New spacing docs and editing to global.itely and page.itely. Other

[lilypond.git] / Documentation / user / page.itely

@c -*- coding: utf-8; mode: texinfo; -*-
@c This file is part of lilypond.tely

@c A menu is needed before every deeper *section nesting of @node's; run
@c     M-x texinfo-all-menus-update
@c to automatically fill in these menus before saving changes

@node Spacing issues
@chapter Spacing issues

The global paper layout is determined by three factors: the page layout, the
line breaks, and the spacing.  These all influence each other.  The
choice of spacing determines how densely each system of music is set.
This influences where line breaks are chosen, and thus ultimately, how
many pages a piece of music takes.

Globally spoken, this procedure happens in three steps: first,
flexible distances (``springs'') are chosen, based on durations.  All
possible line breaking combinations are tried, and the one with the
best results -- a layout that has uniform density and requires as
little stretching or cramping as possible -- is chosen.

After spacing and linebreaking, the systems are distributed across
pages, taking into account the size of the page, and the size of the
titles.

@menu
* Paper and pages::             
* Music layout::                
* Vertical spacing::            
* Horizontal spacing::          
* Breaks::                      
* Displaying spacing::          
@end menu


@node Paper and pages
@section Paper and pages

This section deals with the boundaries that define the area
that music can be printed inside.

@menu
* Paper size::                  
* Page formatting::             
@end menu


@node Paper size
@subsection Paper size

@cindex paper size
@cindex page size
@findex papersize

To change the paper size, there are two commands,
@example
#(set-default-paper-size "a4")
\paper @{
  #(set-paper-size "a4")
@}
@end example

The first command sets the size of all pages.  The second command sets the
size
of the pages that the @code{\paper} block applies to -- if the @code{\paper}
block is at the top of the file, then it will apply to all pages.  If the
@code{\paper} block is inside a @code{\book}, then the paper size will only
apply to that book.

Support for the following paper sizes are included by default,
@code{a6}, @code{a5}, @code{a4}, @code{a3}, @code{legal}, @code{letter},
@code{11x17} (also known as tabloid).

Extra sizes may be added by editing the definition for
@code{paper-alist} in the initialization file @file{scm/paper.scm}.

@cindex orientation
@cindex landscape

If the symbol @code{landscape} is supplied as an argument to
@code{set-default-paper-size}, the pages will be rotated by 90 degrees,
and wider line widths will be set correspondingly.

@example
#(set-default-paper-size "a6" 'landscape)
@end example

Setting the paper size will adjust a number of @code{\paper} variables
(such as margins).  To use a particular paper size with altered
@code{\paper} variables, set the paper size before setting the variables.


@node Page formatting
@subsection Page formatting

@cindex page formatting
@cindex margins
@cindex header, page
@cindex footer, page

LilyPond will do page layout, set margins, and add headers and
footers to each page.

The default layout responds to the following settings in the
@code{\paper} block.

@findex \paper

@quotation
@table @code
@findex first-page-number
@item first-page-number
The value of the page number of the first page.  Default is@tie{}1.

@findex printfirst-page-number
@item printfirst-page-number
If set to true, will print the page number in the first page.  Default is
false.

@findex print-page-number
@item print-page-number
If set to false, page numbers will not be printed.

@findex paper-width
@item paper-width
The width of the page.

@findex paper-height
@item paper-height
The height of the page.

@findex top-margin
@item top-margin
Margin between header and top of the page.

@findex bottom-margin
@item bottom-margin
Margin between footer and bottom of the page.

@findex left-margin
@item left-margin
Margin between the left side of the page and the beginning of the music.

@findex line-width
@item line-width
The length of the systems.

@findex head-separation
@item head-separation
Distance between the top-most music system and the page header.

@findex foot-separation
@item foot-separation
Distance between the bottom-most music system and the page footer.

@findex page-top-space
Distance from the top of the printable area to the center of the first
staff. This only works for staves which are vertically small. Big staves
are set with the top of their bounding box aligned to the top of the
printable area.

