'\" t
.TH GRN 1 "7 February 2022" "groff 1.22.4"
.SH NAME
grn \- groff preprocessor for gremlin files
.
.
.\" ====================================================================
.\" Legal Terms
.\" ====================================================================
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.\"
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.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
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.\" Permission is granted to copy and distribute modified versions of
.\" this manual under the conditions for verbatim copying, provided that
.\" the entire resulting derived work is distributed under the terms of
.\" a permission notice identical to this one.
.\"
.\" Permission is granted to copy and distribute translations of this
.\" manual into another language, under the above conditions for
.\" modified versions, except that this permission notice may be
.\" included in translations approved by the Free Software Foundation
.\" instead of in the original English.
.
.
.\" Save and disable compatibility mode (for, e.g., Solaris 10/11).
.do nr grn_C \n[.C]
.cp 0
.
.
.\" ====================================================================
.SH SYNOPSIS
.\" ====================================================================
.
.SY grn
.OP \-Cv
.OP \-T dev
.OP \-M dir
.OP \-F dir
.RI [ file
\&.\|.\|.\&]
.YS
.
.
.\" ====================================================================
.SH DESCRIPTION
.\" ====================================================================
.
.I grn
is a preprocessor for including
.I gremlin
pictures in
.I groff
input.
.
.I grn
writes to standard output, processing only input lines between two
that start with
.B .GS
and
.BR .GE .
.
Those lines must contain
.I grn
commands (see below).
.
These commands request a
.I gremlin
file, and the picture in that file is converted and placed in the
.I troff
input stream.
.
The
.B .GS
request may be followed by a C, L, or R to center, left, or right
justify the whole
.I gremlin
picture (default justification is center).
.
If no
.I file
is mentioned, the standard input is read.
.
At the end of the picture, the position on the page is the bottom of the
.I gremlin
picture.
.
If the
.I grn
entry is ended with
.B .GF
instead of
.BR .GE ,
the position is left at the top of the picture.
.
.
.PP
Please note that currently only the \-me macro package has support for
.BR .GS ,
.BR .GE ,
and
.BR .GF .
.
.
.\" ====================================================================
.SH OPTIONS
.\" ====================================================================
.
Whitespace is permitted between a command-line option and its argument.
.
.
.TP
.BI \-T dev
Prepare output for printer
.IR dev .
The default device is
.BR ps .
See
.BR groff (1)
for acceptable devices.
.
.TP
.BI \-M dir
Prepend
.I dir
to the default search path for
.I gremlin
files.
.
The default path is (in that order) the current directory, the home
directory,
.IR /usr/\:lib/\:groff/\:site\-tmac ,
.IR /usr/\:share/\:groff/\:site\-tmac ,
and
.IR /usr/\:share/\:groff/\:1.22.4/\:tmac .
.
.TP
.BI \-F dir
Search
.I dir
for subdirectories
.IR dev name
.RI ( name
is the name of the device) for the
.I DESC
file before the default font directories
.IR /usr/\:share/\:groff/\:site\-font ,
.IR /usr/\:share/\:groff/\:1.22.4/\:font ,
and
.IR /usr/\:lib/\:font .
.
.TP
.B \-C
Recognize
.B .GS
and
.B .GE
(and
.BR .GF )
even when followed by a character other than space or newline.
.\".TP
.\".B \-s
.\"This switch causes the picture to be traversed twice:
.\"The first time, only the interiors of filled polygons (as borderless
.\"polygons) are printed.
.\"The second time, the outline is printed as a series of line segments.
.\"This way, postprocessors that overwrite rather than merge picture elements
.\"(such as PostScript) can still have text and graphics on a shaded
.\"background.
.
.TP
.B \-v
Print the version number.
.
.
.\" ====================================================================
.SH "GRN COMMANDS"
.\" ====================================================================
.
Each input line between
.B .GS
and
.B .GE
may have one
.I 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.
.
.
.PP
Commands that affect a picture's environment (those listed before
.BR 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:
.TP
.BI 1\  N
.TQ
.BI 2\  N
.TQ
.BI 3\  N
.TQ
.BI 4\  N
.
Set
.IR gremlin 's
text size number 1 (2, 3, or 4) to
.I N
points.
.
The default is 12 (16, 24, and 36, respectively).
.
.TP
.BI roman\  f
.TQ
.BI italics\  f
.TQ
.BI bold\  f
.TQ
.BI special\  f
Set the roman (italics, bold, or special) font to
.IR troff 's
font
.I f
(either a name or number).
