@node Introduction
@chapter Introduction
-There are a lot of programs that let you print sheet music with a
-computer. Unfortunately, most of them do not do good job. If you
-regularly from both recent and old music, you can probably agree with
-us on that. Most computer printouts have a bland, mechanical look,
-and are unpleasant to play from. Musicians are usually more absorbed
-with performing the music than with studying its looks, so they
-usually cannot pinpoint what exactly is so disconcerting about
-computer prints.
-
-However, it only takes a little attention to see for yourself what is
-what the differences are. The procedure is easy. Find two editions of
-the same piece, an old edition a reputable publishing house, and one
-which is formatted with a computer. If you are unsure, both can be
-told apart easily. Traditional hand-work has slight variations in
-symbol placements, while computer programs repeat all their errors in
-placement with iron rigidity. To illustrate this, we show two scanned
-fragments of the same piece, the first Cello Suite by Johann Sebastian
-Bach. The top one was hand made (published in 1950 by
-B@"{a}renreiter), while the bottom one was computer made (published in
-2000 by Henle).
-
-@ignore
+[TODO: should have introduction of introduction]
+
+The art of music typography is called @emph{(plate) engraving}. The
+term derives from the traditional process of music printing. Only a
+few decades ago, sheet music was made by cutting and stamping the
+music into zinc or pewter plates in mirror image. The plate would be
+inked, and the depressions caused by the cutting and stamping would
+hold ink. An image was formed by pressing paper to the plate. The
+stamping and cutting was completely done by hand. Making corrections
+was cumbersome, so engraving had to be done correctly in one go. Of
+course, this was a highly specialized skill, and a craftsman had to
+complete around 10 years of practical training before he could be a
+master engraver.
+
+
+Nowadays, all newly printed music is produced on computers. This has
+obvious advantages: prints are cheaper to make, and editorial work can
+be done over e-mail. Unfortunately, the pervasive use of computers has
+also decreased the graphical quality of scores. Computer printouts
+have a bland, mechanical look, which makes them unpleasant to play
+from.
+
+The images below illustrate the difference between traditional
+engraving and typical computer output, and the third picture shows how
+LilyPond mimicks the traditional look. The left picture shows a scan
+of a flat symbol from a Henle edition published in 2000. In the center
+show symbol from a hand engraved B@"{a}renreiter edition of the same
+music. The left scan illustrates typical flaws of computer print: the
+staff line are thin, the weight of the symbol matches the light lines,
+and the glyph has a straight layout with sharp corners. By contrast,
+the B@"{a}renreiter has a bold and almost voluptuous rounded look.
+Our flat symbol is designed after, among others, this one. It is
+rounded, and its weight harmonizes with the thickness of our staff
+lines, which are also much thicker than Henle's lines.
+
+@multitable @columnfractions .1 .3 .3 .3
+@item @tab
+@ifnotinfo
@iftex
-@image{baer-suite1-line,15cm}
-
-@image{henle-suite1-line,15.3cm}
+@image{henle-flat-bw,4cm}
@end iftex
+@ifnottex
+@image{henle-flat-bw,,,png}
+@end ifnottex
-@ifhtml
-@html
-<img src="baer-suite1-line.png">
-<p>
-<img src="henle-suite1-line.png">
-<p>
-@end html
-@end ifhtml
-@end ignore
+@tab
+@iftex
+@image{baer-flat-bw,4cm}
+@end iftex
+@ifnottex
+@image{baer-flat-bw,,,png}
+@end ifnottex
+@tab
+@iftex
+@image{lily-flat-bw,4cm}
+@end iftex
+@ifnottex
+@image{lily-flat-bw,,,png}
+@end ifnottex
+@end ifnotinfo
+@ifinfo
+@c workaround for makeinfo-4.6: line breaks and multi-column cookies
+@image{henle-flat-bw,,,png} @image{baer-flat-bw,,,png} @image{lily-flat-bw,,,png}
+@end ifinfo
-The fragments come from different editions, so there are some
-editorial differences regarding the slurs. However, we want to compare
-the typography of both. We can see that the Henle edition looks
-mechanical. This is caused by lack of variation in the spacing: the
-note heads in both systems are on the same horizontal positions, as is
-the bar line. A second difference is in the blackness of the page: the
-B@"{a}renreiter has a stronger look, simply because it uses a heavier
-font, and thicker staff lines. In the printed editions, the Henle
-version is 7 mm wider (approximately 4 %). Often, this difference is
-larger: computer scores tend to be spaced very widely, thus putting
-less information on a page, on average. Besides these global
-characteristics, software also make errors in the details. Beams
-should normally completely cover staff lines. In this case, the
-programmers have tried to do so, but forgot to take into account the
-thickness of the staff lines. The result is that the endings of all
-sloped beams are wedge-formed. The effect is subtle, it may not show
-up in this reproduction due to limits of the resolution, but it is
-certainly noticeable in the original.
