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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 con-verted converted
       verted and placed in the troff input stream.  The .GS request may be followed by a C, L, or R to cen-ter, center,
       ter,  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/lib/groff/site-tmac,  /usr/share/groff/site-tmac, /usr/share/groff/sitetmac,
              tmac, and /usr/share/groff/1.19.2/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/site-font,  /usr/share/groff/1.19.2/font,
              and /usr/lib/font.

       -C     Recognize .GS and .GE (and .GF) even when followed by a character 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, 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 _' 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 reg-isters, registers,
       isters,  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 place-ment. placement.
       ment.

       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 ver-sion, version,
       sion, 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 con-tain contain
       tain  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  ver-sion. version.
              sion.   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  for-mat format
              mat (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.

ELEMENT SPECIFICATIONS
             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         B'zier
                                     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 dis-play display
              play 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  poly-gons, polygons,
              gons, 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''.

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 termi-nated terminated
       nated 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/1.19.2/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                            7 August 2004                                         GRN(1)

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