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 Set the library to directory dir. If a gremlin
file cannot be found in the current directory, dir
is prepended to the filename for a second try. The
default library directory is /usr/share/tmac.
-Fdir Search dir for subdirectories devname (name is the
name of the device) for the DESC file before the
-C Recognize .GS and .GE (resp. .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:
4 N Set gremlin's text size number 1 (2, 3, or 4) to N
points. The default is 12 (resp. 16, 24, and 36).
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).
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 illegal to include a gremlin picture with polygons
without specifying a stipple font.
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'.
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 corresponds 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 current point size.
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
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.
Forces the picture to be N inches wide. This overrides
any scaling factors present in the same picture.
`width 0' is ignored.
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.
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.
0 240.00 128.00 0 240.00 128.00
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
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
Table 1. File examples
o The first line of each gremlin file contains either
the string gremlinfile (AED version) or sungremlin-
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''.
ELEMENT SPECIFICATIONS [Toc] [Back]
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
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
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
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 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.
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''.
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.
Device description file for device name.
gremlin(1), groff(1), pic(1), ideal(1)
David Slattengren and Barry Roitblat wrote the original
Daniel Senderowicz and Werner Lemberg modified it for
Groff Version 1.16.1 April 8, 2001 GRN(1)
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