\version "2.20.0"

% custom engraver by Kevin Barry
#(define (Time_signature_markup_engraver context)
   (let ((time-sig '())
         (time-sig-copy #f)
         (previous-was-grace #f)) ; to avoid printing twice at grace notes
     (make-engraver
      (acknowledgers
       ((time-signature-interface engraver grob source-engraver)
        (let* ((current-moment (ly:context-current-moment context))
               (grace-nom (ly:moment-grace-numerator current-moment)))
          (if (not (eqv? 0 grace-nom))
              (begin
               (set! previous-was-grace #t)
               (set! time-sig grob))
              (if (and (eqv? 0 grace-nom) previous-was-grace)
                  (begin
                   (set! previous-was-grace #f)
                   (set! time-sig '()))
                  (set! time-sig grob))))))
      ((process-acknowledged engraver)
       (and (not (null? time-sig))
            (let* ((time-sig-copy (ly:engraver-make-grob
                                   engraver
                                   'TextScript
                                   time-sig))
                   (copy-prop (lambda (prop)
                                (ly:grob-set-property!
                                 time-sig-copy
                                 prop
                                 (ly:grob-property time-sig prop))))
                   (timing-context (ly:context-find context 'Timing))
                   (timing-time-sig
                    (ly:context-grob-definition timing-context 'TimeSignature))
                   (timing-time-sig-stencil
                    (ly:assoc-get 'stencil timing-time-sig '()))
                   (prop-list '(fraction
                                style
                                font-size
                                extra-spacing-width
                                cause)))
              (map copy-prop prop-list)
              (ly:grob-set-property! time-sig-copy 'stencil
                timing-time-sig-stencil)
              (ly:grob-set-parent! time-sig-copy Y time-sig)
              (ly:grob-set-parent! time-sig-copy X time-sig)
              (set! time-sig '())
              )))
      ((stop-translation-timestep engraver)
       (set! time-sig-copy #f)))))

#(define (remove-except-at-line-end grob)
   (if (not (equal? (ly:item-break-dir grob) LEFT))
       (ly:grob-set-property! grob 'stencil #f)))

#(define (remove-at-end grob)
   (if (equal? (ly:item-break-dir grob) LEFT)
       (ly:grob-set-property! grob 'stencil #f)))

#(define (center-over-barline grob)
   (if (equal? (ly:item-break-dir grob) 0)
       (let* ((x-extent (ly:grob-property grob 'X-extent))
              (width (interval-length x-extent)))
         (ly:grob-set-property! grob 'X-offset (* -1 (/ width 2))))))

#(define (center-over-barline-and-remove-at-end grob)
   (begin
    (remove-at-end grob)
    (center-over-barline grob)))

#(define (left-align-at-end grob)
   (and (and (ly:item? grob)
             (equal? (ly:item-break-dir grob) LEFT))
        (ly:grob-set-property! grob 'self-alignment-X 1)))

% definition of shift-right-at-line-begin
#(define (shift-right-at-line-begin g)
  "Shift an item to the right, but only at the start of the line."
  (if (and (ly:item? g)
           (equal? (ly:item-break-dir g) RIGHT))
      (ly:grob-translate-axis! g 3.5 X)))

timeSignatures = {
  \tempo 4 = 80
  \time 4/4 s1
  \time 3/8 s4.
  \time 3/4 s2.
  \time 4/4 s1
  \time 2/4 \acciaccatura s8 s2
  \compoundMeter #'((3 8) (1 16) (1 16) (1 16))
  s4. s16 s16 s16
  \time 4/4 s1
}

\paper {
    top-margin = #15
    bottom-margin = #15
    left-margin = #15
    right-margin = #15
    system-system-spacing =
    #`((basic-distance . 10)
       (minimum-distance . 6)
       (padding . 2)
      )
}

\markup \column \fontsize #4 {
  "Approach #1"
  "(http://lsr.di.unimi.it/LSR/Snippet?id=272)"
}

\score {
  \layout {
    \context {
      \Score
      \override MetronomeMark.break-align-symbols = #'(staff-bar time-signature)
    }
    \context {
      \Staff
      \override MultiMeasureRest.spacing-pair = #'(break-alignment . staff-bar)
      \override Clef.font-size = #5
      \remove "Time_signature_engraver"
    }
    \context {
      \Score
    }
  }
  <<
    \new Dynamics \with {          
    \consists "Time_signature_engraver"
    \consists "Axis_group_engraver"
    \override TimeSignature.font-size = #8
    \override TimeSignature.break-align-symbol = ##f
    \override TimeSignature.X-offset =
      #ly:self-alignment-interface::x-aligned-on-self
    \override TimeSignature.self-alignment-X = #LEFT
    \override TimeSignature.after-line-breaking =
      #shift-right-at-line-begin
    \numericTimeSignature
    }
    {
      \timeSignatures
    }
    
    \new StaffGroup <<
      \relative c' {
        \time 4/4
        c4 ( ^"↑ Problem 1d"
        d4 e4 f4 ) |
        
        \time 3/8
        a'4 ( g8 ) |
        
        \time 3/4
        R2. 
        ^\markup {
          \column {
            "← Problem 1a"
            "Problem 1c →"
            " "
            " "
          }
        } |
        
