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PIC(1)											   PIC(1)

       pic - compile pictures for troff or TeX

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

       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 cen-
       ter each picture.

       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

       -C     Recognize .PS and .PE even when followed by a character other than  space  or  new-

       -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 exten-
	      sions 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.

       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 doc-
       umentation is available in the file


   TeX mode
       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.

       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

       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

       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 dis-
	      carded.  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 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

       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 lim-
	      ited 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

		     x = 3
		     y = 3
		       x := 5
		       y = 5
		     print x " " y

	      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 }.

       The syntax for expressions has been significantly extended:

       x ^ y (exponentiation)
       atan2(y, x)
       log(x) (base 10)
       exp(x) (base 10, ie 10^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)
       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 max-
       psht.  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.

       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 verti-
       cally 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 tex-
       twid; if the height attribute is not supplied then the height will be taken to be the num-
       ber 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  sup-

       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
       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 key-
       words 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).

       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

       Objects can have an aligned attribute.  This will only work if 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 example,

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

       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 .

       /usr/share/groff/1.18.1/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)

       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.

       W. Richard Stevens - Turning PIC Into HTML

       W. Richard Stevens - Examples of picMacros

       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 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 1.18.1			20 September 2002				   PIC(1)
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