@findex ragged-bottom
@item ragged-bottom
If set to true, systems will not be spread vertically across the page.  This
does not affect the last page.

This should be set to true for pieces that have only two or three
systems per page, for example orchestral scores.

@findex ragged-last-bottom
@item ragged-last-bottom
If set to false, systems will be spread vertically to fill the last page.

Pieces that amply fill two pages or more should have this set to
true.

@findex system-count
@item system-count
This variable, if set, specifies into how many lines a score should be
broken.

@findex between-system-space
@item between-system-space
This dimensions determines the distance between systems.  It is the
ideal distance between the center of the bottom staff of one system
and the center of the top staff of the next system.

Increasing this will provide a more even appearance of the page at the
cost of using more vertical space.

@findex between-system-padding
@item between-system-padding
This dimension is the minimum amount of white space that will always
be present between the bottom-most symbol of one system, and the
top-most of the next system.

Increasing this will put systems whose bounding boxes almost touch
farther apart.


@findex horizontal-shift
@item horizontal-shift
All systems (including titles and system separators) are shifted by
this amount to the right. Page markup, such as headers and footers are
not affected by this. The purpose of this variable is to make space
for instrument names at the left.

@findex after-title-space
@item after-title-space
Amount of space between the title and the first system.

@findex after-title-space
@item before-title-space
Amount of space between the last system of the previous piece and the
title of the next.

@findex between-title-space
@item between-title-space
Amount of space between consecutive titles (e.g., the title of the
book and the title of a piece).

@findex printallheaders
@item printallheaders
Setting this to #t will print all headers for each \score in a
\book.  Normally only the piece and opus \headers are printed.

@findex systemSeparatorMarkup
@item systemSeparatorMarkup
This contains a markup object, which will be inserted between
systems.  This is often used for orchestral scores.

The markup command @code{\slashSeparator} is provided as a sensible
default,  for example

@lilypond[ragged-right]
\book {
  \score {
    \relative { c1 \break c1 }
  }
  \paper {
    systemSeparatorMarkup = \slashSeparator
  }
}
@end lilypond


@end table
@end quotation

Example:

@example
\paper@{
  paper-width = 2\cm
  top-margin = 3\cm
  bottom-margin = 3\cm
  ragged-last-bottom = ##t
@}
@end example

You can also define these values in Scheme.  In that case @code{mm},
@code{in}, @code{pt}, and @code{cm} are variables defined in
@file{paper-defaults.ly} with values in millimeters.  That is why the
value must be multiplied in the example

@example
\paper @{
  #(define bottom-margin (* 2 cm))
@}
@end example

The header and footer are created by the functions @code{make-footer}
and @code{make-header}, defined in @code{\paper}.  The default
implementations are in @file{ly/@/paper@/-defaults@/.ly} and
@file{ly/@/titling@/-init@/.ly}.

The page layout itself is done by two functions in the
@code{\paper} block, @code{page-music-height} and
@code{page-make-stencil}.  The former tells the line-breaking algorithm
how much space can be spent on a page, the latter creates the actual
page given the system to put on it.


@refbugs

The option right-margin is defined but doesn't set the right margin
yet.  The value for the right margin has to be defined adjusting the
values of @code{left-margin} and @code{line-width}.

The default page header puts the page number and the @code{instrument}
field from the @code{\header} block on a line.

The titles (from the @code{\header@{@}} section) are treated as a
system, so @code{ragged-bottom} and @code{ragged-last-bottom} will
add space between the titles and the first system of the score.


@node Music layout
@section Music layout

@menu
* Setting global staff size::   
* Score layout::                
@end menu


@node Setting global staff size
@subsection Setting global staff size

@cindex font size, setting
@cindex staff size, setting
@findex layout file

To set the global staff size, use @code{set-global-staff-size}.

@example
#(set-global-staff-size 14)
@end example

@noindent
This sets the global default size to 14pt staff height and scales all
fonts accordingly.

