GRN(1)                     OpenBSD Reference Manual                     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
       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/local/lib/groff/site-tmac,
              /usr/local/share/groff/site-tmac, and
              /usr/local/share/groff/1.21/tmac.

       -Fdir  Search dir for subdirectories devname (name is the name of the
              device) for the DESC file before the default font directories
              /usr/local/share/groff/site-font,
              /usr/local/share/groff/1.21/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 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 valid in a single line of
       troff input is valid 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).

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
       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


       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
              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.

       o      The rest of the file consists of zero or more element
              specifications.  After the last element specification is a line
              containing 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         Bzier
                      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
              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).

       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 valid 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 valid.  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.

       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/local/share/groff/1.21/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 1.21             31 December 2010                         GRN(1)
