the smallest version that fits. Example: (qr->svg (qr-encode "https://example.org") 4 4)