The Feta font provides musical symbols at eight different
sizes.  Each font is tuned for a different staff size: at a smaller size
the font becomes heavier, to match the relatively heavier staff lines.
The recommended font sizes are listed in the following table:

@quotation
@multitable @columnfractions .15 .2 .22 .2

@item @b{font name}
@tab @b{staff height (pt)}
@tab @b{staff height (mm)}
@tab @b{use}

@item feta11
@tab 11.22
@tab 3.9
@tab pocket scores

@item feta13
@tab 12.60
@tab 4.4
@tab

@item feta14
@tab 14.14
@tab 5.0
@tab

@item feta16
@tab 15.87
@tab 5.6
@tab

@item feta18
@tab 17.82
@tab 6.3
@tab song books

@item feta20
@tab 20
@tab 7.0
@tab standard parts

@item feta23
@tab 22.45
@tab 7.9
@tab

@item feta26
@tab 25.2
@tab 8.9
@tab
@c modern rental material?

@end multitable
@end quotation

These fonts are available in any sizes.  The context property
@code{fontSize} and the layout property @code{staff-space} (in
@internalsref{StaffSymbol}) can be used to tune the size for individual
staves.  The sizes of individual staves are relative to the global size.

@example

@end example

@seealso

This manual: @ref{Selecting notation font size}.


@node Score layout
@subsection Score layout

@findex \layout

While @code{\paper} contains settings that relate to the page formatting
of the whole document, @code{\layout} contains settings for score-specific
layout.

@example
\layout @{
  indent = 2.0\cm
  \context @{ \Staff
    \override VerticalAxisGroup #'minimum-Y-extent = #'(-6 . 6)
  @}
  \context @{ \Voice
    \override TextScript #'padding = #1.0
    \override Glissando #'thickness = #3
  @}
@}
@end example


@seealso

This manual: @ref{Changing context default settings}


@node Vertical spacing
@section Vertical spacing

@cindex vertical spacing

Vertical spacing is controlled by three things: the amount of
space available (i.e. paper size and margins), the amount of
space between systems, and the amount of space between
staves inside a system.

@menu
* Vertical spacing inside a system::  
* Vertical spacing of piano staves::  
* Vertical spacing between systems::  
* Controlling spacing of individual systems::  
@end menu


@node Vertical spacing inside a system
@subsection Vertical spacing inside a system

@cindex distance between staves
@cindex staff distance
@cindex space between staves
@cindex space inside systems

The height of each system is determined automatically.  To prevent
staves from bumping into each other, some minimum distances are set.
By changing these, you can put staves closer together.  This
reduces the amount of space each system requires, and may result
in having more systems per page.

Normally staves are stacked vertically.  To make staves maintain a
distance, their vertical size is padded.  This is done with the
property @code{minimum-Y-extent}.  When applied to a
@internalsref{VerticalAxisGroup}, it controls the size of a horizontal
line, such as a staff or a line of lyrics.  @code{minimum-Y-extent}
takes a pair of numbers, so
if you want to make it smaller than its default @code{#'(-4 . 4)}
then you could set

@example
\override Staff.VerticalAxisGroup #'minimum-Y-extent = #'(-3 . 3)
@end example

@noindent
This sets the vertical size of the current staff to 3 staff spaces on
either side of the center staff line.  The value @code{(-3 . 3)} is
interpreted as an interval, where the center line is the 0, so the
first number is generally negative.  The numbers need not match;
for example, the staff can be made larger at the bottom by setting
it to @code{(-6 . 4)}.


@seealso

Internals: Vertical alignment of staves is handled by the
@internalsref{VerticalAlignment} object. The context parameters
specifying the vertical extent are described in connection with
the @internalsref{Axis_group_engraver}.

Example files: @inputfileref{input/regression/,page-spacing.ly},
@inputfileref{input/regression/,alignment-vertical-spacing.ly}.


@node Vertical spacing of piano staves
@subsection Vertical spacing of piano staves

The distance between staves of a @internalsref{PianoStaff} cannot be
computed during formatting.  Rather, to make cross-staff beaming work
correctly, that distance has to be fixed beforehand.

The distance of staves in a @code{PianoStaff} is set with the
@code{forced-distance} property of the
@internalsref{VerticalAlignment} object, created in
@internalsref{PianoStaff}.

