Ubuntu Manpage: grn - embed Gremlin images in groff documents

Name

       grn - embed Gremlin images in groff documents

Synopsis

       grn [-C] [-T dev] [-M dir] [-F dir] [file ...]

       grn -?
       grn --help

       grn -v
       grn --version

Description

grn is a preprocessor for including gremlin pictures in troff(1) 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 macros request a gremlin file;
the picture in that file is converted and placed in the troff input stream. .GS may be
called with a C, L, or R argument to center, left-, or right-justify the whole gremlin
picture (the default is to 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.

Currently only the me macro package has support for .GS, .GE, and .GF.

grn produces drawing escape sequences that use groff's color scheme extension (\D'F ...'),
and thus may not work with other troffs.

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 lowercase 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
Force the picture to be N inches wide. This overrides any scaling factors present
in the same picture. “width 0” is ignored.

height N
Force the 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 multiple file commands are given, the last
one controls. If name doesn't exist, an error message is reported and processing
continues from the .GE line.

Usage with groff
Since grn is a preprocessor, it has no access to elements of formatter state, such as
indentation, line length, type size, or register values. Consequently, no troff input can
be placed between the .GS and .GE macros. However, gremlin text elements are subsequently
processed by troff, so anything valid in a single line of troff input is valid in a line
of gremlin text (barring the dot control character “.” 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(1) before grn,
pic(1), and/or ideal to avoid overworking tbl. eqn(1) should always be run last.
groff(1) will automatically run preprocessors in the correct order.

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 the me macros
will ensure proper placement.

grn uses troff's 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 macro (this is for
those who want to rewrite these macros).

Gremlin file format
There exist two distinct gremlin file formats: the original format for AED graphic
terminals, and the Sun or X11 version. An extension used by 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 in 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 below.

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

• The first line of each gremlin file contains either the string “gremlinfile” (AED) 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 (a drawing area
wider than it is tall, with a menu across the top). 1 means that gremlin will display
things in vertical format (a drawing area taller than it is wide, with a menu on the
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 truncated to that length.

Element specifications
• The first line of each element contains a single decimal number giving the type of the
element (AED) or its name (Sun/X11).

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 Bézier
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

• 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) or a single asterisk, “*” (Sun/X11).

• 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 troff)
2 italics (I font in troff)
3 bold (B font in troff)
4 special (S font in troff)

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 used only for text elements, and contains the text string.
There can be spaces inside the text. For arcs, curves, and vectors, the character count
is zero (0), followed by exactly one space before the newline.

Coordinates
gremlin was designed for AED terminals, 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 from 0 to 367. Although
you needn't absolutely stick to this range, you'll get better 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 the
printf(3) format “%f1.2”; it's probably a good idea to use the same format if you want to
modify the grn code.

Sun/X11 coordinates
There is no 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.

Options

       -?  and  --help  display a usage message, while -v and --version show version information;
       all exit afterward.

       -C     Recognize .GS and .GE (and .GF) even when followed by a character other than  space
              or newline.

       -F dir Search  dir  for subdirectories devname (name is the name of the output driver) for
              the DESC file before the default font directories /usr/share/groff/site-font, /usr/
              share/groff/1.23.0/font, and /usr/lib/font.

       -M dir Prepend  dir  to the search path for gremlin files.  The default search path is the
              current directory, the home directory, /usr/share/groff/site-tmac, and  /usr/share/
              groff/1.23.0/tmac, in that order.

       -T dev Prepare  device  output  using output driver dev.  The default is ps.  See groff(1)
              for a list of valid devices.

Files

       /usr/share/groff/1.23.0/font/devname/DESC
              describes the output device name.

Authors