LilyPond Internals Reference: 2.1.21 Staff

### 2.1.21 Staff

Handles clefs, bar lines, keys, accidentals. It can contain `Voice` contexts.

This context creates the following layout object(s):

Accidental, AccidentalCautionary, AccidentalPlacement, AccidentalSuggestion, BarLine, BassFigure, BassFigureAlignment, BassFigureAlignmentPositioning, BassFigureBracket, BassFigureContinuation, BassFigureLine, Clef, CueClef, CueEndClef, DotColumn, InstrumentName, KeyCancellation, KeySignature, LedgerLineSpanner, NoteCollision, OctavateEight, OttavaBracket, PianoPedalBracket, RestCollision, ScriptRow, SostenutoPedal, SostenutoPedalLineSpanner, StaffSpacing, StaffSymbol, SustainPedal, SustainPedalLineSpanner, TimeSignature, UnaCordaPedal, UnaCordaPedalLineSpanner and VerticalAxisGroup.

This context sets the following properties:

- Set translator property `createSpacing` to `#t`.
- Set translator property `ignoreFiguredBassRest` to `#f`.
- Set translator property `instrumentName` to `'()`.
- Set translator property `localKeySignature` to `'()`.
- Set translator property `shortInstrumentName` to `'()`.

Context Staff can contain CueVoice and Voice.

This context is built from the following engraver(s):

> `Accidental_engraver`

>   Make accidentals. Catch note heads, ties and notices key-change events. This engraver usually lives at Staff level, but reads the settings for Accidental at `Voice` level, so you can `\override` them at `Voice`.

>   Properties (read)

>   > `autoAccidentals` (list)

>   >   List of different ways to typeset an accidental.

>   >   For determining when to print an accidental, several different rules are tried. The rule that gives the highest number of accidentals is used.

>   >   Each entry in the list is either a symbol or a procedure.

>   >   symbol

>   >     The symbol is the name of the context in which the following rules are to be applied. For example, if context is Score then all staves share accidentals, and if context is Staff then all voices in the same staff share accidentals, but staves do not.

>   >   procedure

>   >     The procedure represents an accidental rule to be applied to the previously specified context.

>   >     The procedure takes the following arguments:

>   >     `context`

>   >       The current context to which the rule should be applied.

>   >     `pitch`

>   >       The pitch of the note to be evaluated.

>   >     `barnum`

>   >       The current bar number.

>   >     `measurepos`

>   >       The current measure position.

>   >     The procedure returns a pair of booleans. The first states whether an extra natural should be added. The second states whether an accidental should be printed. `(#t . #f)` does not make sense.

>   > `autoCautionaries` (list)

>   >   List similar to `autoAccidentals`, but it controls cautionary accidentals rather than normal ones. Both lists are tried, and the one giving the most accidentals wins. In case of draw, a normal accidental is typeset.

>   > `extraNatural` (boolean)

>   >   Whether to typeset an extra natural sign before accidentals changing from a non-natural to another non-natural.

>   > `harmonicAccidentals` (boolean)

>   >   If set, harmonic notes in chords get accidentals.

>   > `internalBarNumber` (integer)

>   >   Contains the current barnumber. This property is used for internal timekeeping, among others by the `Accidental_engraver`.

>   > `keySignature` (list)

>   >   The current key signature. This is an alist containing `(step . alter)` or `((octave . step) . alter)`, where step is a number in the range 0 to 6 and alter a fraction, denoting alteration. For alterations, use symbols, e.g. `keySignature = #`((6 . ,FLAT))`.

>   > `localKeySignature` (list)

>   >   The key signature at this point in the measure. The format is the same as for `keySignature`, but can also contain `((octave . name) . (alter barnumber . measureposition))` pairs.

>   Properties (write)

>   > `localKeySignature` (list)

>   >   The key signature at this point in the measure. The format is the same as for `keySignature`, but can also contain `((octave . name) . (alter barnumber . measureposition))` pairs.

>   This engraver creates the following layout object(s):

>   Accidental, AccidentalCautionary, AccidentalPlacement and AccidentalSuggestion.

> `Axis_group_engraver`

>   Group all objects created in this context in a `VerticalAxisGroup` spanner.

>   Properties (read)

>   > `currentCommandColumn` (graphical (layout) object)

>   >   Grob that is X-parent to all current breakable (clef, key signature, etc.) items.

>   This engraver creates the following layout object(s):

>   VerticalAxisGroup.

> `Bar_engraver`

>   Create barlines. This engraver is controlled through the `whichBar` property. If it has no bar line to create, it will forbid a linebreak at this point.

>   Properties (read)

>   > `whichBar` (string)

>   >   This property is read to determine what type of bar line to create.

>   >   Example:

>   >   >     \set Staff.whichBar = "|:"

>   >   This will create a start-repeat bar in this staff only. Valid values are described in bar-line-interface.

>   Properties (write)

>   > `forbidBreak` (boolean)

>   >   If set to `##t`, prevent a line break at this point.

>   This engraver creates the following layout object(s):

>   BarLine.

> `Beam_collision_engraver`

>   Help beams avoid colliding with notes and clefs in other voices.

> `Clef_engraver`

>   Determine and set reference point for pitches.

>   Properties (read)

>   > `clefGlyph` (string)

>   >   Name of the symbol within the music font.

>   > `clefOctavation` (integer)

>   >   Add this much extra octavation. Values of 7 and -7 are common.

>   > `clefPosition` (number)

>   >   Where should the center of the clef symbol go, measured in half staff spaces from the center of the staff.

>   > `explicitClefVisibility` (vector)

>   >   ‘`break-visibility`’ function for clef changes.

>   > `forceClef` (boolean)

>   >   Show clef symbol, even if it has not changed. Only active for the first clef after the property is set, not for the full staff.

>   This engraver creates the following layout object(s):

>   Clef and OctavateEight.

> `Collision_engraver`

>   Collect `NoteColumns`, and as soon as there are two or more, put them in a `NoteCollision` object.

>   This engraver creates the following layout object(s):

>   NoteCollision.

> `Cue_clef_engraver`

>   Determine and set reference point for pitches in cued voices.

>   Properties (read)

>   > `clefOctavation` (integer)

>   >   Add this much extra octavation. Values of 7 and -7 are common.

>   > `cueClefGlyph` (string)

>   >   Name of the symbol within the music font.

>   > `cueClefOctavation` (integer)

>   >   Add this much extra octavation. Values of 7 and -7 are common.

>   > `cueClefPosition` (number)

>   >   Where should the center of the clef symbol go, measured in half staff spaces from the center of the staff.

>   > `explicitCueClefVisibility` (vector)

>   >   ‘`break-visibility`’ function for cue clef changes.

>   > `middleCCuePosition` (number)

>   >   The position of the middle C, as determined only by the clef of the cue notes. This can be calculated by looking at `cueClefPosition` and `cueClefGlyph`.

>   This engraver creates the following layout object(s):

>   CueClef, CueEndClef and OctavateEight.

> `Dot_column_engraver`

>   Engrave dots on dotted notes shifted to the right of the note. If omitted, then dots appear on top of the notes.

>   This engraver creates the following layout object(s):

>   DotColumn.

> `Figured_bass_engraver`

>   Make figured bass numbers.

>   Music types accepted:

>   bass-figure-event and rest-event

>   Properties (read)

>   > `figuredBassAlterationDirection` (direction)

>   >   Where to put alterations relative to the main figure.

>   > `figuredBassCenterContinuations` (boolean)

>   >   Whether to vertically center pairs of extender lines. This does not work with three or more lines.

>   > `figuredBassFormatter` (procedure)

>   >   A routine generating a markup for a bass figure.

>   > `ignoreFiguredBassRest` (boolean)

>   >   Don’t swallow rest events.

>   > `implicitBassFigures` (list)

>   >   A list of bass figures that are not printed as numbers, but only as extender lines.

>   > `useBassFigureExtenders` (boolean)

>   >   Whether to use extender lines for repeated bass figures.

>   This engraver creates the following layout object(s):

>   BassFigure, BassFigureAlignment, BassFigureBracket, BassFigureContinuation and BassFigureLine.

> `Figured_bass_position_engraver`

>   Position figured bass alignments over notes.

>   This engraver creates the following layout object(s):

>   BassFigureAlignmentPositioning.

> `Font_size_engraver`

>   Put `fontSize` into `font-size` grob property.

>   Properties (read)

>   > `fontSize` (number)

>   >   The relative size of all grobs in a context.

> `Grob_pq_engraver`

>   Administrate when certain grobs (e.g., note heads) stop playing.

>   Properties (read)

>   > `busyGrobs` (list)

>   >   A queue of `(end-moment . GROB)` cons cells. This is for internal (C++) use only. This property contains the grobs which are still busy (e.g. note heads, spanners, etc.).

>   Properties (write)

>   > `busyGrobs` (list)

>   >   A queue of `(end-moment . GROB)` cons cells. This is for internal (C++) use only. This property contains the grobs which are still busy (e.g. note heads, spanners, etc.).

> `Instrument_name_engraver`

>   Create a system start text for instrument or vocal names.

>   Properties (read)

>   > `currentCommandColumn` (graphical (layout) object)

>   >   Grob that is X-parent to all current breakable (clef, key signature, etc.) items.

>   > `instrumentName` (markup)

>   >   The name to print left of a staff. The `instrumentName` property labels the staff in the first system, and the `shortInstrumentName` property labels following lines.

>   > `shortInstrumentName` (markup)

>   >   See `instrumentName`.

>   > `shortVocalName` (markup)

>   >   Name of a vocal line, short version.

>   > `vocalName` (markup)

>   >   Name of a vocal line.

>   This engraver creates the following layout object(s):

>   InstrumentName.

> `Key_engraver`

>   Engrave a key signature.

>   Music types accepted:

>   key-change-event

>   Properties (read)

>   > `createKeyOnClefChange` (boolean)

>   >   Print a key signature whenever the clef is changed.

>   > `explicitKeySignatureVisibility` (vector)

>   >   ‘`break-visibility`’ function for explicit key changes. ‘`\override`’ of the `break-visibility` property will set the visibility for normal (i.e., at the start of the line) key signatures.

>   > `extraNatural` (boolean)

>   >   Whether to typeset an extra natural sign before accidentals changing from a non-natural to another non-natural.

>   > `keyAlterationOrder` (list)

>   >   An alist that defines in what order alterations should be printed. The format is `(step . alter)`, where step is a number from 0 to 6 and alter from -2 (sharp) to 2 (flat).

>   > `keySignature` (list)

>   >   The current key signature. This is an alist containing `(step . alter)` or `((octave . step) . alter)`, where step is a number in the range 0 to 6 and alter a fraction, denoting alteration. For alterations, use symbols, e.g. `keySignature = #`((6 . ,FLAT))`.

>   > `lastKeySignature` (list)

>   >   Last key signature before a key signature change.

>   > `middleCClefPosition` (number)

>   >   The position of the middle C, as determined only by the clef. This can be calculated by looking at `clefPosition` and `clefGlyph`.

>   > `printKeyCancellation` (boolean)

>   >   Print restoration alterations before a key signature change.

>   Properties (write)

>   > `keySignature` (list)

>   >   The current key signature. This is an alist containing `(step . alter)` or `((octave . step) . alter)`, where step is a number in the range 0 to 6 and alter a fraction, denoting alteration. For alterations, use symbols, e.g. `keySignature = #`((6 . ,FLAT))`.

>   > `lastKeySignature` (list)

>   >   Last key signature before a key signature change.

>   > `tonic` (pitch)

>   >   The tonic of the current scale.

>   This engraver creates the following layout object(s):

>   KeyCancellation and KeySignature.

> `Ledger_line_engraver`

>   Create the spanner to draw ledger lines, and notices objects that need ledger lines.

>   This engraver creates the following layout object(s):

>   LedgerLineSpanner.

> `Ottava_spanner_engraver`

>   Create a text spanner when the ottavation property changes.

>   Properties (read)

>   > `currentMusicalColumn` (graphical (layout) object)

>   >   Grob that is X-parent to all non-breakable items (note heads, lyrics, etc.).

