gpic
(1)
Name
gpic - compile pictures for troff or TeX
Synopsis
gpic [ -nvCSU ] [ filename ... ]
gpic -t [ -cvzCSU ] [ filename ... ]
Description
User Commands GPIC(1)
NAME
gpic - compile pictures for troff or TeX
SYNOPSIS
gpic [ -nvCSU ] [ filename ... ]
gpic -t [ -cvzCSU ] [ filename ... ]
DESCRIPTION
This manual page describes the GNU version of pic, which is
part of the groff document formatting system. pic compiles
descriptions of pictures embedded within troff or TeX input
files into commands that are understood by TeX or troff.
Each picture starts with a line beginning with .PS and ends
with a line beginning with .PE. Anything outside of .PS and
.PE is passed through without change.
It is the user's responsibility to provide appropriate defi-
nitions of the PS and PE macros. When the macro package
being used does not supply such definitions (for example,
old versions of -ms), appropriate definitions can be
obtained with -mpic: These will center each picture.
OPTIONS
Options that do not take arguments may be grouped behind a
single -. The special option -- can be used to mark the end
of the options. A filename of - refers to the standard
input.
-C Recognize .PS and .PE even when followed by a character
other than space or newline.
-S Safer mode; do not execute sh commands. This can be
useful when operating on untrustworthy input. (enabled
by default)
-U Unsafe mode; revert the default option -S.
-n Don't use the groff extensions to the troff drawing
commands. You should use this if you are using a post-
processor that doesn't support these extensions. The
extensions are described in groff_out(5). The -n
option also causes pic not to use zero-length lines to
draw dots in troff mode.
-t TeX mode.
-c Be more compatible with tpic. Implies -t. Lines
beginning with \ are not passed through transparently.
Lines beginning with . are passed through with the
initial . changed to \. A line beginning with .ps is
given special treatment: it takes an optional integer
argument specifying the line thickness (pen size) in
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milliinches; a missing argument restores the previous
line thickness; the default line thickness is 8 milli-
inches. The line thickness thus specified takes effect
only when a non-negative line thickness has not been
specified by use of the thickness attribute or by set-
ting the linethick variable.
-v Print the version number.
-z In TeX mode draw dots using zero-length lines.
The following options supported by other versions of pic are
ignored:
-D Draw all lines using the \D escape sequence. pic
always does this.
-T dev
Generate output for the troff device dev. This is
unnecessary because the troff output generated by pic
is device-independent.
USAGE
This section describes only the differences between GNU pic
and the original version of pic. Many of these differences
also apply to newer versions of Unix pic. A complete docu-
mentation is available in the file
/usr/share/doc/groff/1.19.2/pic.ms
TeX mode
TeX mode is enabled by the -t option. In TeX mode, pic will
define a vbox called \graph for each picture. Use the fig-
name command to change the name of the vbox. You must your-
self print that vbox using, for example, the command
\centerline{\box\graph}
Actually, since the vbox has a height of zero (it is defined
with \vtop) this will produce slightly more vertical space
above the picture than below it;
\centerline{\raise 1em\box\graph}
would avoid this.
To make the vbox having a positive height and a depth of
zero (as used e.g. by LaTeX's graphics.sty), define the fol-
lowing macro in your document:
\def\gpicbox#1{%
\vbox{\unvbox\csname #1\endcsname\kern 0pt}}
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Now you can simply say \gpicbox{graph} instead of
\box\graph.
You must use a TeX driver that supports the tpic specials,
version 2.
Lines beginning with \ are passed through transparently; a %
is added to the end of the line to avoid unwanted spaces.
You can safely use this feature to change fonts or to change
the value of \baselineskip. Anything else may well produce
undesirable results; use at your own risk. Lines beginning
with a period are not given any special treatment.