+@item @tab
+Henle (2000)
+@tab
+B@"{a}renreiter (1950)
+@tab
+LilyPond Feta font (2003)
-Looking at such detail to the formatting of a score certainly is
-nitpicky. However, all these details serve a purpose, and that is to
-help the musician perform better: variation in spacing give each line
-a unique, which helps you remember where you are when you look
-away. Boldly print notes stand out more clearly when viewed from a
-distance. Tightly spaced scores take up less pages, which reduces the
-frequency of page turns. Correctly formatted beams and slurs indicate
-the direction of music, and without distracting the reader with
-unnecessary clusters of ink. Clearly, good music typography is
-desirable.
+@end multitable
-What is wrong with other computer printed scores?
-What is engraving?
+@cindex musical symbols
+@cindex font
+@cindex blackness
+@cindex balance
-Music notation vs. Engraving. (vs. composing)
+In spacing, the distribution of space should reflect the durations
+between notes. However, many modern scores adhere to the durations
+with mathematical precision, and that leads to a poor result. In the
+next example, a motive is printed twice. It is printed using exact
+mathematical spacing, and with some corrections. Can you spot which
+fragment is which?
-Why do you care about engraving?
+@cindex optical spacing
+@lilypond[noindent]
+ \score { \notes {
+ \override Staff.NoteSpacing #'stem-spacing-correction
+ = #0.6
+ c'4 e''4 e'4 b'4 |
+ \stemDown b'4 e''4 a'4 e''4| \stemBoth
+ \bar "||"
+ \override Staff.NoteSpacing #'stem-spacing-correction
+ = #0.0
+ \override Staff.StaffSpacing #'stem-spacing-correction
+ = #0.0
+ c'4 e''4 e'4 b'4 |
+ \stemDown b'4 e''4 a'4 e''4|
+ }
+ \paper { raggedright = ##t } }
+@end lilypond
-Why would I care about engraving?
+@cindex regular rhythms
+@cindex regular spacing
-You say your program is special; you must be trying to sell it?
+The fragment only uses quarter notes: notes that are played in a
+constant rhythm. The spacing should reflect that. Unfortunately, the
+eye deceives us a little: not only does it notice the distance between
+note heads, it also takes into account the distance between
+consecutive stems. As a result, the notes of an up-stem/down-stem
+combination should be put farther apart, and the notes of a down-up
+combination should be put closer together, all depending on the
+combined vertical positions of the notes. The first two measures are
+printed with this correction, the last two measures without. The notes
+in the last two measures form down-stem/up-stem clumps of notes.
-Freedom
+@cindex typography
-Preserving/reinventing the art of engraving
+Musicians are usually more absorbed with performing the music than
+with studying its looks, so this nitpicking about typographical
+details may seem academical. That is not justified. In larger pieces
+with monotonous rhythms, spacing corrections lead to subtle variations
+in the layout of every line, giving each one a distinct visual
+signature. Without this signature, all lines would look the same, they
+become like a labyrinth. If the musician looks away once or has a
+lapse in his concentration, he will be lost on the page.
+
+Similarly, the strong visual look of bold symbols on heavy staff lines
+stands out better when music is far away from reader, for example, if
+it is on a music stand. A careful distribution of white space allows
+music to be set very tightly without cluttering symbols together. The
+result minimizes the number of page turns,
+
+This is a common characteristic of typography. Layout should be
+pretty, not only for its own sake, but especially because it helps the
+reader in his task. For performance material like sheet music, this is
+doubly important: musicians have a limited amount of attention. The
+less attention they need for reading, the more they can focus on
+playing itself. In other words, better typography translates to better
+performances.
+
+Hopefully, these examples also demonstrate that music typography is an
+art that is subtle and complex, and to produce it requires
+considerable expertise, which musicians usually do not have. LilyPond
+is our effort to bring the graphical excellence of hand-engraved music
+to the computer age, and make it available to normal musicians. We
+have tuned our algorithms, font-designs, and program settings to
+produce prints that match the quality of the old editions we love to
+see and love to play from.
-Typography in LilyPond.
-Input format. Issue is overrated.
+@menu
+* Automated engraving::
+* What symbols to engrave?::
+* Music representation::
+* Example applications::
+* About this manual::
+@end menu
+@node Automated engraving
+@section Automated engraving
+How do we go about implementing typography? If craftsmen need over
+ten years to become true masters, how could we simple hackers ever
+write a program to take over their jobs?
-************
+The answer is: we cannot. Typography relies on human judgement of
+appearance, so people cannot be replaced ultimately. However, much of
+the dull work can be automated. If LilyPond solves most of the common
+situations correctly, then this will be a huge improvement over
+existing software. The remaining cases can be tuned by hand. Over the
+course of years, the software can be refined to do more and more
+automatically, so manual overrides are less and less necessary.
+When we started, we wrote the program in C++. With this design, the
+program functionality was set in stone stone by us developers. That
+proved to be unsatisfactory:
-LilyPond is a program to print sheet music. If you have used notation
-programs before, then the way to use this program might be surprising
-at first sight: in order to print music you have to enter musical
-codes in a file. Then you run the program on the file, and the music
-is produced without any further intervention. For example, something
-like this:
+@itemize @bullet
+@item When LilyPond makes mistakes,
+ users need to override formatting decisions. Therefore, the user
+must access to the formatting engine. Hence, rules and settings cannot
+be fixed by us at compile time, but they must be accessible for users
+at run-time.
