Provided by: groff-base_1.23.0-5_amd64 bug

Name

       pic - compile pictures for troff or TeX

Synopsis

       pic [-CnSU] [file ...]

       pic -t [-cCSUz] [file ...]

       pic --help

       pic -v
       pic --version

Description

       The  GNU  implementation  of  pic  is part of the groff(1) document formatting system.  pic is a troff(1)
       preprocessor that translates descriptions of diagrammatic pictures embedded in roff(7) or TeX input files
       into the language understood by TeX or troff.  It copies the contents of each file to the standard output
       stream, except that lines between .PS and any of .PE, .PF, or .PY are interpreted as picture descriptions
       in  the  pic  language.   End  a  pic picture with .PE to leave the drawing position at the bottom of the
       picture, and with .PF or .PY to leave it at the top.  Normally, pic is not executed directly by the user,
       but  invoked by specifying the -p option to groff(1).  If no file operands are given on the command line,
       or if file is “-”, the standard input stream is read.

       It is the user's responsibility to provide appropriate definitions of the PS, PE, and one or both of  the
       PF  and  PY macros.  When a macro package does not supply these, obtain simple definitions with the groff
       option -mpic; these will center each picture.

       GNU pic supports PY as a synonym of PF to work around a name space collision with the mm  macro  package,
       which defines PF as a page footer management macro.  Use PF preferentially unless a similar problem faces
       your document.

Options

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

       -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.

       -C     Recognize .PS, .PE, .PF, and .PY even when followed by a character other than space or newline.

       -n     Don't use groff extensions to the troff drawing commands.  Specify this option if a  postprocessor
              you're using doesn't support these extensions, described in groff_out(5).  This option also causes
              pic not to use zero-length lines to draw dots in troff mode.

       -S     Operate in safer mode; sh commands are ignored.  This mode, enabled by default, can be useful when
              operating on untrustworthy input.

       -t     Produce TeX output.

       -U     Operate in unsafe mode; sh commands are interpreted.

       -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.  GNU pic always does this.

       -T dev Generate  output for the troff device dev.  This is unnecessary because the troff output generated
              by GNU pic is device-independent.

Usage

       This section primarily discusses the differences between GNU pic and the  Eighth  Edition  Research  Unix
       version of AT&T pic (1985).  Many of these differences also apply to later versions of AT&T pic.

   TeX mode
       TeX-compatible  output  is  produced  when  the  -t  option is specified.  You must use a TeX driver that
       supports tpic version 2 specials.  (tpic was a fork of AT&T pic  by  Tim  Morgan  of  the  University  of
       California  at  Irvine that diverged from its source around 1984.  It is best known today for lending its
       name to a group of \special commands it produced for TeX.)

       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 the value of \baselineskip.
       Anything else may well produce undesirable results; use at your own risk.  By  default,  lines  beginning
       with a dot are not treated specially—but see the -c option.

       In  TeX  mode,  pic  will define a vbox called \graph for each picture.  Use GNU pic's figname command to
       change the name of the vbox.  You must print that vbox yourself using the command
              \centerline{\box\graph}
       for instance.  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  give  the  vbox  a  positive  height  and  a  depth of zero (as used by LaTeX's
       graphics.sty, for example) define the following macro in your document.
              \def\gpicbox#1{%
                \vbox{\unvbox\csname #1\endcsname\kern 0pt}}
       You can then simply say \gpicbox{graph} instead of \box\graph.

   Commands
       Several commands new to GNU pic accept delimiters, shown in their synopses as braces  {  }.   Nesting  of
       braces  is  supported.  Any other characters (except a space, tab, or newline) may be used as alternative
       delimiters, in which case the members of a given pair must be identical.  Strings are  recognized  within
       delimiters of either kind; they may contain the delimiter character or unbalanced braces.