Commands
for variable = expr1 to expr2 [by [*]expr3] do X body X
Set variable to expr1. While the value of variable is
less than or equal to expr2, do body and increment
variable by expr3; if by is not given, increment vari-
able by 1. If expr3 is prefixed by * then variable
will instead be multiplied by expr3. The value of
expr3 can be negative for the additive case; variable
is then tested whether it is greater than or equal to
expr2. For the multiplicative case, expr3 must be
greater than zero. If the constraints aren't met, the
loop isn't executed. X can be any character not occur-
ring in body.
if expr then X if-true X [else Y if-false Y]
Evaluate expr; if it is non-zero then do if-true, oth-
erwise do if-false. X can be any character not occur-
ring in if-true. Y can be any character not occurring
in if-false.
print arg...
Concatenate the arguments and print as a line on
stderr. Each arg must be an expression, a position, or
text. This is useful for debugging.
command arg...
Concatenate the arguments and pass them through as a
line to troff or TeX. Each arg must be an expression,
a position, or text. This has a similar effect to a
line beginning with . or \, but allows the values of
variables to be passed through. For example,
.PS
x = 14
command ".ds string x is " x "."
.PE
\*[string]
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prints
x is 14.
sh X command X
Pass command to a shell. X can be any character not
occurring in command.
copy "filename"
Include filename at this point in the file.
copy ["filename"] thru X body X [until "word"]
copy ["filename"] thru macro [until "word"]
This construct does body once for each line of file-
name; the line is split into blank-delimited words, and
occurrences of $i in body, for i between 1 and 9, are
replaced by the i-th word of the line. If filename is
not given, lines are taken from the current input up to
.PE. If an until clause is specified, lines will be
read only until a line the first word of which is word;
that line will then be discarded. X can be any charac-
ter not occurring in body. For example,
.PS
copy thru % circle at ($1,$2) % until "END"
1 2
3 4
5 6
END
box
.PE
is equivalent to
.PS
circle at (1,2)
circle at (3,4)
circle at (5,6)
box
.PE
The commands to be performed for each line can also be
taken from a macro defined earlier by giving the name
of the macro as the argument to thru.
reset
reset variable1[,] variable2 ...
Reset pre-defined variables variable1, variable2 ... to
their default values. If no arguments are given, reset
all pre-defined variables to their default values.
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Note that assigning a value to scale also causes all
pre-defined variables that control dimensions to be
reset to their default values times the new value of
scale.
plot expr ["text"]
This is a text object which is constructed by using
text as a format string for sprintf with an argument of
expr. If text is omitted a format string of "%g" is
used. Attributes can be specified in the same way as
for a normal text object. Be very careful that you
specify an appropriate format string; pic does only
very limited checking of the string. This is depre-
cated in favour of sprintf.
variable := expr
This is similar to = except variable must already be
defined, and expr will be assigned to variable without
creating a variable local to the current block. (By
contrast, = defines the variable in the current block
if it is not already defined there, and then changes
the value in the current block only.) For example, the
following:
.PS
x = 3
y = 3
[
x := 5
y = 5
]
print x " " y
.PE
prints
5 3
Arguments of the form
X anything X
are also allowed to be of the form
{ anything }
In this case anything can contain balanced occurrences of {
and }. Strings may contain X or imbalanced occurrences of {
and }.
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Expressions
The syntax for expressions has been significantly extended:
x ^ y (exponentiation)
sin(x)
cos(x)
atan2(y, x)
log(x) (base 10)
exp(x) (base 10, ie 10^x)
sqrt(x)
int(x)
rand() (return a random number between 0 and 1)
rand(x) (return a random number between 1 and x; deprecated)
srand(x) (set the random number seed)
max(e1, e2)
min(e1, e2)
!e
e1 && e2
e1 || e2
e1 == e2
e1 != e2
e1 >= e2
e1 > e2
e1 <= e2
e1 < e2
"str1" == "str2"
"str1" != "str2"
String comparison expressions must be parenthesised in some
contexts to avoid ambiguity.
Other Changes
A bare expression, expr, is acceptable as an attribute; it
is equivalent to dir expr, where dir is the current direc-
tion. For example
line 2i
means draw a line 2 inches long in the current direction.
