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grn(1)

NAME

       grn - groff preprocessor for gremlin files

SYNOPSIS

       grn [ -Cv ] [ -Tdev ] [ -Mdir ] [ -Fdir ] [ file... ]

       It is possible to have whitespace between a command line option and its
       parameter.

DESCRIPTION

       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 jus-
       tify 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 (resp.  .GF) even when followed by a char-
	      acter other than space or newline.

       -v     Print the version number.

GRN COMMANDS

       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:
       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 (resp. I, B, and
	      S).

       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 (resp. medium and thick)
	      lines to N times 0.15pt (this value can be  changed  at  compile
	      time).   The  default  is  1.0 (resp. 3.0 and 5.0), which corre-
	      sponds to 0.15pt (resp. 0.45pt and 0.75pt).  A  thickness  value
	      of zero selects the smallest available line thickness.  Negative
	      values cause the line thickness to be proportional to  the  cur-
	      rent 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.

NOTES ABOUT GROFF

       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 expres-
       sions 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).

GREMLIN FILE FORMAT

       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 nega-
       tive 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  dif-
       ference	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

       o      The  first  line of each gremlin file contains either the string
	      ing 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.

       o      The rest of the file consists of zero or more element specifica-
	      tions.   After the last element specification is a line contain-
	      ing the string ``-1''.

       o      Lines longer than 127 characters are chopped to this limit.

ELEMENT SPECIFICATIONS

       o      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	      Bezier
		      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

       o      After the object type comes a variable  number  of  lines,  each
	      specifying  a point used to display the element.	Each line con-
	      tains an x-coordinate and a y-coordinate in floating point  for-
	      mat, separated by spaces.  The list of points is terminated by a
	      line containing the string ``-1.0 -1.0'' (AED version) or a sin-
	      gle asterisk, ``*'' (SUN/X11 version).

       o      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

			    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 for-
	      matting 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  poly-
	      gon  with.   The	number is used to index into a stipple font at
	      print time.

       o      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''.

NOTES ON COORDINATES

       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.

NOTES ON SUN/X11 COORDINATES

       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.

FILES

       /usr/share/groff_font/devname/DESC
	      Device description file for device name.

SEE ALSO

       gremlin(1), groff(1), pic(1), ideal(1)

HISTORY

       David Slattengren and Barry Roitblat wrote the original Berkeley grn.

       Daniel Senderowicz and Werner Lemberg modified it for groff.

Groff Version 1.19		11 October 2002 			GRN(1)

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