+
+@item Engraving is a matter of visual judgement, and therefore a matter of
+taste. As knowledgeable as we are, users can disagree with our
+personal decisions. Therefore, the definitions of typographical style
+must also be accessible to the user.
+
+@item Finally, we continually refine the formatting algorithms, so we
+need a flexible approach to rules. The C++ language forces a certain
+method of grouping rules that do not match well with how music
+notation works.
-@lilypond[fragment,verbatim, relative 1, intertext="produces this:
+@end itemize
-"]
-\key c \minor r8 c16 b c8 g as c16 b c8 d | g,4
+The formatting architecture of LilyPond addresses these needs. It is
+built around the notion graphical objects, carrying variables. The
+architecture encompasses formatting rules, typographical style and
+individual formatting decisions.
+
+Variables control layout decisions. For example, many objects have a
+direction variable that encodes the choice between up and down (or
+left and right). Here you see two chords, with accents and
+arpeggio. In the first chord, the objects have all directions down (or
+left). The second chord has all directions up (right).
+
+@lilypond[raggedright,relative=1]
+\new Score \with {
+ \override SpacingSpanner #'spacing-increment = #3
+ \override TimeSignature #'transparent = ##t
+} {
+ \stemDown
+ <e g b>4_>-\arpeggio
+
+ \override Arpeggio #'direction = #RIGHT
+ \stemUp
+ <e g b>4^>-\arpeggio
+}
@end lilypond
-@cindex encoding music
+The process of formatting a score consists of reading and
+writing object variables.
-Encoding music using letters and digits may appear strange,
-intimidating or even clumsy at first. Nevertheless, when you take the
-effort to learn the codes and the program you will find that it is
-easier than it seems. Entering music can be done quickly, and you
-never have to remember how you made the program do something
-complicated: it is all in the input code, and you only have to read
-the file to see how it works. Moreover, you are rewarded with very
-nicely looking output.
+Some variables have a preset value. For example, the thickness of many
+lines ---a characteristic of typographical style--are preset
+variables. Changing them gives a different typographical impression:
-In this chapter, we will explain the reasoning behind this unusual
-design, and how this approach affects you as a user.
+@lilypond[]
+frag= \notes {
+ \clef bass f8 as8
+ c'4-~ c'16 as g f e16 g bes c' des'4
+ }
+\paper { raggedright = ##t }
+\score {
+<< \new Staff \frag
+ \new Staff \with {
+ \override Beam #'thickness = #0.3
+ \override Stem #'thickness = #0.5
+ \override Bar #'thickness = #3.6
+ \override Tie #'thickness = #2.2
+ \override StaffSymbol #'thickness = #3.0
+ \override Tie #'extra-offset = #'(0 . 0.3)
+ } \frag
+ >>
+}
+@end lilypond
+Formatting rules are also preset variables: each object has variables
+containing procedures. These procedure perform the actual formatting,
+and by substituting different ones, we can change behavior. In the
+following example, the rule that note head objects use to produce
+their symbol is changed during the music fragment:
-@menu
-* Music engraving::
-* Computerized typography::
-* Music representation::
-* Example applications::
-* About this manual::
-@end menu
-@node Music engraving
-@section Music engraving
+@lilypond[raggedright]
+#(define (mc-squared gr org cur)
+ (let*
+ ((ifs (ly:grob-property gr 'interfaces))
+ (sp (ly:grob-property gr 'staff-position)) )
+ (if (and (memq 'note-head-interface ifs)
+ (memq sp '(-2 -3 -5)))
+ (begin
+ (ly:grob-set-property! gr 'print-function brew-new-markup-stencil)
+ (ly:grob-set-property! gr 'font-family 'roman)
+ (ly:grob-set-property!
+ gr 'text
+ (make-raise-markup -0.5
+ (case sp
+ ((-5) (make-simple-markup "m"))
+ ((-3) (make-simple-markup "c "))
+ ((-2) (make-smaller-markup (make-bold-markup "2")))
+ (else (make-simple-markup "bla"))
+ ))))
+ )))
+
+\score {
+ \notes \context Voice \relative c'
+ {
+ \stemUp
+ \set autoBeaming = ##f
+ \time 2/4
+ { <d f g>4
+ \once \override NoteHead #'print-function
+ = #Note_head::brew_ez_stencil
+ <d f g>
+ \once \override NoteHead #'style
+ = #'cross
+ <d f g>
+ \applyoutput #mc-squared
+ <d f g>
+ << { d8[ es-( fis^^ g] fis2-) }
+ \repeat unfold 5 { \applyoutput #mc-squared s8 } >>
+
+ }
+
+ }
+}
+@end lilypond
+
+@node What symbols to engrave?
+@section What symbols to engrave?
