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NAME    [Toc]    [Back]

       pic - compile pictures for troff or TeX

SYNOPSIS    [Toc]    [Back]

       pic [ -nvCSU ] [ filename ...  ]
       pic -t [ -cvzCSU ] [ filename ...  ]

DESCRIPTION    [Toc]    [Back]

       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    [Toc]    [Back]

       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 zerolength
 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 nonnegative
 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

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

USAGE    [Toc]    [Back]

       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.

   TeX mode    [Toc]    [Back]
       TeX mode is enabled by the -t option.  In TeX mode, pic will  define  a
       vbox called \graph for each picture.  You must yourself print that vbox
       using, for example, the command


       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 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    [Toc]    [Back]
       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.  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  orTeX.   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.

       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,

		     copy thru % circle at ($1,$2) % until "END"
		     1 2
		     3 4
		     5 6

	      is equivalent to

		     circle at (1,2)
		     circle at (3,4)
		     circle at (5,6)

	      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 variable1, variable2 ...
	      Reset  pre-defined  variables  variable1, variable2 ... to their
	      default values.  If no  arguments  are  given,  reset  all  predefined
  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.

	      This is similar to = except variable must  already  be  defined,
	      and  the value of variable will be changed only in the innermost
	      block in which it is defined.  (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.)

       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    [Toc]    [Back]
       The syntax for expressions has been significantly extended:

       x ^ y (exponentiation)
       atan2(y, x)
       log(x) (base 10)
       exp(x) (base 10, ie 10x)
       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)
       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    [Toc]    [Back]
       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  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 legal.

       There is no limit to the depth to which blocks can  be  examined.   For
	      [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 and arcs can be dotted or dashed.  In TeX 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 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  places where a quoted text string can be used, an expression of the

	      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, using only the e, f, g  or  %
       format characters.

       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), circles and ellipses can
       be filled by giving then 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.

       Arrow heads will be drawn as solid triangles if the variable  arrowhead
       is  non-zero  and  either TeX mode is enabled or the -x option has been
       given.  Initially arrowhead has a value of 1.

       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  when  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 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

	      for i = 1 to 4 do {
		 line from `i'th box.nw to `i+1'th box.se

CONVERSION    [Toc]    [Back]

       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(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 PostScript
 interpreter ghostscript (gs) has	built-in  graphics  conversion
       devices that are called with the option

	      gs -sDEVICE=<devname>

	      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    [Toc]    [Back]

	      Example definitions of the PS and PE macros.

SEE ALSO    [Toc]    [Back]

       troff(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  Typesetting  (User
       Manual).   AT&T	Bell  Laboratories, Computing Science Technical Report
       No. 116	 <URL:http://cm.bell-labs.com/cm/cs/cstr/116.ps.gz>   (revised
       May, 1991).

       ps2eps is available from CTAN mirrors, e.g.

       W. Richard Stevens - Turning PIC Into HTML

       W. Richard Stevens - Examples of picMacros

BUGS    [Toc]    [Back]

       Input characters that are illegal for groff (ie those with ASCII code 0
       or between 013 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(R) is a registered trademark of Adobe Systems Incorporation.

Groff Version 1.17.2		 27 June 2001				PIC(1)
[ Back ]
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