It can be adjusted as follows
@example
\new PianoStaff \with @{
  \override VerticalAlignment #'forced-distance = #7
@} @{
  ...
@}
@end example

@noindent
This would bring the staves together at a distance of 7 staff spaces,
measured from the center line of each staff.

The difference is demonstrated in the following example,
@lilypond[quote,verbatim]
\relative c'' <<
  \new PianoStaff \with {
    \override VerticalAlignment #'forced-distance = #7
  } <<
    \new Staff { c1 }
    \new Staff { c }
  >>
  \new PianoStaff <<
    \new Staff { c }
    \new Staff { c }
  >>
>>
@end lilypond


@seealso

Example files: @inputfileref{input/regression/,alignment-vertical-spacing.ly}.


@node Vertical spacing between systems
@subsection Vertical spacing between systems

Space between systems are controlled by four @code{\paper} variables,

@example
\paper @{
  between-system-space = 1.5\cm
  between-system-padding = #1
  ragged-bottom=##f
  ragged-last-bottom=##f
@}
@end example


@node Controlling spacing of individual systems
@subsection Controlling spacing of individual systems

It is also possible to change the distance between for each system
individually.  This is done by including the command

@example
\overrideProperty
#"Score.NonMusicalPaperColumn"
#'line-break-system-details
#'((fixed-alignment-extra-space . 15))
@end example

@noindent
at the line break before the system to be changed. The distance
@code{15} is distributed over all staves that have a fixed distance
alignment.  For example,

@lilypond[ragged-right, fragment, relative=2, staffsize=13]
\new PianoStaff <<
  \new Staff {
    c1\break
  
    \overrideProperty
    #"Score.NonMusicalPaperColumn"
    #'line-break-system-details
    #'((fixed-alignment-extra-space . 15))

    c\break
  }
  \new Staff { c c }
>>
@end lilypond

The distance for @code{fixed-alignment-extra-space} may also be
negative.



@node Horizontal spacing
@section Horizontal Spacing

@menu
* Horizontal Intro::            
* Line length::                 
@end menu


@node Horizontal Intro
@subsection Horizontal Intro

The spacing engine translates differences in durations into stretchable
distances (``springs'') of differring lengths.  Longer durations get
more space, shorter durations get less.  The shortest durations get a
fixed amount of space (which is controlled by
@code{shortest-duration-space} in the @internalsref{SpacingSpanner}
object).  The longer the duration, the more space it gets: doubling a
duration adds a fixed amount (this amount is controlled by
@code{spacing-increment}) of space to the note.

For example, the following piece contains lots of half, quarter, and
8th notes; the eighth note is followed by 1 note head width (NHW).
The quarter note is followed by 2 NHW, the half by 3 NHW, etc.

@lilypond[quote,fragment,verbatim,relative=1]
c2 c4. c8 c4. c8 c4. c8 c8
c8 c4 c4 c4
@end lilypond

Normally, @code{spacing-increment} is set to 1.2 staff space, which is
approximately the width of a note head, and
@code{shortest-duration-space} is set to 2.0, meaning that the
shortest note gets 2.4 staff space (2.0 times the
@code{spacing-increment}) of horizontal space.  This space is counted
from the left edge of the symbol, so the shortest notes are generally
followed by one NHW of space.

If one would follow the above procedure exactly, then adding a single
32nd note to a score that uses 8th and 16th notes, would widen up the
entire score a lot.  The shortest note is no longer a 16th, but a 32nd,
thus adding 1 NHW to every note.  To prevent this, the shortest
duration for spacing is not the shortest note in the score, but rather
the one which occurs most frequently.


The most common shortest duration is determined as follows: in every
measure, the shortest duration is determined.  The most common shortest
duration is taken as the basis for the spacing, with the stipulation
that this shortest duration should always be equal to or shorter than
an 8th note.  The shortest duration is printed when you run
@code{lilypond} with the @code{--verbose} option.

