Info Catalog groff: Manipulating Hyphenation groff: gtroff Reference groff: Tabs and Fields

groff: Manipulating Spacing

 
 5.9 Manipulating Spacing
 ========================
 
  -- Request: .sp [distance]
      Space downwards DISTANCE.  With no argument it advances 1 line.  A
      negative argument causes 'gtroff' to move up the page the specified
      distance.  If the argument is preceded by a '|' then 'gtroff' moves
      that distance from the top of the page.  This request causes a line
      break, and that adds the current line spacing to the space you have
      just specified.  The default scaling indicator is 'v'.
 
      For convenience you may wish to use the following macros to set the
      height of the next line at a given distance from the top or the
      bottom of the page:
 
           .de y-from-top-down
           .  sp |\\$1-\\n[.v]u
           ..
           .
           .de y-from-bot-up
           .  sp |\\n[.p]u-\\$1-\\n[.v]u
           ..
 
      A call to '.y-from-bot-up 10c' means that the bottom of the next
      line will be at 10cm from the paper edge at the bottom.
 
      If a vertical trap is sprung during execution of 'sp', the amount
      of vertical space after the trap is discarded.  For example, this
 
           .de xxx
           ..
           .
           .wh 0 xxx
           .
           .pl 5v
           foo
           .sp 2
           bar
           .sp 50
           baz
 
      results in
 
           foo
 
 
           bar
 
           baz
 
      The amount of discarded space is available in the number register
      '.trunc'.
 
      To protect 'sp' against vertical traps, use the 'vpt' request:
 
           .vpt 0
           .sp -3
           .vpt 1
 
  -- Request: .ls [nnn]
  -- Register: \n[.L]
      Output NNN-1 blank lines after each line of text.  With no
      argument, 'gtroff' uses the previous value before the last 'ls'
      call.
 
           .ls 2    \" This causes double-spaced output
           .ls 3    \" This causes triple-spaced output
           .ls      \" Again double-spaced
 
      The line spacing is associated with the current environment (
      Environments).
 
      The read-only number register '.L' contains the current line
      spacing setting.
 
    Changing Type Sizes, for the requests 'vs' and 'pvs' as
 alternatives to 'ls'.
 
  -- Escape: \x'spacing'
  -- Register: \n[.a]
      Sometimes, extra vertical spacing is only needed occasionally, e.g.
      to allow space for a tall construct (like an equation).  The '\x'
      escape does this.  The escape is given a numerical argument,
      usually enclosed in quotes (like '\x'3p''); the default scaling
      indicator is 'v'.  If this number is positive extra vertical space
      is inserted below the current line.  A negative number adds space
      above.  If this escape is used multiple times on the same line, the
      maximum of the values is used.
 
      Escapes, for details on parameter delimiting characters.
 
      The '.a' read-only number register contains the most recent
      (nonnegative) extra vertical line space.
 
      Using '\x' can be necessary in combination with the '\b' escape, as
      the following example shows.
 
           This is a test with the \[rs]b escape.
           .br
           This is a test with the \[rs]b escape.
           .br
           This is a test with \b'xyz'\x'-1m'\x'1m'.
           .br
           This is a test with the \[rs]b escape.
           .br
           This is a test with the \[rs]b escape.
 
      produces
 
           This is a test with the \b escape.
           This is a test with the \b escape.
                               x
           This is a test with y.
                               z
           This is a test with the \b escape.
           This is a test with the \b escape.
 
  -- Request: .ns
  -- Request: .rs
  -- Register: \n[.ns]
      Enable "no-space mode".  In this mode, spacing (either via 'sp' or
      via blank lines) is disabled.  The 'bp' request to advance to the
      next page is also disabled, except if it is accompanied by a page
      number (see Page Control, for more information).  This mode
      ends when actual text is output or the 'rs' request is encountered,
      which ends no-space mode.  The read-only number register '.ns' is
      set to 1 as long as no-space mode is active.
 
      This request is useful for macros that conditionally insert
      vertical space before the text starts (for example, a paragraph
      macro could insert some space except when it is the first paragraph
      after a section header).
 

Info Catalog groff: Manipulating Hyphenation groff: gtroff Reference groff: Tabs and Fields