pack(n)			     Ck Built-In Commands		       pack(n)



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NAME
       pack - Geometry manager that packs around edges of cavity

SYNOPSIS
       pack option arg ?arg ...?
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DESCRIPTION
       The  pack  command  is  used to communicate with the packer, a geometry
       manager that arranges the children of a parent by packing them in order
       around  the edges of the parent.	 The pack command can have any of sev-
       eral forms, depending on the option argument:

       pack slave ?slave ...? ?options?
	      If the first argument to pack is a window name (any value start-
	      ing  with	 ``.''), then the command is processed in the same way
	      as pack configure.

       pack configure slave ?slave ...? ?options?
	      The arguments consist of the names of one or more slave  windows
	      followed	by  pairs  of arguments that specify how to manage the
	      slaves.  See ``THE PACKER ALGORITHM'' below for details  on  how
	      the  options  are used by the packer.  The following options are
	      supported:

	      -after other
		     Other must the name of another window.  Use its master as
		     the master for the slaves, and insert the slaves just af-
		     ter other in the packing order.

	      -anchor anchor
		     Anchor must be a valid anchor position such as n  or  sw;
		     it	 specifies where to position each slave in its parcel.
		     Defaults to center.

	      -before other
		     Other must the name of another window.  Use its master as
		     the master for the slaves, and insert the slaves just be-
		     fore other in the packing order.

	      -expand boolean
		     Specifies whether the slaves should be expanded  to  con-
		     sume  extra  space in their master.  Boolean may have any
		     proper boolean value, such as 1 or no.  Defaults to 0.

	      -fill style
		     If a slave's parcel is larger than its  requested	dimen-
		     sions,  this  option  may	be  used to stretch the slave.
		     Style must have one of the following values:

		     none   Give the slave its requested dimensions  plus  any
			    internal  padding requested with -ipadx or -ipady.
			    This is the default.

		     x	    Stretch the slave horizontally to fill the	entire
			    width of its parcel (except leave external padding
			    as specified by -padx).

		     y	    Stretch the slave vertically to  fill  the	entire
			    height  of	its parcel (except leave external pad-
			    ding as specified by -pady).

		     both   Stretch the slave  both  horizontally  and	verti-
			    cally.

	      -ipadx amount
		     Amount  specifies how much horizontal internal padding to
		     leave on each side of the slave(s).   Amount  must	 be  a
		     valid  screen distance, such as 2 or .5c.	It defaults to
		     0.

	      -ipady amount
		     Amount specifies how much vertical	 internal  padding  to
		     leave  on each side of the slave(s).  Amount  defaults to
		     0.

	      -padx amount
		     Amount specifies how much horizontal external padding  to
		     leave  on	each side of the slave(s).  Amount defaults to
		     0.

	      -pady amount
		     Amount specifies how much vertical	 external  padding  to
		     leave  on	each side of the slave(s).  Amount defaults to
		     0.

	      -side side
		     Specifies which side of the master the slave(s)  will  be
		     packed  against.	Must  be  left, right, top, or bottom.
		     Defaults to top.

	      If no -after or -before option is specified  then	 each  of  the
	      slaves  will  be inserted at the end of the packing list for its
	      parent unless it is already managed by the packer (in which case
	      it will be left where it is).  If one of these options is speci-
	      fied then all the slaves	will  be  inserted  at	the  specified
	      point.  If any of the slaves are already managed by the geometry
	      manager then any unspecified options for them retain their  pre-
	      vious values rather than receiving default values.

       pack forget slave ?slave ...?
	      Removes each of the slaves from the packing order for its master
	      and unmaps their windows.	 The slaves will no longer be  managed
	      by the packer.

       pack info slave
	      Returns  a  list	whose  elements	 are the current configuration
	      state of the slave given by slave in the same option-value  form
	      that  might  be specified to pack configure.  The first two ele-
	      ments of the list are ``-in master'' where master is the slave's
	      master.

       pack propagate master ?boolean?
	      If  boolean has a true boolean value such as 1 or on then propa-
	      gation is enabled for master, which must be a window  name  (see
	      ``GEOMETRY PROPAGATION'' below).	If boolean has a false boolean
	      value then propagation is disabled for  master.	In  either  of
	      these  cases an empty string is returned.	 If boolean is omitted
	      then the command returns 0 or 1 to indicate whether  propagation
	      is  currently enabled for master.	 Propagation is enabled by de-
	      fault.

       pack slaves master
	      Returns a list of all of the slaves in  the  packing  order  for
	      master.	The  order  of	the  slaves in the list is the same as
	      their order in the packing order.	 If master has no slaves  then
	      an empty string is returned.


