Three-sided box

This example shows how to add a markup command to get a three-sided box around some text (or other markup).

\version "2.24"

% New command to add a three-sided box, with sides north, west, and south.
% Based on the `box-stencil` command defined in `scm/stencil.scm`.
% Note that ";;" is used to comment a line in Scheme.
#(define-public (NWS-box-stencil stencil thickness padding)
   "Add a box around STENCIL, producing a new stencil."
   (let* ((x-ext (interval-widen (ly:stencil-extent stencil X) padding))
          (y-ext (interval-widen (ly:stencil-extent stencil Y) padding))
          (y-rule (make-filled-box-stencil (cons 0 thickness) y-ext))
          (x-rule (make-filled-box-stencil
                   (interval-widen x-ext thickness) (cons 0 thickness))))
     ;; (set! stencil (ly:stencil-combine-at-edge stencil X 1 y-rule padding))
     (set! stencil (ly:stencil-combine-at-edge stencil X LEFT y-rule padding))
     (set! stencil (ly:stencil-combine-at-edge stencil Y UP x-rule 0.0))
     (set! stencil (ly:stencil-combine-at-edge stencil Y DOWN x-rule 0.0))
     stencil))

% The corresponding markup command, based on the `\box` command defined
% in `scm/define-markup-commands.scm`.
#(define-markup-command (NWS-box layout props arg) (markup?)
   #:properties ((thickness 0.1) (font-size 0) (box-padding 0.2))
   "Draw a box round ARG.

Look at THICKNESS, BOX-PADDING, and FONT-SIZE properties to determine
line thickness and padding around the markup."
   (let ((pad (* (magstep font-size) box-padding))
         (m (interpret-markup layout props arg)))
     (NWS-box-stencil m thickness pad)))


\relative c' {
  c1^\markup { \NWS-box ABCD }
  c1^\markup { \NWS-box \note {4} #1.0 }
}