grn
groff preprocessor for gremlin files
see also :
groff - pic
Synopsis
grn [
-Cv ] [ -Tdev ] [
-Mdir ] [ -Fdir ] [
file... ]
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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/1.22.1/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/1.22.1/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.
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.
•
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’’.
files
/usr/share/groff/1.22.1/font/devname/DESC
Device description file for device name.
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.
•
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.
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).
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
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.
history
David
Slattengren and Barry Roitblat wrote the original Berkeley
grn.
Daniel
Senderowicz and Werner Lemberg modified it for
groff.
see also
gremlin,
groff , pic , ideal