GRN(1) manual page
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grn - groff preprocessor for gremlin files
grn [ -Cv
] [ -Tdev ] [ -Mdir ] [ -Fdir ] [ file... ]
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/lib/groff/site-tmac, /usr/share/groff/site-tmac,
and /usr/share/groff/1.22.2/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/1.22.2/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.
It is possible
to have whitespace between a command line option and its parameter.
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.
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).
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 | |
| 0 240.00 128.00 | |
| CENTCENT | |
| 240.00 128.00 | |
| 185.00 120.00 | |
| 240.00
120.00 | |
| 296.00 120.00 | |
| * | |
| 2 3 | |
| 10 A Triangle | |
| POLYGON | |
| 224.00 416.00 | |
| 96.00 160.00 | |
| 384.00 160.00 | |
| * | |
| 5
1 | |
| 0 | |
| -1 | |
| css. |
| 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 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.
- 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.
- 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[’e]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 |
| css. |
| Table 2. |
| Type Specifications in gremlin Files |
- 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).
- 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:
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:
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.
- 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.
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.
:((0w’/usr/share/groff/1.22.2/font/devname/DESC’u+3n)*2u>(0u-0u))
.TP /usr/share/groff/1.22.2/font/devname/DESC Device description file for
device name.
gremlin(1)
, groff(1)
, pic(1)
, ideal(1)
David
Slattengren and Barry Roitblat wrote the original Berkeley grn.
Daniel Senderowicz
and Werner Lemberg modified it for groff.
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