.
The default is R (I, B, and S, respectively).
.
.TP
.BI l\  f
.TQ
.BI stipple\  f
Set the stipple font to
.IR troff 's
stipple font
.I f
(name or number).
.
The command
.B stipple
may be abbreviated down as far as \[oq]st\[cq] (to avoid confusion
with
.BR special ).
.
There is
.I no
default for stipples (unless one is set by the default command), and
it is invalid to include a
.I gremlin
picture with polygons without specifying a
stipple font.
.
.TP
.BI x\  N
.TQ
.BI scale\  N
Magnify the picture (in addition to any default magnification) by
.IR N ,
a floating point number larger than zero.
.
The command
.B scale
may be abbreviated down to \[oq]sc\[cq].
.
.TP
.BI narrow\  N
.TQ
.BI medium\  N
.TQ
.BI thick\  N
.
Set the thickness of
.IR gremlin 's
narrow (medium and thick, respectively) lines to
.I 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.
.
.TP
.BI pointscale\  <off/on>
Scale text to match the picture.
.
Gremlin text is usually printed in the point size specified with the
commands
.BR 1 ,
.BR 2 ,
.BR 3 ,
.RB or\~ 4 ,
regardless of any scaling factors in the picture.
.
Setting
.B pointscale
will cause the point sizes to scale with the picture (within
.IR troff 's
limitations, of course).
.
An operand of anything but
.I off
will turn text scaling on.
.
.TP
.B 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
.I troff
input file, but can be used at any time to reset the
default settings.
.
.TP
.BI width\  N
Forces the picture to be
.I N
inches wide.
.
This overrides any scaling factors present in the same picture.
.RB \[oq] width
.IR 0 \[cq]
is ignored.
.
.TP
.BI height\  N
Forces picture to be
.I N
inches high, overriding other scaling factors.
.
If both \[oq]width\[cq] and \[oq]height\[cq] are specified the tighter
constraint will determine the scale of the picture.
.B Height
and
.B width
commands are not saved with a
.B default
command.
.
They will, however, affect point size scaling if that option is set.
.
.TP
.BI file\  name
Get picture from
.I gremlin
file
.I name
located the current directory (or in the library directory; see the
.B \-M
option above).
.
If two
.B file
commands are given, the second one overrides the first.
.
If
.I name
doesn't exist, an error message is reported and processing
continues from the
.B .GE
line.
.
.
.\" ====================================================================
.SH "NOTES ABOUT GROFF"
.\" ====================================================================
.
Since
.I grn
is a preprocessor, it doesn't know about current indents, point
sizes, margins, number registers, etc.  Consequently, no
.I troff
input can be placed between the
.B .GS
and
.B .GE
requests.
.
However,
.I gremlin
text is now processed by
.IR troff ,
so anything valid in a single line of
.I troff
input is valid in a line of
.I gremlin
text (barring \[oq].\[cq] directives at the beginning of a line).
.
Thus, it is possible to have equations within a
.I gremlin
figure by including in the
.I gremlin
file
.I eqn
expressions enclosed by previously defined delimiters (e.g.\&
.IR $$ ).
.
.
.PP
When using
.I grn
along with other preprocessors, it is best to run
.I tbl
before
.IR grn ,
.IR pic ,
and/or
.I ideal
to avoid overworking
.IR tbl .
.
.I Eqn
should always be run last.
.
.
.PP
A picture is considered an entity, but that doesn't stop
.I troff
from trying to break it up if it falls off the end of a page.
.
Placing the picture between \[oq]keeps\[cq] in \-me macros will ensure
proper placement.
.
.
.PP
.I grn
uses
.IR troff 's
number registers
.B g1
through
.B g9
and sets registers
.B g1
and
.B g2
to the width and height of the
.I gremlin
figure (in device units) before entering the
.B .GS
request (this is for those who want to rewrite these macros).
.
.
.\" ====================================================================
.SH "GREMLIN FILE FORMAT"
.\" ====================================================================
.
There exist two distinct
.I gremlin
file formats, the original format from the
.I AED
graphic terminal version, and the
.I SUN
or
.I X11
version.
.
An extension to the
.IR SUN / X11
version allowing reference points with negative coordinates is
.B not
compatible with the
.I AED
version.
.
As long as a
.I gremlin
file does not contain negative coordinates, either format will be read
correctly by either version of
.I gremlin
or
.IR grn .
.
The other difference from
.IR 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.