       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 and write arguments to the standard error stream followed by a newline.  Each arg must
              be an expression, a position, or text.  This is useful for debugging.

       command arg ...
              Concatenate arguments and pass them as a line to troff or TeX.  Each arg must be an expression,  a
              position, or text.  command allows the values of pic variables to be passed to the formatter.  For
              example,
                     .PS
                     x = 14
                     command ".ds string x is " x "."
                     .PE
                     \*[string]
              produces
                     x is 14.
              when formatted with troff.

       sh X command X
              Pass command to a shell.

       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
              and
                     .PS
                     circle at (1,2)
                     circle at (3,4)
                     circle at (5,6)
                     box
                     .PE
              are equivalent.  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.  The argument after thru is
              looked up as a macro name first;  if  not  defined,  its  first  character  is  interpreted  as  a
              delimiter.

       reset
       reset pvar1[,] pvar2 ...
              Reset  predefined  variables  pvar1, pvar2 ... to their default values; if no arguments are given,
              reset all predefined variables to their default  values.   Variable  names  may  be  separated  by
              commas,  spaces,  or  both.   Assigning a value to scale also causes all predefined 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.

       var := expr
              This syntax resembles variable assignment with = except that var must already be defined, and expr
              will  be  assigned to var without creating a variable local to the current block.  (By contrast, =
              defines var in the current block if it is not already defined there, and then changes the value in
              the current block only.)  For example,
                     .PS
                     x = 3
                     y = 3
                     [
                     x := 5
                     y = 5
                     ]
                     print x   y
                     .PE
              writes
                     5 3
              to the standard error stream.

   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, i.e. 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.  GNU pic
       will always scale a picture by the same amount vertically as well as  horizontally.   This  is  different
       from 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.  Only the modifiers “#”, “-”,
       “+”,  and  “  ” [space]), a minimum field width, an optional precision, and the conversion specifiers %e,
       %E, %f, %g, %G, and %% are supported.

       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.

       Additional modifiers are available to draw colored objects: outline[d] sets the  color  of  the  outline,
       shaded  the  fill  color, and colo[u]r[ed] sets both.  All expect a subsequent string argument specifying
       the color.
              circle shaded "green" outline "black"
       Color is not yet supported in TeX mode.  Device macro files like ps.tmac declare  color  names;  you  can
       define additional ones with the defcolor request (see groff(7)).

       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.  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(1) or
       gropdf(1).  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.  This attribute will have no effect on objects whose start and end points are coincident.

       In places where nth is allowed, 'expr'th is also allowed.  “'th“ is a single token: no space  is  allowed
       between the apostrophe 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 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(1)) 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(5)  file  can  be
       then converted to virtually any graphics format using the tools of the netpbm package.

Files

       /usr/share/groff/1.23.0/tmac/pic.tmac
              offers simple definitions of the PS, PE, PF, and PY macros.

Bugs

       Characters  that  are  invalid as input to GNU troff (see the groff Texinfo manual or groff_char(7) for a
       list) are rejected even in TeX mode.

       The interpretation of fillval is incompatible  with  the  pic  in  Tenth  Edition  Research  Unix,  which
       interprets 0 as black and 1 as white.

See also

       /usr/share/doc/groff-base/pic.ps.gz
              “Making  Pictures with GNU pic”, by Eric S. Raymond.  This file, together with its source, pic.ms,
              is part of the groff distribution.

       “PIC—A Graphics Language for Typesetting: User Manual”, by Brian W. Kernighan, 1984 (revised 1991),  AT&T
       Bell Laboratories Computing Science Technical Report No. 116

       ps2eps is available from CTAN mirrors, e.g., ⟨ftp://ftp.dante.de/tex-archive/support/ps2eps/⟩

       W. Richard Stevens, Turning PIC into HTMLhttp://www.kohala.com/start/troff/pic2html.html⟩

       W. Richard Stevens, Examples of pic Macroshttp://www.kohala.com/start/troff/pic.examples.pstroff(1), groff_out(5), tex(1), gs(1), ps2eps(1), pstopnm(1), ps2epsi(1), pnm(5)