THE PACKER ALGORITHM
       For  each  master the packer maintains an ordered list of slaves called
       the packing list.  The -in, -after, and -before	configuration  options
       are  used to specify the master for each slave and the slave's position
       in the packing list.  If none of these options is  given	 for  a	 slave
       then the slave is added to the end of the packing list for its parent.

       The  packer  arranges  the  slaves for a master by scanning the packing
       list in order.  At the time it processes each slave, a rectangular area
       within  the  master is still unallocated.  This area is called the cav-
       ity;  for the first slave it is the entire area of the master.

       For each slave the packer carries out the following steps:

       [1]    The packer allocates a rectangular parcel for  the  slave	 along
	      the  side	 of  the cavity given by the slave's -side option.  If
	      the side is top or bottom then the width of the  parcel  is  the
	      width  of	 the  cavity and its height is the requested height of
	      the slave plus the -ipady and -pady options.  For	 the  left  or
	      right  side the height of the parcel is the height of the cavity
	      and the width is the requested  width  of	 the  slave  plus  the
	      -ipadx  and  -padx  options.  The parcel may be enlarged further
	      because of the -expand option (see ``EXPANSION'' below)

       [2]    The packer chooses the dimensions of the slave.  The width  will
	      normally	be  the	 slave's requested width plus twice its -ipadx
	      option and the height will normally  be  the  slave's  requested
	      height  plus twice its -ipady option.  However, if the -fill op-
	      tion is x or both then the width of the  slave  is  expanded  to
	      fill  the width of the parcel, minus twice the -padx option.  If
	      the -fill option is y or both then the height of	the  slave  is
	      expanded	to fill the width of the parcel, minus twice the -pady
	      option.

       [3]    The packer positions the slave over its parcel.  If the slave is
	      smaller than the parcel then the -anchor option determines where
	      in the parcel the slave will be placed.  If -padx	 or  -pady  is
	      non-zero,	 then the given amount of external padding will always
	      be left between the slave and the edges of the parcel.

       Once a given slave has been packed, the area  of	 its  parcel  is  sub-
       tracted	from  the cavity, leaving a smaller rectangular cavity for the
       next slave.  If a slave doesn't use all of its parcel, the unused space
       in  the	parcel	will  not be used by subsequent slaves.	 If the cavity
       should become too small to meet the needs of a  slave  then  the	 slave
       will  be	 given	whatever  space	 is left in the cavity.	 If the cavity
       shrinks to zero size, then all remaining slaves	on  the	 packing  list
       will  be unmapped from the screen until the master window becomes large
       enough to hold them again.


EXPANSION
       If a master window is so large that there will be extra space left over
       after  all of its slaves have been packed, then the extra space is dis-
       tributed uniformly among all of the slaves for which the -expand option
       is  set.	  Extra	 horizontal  space is distributed among the expandable
       slaves whose -side is left or right, and extra vertical space  is  dis-
       tributed among the expandable slaves whose -side is top or bottom.


GEOMETRY PROPAGATION
       The packer normally computes how large a master must be to just exactly
       meet the needs of its slaves, and  it  sets  the	 requested  width  and
       height  of the master to these dimensions.  This causes geometry infor-
       mation to propagate up through a window hierarchy to a top-level window
       so  that	 the entire sub-tree sizes itself to fit the needs of the leaf
       windows.	 However, the pack propagate command may be used to  turn  off
       propagation  for	 one or more masters.  If propagation is disabled then
       the packer will not set the requested width and height of  the  packer.
       This  may  be  useful  if, for example, you wish for a master window to
       have a fixed size that you specify.


RESTRICTIONS ON MASTER WINDOWS
       The master for each slave must be the slave's parent  This  restriction
       is necessary to guarantee that the slave can be placed over any part of
       its master that is visible without danger of the slave being clipped by
       its parent.


KEYWORDS
       geometry manager, location, packer, parcel, propagation, size



Ck				      8.0			       pack(n)
