grn - groff preprocessor for gremlin files
grn [ -Cv ] [ -Tdev ] [ -Mdir ] [
  -Fdir ] [ file... ]
It is possible to have whitespace between a command line option
    and its parameter.
grn is a preprocessor for including gremlin pictures in
  groff input. grn writes to standard output, processing only
  input lines between two that start with .GS and .GE. Those lines
  must contain grn commands (see below). These commands request a
  gremlin file, and the picture in that file is converted and placed in
  the troff input stream. The .GS request may be followed by a C,
  L, or R to center, left, or right justify the whole gremlin picture
  (default justification is center). If no file is mentioned, the
  standard input is read. At the end of the picture, the position on the page is
  the bottom of the gremlin picture. If the grn entry is ended
  with .GF instead of .GE, the position is left at the top of the
  picture.
Please note that currently only the -me macro package has support
    for .GS, .GE, and .GF.
The following command-line options are understood:
  - -Tdev
- Prepare output for printer dev. The default device is ps.
      See groff(1) for acceptable devices.
- -Mdir
- Prepend dir to the default search path for gremlin files.
      The default path is (in that order) the current directory, the home
      directory, /usr/share/tmac, /usr/share/tmac, and
      /usr/share/tmac.
- -Fdir
- Search dir for subdirectories devname (name is
      the name of the device) for the DESC file before the default font
      directories /usr/share/groff_font, /usr/share/groff_font,
      and /usr/share/groff_font.
- -C
- Recognize .GS and .GE (and .GF) even when followed by
      a character other than space or newline.
- -v
- Print the version number.
Each input line between .GS and .GE may have one grn
  command. Commands consist of one or two strings separated by white space, the
  first string being the command and the second its operand. Commands may be
  upper or lower case and abbreviated down to one character.Commands that affect a picture's environment (those listed before
    default, see below) are only in effect for the current picture: The
    environment is reinitialized to the defaults at the start of the next
    picture. The commands are as follows:
  - 1 N
- 2 N
- 3 N
- 4 N
- Set gremlin's text size number 1 (2, 3, or 4) to N points.
      The default is 12 (16, 24, and 36, respectively).
- roman f
- italics f
- bold f
- special f
- Set the roman (italics, bold, or special) font to troff's font
      f (either a name or number). The default is R (I, B, and S,
      respectively).
- l f
- stipple f
- Set the stipple font to troff's stipple font f (name or
      number). The command stipple may be abbreviated down as far as `st'
      (to avoid confusion with special). There is no default for
      stipples (unless one is set by the default command), and it is invalid to
      include a gremlin picture with polygons without specifying a
      stipple font.
- x N
- scale N
- Magnify the picture (in addition to any default magnification) by
      N, a floating point number larger than zero. The command
      scale may be abbreviated down to `sc'.
- narrow N
- medium N
- thick N
- Set the thickness of gremlin's narrow (medium and thick,
      respectively) lines to N times 0.15pt (this value can be changed at
      compile time). The default is 1.0 (3.0 and 5.0, respectively), which
      corresponds to 0.15pt (0.45pt and 0.75pt, respectively). A thickness value
      of zero selects the smallest available line thickness. Negative values
      cause the line thickness to be proportional to the current point
    size.
- pointscale <off/on>
- Scale text to match the picture. Gremlin text is usually printed in the
      point size specified with the commands 1, 2, 3,
      or 4, regardless of any scaling factors in the picture.
      Setting pointscale will cause the point sizes to scale with the
      picture (within troff's limitations, of course). An operand of
      anything but off will turn text scaling on.
- default
- Reset the picture environment defaults to the settings in the current
      picture. This is meant to be used as a global parameter setting mechanism
      at the beginning of the troff input file, but can be used at any
      time to reset the default settings.
- width N
- Forces the picture to be N inches wide. This overrides any scaling
      factors present in the same picture. `width 0' is
    ignored.
- height N
- Forces picture to be N inches high, overriding other scaling
      factors. If both `width' and `height' are specified the tighter constraint
      will determine the scale of the picture. Height and width
      commands are not saved with a default command. They will, however,
      affect point size scaling if that option is set.
- file name
- Get picture from gremlin file name located the current
      directory (or in the library directory; see the -M option above).
      If two file commands are given, the second one overrides the first.
      If name doesn't exist, an error message is reported and processing
      continues from the .GE line.
Since grn is a preprocessor, it doesn't know about current indents, point
  sizes, margins, number registers, etc. Consequently, no troff input can
  be placed between the .GS and .GE requests. However,
  gremlin text is now processed by troff, so anything legal in a
  single line of troff input is legal in a line of gremlin text
  (barring `.' directives at the beginning of a line). Thus, it is possible to
  have equations within a gremlin figure by including in the
  gremlin file eqn expressions enclosed by previously defined
  delimiters (e.g. $$).When using grn along with other preprocessors, it is best
    to run tbl before grn, pic, and/or ideal to
    avoid overworking tbl. Eqn should always be run last.
A picture is considered an entity, but that doesn't stop
    troff from trying to break it up if it falls off the end of a page.
    Placing the picture between `keeps' in -me macros will ensure proper
    placement.
grn uses troff's number registers g1 through
    g9 and sets registers g1 and g2 to the width and height
    of the gremlin figure (in device units) before entering the
    .GS request (this is for those who want to rewrite these macros).
There exist two distinct gremlin file formats, the original format from
  the AED graphic terminal version, and the SUN or X11
  version. An extension to the SUN/X11 version allowing reference
  points with negative coordinates is not compatible with the AED
  version. As long as a gremlin file does not contain negative
  coordinates, either format will be read correctly by either version of
  gremlin or grn. The other difference to the
  SUN/X11 format is the use of names for picture objects (e.g.,
  POLYGON, CURVE) instead of numbers. Files representing the same picture are
  shown in Table 1 in each format.
  