.sp
.TS
center, tab(@);
l lw(0.1i) l.
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
.T&
css.
.sp
Table 1.  File examples
.TE
.sp
.IP \(bu
The first line of each
.I gremlin
file contains either the string
.B gremlinfile
.RI ( AED
version) or
.B sungremlinfile
.RI ( SUN / X11 )
.IP \(bu
The second line of the file contains an orientation, and
.B x
and
.B y
values for a positioning point, separated by spaces.
The orientation, either
.B 0
or
.BR 1 ,
is ignored by the
.IR SUN / X11
version.
.
.B 0
means that
.I gremlin
will display things in horizontal format (drawing area wider than it is
tall, with menu across top).
.
.B 1
means that
.I gremlin
will display things in vertical format (drawing area taller than it is
wide, with menu on left side).
.
.B x
and
.B 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
\[lq]1 0.00 0.00\[rq] is suggested.
.
.IP \(bu
The rest of the file consists of zero or more element specifications.
.
After the last element specification is a line containing the string
\[lq]\-1\[rq].
.
.IP \(bu
Lines longer than 127 characters are chopped to this limit.
.
.
.\" ====================================================================
.SH "ELEMENT SPECIFICATIONS"
.\" ====================================================================
.
.IP \(bu
The first line of each element contains a single decimal number giving
the type of the element
.RI ( AED
version) or its ASCII name
.RI ( SUN / X11
version).
.
See Table 2.
.sp
.TS
center, tab(@);
css
ccc
nll.
\fIgremlin\fP File Format \(mi Object Type Specification
.sp
\fIAED\fP Number@\fISUN\/\fP/\,\fIX11\fP 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
.T&
css.
.sp
Table 2.
Type Specifications in \fIgremlin\fP Files
.TE
.sp
.IP \(bu
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 \[lq]\-1.0
\-1.0\[rq]
.RI ( AED
version) or a single asterisk, \[lq]*\[rq]
.RI ( SUN / X11
version).
.
.IP \(bu
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:
.sp
.TS
center, tab(@);
ncw(0.1i)l.
1 \(mi@@thin dotted lines
2 \(mi@@thin dot-dashed lines
3 \(mi@@thick solid lines
4 \(mi@@thin dashed lines
5 \(mi@@thin solid lines
6 \(mi@@medium solid lines
.TE
.sp
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:
.sp
.TS
center, tab(@);
ncw(0.1i)l.
1 \(mi@@roman (R font in groff)
2 \(mi@@italics (I font in groff)
3 \(mi@@bold (B font in groff)
4 \(mi@@special (S font in groff)
.TE
.sp
If you're using
.I grn
to run your pictures through
.IR groff ,
the font is really just a starting font:
.
The text string can contain formatting sequences like
\[lq]\efI\[rq]
or
\[lq]\ed\[rq]
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.
.
.IP \(bu
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 \[lq]0\[rq].
.
.
.\" ====================================================================
.SH "NOTES ON COORDINATES"
.\" ====================================================================
.
.I gremlin
was designed for
.IR AED s,
and its coordinates reflect the
.I 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.
.
.I gremlin
writes out coordinates using format \[lq]%f1.2\[rq]; it's probably
a good idea to use the same format if you want to modify the
.I grn
code.
.
.
.\" ====================================================================
.SH "NOTES ON SUN/X11 COORDINATES"
.\" ====================================================================
.
There is no longer a restriction on the range of coordinates used to
create objects in the
.IR SUN / X11
version of
.IR gremlin .
.
However, files with negative coordinates
.B will
cause problems if displayed on the
.IR AED .
.
.
.\" ====================================================================
.SH FILES
.\" ====================================================================
.
.TP
.IR /usr/\:share/\:groff/\:1.22.4/\:font/dev name /DESC
Device description file for device
.IR name .
.
.
.\" ====================================================================
.SH AUTHORS
.\" ====================================================================
David Slattengren and Barry Roitblat wrote the original Berkeley
.IR grn .
.
Daniel Senderowicz and Werner Lemberg modified it for
.IR groff .
.
.
.\" ====================================================================
.SH "SEE ALSO"
.\" ====================================================================
.
.BR gremlin (1),
.BR groff (1),
.BR pic (1),
.BR ideal (1)
.
.
.\" Restore compatibility mode (for, e.g., Solaris 10/11).
.cp \n[grn_C]
.
.
.\" Local Variables:
.\" mode: nroff
.\" End:
.\" vim: set filetype=groff: