GRN(1)                                                                  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 (and .GF) even when followed by a  charac-
              ter 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:

       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, respec-
              tively) 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  pro-
              portional 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.

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
              gremlinfile (AED version) or sungremlinfile (SUN/X11)

       o      The second line of the file contains an orientation, and x and y
              values for a positioning point, separated by spaces.  The orien-
              tation, 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 (draw-
              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
                              5 -       thin solid lines
                              6 -       medium solid lines

              For polygons, one more value, 0, is legal.  It specifies a poly-
              gon  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 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 1.19.2            6 February 2006                         GRN(1)