    | sungremlinfile |  | gremlinfile | 
  
    | 0 240.00 128.00 |  | 0 240.00 128.00 | 
  
    | CENTCENT |  | 2 | 
  
    | 240.00 128.00 |  | 240.00 128.00 | 
  
    | 185.00 120.00 |  | 185.00 120.00 | 
  
    | 240.00 120.00 |  | 240.00 120.00 | 
  
    | 296.00 120.00 |  | 296.00 120.00 | 
  
    | * |  | -1.00 -1.00 | 
  
    | 2 3 |  | 2 3 | 
  
    | 10 A Triangle |  | 10 A Triangle | 
  
    | POLYGON |  | 6 | 
  
    | 224.00 416.00 |  | 224.00 416.00 | 
  
    | 96.00 160.00 |  | 96.00 160.00 | 
  
    | 384.00 160.00 |  | 384.00 160.00 | 
  
    | * |  | -1.00 -1.00 | 
  
    | 5 1 |  | 5 1 | 
  
    | 0 |  | 0 | 
  
    | -1 |  | -1 | 
  
    | Table 1. File examples | 
  - The first line of each gremlin file contains either the string
      gremlinfile (AED version) or sungremlinfile
      (SUN/X11)
- The second line of the file contains an orientation, and x and
      y values for a positioning point, separated by spaces. The
      orientation, either 0 or 1, is ignored by the
      SUN/X11 version. 0 means that gremlin will
      display things in horizontal format (drawing area wider than it is tall,
      with menu across top). 1 means that gremlin will display
      things in vertical format (drawing area taller than it is wide, with menu
      on left side). x and y are floating point values giving a
      positioning point to be used when this file is read into another file. The
      stuff on this line really isn't all that important; a value of ``1 0.00
      0.00'' is suggested.
- The rest of the file consists of zero or more element specifications.
      After the last element specification is a line containing the string
      ``-1''.
- Lines longer than 127 characters are chopped to this limit.
  - The first line of each element contains a single decimal number giving the
      type of the element (AED version) or its ASCII name
      (SUN/X11 version). See Table 2.
    
    
      
        | gremlin File Format
          − Object Type Specification |  
        | AED Number | SUN/X11 Name | Description |  
        | 0 | BOTLEFT | bottom-left-justified text |  
        | 1 | BOTRIGHT | bottom-right-justified text |  
        | 2 | CENTCENT | center-justified text |  
        | 3 | VECTOR | vector |  
        | 4 | ARC | arc |  
        | 5 | CURVE | curve |  
        | 6 | POLYGON | polygon |  
        | 7 | BSPLINE | b-spline |  
        | 8 | BEZIER | Bézier |  
        | 10 | TOPLEFT | top-left-justified text |  
        | 11 | TOPCENT | top-center-justified text |  
        | 12 | TOPRIGHT | top-right-justified text |  
        | 13 | CENTLEFT | left-center-justified text |  
        | 14 | CENTRIGHT | right-center-justified text |  
        | 15 | BOTCENT | bottom-center-justified text |  
        | Table 2. |  
        | Type Specifications in
          gremlin Files |  
 
- After the object type comes a variable number of lines, each specifying a
      point used to display the element. Each line contains an x-coordinate and
      a y-coordinate in floating point format, separated by spaces. The list of
      points is terminated by a line containing the string ``-1.0 -1.0''
      (AED version) or a single asterisk, ``*'' (SUN/X11
      version).
- After the points comes a line containing two decimal values, giving the
      brush and size for the element. The brush determines the style in which
      things are drawn. For vectors, arcs, and curves there are six legal brush
      values:
    
    
      
        | 1 − |  | thin dotted lines |  
        | 2 − |  | thin dot-dashed lines |  
        | 3 − |  | thick solid lines |  
        | 4 − |  | thin dashed lines |  
        | 5 − |  | thin solid lines |  
        | 6 − |  | medium solid lines |  
 For polygons, one more value, 0, is legal. It specifies a
        polygon with an invisible border. For text, the brush selects a font as
        follows: 
      
        | 1 − |  | roman (R font in groff) |  
        | 2 − |  | italics (I font in groff) |  
        | 3 − |  | bold (B font in groff) |  
        | 4 − |  | special (S font in groff) |  
 If you're using grn to run your pictures through
        groff, the font is really just a starting font: The text string
        can contain formatting sequences like ``\fI'' or ``\d'' which may change
        the font (as well as do many other things). For text, the size field is
        a decimal value between 1 and 4. It selects the size of the font in
        which the text will be drawn. For polygons, this size field is
        interpreted as a stipple number to fill the polygon with. The number is
        used to index into a stipple font at print time. 
- The last line of each element contains a decimal number and a string of
      characters, separated by a single space. The number is a count of the
      number of characters in the string. This information is only used for text
      elements, and contains the text string. There can be spaces inside the
      text. For arcs, curves, and vectors, this line of the element contains the
      string ``0''.
gremlin was designed for AEDs, and its coordinates reflect the
  AED coordinate space. For vertical pictures, x-values range 116 to 511,
  and y-values from 0 to 483. For horizontal pictures, x-values range from 0 to
  511 and y-values range from 0 to 367. Although you needn't absolutely stick to
  this range, you'll get best results if you at least stay in this vicinity.
  Also, point lists are terminated by a point of (-1, -1), so you shouldn't ever
  use negative coordinates. gremlin writes out coordinates using format
  ``%f1.2''; it's probably a good idea to use the same format if you want to
  modify the grn code.
There is no longer a restriction on the range of coordinates used to create
  objects in the SUN/X11 version of gremlin. However, files
  with negative coordinates will cause problems if displayed on the
  AED.
  - /usr/share/groff_font/devname/DESC
- Device description file for device name.
gremlin(1), groff(1), pic(1), ideal(1)
David Slattengren and Barry Roitblat wrote the original Berkeley grn.Daniel Senderowicz and Werner Lemberg modified it for
    groff.