GRN
Section: User Commands (1)
Updated: 24 February 2006
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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/lib/groff/site-tmac,
/usr/share/groff/site-tmac,
and
/usr/share/groff/1.18.1.4/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/1.18.1.4/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
|
- *
-
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.
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['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
|
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:
| 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.
- *
-
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
u+3n
-
-
/usr/share/groff/1.18.1.4/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.