@cindex engraving
@cindex typography
-Making sheet music may seem trivial at first (``you print 5 lines, and
-then put in the notes at different heights''),
-
-
-Hier over notatie.
-
-@emph{music engraving}, i.e. professional music typography, is in
-another ballpark. The term `music engraving' derives from the
-traditional process of music printing. Only a few decades ago, sheet
-music was made by cutting and stamping the music into zinc or pewter
-plates, mirrored. The plate would be inked, and the depressions caused
-by the cutting and stamping would hold ink. An image was formed by
-pressing paper to the plate. Stamping and cutting was completely done
-by hand. Making corrections was cumbersome, so engraving had to be
-done correctly in one go. As you can imagine this was a highly
-specialized skill, much more so than the traditional process of
-printing books.
-@cindex craftsmanship
-@cindex master
-In the traditional German craftsmanship six years of full-time
-training, more than any other craft, were required before a student
-could call himself a master of the art. After that many more years of
-practical experience were needed to become an established music
-engraver. Even today, with the use of high-speed computers and
-advanced software, music requires lots of manual fine tuning before it
-is acceptable for publication.
-
-When we wanted to write a computer program to create music typography,
-we encountered the first problem: there were no sets of musical
-symbols available: either they were not available freely, or they did
-not look well to our taste. Not let down, we decided to try font
-design ourselves. We created a font of musical symbols, relying on
-nice printouts of hand-engraved music. The experience helped develop
-a typographical taste, and it made us appreciate subtle design
-details. Without that experience, we would not have realized the
-shortcomings of the fonts were that we admired at first.
+The formatting process in LilyPond decides where to place
+symbols. However, this can only be done once it is decided @emph{what}
+symbols should be printed, in other words what notation to use.
+
+Common music notation is a system of recording music that has evolved
+over the past 1000 years. The form that is now in common use, dates
+from the early renaissance. Although, the basic form (i.e. note heads on a
+5-line staff) has not changed, the details still change to express the
+innovations of contemporary notation. Hence, it encompasses some 500
+years of music. Its applications range from monophonic melodies to
+monstrous counterpoint for large orchestras.
+
+How can we get a grip on such a many-headed beast, and force it into
+the confines of a computer program? We have broken up the problem of
+notation (as opposed to engraving, i.e. typography) into digestible
+and programmable chunks: every type of symbol is handled by a separate
+module, a so-called plug-in. Each plug-in is completely modular and
+independent, so each can be developed and improved separately. People
+that translate musical ideas to graphic symbols are called copyists or
+engravers, so by analogy, each plug-in is called @code{engraver}.
+
+In the following example, we see how we start out with a plug-in for
+note heads, the @code{Note_heads_engraver}.
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Stem_engraver"
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Clef_engraver"
+ \remove "Bar_engraver"
+ \remove "Time_signature_engraver"
+ \remove "Staff_symbol_engraver"
+ \consists "Pitch_squash_engraver"
+ }
+
+}
+}
+@end lilypond
+Then a @code{Staff_symbol_engraver} adds the staff:
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Stem_engraver"
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Clef_engraver"
+ \remove "Bar_engraver"
+ \consists "Pitch_squash_engraver"
+ \remove "Time_signature_engraver"
+ }
+
+}
+}
+@end lilypond
-@lilypond[noindent]
-#(define magfact 3.0)
-\score { \notes { as'2 r4 }
- \paper {
- raggedright = ##t
- \translator {
- \ScoreContext
- AccidentalPlacement \override #'right-padding = #3.0
- StaffSymbol \override #'transparent = ##t
- Clef \override #'transparent = ##t
- TimeSignature \override #'transparent = ##t
- Accidental \override #'font-magnification = #magfact
- Rest \override #'font-magnification = #magfact
- NoteHead \override #'font-magnification = #magfact
- Stem \override #'transparent = ##t
- } } }
+ The @code{Clef_engraver} defines a reference point for the staff:
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Stem_engraver"
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Bar_engraver"
+ \remove "Time_signature_engraver"
+ }
+
+}
+}
@end lilypond
-@cindex musical symbols
-@cindex font
-@cindex blackness
-@cindex balance
+And the @code{Stem_engraver} adds stems:
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Bar_engraver"
+ \remove "Time_signature_engraver"
+ }
+}
+}
+@end lilypond
+The @code{Stem_engraver} is notified of any note head coming along.
+Every time one (or more, for a chord) note head is seen, a stem
+object is created and connected to the note head.
-The figure above shows a few notable glyphs. For example, the
-vertical stem of the flat symbol should be brushed slightly,
-i.e. becoming wider at the top. the half-notehead is not elliptic but
-slightly diamond shaped. Fine endings, such as the one on the bottom
-of the quarter rest, should not end in sharp points, but rather in
-rounded shapes. Taken together, the blackness of the font must be
-carefully tuned together with the thickness of lines, beams and slurs
-to give a strong yet balanced overall impression.
+By adding engravers for beams, slurs, accents, accidentals, bar lines,
+time signature, and key signature, we get a complete piece of
+notation.
