pic
compile pictures for troff or TeX
see also :
troff - tex - gs - pstopnm - ps2epsi
Synopsis
pic [
-nvCSU ] [ filename ... ]
pic -t [ -cvzCSU ] [ filename
... ]
add an example, a script, a trick and tips
examples
no example yet ...
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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
definitions 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
postprocessor 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 milliinches; a missing
argument restores the previous line thickness; the default
line thickness is 8 milliinches. 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 setting 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.
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
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® 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.
An alternative may be to use the -Tpdf option to convert
your picture directly into PDF format. The MediaBox of the
file produced can be controlled by passing a -P-p
papersize to groff.
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/1.22.1/tmac/pic.tmac
Example definitions of the PS and PE macros.
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 documentation is available in the file
/usr/share/doc/groff-base/pic.ms.gz
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 figname command to change the name of the
vbox. You must yourself 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 following
macro in your document:
\def\gpicbox#1{%
\vbox{\unvbox\csname #1\endcsname\kern 0pt}}
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 variable 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 occurring 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,
otherwise do if-false. X can be any character not
occurring 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]
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
filename; 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 character 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. 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 deprecated 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 }.
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 direction. 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 measurement
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
Text attributes can be compounded. For example,
"foo" above ljust
is valid.
There is no limit to the depth to which blocks can be examined.
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 corners can be dotted or dashed.
Boxes can have slanted sides. This effectively changes the shape
of a box from a rectangle to an arbitrary parallelogram. The
xslanted and yslanted attributes specify the x and
y offset of the box’s upper right corner from its default
position.
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 picture 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 associated 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,...)
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
supplied.
The thickness of the lines used to draw objects is controlled 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 possible 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 or slanted sides),
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
keywords expect a suffix specifying the color, for example
circle shaded "green" outline "black"
Currently, color support isn’t available in TeX mode. Predefined
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 troff(1)
for more details).
To change the name of the vbox in TeX mode, set the
pseudo-variable figname (which is actually a specially
parsed command) 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, or gropdf. 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 direction 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
}
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®
is a registered trademark of Adobe Systems
Incorporation.
see also
troff ,
groff_out, tex , gs ,
ps2eps, pstopnm , ps2epsi ,
pnm
Eric S.
Raymond, Making Pictures With GNU PIC.
/usr/share/doc/groff-base/pic.ps (this file, together with
its source file, pic.ms, is part of the groff
documentation)
Tpic: Pic for
TeX
Brian W.
Kernighan, PIC — A Graphics Language for
Typesetting (User Manual). AT&T Bell Laboratories,
Computing Science 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>