These durations may also be customized.  If you set the
@code{common-shortest-duration} in @internalsref{SpacingSpanner}, then
this sets the base duration for spacing.  The maximum duration for this
base (normally an 8th), is set through @code{base-shortest-duration}.

@findex common-shortest-duration
@findex base-shortest-duration
@findex stem-spacing-correction
@findex spacing

Notes that are even shorter than the common shortest note are
followed by a space that is proportional to their duration relative to
the common shortest note.  So if we were to add only a few 16th notes
to the example above, they would be followed by half a NHW:

@lilypond[quote,fragment,verbatim,relative=2]
c2 c4. c8 c4. c16[ c] c4. c8 c8 c8 c4 c4 c4
@end lilypond


In the introduction (see @ref{Engraving}), it was explained that stem
directions influence spacing.  This is controlled with the
@code{stem-spacing-correction} property in the
@internalsref{NoteSpacing}, object.  These are generated for every
@internalsref{Voice} context.  The @code{StaffSpacing} object
(generated in @internalsref{Staff} context) contains the same property
for controlling the stem/bar line spacing.  The following example shows
these corrections, once with default settings, and once with
exaggerated corrections:

@lilypond[quote,ragged-right]
{
  c'4 e''4 e'4 b'4 |
  b'4 e''4 b'4 e''4|
  \override Staff.NoteSpacing #'stem-spacing-correction = #1.5
  \override Staff.StaffSpacing #'stem-spacing-correction = #1.5
  c'4 e''4 e'4 b'4 |
  b'4 e''4 b'4 e''4|
}
@end lilypond

Proportional notation is supported; see @ref{Proportional notation}.

By default, spacing in tuplets depends on various non-duration
factors (such as accidentals, clef changes, etc).  To disregard
such symbols and force uniform equal-duration spacing, use
@code{Score.SpacingSpanner #'uniform-stretching}.  This
property can only be changed at the beginning of a score,

@lilypond[quote,ragged-right,relative=2,fragment,verbatim]
\new Score \with {
  \override SpacingSpanner #'uniform-stretching = ##t
} <<
  \new Staff{
    \times 4/5 {
      c8 c8 c8 c8 c8
    }
    c8 c8 c8 c8
  }
  \new Staff{
    c8 c8 c8 c8
    \times 4/5 {
      c8 c8 c8 c8 c8
    }
  }
>>
@end lilypond


When @code{strict-note-spacing} is set, notes are spaced without
regard for clefs, bar lines, and grace notes,

@lilypond[quote,ragged-right,relative=2,fragment,verbatim]
\override Score.SpacingSpanner #'strict-note-spacing = ##t
\new Staff { c8[ c \clef alto c \grace { c16[ c] } c8 c c]  c32[ c32] }
@end lilypond


@seealso

Internals: @internalsref{SpacingSpanner}, @internalsref{NoteSpacing},
@internalsref{StaffSpacing}, @internalsref{SeparationItem}, and
@internalsref{SeparatingGroupSpanner}.

@refbugs

Spacing is determined on a score wide basis.  If you have a score that
changes its character (measured in durations) halfway during the
score, the part containing the longer durations will be spaced too
widely.

There is no convenient mechanism to manually override spacing.  The
following work-around may be used to insert extra space into a score.
@example
 \once \override Score.SeparationItem #'padding = #1
@end example

No work-around exists for decreasing the amount of space.


@node Line length
@subsection Line length

@cindex page breaks
@cindex breaking pages

@findex indent
@findex line-width
@findex ragged-right
@findex ragged-last

@c Although line-width can be set in \layout, it should be set in paper
@c block, to get page layout right.
@c Setting indent in \paper block makes not much sense, but it works.

@c Bit verbose and vague, use examples?
The most basic settings influencing the spacing are @code{indent} and
@code{line-width}.  They are set in the @code{\layout} block.  They
control the indentation of the first line of music, and the lengths of
the lines.

If @code{ragged-right} is set to true in the @code{\layout} block, then
systems ends at their natural horizontal length, instead of being spread
horizontally to fill the whole line.  This is useful for
short fragments, and for checking how tight the natural spacing is.