-Producing a strong and balanced look is the real challenge of music
-engraving. It is a recurring theme with many variations. In spacing,
-strength and balance are in layout that is `heavy' enough---without
-big gaps of space--- and without big clusters of black. The
-distribution of space should reflect the character of the music.
+@lilypond[]
+\include "engraver-example.lyinc"
-Spacing is an example of a subtlety of formatting music. The distances
-between notes should reflect the durations between notes, but adhering
-with mathematical precision to the duration will lead to a poor
-result. Shown here is an example of a motive, printed twice. It is
-printed using exact mathematical spacing, and with some
-corrections. Can you spot which fragment is which?
+\score { \topVoice }
+@end lilypond
-@cindex optical spacing
-@lilypond[noindent]
- \score { \notes {
- \property Staff.NoteSpacing \set #'stem-spacing-correction
- = #0.6
- c'4 e''4 e'4 b'4 |
- \stemDown b'4 e''4 a'4 e''4| \stemBoth
- \property Staff.NoteSpacing \override #'stem-spacing-correction
- = #0.0
- \property Staff.StaffSpacing \override #'stem-spacing-correction
- = #0.0
- c'4 e''4 e'4 b'4 |
- \stemDown b'4 e''4 a'4 e''4|
- }
- \paper { raggedright = ##t } }
-@end lilypond
-@cindex regular rhythms
-@cindex regular spacing
+This system works well for monophonic music, but what about
+polyphony? In polyphonic notation, many voices can share a staff.
-The fragment that was printed uses only quarter notes: notes that are
-played in a constant rhythm. The spacing should reflect
-that. Unfortunately, the eye deceives us a little: the eye not only
-notices the distance between note heads, but also between consecutive
-stems. As a result, the notes of a up-stem/down-stem combination
-should be put farther apart, and the notes of a down-up combination
-should be put closer together, all depending on the combined vertical
-positions of the notes. The first two measures are printed with this
-correction, the last two measures without. The notes in the last two
-measures form down-stem/up-stems clumps of notes.
-
-@node Computerized typography
-@section Computerized typography
-
-The example in the previous section is one illustration of how subtle
-music engraving can be is a subtle. Producing good engraving requires
-skill and knowledge.
-
-
-It was our challenge to see if we could put typographical knowledge
-into a computer program. Capturing that knowledge has two aspects:
-first, it has to be acquired. Then, it has to be encoded in
-data-structures and algorithms. As the previous example shows, there
-is a lot of subtlety involved in music engraving, and unfortunately,
-only a small fraction of these tiny details are documented.
-
-One reason for the time that it takes to become a master engraver, is
-that all these details must be learned either from experience or from
-other engravers: as an engraver gets older and wiser, he will be able
-to produce better and more complex pieces. A similar situation is
-present when putting typography into computer programs. It is not
-possible to come up with a final solution for a problem at the first
-try. Instead, we start out with simple solution that might cover 75%
-of the cases, and gradually refine that solution over the course of
-months or years, so that 90 or 95 % of the cases are handled.
-
-This has an important implication for the design of the
-program. During development, almost every piece of formatting code
-must be considered as temporary. When the need arises, is to be
-replaced a solution that will cover even more cases. A clean way to
-accomplish this, is a ``plug-in'' architecture: an architecture where
-new pieces of code can be inserted in the program dynamically. In
-such a program, a new solution can be developed along-side the
-existing code. It can be perfected separately until it is better than
-the existing solution, at which point, the new solution is switched on
-by default, and the old one is removed.
-
-Until that time, users must have a way to deal with imperfections:
-these 25%, 10% or 5% of the cases that are not handled
-automatically. In these cases, a user must be able to override
-formatting decisions. A way to accomplish this, is to store decisions
-in generic variables, and let the user manipulate these variables.
-For example, consider the following fragment of notation.
-
-@lilypond
-\score { \notes {
- g'4-\f g4
- }
-\paper { raggedright = ##t }
- }
+@lilypond[]
+\include "engraver-example.lyinc"
+\score { \context Staff << \topVoice \\ \botVoice >> }
@end lilypond
-@noindent
-The position of the forte symbol is slightly awkward, because it is
-next to the low note, whereas dynamics should be below notes in
-general. This may be remedied by inserting extra space between the
-high note and the `f', as shown in this example
-
-@lilypond
-\score { \notes {
- \once\property Voice. DynamicLineSpanner \override #'padding = #4.0
- g'4-\f g4
- }
-\paper { raggedright = ##t }
- }
+In this situation, the accidentals and staff are shared, but the
+stems, slurs, beams, etc. are private to each voice. Hence, engravers
+should be grouped. The engravers for note heads, stems, slurs, etc. go
+into a group called ``Voice context,'' while the engravers for key,
+accidental, bar, etc. go into a group called ``Staff context.'' In the
+case of polyphony, a single Staff context contains more than one Voice
+context. In polyphonic notation, many voices can share a staff:
+Similarly, more Staff contexts can be put into a single Score context.
