Info Catalog lilypond-learning: Modifying context properties lilypond-learning: Contexts and engravers

lilypond-learning: Adding and removing engravers

 
 3.3.5 Adding and removing engravers
 -----------------------------------
 
 We have seen that contexts each contain several engravers, each of which
 is responsible for producing a particular part of the output, like bar
 lines, staves, note heads, stems, etc.  If an engraver is removed from a
 context, it can no longer produce its output.  This is a crude way of
 modifying the output, but it can sometimes be useful.
 
 Changing a single context
 .........................
 
 To remove an engraver from a single context we use the ‘\with’ command
 placed immediately after the context creation command, as in the
 previous section.
 
    As an illustration, let’s repeat an example from the previous section
 with the staff lines removed.  Remember that the staff lines are
 produced by the ‘Staff_symbol_engraver’.
 
      \new Staff \with {
        \remove "Staff_symbol_engraver"
      }
      \relative c' {
        c4 d
        \set fontSize = #-4  % make note heads smaller
        e4 f |
        \set fontSize = #2.5  % make note heads larger
        g4 a
        \unset fontSize  % return to default size
        b4 c |
      }
      [image src="" alt="[image of music]" text="image of music"]
 
    Engravers can also be added to individual contexts.  The command to
 do this is
 
    ‘\consists ENGRAVER_NAME’,
 
 placed inside a ‘\with’ block.  Some vocal scores have an ambitus placed
 at the beginning of a staff to indicate the range of notes in that staff
 – see (music-glossary)ambitus.  The ambitus is produced by the
 ‘Ambitus_engraver’, which is not normally included in any context.  If
 we add it to the ‘Voice’ context, it calculates the range from that
 voice only:
 
      \new Staff <<
        \new Voice \with {
          \consists "Ambitus_engraver"
        } {
          \relative c'' {
            \voiceOne
            c4 a b g
          }
        }
        \new Voice {
          \relative c' {
            \voiceTwo
            c4 e d f
          }
        }
      >>
      [image src="" alt="[image of music]" text="image of music"]
 
 but if we add the ambitus engraver to the ‘Staff’ context, it calculates
 the range from all the notes in all the voices on that staff:
 
      \new Staff \with {
        \consists "Ambitus_engraver"
      }
      <<
        \new Voice {
          \relative c'' {
            \voiceOne
            c4 a b g
          }
        }
        \new Voice {
          \relative c' {
            \voiceTwo
            c4 e d f
          }
        }
      >>
      [image src="" alt="[image of music]" text="image of music"]
 
 Changing all contexts of the same type
 ......................................
 
 The examples above show how to remove or add engravers to individual
 contexts.  It is also possible to remove or add engravers to every
 context of a specific type by placing the commands in the appropriate
 context in a ‘\layout’ block.  For example, if we wanted to show an
 ambitus for every staff in a four-staff score, we could write
 
      \score {
        <<
          \new Staff {
            \relative c'' {
              c4 a b g
            }
          }
          \new Staff {
            \relative c' {
              c4 a b g
            }
          }
          \new Staff {
            \clef "G_8"
            \relative c' {
              c4 a b g
            }
          }
          \new Staff {
            \clef "bass"
            \relative c {
              c4 a b g
            }
          }
        >>
        \layout {
          \context {
            \Staff
            \consists "Ambitus_engraver"
          }
        }
      }
      [image src="" alt="[image of music]" text="image of music"]
 
 The values of context properties may also be set for all contexts of a
 particular type by including the ‘\set’ command in a ‘\context’ block in
 the same way.
 
 
 See also
 ........
 
DONTPRINTYET     Notation Reference: (lilypond-notation)Modifying context
 plug-ins, *note(lilypond-notation)Changing context default
DONTPRINTYET     Notation Reference: (lilypond-notation)Modifying context
 plug-ins, (lilypond-notation)Changing context default

 settings.
 
 
 Known issues and warnings
 .........................
 
 The ‘Stem_engraver’ and ‘Beam_engraver’ attach their objects to note
 heads.  If the ‘Note_heads_engraver’ is removed no note heads are
 produced and therefore no stems or beams are created either.
 

Info Catalog lilypond-learning: Modifying context properties lilypond-learning: Contexts and engravers