The `i' (or `I') character is ignored; to use another mea-
surement unit, set the scale variable to an appropriate
value.
The maximum width and height of the picture are taken from
the variables maxpswid and maxpsht. Initially these have
values 8.5 and 11.
Scientific notation is allowed for numbers. For example
x = 5e-2
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Text attributes can be compounded. For example,
"foo" above ljust
is valid.
There is no limit to the depth to which blocks can be exam-
ined. For example,
[A: [B: [C: box ]]] with .A.B.C.sw at 1,2
circle at last [].A.B.C
is acceptable.
Arcs now have compass points determined by the circle of
which the arc is a part.
Circles, ellipses, and arcs can be dotted or dashed. In TeX
mode splines can be dotted or dashed also.
Boxes can have rounded corners. The rad attribute specifies
the radius of the quarter-circles at each corner. If no rad
or diam attribute is given, a radius of boxrad is used.
Initially, boxrad has a value of 0. A box with rounded cor-
ners can be dotted or dashed.
The .PS line can have a second argument specifying a maximum
height for the picture. If the width of zero is specified
the width will be ignored in computing the scaling factor
for the picture. Note that GNU pic will always scale a pic-
ture by the same amount vertically as well as horizontally.
This is different from the DWB 2.0 pic which may scale a
picture by a different amount vertically than horizontally
if a height is specified.
Each text object has an invisible box associated with it.
The compass points of a text object are determined by this
box. The implicit motion associated with the object is also
determined by this box. The dimensions of this box are
taken from the width and height attributes; if the width
attribute is not supplied then the width will be taken to be
textwid; if the height attribute is not supplied then the
height will be taken to be the number of text strings asso-
ciated with the object times textht. Initially textwid and
textht have a value of 0.
In (almost all) places where a quoted text string can be
used, an expression of the form
sprintf("format", arg,...)
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can also be used; this will produce the arguments formatted
according to format, which should be a string as described
in printf(3) appropriate for the number of arguments sup-
plied.
The thickness of the lines used to draw objects is con-
trolled by the linethick variable. This gives the thickness
of lines in points. A negative value means use the default
thickness: in TeX output mode, this means use a thickness of
8 milliinches; in TeX output mode with the -c option, this
means use the line thickness specified by .ps lines; in
troff output mode, this means use a thickness proportional
to the pointsize. A zero value means draw the thinnest pos-
sible line supported by the output device. Initially it has
a value of -1. There is also a thick[ness] attribute. For
example,
circle thickness 1.5
would draw a circle using a line with a thickness of 1.5
points. The thickness of lines is not affected by the value
of the scale variable, nor by the width or height given in
the .PS line.
Boxes (including boxes with rounded corners), circles and
ellipses can be filled by giving them an attribute of
fill[ed]. This takes an optional argument of an expression
with a value between 0 and 1; 0 will fill it with white, 1
with black, values in between with a proportionally gray
shade. A value greater than 1 can also be used: this means
fill with the shade of gray that is currently being used for
text and lines. Normally this will be black, but output
devices may provide a mechanism for changing this. Without
an argument, then the value of the variable fillval will be
used. Initially this has a value of 0.5. The invisible
attribute does not affect the filling of objects. Any text
associated with a filled object will be added after the
object has been filled, so that the text will not be
obscured by the filling.
Three additional modifiers are available to specify colored
objects: outline[d] sets the color of the outline, shaded
the fill color, and colo[u]r[ed] sets both. All three key-
words expect a suffix specifying the color, for example
circle shaded "green" outline "black"
Currently, color support isn't available in TeX mode. Pre-
defined color names for groff are in the device macro files,
for example ps.tmac; additional colors can be defined with
the .defcolor request (see the manual page of gtroff(1) for
more details).
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To change the name of the vbox in TeX mode, set the pseudo-
variable figname (which is actually a specially parsed com-
mand) within a picture. Example:
.PS
figname = foobar;
...
.PE
The picture is then available in the box \foobar.
pic assumes that at the beginning of a picture both glyph
and fill color are set to the default value.