+
+@lilypond[]
+\include "engraver-example.lyinc"
+\score {
+<< \new Staff << \topVoice \\ \botVoice >>
+\new Staff << \pah \\ \hoom >>
+ >>
+}
@end lilypond
-This was achieved with the input statement
-@example
- \property Voice. DynamicLineSpanner \override #'padding = #4.0
-@end example
-which increases the amount of space (@code{padding}) between the note
-and the dynamic symbol to 4.0 (which is measured in staff space, so
-4.0 equals the height of a staff).
-
-Both design aspects, a plug-in architecture, and formatting variables,
-are built on top of GUILE, an interpreter for the programming language
-Scheme, which is a member of the LISP family. Variables are stored as
-Scheme objects, and attached to graphical objects such as note heads
-and stems. The variables are a means to adjust formatting details in
-individual cases, but they are used in a more general manner.
-
-Consider the case of a publisher that is not satisfied with the in the
-default layout, and wants heavier stems. Normally, they are @code{1.3}
-times the thickness of staff lines, but suppose that their editions
-require them to be twice the thickness of the staff lines. The same
-mechanism can be used to adjust a setting globally. By issuing
+@node Music representation
+@section Music representation
+
+Ideally, the input format for any high-level formatting system is an
+abstract description of the content. In this case, that would be the
+music itself. This poses a formidable problem: how can we define what
+music really is? Instead of trying to find an answer, we have reversed
+the question. We write a program capable of producing sheet music,
+and adjust the format to be as lean as possible. When the format can
+no longer be trimmed down, by definition we are left with content
+itself. Our program serves as a formal definition of a music
+document.
+
+
+The syntax is also the user-interface for LilyPond, hence it is easily typable, e.g.,
@example
- \property Score.Stem \override #'thickness = #2.0
+ c'4 d'8
@end example
-the entire piece is formatted with thick stems:
-@lilypond
-\score { \notes {
- \property Score.Stem \override #'thickness = #2.0
- \once\property Voice. DynamicLineSpanner \override #'padding = #4.0
- g'4-\f g4
- }
-\paper { raggedright = ##t }
- }
+Are a quarter note C (the middle C) and eighth note D1 (the D above
+middle C), as in this example:
+
+@lilypond[fragment]
+ c'4 d'8
@end lilypond
-@noindent
-In effect, by setting these variables, users can define their own
-layout styles.
-
-``Plug-ins'' are also implemented using Scheme. A formatting
-``plug-in'' takes the form of a function written in Scheme (or a C++
-function made available as a Scheme function), and it is also stored
-in a variable. For example, the placement of the forte symbol in the
-example above is calculated by the function
-@code{Side_position_interface::aligned_side}. If we want to replace
-this function by a more advanced one, we could issue
-@example
- \property Voice.DynamicLineSpanner \override #'Y-offset-callbacks
- = #`(,gee-whiz-gadget)
-@end example
+On a microscopic scale, such syntax is easy to use. On a larger scale,
+syntax also needs structure. How else can you enter complex pieces
+like symphonies and operas? The structure is formed by the concept of
+music expressions: by combining small fragments of music into larger
+ones, more complex music can be expressed. For example,
-@noindent
-Now, the formatting process will trigger a call to our new
-@code{gee-whiz-gadget} function when the position of the f symbol has
-to be determined.
+@lilypond[verbatim,fragment,relative=1]
+c4
+@end lilypond
-The full scope of this functionality certainly is intimidating, but
-there is no need to fear: normally, it is not necessary to define
-style-sheets or rewrite formatting functions. In fact, LilyPond gets a
-lot of formatting right automatically, so adjusting individual layout
-situations is not needed very often at all.
+Combine this simultaneously with two other notes by enclosing in << and >>.
-@node Music representation
-@section Music representation
+@lilypond[verbatim,fragment,relative=1]
+ <<c4 d4 e4>>
+@end lilypond
-One of the big questions when writing batch programs, is what kind of
-input the program should expect. Many music notation programs offer a
-graphical interface that shows notation, and allow you to enter the
-music by placing notes on a staff. From our point of view, this design
-is a form of cheating. After all, the core message of a piece of music
-notation simply is the music itself. If you start by offering notation
-to the user, you have already skipped one conversion, even if it is
-implicit. If we want to generate music notation from something else,
-then the obvious candidate for the source is the music itself.
-
-On paper this theory sounds very good. In practice, it opens a can of
-worms. What really @emph{is} music? Many philosophical treatises must
-have been written on the subject. Instead of losing ourselves in
-philosophical arguments over the essence of music, we have reversed
-the question to yield a more practical approach. Our assumption is
-that the printed score contains all of the music of piece. We build a
-program that uses some input format to produce such a score. Over the
-course of time, the program evolves. While this happens, we can remove
-more and more elements of the input format: as the program improves,
-it can fill in irrelevant details of the input by itself. At some
-(hypothetical) point, the program is finished: there is no possibility
-to remove any more elements from the syntax. What we have left is by
-definition exactly the musical meaning of the score.
-
-There are also more practical concerns. Our users have to key in the
-music into the file directly, so the input format should have a
-friendly syntax. As programmers and scientists, we want a
-clean formal definition. After all, producing music notation is a
-difficult problem, and in the scientific world, problems can only be
-solved if they are well-specified. Moreover, formally defined formats
-are easier to write programs for.