>   > `middleCOffset` (number)

>   >   The offset of middle C from the position given by `middleCClefPosition` This is used for ottava brackets.

>   > `ottavation` (markup)

>   >   If set, the text for an ottava spanner. Changing this creates a new text spanner.

>   This engraver creates the following layout object(s):

>   OttavaBracket.

> `Output_property_engraver`

>   Apply a procedure to any grob acknowledged.

>   Music types accepted:

>   apply-output-event

> `Piano_pedal_align_engraver`

>   Align piano pedal symbols and brackets.

>   Properties (read)

>   > `currentCommandColumn` (graphical (layout) object)

>   >   Grob that is X-parent to all current breakable (clef, key signature, etc.) items.

>   This engraver creates the following layout object(s):

>   SostenutoPedalLineSpanner, SustainPedalLineSpanner and UnaCordaPedalLineSpanner.

> `Piano_pedal_engraver`

>   Engrave piano pedal symbols and brackets.

>   Music types accepted:

>   sostenuto-event, sustain-event and una-corda-event

>   Properties (read)

>   > `currentCommandColumn` (graphical (layout) object)

>   >   Grob that is X-parent to all current breakable (clef, key signature, etc.) items.

>   > `pedalSostenutoStrings` (list)

>   >   See `pedalSustainStrings`.

>   > `pedalSostenutoStyle` (symbol)

>   >   See `pedalSustainStyle`.

>   > `pedalSustainStrings` (list)

>   >   A list of strings to print for sustain-pedal. Format is `(up updown down)`, where each of the three is the string to print when this is done with the pedal.

>   > `pedalSustainStyle` (symbol)

>   >   A symbol that indicates how to print sustain pedals: `text`, `bracket` or `mixed` (both).

>   > `pedalUnaCordaStrings` (list)

>   >   See `pedalSustainStrings`.

>   > `pedalUnaCordaStyle` (symbol)

>   >   See `pedalSustainStyle`.

>   This engraver creates the following layout object(s):

>   PianoPedalBracket, SostenutoPedal, SustainPedal and UnaCordaPedal.

> `Rest_collision_engraver`

>   Handle collisions of rests.

>   Properties (read)

>   > `busyGrobs` (list)

>   >   A queue of `(end-moment . GROB)` cons cells. This is for internal (C++) use only. This property contains the grobs which are still busy (e.g. note heads, spanners, etc.).

>   This engraver creates the following layout object(s):

>   RestCollision.

> `Script_row_engraver`

>   Determine order in horizontal side position elements.

>   This engraver creates the following layout object(s):

>   ScriptRow.

> `Separating_line_group_engraver`

>   Generate objects for computing spacing parameters.

>   Properties (read)

>   > `createSpacing` (boolean)

>   >   Create `StaffSpacing` objects? Should be set for staves.

>   Properties (write)

>   > `hasStaffSpacing` (boolean)

>   >   True if the current `CommandColumn` contains items that will affect spacing.

>   This engraver creates the following layout object(s):

>   StaffSpacing.

> `Staff_collecting_engraver`

>   Maintain the `stavesFound` variable.

>   Properties (read)

>   > `stavesFound` (list of grobs)

>   >   A list of all staff-symbols found.

>   Properties (write)

>   > `stavesFound` (list of grobs)

>   >   A list of all staff-symbols found.

> `Staff_symbol_engraver`

>   Create the constellation of five (default) staff lines.

>   Music types accepted:

>   staff-span-event

>   This engraver creates the following layout object(s):

>   StaffSymbol.

> `Time_signature_engraver`

>   Create a TimeSignature whenever `timeSignatureFraction` changes.

>   Properties (read)

>   > `implicitTimeSignatureVisibility` (vector)

>   >   break visibility for the default time signature.

>   > `timeSignatureFraction` (pair of numbers)

>   >   A pair of numbers, signifying the time signature. For example, `#'(4 . 4)` is a 4/4 time signature.

>   This engraver creates the following layout object(s):

>   TimeSignature.

#### Internals Reference