Arrow heads will be drawn as solid triangles if the variable
arrowhead is non-zero and either TeX mode is enabled or the
-n option has not been given. Initially arrowhead has a
value of 1. Note that solid arrow heads are always filled
with the current outline color.
The troff output of pic is device-independent. The -T
option is therefore redundant. All numbers are taken to be
in inches; numbers are never interpreted to be in troff
machine units.
Objects can have an aligned attribute. This will only work
if the postprocessor is grops. Any text associated with an
object having the aligned attribute will be rotated about
the center of the object so that it is aligned in the direc-
tion from the start point to the end point of the object.
Note that this attribute will have no effect for objects
whose start and end points are coincident.
In places where nth is allowed `expr'th is also allowed.
Note that 'th is a single token: no space is allowed between
the ' and the th. For example,
for i = 1 to 4 do {
line from `i'th box.nw to `i+1'th box.se
}
CONVERSION
To obtain a stand-alone picture from a pic file, enclose
your pic code with .PS and .PE requests; roff configuration
commands may be added at the beginning of the file, but no
roff text.
It is necessary to feed this file into groff without adding
any page information, so you must check which .PS and .PE
requests are actually called. For example, the mm macro
package adds a page number, which is very annoying. At the
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moment, calling standard groff without any macro package
works. Alternatively, you can define your own requests,
e.g. to do nothing:
.de PS
..
.de PE
..
groff itself does not provide direct conversion into other
graphics file formats. But there are lots of possibilities
if you first transform your picture into PostScript(Reg.)
format using the groff option -Tps. Since this ps-file
lacks BoundingBox information it is not very useful by
itself, but it may be fed into other conversion programs,
usually named ps2other or pstoother or the like. Moreover,
the PostScript interpreter ghostscript (gs) has built-in
graphics conversion devices that are called with the option
gs -sDEVICE=<devname>
Call
gs --help
for a list of the available devices.
As the Encapsulated PostScript File Format EPS is getting
more and more important, and the conversion wasn't regarded
trivial in the past you might be interested to know that
there is a conversion tool named ps2eps which does the right
job. It is much better than the tool ps2epsi packaged with
gs.
For bitmapped graphic formats, you should use pstopnm; the
resulting (intermediate) PNM file can be then converted to
virtually any graphics format using the tools of the netpbm
package .
FILES
/usr/share/groff/1.19.2/tmac/pic.tmac
Example definitions of the PS and PE macros.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
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+---------------+-----------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------------+
|Availability | text/groff/groff-core |
+---------------+-----------------------+
|Stability | Uncommitted |
+---------------+-----------------------+
SEE ALSO
gtroff(1), groff_out(5), tex(1), gs(1), ps2eps(1),
pstopnm(1), ps2epsi(1), pnm(5)
Tpic: Pic for TeX
Brian W. Kernighan, PIC -- A Graphics Language for Typeset-
ting (User Manual). AT&T Bell Laboratories, Computing Sci-
ence Technical Report No. 116 <http://cm.bell-
labs.com/cm/cs/cstr/116.ps.gz> (revised May, 1991).
ps2eps is available from CTAN mirrors, e.g.
<ftp://ftp.dante.de/tex-archive/support/ps2eps/>
W. Richard Stevens - Turning PIC Into HTML
<http://www.kohala.com/start/troff/pic2html.html>
W. Richard Stevens - Examples of picMacros
<http://www.kohala.com/start/troff/pic.examples.ps>
BUGS
Input characters that are invalid for groff (i.e., those
with ASCII code 0, or 013 octal, or between 015 and 037
octal, or between 0200 and 0237 octal) are rejected even in
TeX mode.
The interpretation of fillval is incompatible with the pic
in 10th edition Unix, which interprets 0 as black and 1 as
white.
PostScript(Reg.) is a registered trademark of Adobe Systems
Incorporation.
NOTES
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://ftp.gnu.org/gnu/groff/groff-1.19.2.tar.gz
Further information about this software can be found on the
open source community website at http://www.gnu.org/soft-
ware/groff/.
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