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[OBSOLETE] Adding a QR code
This snippet lets you draw a QR-code, for example to provide a link to the composer’s, or the music editor’s website.
Actually encoding the URL into a QR-code is not done here (this just draws the QR-code from a grid of "black" or "white" values), but see the code for a short Python snippet you can use to avoid having to fill for each small square if it’s black or white.
This snippet is obsolete starting from LilyPond 2.25.3, which
adds a \qr-code markup command that takes a URL directly
instead of a grid of "black" and "white" values. It is used like
\markup \qr-code #10 "https://lilypond.org".
%% Original thread: https://lists.gnu.org/archive/html/lilypond-user-fr/2022-07/msg00005.html %% (snippet author: Jean Abou Samra <jean@abou-samra.fr>) \paper { tagline = ##f } #(define (index-map f . lsts) "Applies @code{f} to corresponding elements of @code{lists}, just as @code{map}, providing an additional counter starting at zero. @code{f} needs to have the counter in its arguments like @code{(index-map (lambda (i arg) <body>) lists)}" (let loop ((lsts lsts) (acc '()) (i 0)) (if (any null? lsts) (reverse! acc) (loop (map cdr lsts) (cons (apply f i (map car lsts)) acc) (1+ i))))) #(define-markup-command (qr-code layout props data) (string?) #:properties ((width 10)) (let* (;; Return lines in reversed order, since translating in Y-axis ;; uses increasing values. Meaning lines will be stacked upwards. (lines (reverse (remove string-null? (map string-trim-both (string-split data #\newline))))) (n (length lines)) (square-width (/ width n)) (box (make-filled-box-stencil `(0 . ,square-width) `(0 . ,square-width)))) ;; Build the final qr-code-stencil from line-stencils list (apply ly:stencil-add ;; Get a list of line-stencils (index-map (lambda (i line) ;; Build a line-stencil from square-stencils list (apply ly:stencil-add ;; Get a list of (already translated) square-stencils ;; per line (index-map (lambda (j char) (ly:stencil-translate (stencil-with-color box (case char ((#\0) white) ((#\1) black) (else (ly:warning "unrecognized character ~a, should be 0 or 1" char) red))) (cons (* j square-width) (* i square-width)))) (string->list line)))) lines)))) %{ A string representation of the QR code. 0 means white, 1 means black. You can generate this automatically using Python and the pyqrcode module ("pip install pyqrcode"). Use this line of code in a Python prompt: >>> import pyqrcode; print(pyqrcode.create("https://lilypond.org").text(quiet_zone=0)) %} lilypondDotOrg = "11111110011100011110101111111 10000010010000010111101000001 10111010010110001000101011101 10111010001010111101001011101 10111010110100000111001011101 10000010011100011001101000001 11111110101010101010101111111 00000000111000111110100000000 00110011101100001000111010000 10101001111000001000001111101 00110111010100000110001011010 01010001100110010111000110001 01111011110010011110010100111 01111101001101010001001101101 01111011000001000011001111011 11001001001011001000111011010 11100110111011011001110111000 00001100010001001011100100100 10111111011001010011001000100 00001100001000101011011011100 01010010000011000000111111111 00000000110011100010100011001 11111110101001101011101010110 10000010000110111110100010011 10111010011010111100111111111 10111010110001101111000011110 10111010100101101010100101001 10000010001001000100000010010 11111110010100110010111100010" \markup \qr-code \lilypondDotOrg \markup \vspace #5 \markup \override #'(width . 15) \qr-code \lilypondDotOrg
![[image of music]](../ab/lily-2646d1f3.png)
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