@cindex page layout
@cindex vertical spacing

The option @code{ragged-last} is similar to @code{ragged-right}, but
only affects the last line of the piece.  No restrictions are put on
that line.  The result is similar to formatting text paragraphs.  In a
paragraph, the last line simply takes its natural horizontal length.
@c Note that for text there are several options for the last line.
@c While Knuth TeX uses natural length, lead typesetters use the same
@c stretch as the previous line.  eTeX uses \lastlinefit to
@c interpolate between both these solutions.

@example
\layout @{
  indent = #0
  line-width = #150
  ragged-last = ##t
@}
@end example


@node Breaks
@section Breaks

@menu
* Line breaking::               
* Page breaking::               
@end menu

@node Line breaking
@subsection Line breaking

@cindex line breaks
@cindex breaking lines

Line breaks are normally computed automatically.  They are chosen so
that lines look neither cramped nor loose, and that consecutive lines
have similar density.

Occasionally you might want to override the automatic breaks; you can
do this by specifying @code{\break}.  This will force a line break at
this point.  Line breaks can only occur at places where there are bar
lines.  If you want to have a line break where there is no bar line,
you can force an invisible bar line by entering @code{\bar
""}.  Similarly, @code{\noBreak} forbids a line break at a
point.


@cindex regular line breaks
@cindex four bar music.

For line breaks at regular intervals use @code{\break} separated by
skips and repeated with @code{\repeat}:
@example
<< \repeat unfold 7 @{
         s1 \noBreak s1 \noBreak
         s1 \noBreak s1 \break @}
   @emph{the real music}
>>
@end example

@noindent
This makes the following 28 measures (assuming 4/4 time) be broken every
4 measures, and only there.

@refcommands

@code{\break}, and @code{\noBreak}.
@findex \break
@findex \noBreak

@seealso

Internals: @internalsref{BreakEvent}.

A linebreaking configuration can now be saved as a @code{.ly} file
automatically.  This allows vertical alignments to be stretched to
fit pages in a second formatting run.  This is fairly new and
complicated; see @inputfileref{input/regression/,page-layout-twopass.ly}
for details.

@refbugs

Line breaks can only occur if there is a ``proper'' bar line.  A note
which is hanging over a bar line is not proper, such as

@lilypond[quote,ragged-right,relative=2,fragment,verbatim]
c4 c2 c2 \break   % this does nothing
c2 c4 |           % a break here would work
c4 c2 c4 ~ \break % as does this break
c4 c2 c4
@end lilypond


@node Page breaking
@subsection Page breaking

The default page breaking may be overriden by inserting
@code{\pageBreak} or @code{\noPageBreak} commands.  These commands are
analogous to @code{\break} and @code{\noBreak}.  They should be
inserted at a bar line.  These commands force and forbid a page-break
from happening.  Of course, the @code{\pageBreak} command also forces
a line break.

Page breaks are computed by the @code{page-breaking} function in the
@code{\paper} block.

To force a new page for a new piece (in a collection of pieces or a
piece in several movements), use @code{breakbefore} in the header.

@example
\header@{
  breakbefore = ##t
  piece = ""
@}
@end example

@refcommands

@findex \pageBreak
@code{\pageBreak}
@findex \noPageBreak
@code{\noPageBreak}


@refbugs

The @code{breakbefore=##t} header requires that there is a @code{piece}
header as well.  It may be used as a normal header, or left  blank
(@code{=""}) as in the example above, but it must be present.


@node Displaying spacing
@section Displaying spacing

@findex annotate-spacing
@cindex Spacing, display of properties

To graphically display the dimensions of vertical properties
that may be altered for page formatting, use

@lilypond[verbatim]
\paper { annotate-spacing = ##t }
{ c4 }
@end lilypond

@noindent
@c  FIXME: really bad vagueness due to bug in annotate-spacing.  -gp
Some unit dimensions are measured in staff spaces, while others
are measured in millimeters.
The pairs
(@var{a},@var{b}) are intervals, where @var{a} is the lower edge and
@var{b} the upper edge of the interval.