-
-These ideas shaped our music representation: it is a compact format
-that can easily be typed by hand. It complex musical constructs from
-simple entities like notes and rests, in much the same way that one
-builds complex formulas from simple expressions such as numbers and
-mathematical operators.
+
+This expression is put in sequence by enclosing it in braces, i.e.,
+
+@verbatim
+ { <<c4 d4 e4>> f4 }
+@end verbatim
+
+@lilypond[relative=1]
+ \new Voice { <<c4 d4 e4>> f4 }
+@end lilypond
+
+The above is another expression, and therefore, it many combined again
+with a simultaneous expression (in this case, a half note).
+
+@verbatim
+ << { <<c4 d4 e4>> f4 } g2 >>
+@end verbatim
+@lilypond[fragment,relative=1]
+<< g2 \\ { <c d e>4 f4 } >>
+@end lilypond
+
+
+Such recursive structures can be specified neatly and formally in a
+context-free grammar. The parsing code is also generated from this
+grammar. In other words, the syntax of LilyPond is clearly and
+unambiguously defined.
+
+User-interfaces and syntax are what people see and deal with
+most. They are partly a matter of taste, and also subject of much
+discussion. Although discussions on taste do have their merit, they
+are not very productive. In the larger picture of LilyPond, the
+importance of input syntax is small: inventing neat syntax is easy,
+writing decent formatting code is much harder. This is also
+illustrated by the line-counts for the respective components: parsing
+and representation take up less than 10% of the code.
+
@node Example applications
@section Example applications
-As programmers and hedonists we enjoy beauty in code, and code that
-produces beautiful typeset music, but nevertheless this program can
-applied to do useful things. In this section, we show a few small
-examples of what is possible.
-
-The simplest application is printing notes.
+We have written LilyPond as an experiment of how to condense the art
+of music engraving into a computer program. Thanks to all that hard
+work, the program can now be used to perform useful tasks. The
+simplest application is printing notes:
@lilypond[relative=1]
\time 2/4 c4 c g'4 g a4 a g2
@end lilypond
-To these notes, chord names and lyrics may be added, yielding
-a lead sheet.
+By adding chord names and lyrics we obtain a lead sheet:
@lilypond[raggedright]
-\score { <
+\score { <<
\context ChordNames \chords { c2 c f2 c }
- \notes \relative c' { \time 2/4 c4 c g'4 g a4 a g2 }
- \context Lyrics \lyrics { twin4 kle twin kle lit tle star2 } > }
+ \new Staff \notes \relative c' { \time 2/4 c4 c g'4 g a4 a g2 }
+ \context Lyrics \lyrics { twin4 kle twin kle lit tle star2 } >> }
@end lilypond
-The following example combines some more exotic uses of notation
+Polyphonic notation and piano music can also be printed. The following
+example combines some more exotic constructs:
@lilypondfile{screech-boink.ly}
-The fragments shown above have all been written by hand, but that is not
-a requirement. Since the formatting engine is mostly automatic, it can
-serve as an output means for other programs that manipulate music. It
-can also be used to convert databases of musical fragments to images for
-use on websites on multimedia presentations.
+The fragments shown above have all been written by hand, but that is
+not a requirement. Since the formatting engine is mostly automatic, it
+can serve as an output means for other programs that manipulate
+music. For example, it can also be used to convert databases of
+musical fragments to images for use on websites and multimedia
+presentations.
This manual also shows an application: the input format is plain text,
and can therefore be easily embedded in other text-based formats, such
@node About this manual
@section About this manual
-The manual is divided into the following chapters
+The manual is divided into the following chapters:
@itemize @bullet
@item
@ifhtml The
@end ifhtml
@emph{@ref{Tutorial}}
-gives a gentle introduction into typesetting music.
+gives a gentle introduction to typesetting music.
First time users should start here.
@item
@ifhtml
The
@end ifhtml
@emph{@ref{Notation manual}}
-discusses topics grouped by notation construct.
+discusses topics grouped by notation construct. Once you master the
+basics, this is the place to look up details.
+@item
+@ifhtml
+The
+@end ifhtml
+@emph{@ref{Literature list}}
+ contains a set of useful reference books, for those who wish to know
+ more on notation and engraving.
@item
@ifhtml
The
@end ifhtml
@emph{@ref{Technical manual}}
@c
-discusses the general design of the program, and how to extend
+discusses the general design of the program, and how to extend its
functionality.
@item
@ifhtml
- The chapter
+The chapter
@end ifhtml
@emph{@ref{Invoking LilyPond}} explains how to run LilyPond and its helper
programs.
+
+@item
+@ifhtml
+The
+@end ifhtml
+@emph{@ref{lilypond-book manual}}
+explains the details behind creating documents with in-line music
+examples (like this manual).
