# CentOS 7.0 - man page for gpic (centos section 1)

PIC(1)							      General Commands Manual							    PIC(1)

NAME
pic - compile pictures for troff or TeX

SYNOPSIS
pic [ -nvCSU ] [ filename ... ]
pic -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 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 pic-
ture.

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.

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-1.22.2/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 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  multi-
plicative  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  dimen-
sions 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 omit-
ted 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)  appro-
priate 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 vari-
able, 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 fill-
ing  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

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  pic-
ture.  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
}

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 trans-
form your picture into PostScript(R) 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 Post-
Script 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 graph-
ics format using the tools of the netpbm package .

FILES
/usr/share/groff/1.22.2/tmac/pic.tmac   Example definitions of the PS and PE macros.

troff(1), groff_out(5), tex(1), gs(1), ps2eps(1), pstopnm(1), ps2epsi(1), pnm(5)

Eric S. Raymond, Making Pictures With GNU PIC.
/usr/share/doc/groff-1.22.2/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>

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.

Groff Version 1.22.2						  7 February 2013							    PIC(1)`