pic
Copyright (C) 1989-2000, 2001, 2002 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
Permission is granted to copy and distribute modified versions of this
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permission notice identical to this one.
Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be included in
translations approved by the Free Software Foundation instead of in
the original English.
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NAME
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pic - compile pictures for troff or TeX
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SYNOPSIS
.
pic
[
-nvCSU
]
[
filename
...
]
pic -t [ -cvzCSU ] [ filename ... ] . .
pic -t [ -cvzCSU ] [ filename ... ] . .
DESCRIPTION
.
This manual page describes the GNU version of
R pic ,
which is part of the groff document formatting system.
pic
compiles descriptions of pictures embedded within
troff
or input files into commands that are understood by or
R troff .
Each picture starts with a line beginning with
.PS
and ends with a line beginning with
R .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
R -mpic :
these will center each picture.
.
.
OPTIONS
.
Options that do not take arguments may be grouped behind a single
R - .
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
R -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
mode.
.
-c
Be more compatible with
R tpic .
Implies
R -t .
Lines beginning with
\
are not passed through transparently.
Lines beginning with
.
are passed through with the initial
.
changed to
R .
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 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.
.
I -T dev
Generate output for the
troff
device
R 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
R pic .
Many of these differences also apply to newer versions of Unix
R pic .
A complete documentation is available in the file
\centerline{\box\graph}
Actually, since the vbox has a height of zero this will produce
slightly more vertical space above the picture than below it;
\centerline{\raise 1em\box\graph}
would avoid this.
You must use a 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
R \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
R expr1 .
While the value of
variable
is less than or equal to
R expr2 ,
do
body
and increment
variable
by
R expr3 ;
if
by
is not given, increment
variable
by 1.
If
expr3
is prefixed by
*
then
variable
will instead be multiplied by
R expr3 .
X
can be any character not occurring in
R body .
.
if expr then X if-true X
[else Y if-false Y]
Evaluate
R expr ;
if it is non-zero then do
R if-true ,
otherwise do
R if-false .
X
can be any character not occurring in
R if-true .
Y
can be any character not occurring in
R 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 .
Each
arg
must be an expression, a position, or text.
This has a similar effect to a line beginning with
.
or
R ,
but allows the values of variables to be passed through.
.
sh X command X
Pass
command
to a shell.
X
can be any character not occurring in
R 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
R filename ;
the line is split into blank-delimited words,
and occurrences of
I $ i
in
R body ,
for
i
between 1 and 9,
are replaced by the
R i -th
word of the line.
If
filename
is not given, lines are taken from the current input up to
R .PE .
If an
until
clause is specified,
lines will be read only until a line the first word of which is
R word ;
that line will then be discarded.
X
can be any character not occurring in
R 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
R thru .
.
reset
reset variable1[,] variable2 .\^.\^.
Reset pre-defined variables
R 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
R 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
R sprintf .
.
B 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
R 5 3 .
.
Arguments of the form
X anything X
are also allowed to be of the form
I { anything }
In this case
anything
can contain balanced occurrences of
{
and
R } .
Strings may contain
X
or imbalanced occurrences of
{
and
R } .
.
Expressions
. The syntax for expressions has been significantly extended: .B x ^ y
(exponentiation)
I sin( x )
I cos( x )
I atan2( y , x )
I log( x ) (base 10)
I exp( x ) (base 10, ie
I sqrt( x )
I int( x )
rand() (return a random number between 0 and 1)
I rand( x ) (return a random number between 1 and R x ; deprecated)
I srand( x ) (set the random number seed)
I max( e1 , e2 )
I min( e1 , e2 )
I ! e
e1 && e2
e1 || e2
e1 == e2
e1 != e2
e1 >= e2
e1 > e2
e1 <= e2
e1 < e2
"str1" == "str2"
"str1" != "str2"
.
I sin( x )
I cos( x )
I atan2( y , x )
I log( x ) (base 10)
I exp( x ) (base 10, ie
I sqrt( x )
I int( x )
rand() (return a random number between 0 and 1)
I rand( x ) (return a random number between 1 and R x ; deprecated)
I srand( x ) (set the random number seed)
I max( e1 , e2 )
I min( e1 , e2 )
I ! 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, R expr , is acceptable as an attribute; it is equivalent to R 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
R 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 legal.
.
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. .
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 and arcs can be dotted or dashed.
In mode splines can be dotted or dashed.
.
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.
.
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
R 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
R 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
I sprintf( format , arg ,...)
can also be used;
this will produce the arguments formatted according to
R 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 output mode, this means use a thickness of 8 milliinches;
in 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
R 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
R 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:
R outline [ d ]
sets the color of the outline,
shaded
the fill color, and
R 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 mode.
Predefined color names for
groff
are in the device macro files, for example
R ps.tmac ;
additional colors can be defined with the
.defcolor
request (see the manual page of
troff(1)
for more details).
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 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
R 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 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
B n th
is allowed
I ` expr 'th
is also allowed.
Note that
'th
is a single token: no space is allowed between the
'
and the
R 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 transform your picture
into PostScript® format using the
groff
option
R -Tps .
Since this
R ps -file
lacks BoundingBox information it is not very useful by itself, but it
may be fed into other conversion programs, usually named
I ps2 other
or
I psto other
or the like.
Moreover, the PostScript interpreter
ghostscript
(gs)
has built-in graphics conversion devices that are called with the option
I 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
R gs .
For bitmapped graphic formats, you should use
R 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/1.18.1/tmac/pic.tmac
Example definitions of the
PS
and
PE
macros.
.
.
SEE ALSO
Tpic: Pic for
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/>
<ftp://ftp.dante.de/tex-archive/support/ps2eps/>
W. Richard Stevens - Turning PIC Into HTML
<http://www.kohala.com/start/troff/pic2html.html>
<http://www.kohala.com/start/troff/pic2html.html>
W. Richard Stevens - Examples of picMacros
<http://www.kohala.com/start/troff/pic.examples.ps> . .
<http://www.kohala.com/start/troff/pic.examples.ps> . .
BUGS
.
Input characters that are invalid for
groff
(ie those with
ASCII
code 0, or 013 octal, or between 015 and 037 octal, or between 0200 and 0237
octal) are rejected even in 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.
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