        \time 4/4
        c1 |
        
        \time 2/4
        a8 ^"↑ Problem 1b"
        g8 f8 e8 |
        
        \compoundMeter #'((3 8) (1 16) (1 16) (1 16))
        a2 g16 |
        
        \time 4/4
        c4 c c c |
      }
      
      \relative c' {
        \time 4/4
        R1 |
        
        \time 3/8
        R4. |
        
        \clef bass
        \time 3/4
        a,2. \> \startTextSpan |
        \break
        
        \time 4/4
        c2 e2 \! \stopTextSpan |

        \time 2/4
        \acciaccatura f8 a8 
        g8 f8 e8 |
        
        \compoundMeter #'((3 8) (1 16) (1 16) (1 16))
        a2 g16 |
        
        \time 4/4
        c4 c c c |
      }
    >>
  >>
} \pageBreak

\markup \column \fontsize #4 {
  "Approach #2"
  "(\override TimeSignature.break-align-symbol = #'staff-bar)"
}

\score {
  \layout {
    \context {
      \Score
      \override MetronomeMark.break-align-symbols = #'(staff-bar time-signature)
    }
    \context {
      \Staff
      \override MultiMeasureRest.spacing-pair = #'(break-alignment . staff-bar)
      \override Clef.font-size = #5
      \remove "Time_signature_engraver"
    }
    \context {
      \Score
    }
  }
  <<
    \new Dynamics \with {          
    \consists "Time_signature_engraver"
    \consists "Axis_group_engraver"
    \override TimeSignature.font-size = #8
    \override TimeSignature.break-align-symbol = #'staff-bar
    \override TimeSignature.X-offset =
      #ly:self-alignment-interface::x-aligned-on-self
    \override TimeSignature.self-alignment-X = #LEFT
    \numericTimeSignature
    }
    {
      \timeSignatures
    }
    
    \new StaffGroup <<
      \relative c' {
        \time 4/4
        \textLengthOn
        c4 ( ^"← Problem 2b"
        \textLengthOff
        d4 e4 f4 ) |
        
        \time 3/8
        a'4 ( g8 ) |
        
        \time 3/4
        R2. |
        
        \time 4/4
        \override Score.RehearsalMark.X-offset = #-1.5
        \mark "↓ Problem 2d"
        c1 |
        
        \time 2/4
        a8 ^"↑ Problem 2c"
        g8 f8 e8 |
        
        \compoundMeter #'((3 8) (1 16) (1 16) (1 16))
        a2 g16 |
        
        \time 4/4
        c4 c c c |
      }
      
      \relative c' {
        \time 4/4
        R1 |
        
        \time 3/8
        R4. |
        
        \clef bass
        \time 3/4
        a,2. \> \startTextSpan |
        \break
        
        \time 4/4
        c2 ^"↓ Problem 2a" _"↑" e2 \! \stopTextSpan |

        \time 2/4
        \acciaccatura f8 a8 
        g8 f8 e8 |
        
        \compoundMeter #'((3 8) (1 16) (1 16) (1 16))
        a2 g16 |
        
        \time 4/4
        c4 c c c |
      }
    >>
  >>
} \pageBreak

\markup \column \fontsize #4 {
  "Approach #3"
  "(custom engraver by Kevin Barry)"
}

\score {
  \layout {
    \context {
      \Score
      \override MetronomeMark.break-align-symbols = #'(staff-bar time-signature)
    }
    \context {
      \Staff
      \override MultiMeasureRest.spacing-pair = #'(break-alignment . staff-bar)
      \override Clef.font-size = #5
      \remove "Time_signature_engraver"
    }
    \context {
      \Score
    }
  }
  <<
    \new Dynamics \with {          
      \consists "Time_signature_engraver"
      \consists \Time_signature_markup_engraver
      \override TimeSignature.font-size = #8
      \override TimeSignature.before-line-breaking = #remove-except-at-line-end
      \override TimeSignature.break-align-symbol = #'staff-bar
      \override TextScript.before-line-breaking = #remove-at-end
      %↓ The only solution to problem 2b but it causes collisions
      %\override TextScript.extra-spacing-width = #'(+inf.0 . -inf.0)
      \override TextScript.extra-spacing-width = #'(0 . 0.8)
      \override TextScript.direction = #UP
      \override TextScript.Y-offset = #0
      \numericTimeSignature
    }
    {
      \timeSignatures
    }
    
    \new StaffGroup <<
      \relative c' {
        \time 4/4
        \textLengthOn
        c4 ( ^"← Problem 2b"
        \textLengthOff
        d4 e4 f4 ) |
        
        \time 3/8
        a'4 ( g8 ) |
        
        \time 3/4
        R2. |
        
        \time 4/4
        \override Score.RehearsalMark.X-offset = #-1.5
        \mark "↓ Problem 2d"
        c1 |
        
        \time 2/4
        a8 g8 f8 e8 |
        
        \compoundMeter #'((3 8) (1 16) (1 16) (1 16))
        a2 g16 |
        
        \time 4/4
        c4 c c c |
      }
      
      \relative c' {
        \time 4/4
        R1 |
        
        \time 3/8
        R4. |
        
        \clef bass
        \time 3/4
        a,2. \> \startTextSpan |
        \break
        
        \time 4/4
        c2 e2 \! \stopTextSpan |

        \time 2/4
        \acciaccatura f8 a8 
        g8 f8 e8 |
        
        \compoundMeter #'((3 8) (1 16) (1 16) (1 16))
        a2 g16 |
        
        \time 4/4
        c4 c c c |
      }
    >>
  >>
} \pageBreak