+
+
+@item
+@ifhtml
+The chapter
+@end ifhtml
+@emph{@ref{Converting from other formats}}
+explains how to run the conversion programs. These programs
+are supplied with the LilyPond package, and convert a variety of music
+formats to the @code{.ly} format. In addition, this section explains
+how to upgrade input files from previous versions of LilyPond.
+
@end itemize
-Once you are experienced, you can simply use the manual as reference:
+Once you are an experienced user, you can use the manual as reference:
there is an extensive index@footnote{If you are looking for something,
-and you cannot find it by using the index, that is considered a bug.
-In that case, please file a bug report.}, but the document is also
+and you cannot find it in the manual, that is considered a bug. In
+that case, please file a bug report.}, but the document is also
available in
@ifnothtml
a big HTML page,
@cindex search in manual
@cindex using the manual
-@c TODO: advise to buy a book on notation?
-If you are not familiar with music notation, or music terminology
-(especially if you are a foreigner), then it is advisable to consult
-the glossary as well. The glossary explains musical terms, and
-includes translations to various languages. It is a
+If you are not familiar with music notation or music terminology
+(especially if you are a non-native English speaker), then it is
+advisable to consult the glossary as well. The glossary explains
+musical terms, and includes translations to various languages. It is a
@ifhtml
-@uref{../glossary.html,separate document}
+@uref{../music-glossary.html,separate document}.
@end ifhtml
@ifnothtml
-separate document, available in HTML and PDF and can be printed as
-well.
+separate document, available in HTML and PDF.
@end ifnothtml
@cindex idiom
@cindex jargon
This manual is not complete without a number of other documents. They
are not available in print, but should be included with the
-documentation package for your platform
+documentation package for your platform:
@itemize @bullet
@item
-Generated internal documentation.
+Program reference
@ifhtml
-available @uref{../lilypond-internals/lilypond-internals.html,here}
+(available @uref{../lilypond-internals/lilypond-internals.html,here})
@end ifhtml
+The program reference is a set of heavily cross linked HTML pages,
+which documents the nit-gritty details of each and every LilyPond
+class, object and function. It is produced directly from the
+formatting definitions used.
+
Almost all formatting functionality that is used internally, is
available directly to the user. For example, all variables that
control thicknesses, distances, etc, can be changed in input
-files. There are a huge number of formatting options, and it would be
-impossible to describe them all in a hand-written manual. The
-generated internal documentation is a heavily crosslinked HTML
-document, produced directly from the formatting definitions used. It
-documents the nit-gritty details of each and every LilyPond class, object and
-function.
-
-Each section of the reference manual has a @b{See also}
-subsection, with links (in the HTML document, at least) to the
-generated documentation.
+files. There are a huge number of formatting options, and all of them
+are described in the generated documentation. Each section of the
+notation manual has a @b{See also} subsection, which refers to the
+the generated documentation. In the HTML document, these subsections
+have clickable links.
@item
Templates
@ifhtml
-(available @uref{../../../input/templates/out-www/collated-files.html,here})
+(available @uref{../../../input/template/out-www/collated-files.html,here})
@end ifhtml
-When you have gone through the tutorial, in theory you are able to
-start writing input files. In practice, writing files from scratch
-turns out to be intimidating. To give a headstart, we have collected
-a number of often-used formats in example files. These files can be
-used as a start, by copying the template, and adding notes in the
-appropriate places.
+After you have gone through the tutorial, you should be able to write
+input files. In practice, writing files from scratch turns out to be
+intimidating. To give you a head start, we have collected a number of
+often-used formats in example files. These files can be used as a
+start: simply copy the template, and add notes in the appropriate
+places.
@item
Various input examples
@ifhtml
-available @uref{../../../input/test/out-www/collated-files.html,here}
+(available @uref{../../../../input/test/out-www/collated-files.html,here})
@end ifhtml
@cindex snippets
@item
- The regression test
+ The regression tests
@ifhtml
-available @uref{../../../input/regression/out-www/collated-files.html,here}
+(available @uref{../../../input/regression/out-www/collated-files.html,here})
@end ifhtml
-We strive to test each feature in one test file. This collection of is
-primarily to help us debug problems, but it can be instructive to see
-how we excercise the program. The format is like the input examples.
+This collection of files tests each notation and engraving feature of
+LilyPond in one file. The collection is primarily there to help us
+debug problems, but it can be instructive to see how we exercise the
+program. The format is like the tips and tricks document.
@end itemize
+In all HTML documents that have music fragments embedded, the LilyPond
+input that was used to produce that image can be viewed by clicking
+the image.
+
The location of the documentation files that are mentioned here can
vary from system to system. On occasion, this manual refers to
initialization and example files. Throughout this manual, we refer to
@cindex internal documentation
@cindex Scheme
@cindex extending lilypond
-@cindex bugreport
+@cindex bug report
@cindex index
Finally, this and all other manuals, are available online both as PDF
-files for print and HTML files for browsing. They are available from
-the web site, which can be found at @uref{http://www.lilypond.org/}.
+files and HTML from the web site, which can be found at
+@uref{http://www.lilypond.org/}.
@cindex website
@cindex URL
projects / lilypond.git / blobdiff