pack(n) 						       Tk 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 several forms, depending on the option argument:

       pack slave ?slave ...? ?options?
	      If the first argument to pack is a window name (any value starting 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  after  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 before  other
		     in the packing order.

	      -expand boolean
		     Specifies	whether the slaves should be expanded to consume 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 dimensions, 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 padding as specified by
			    -pady).

		     both   Stretch the slave both horizontally and vertically.

	      -in other
		     Insert the slave(s) at the end of the packing order for the master window given by other.

	      -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 may be a list of two
		     values to specify padding for left and right separately.  Amount defaults to 0.

	      -pady amount
		     Amount specifies how much vertical external padding to leave on each side of the slave(s).  Amount may be a list of two  val-
		     ues to specify padding for top and bottom separately.  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 -in, -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 specified
	      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 previous 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 elements 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 propagation is enabled for master, which must be a window name (see GEOME-
	      TRY 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 default.

       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 cavity;  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 option 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 subtracted from the cavity, leaving a smaller rectangular cavity for the next
       slave.  If a slave does not 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
       distributed uniformly among all of the slaves for which the -expand option is set.  Extra horizontal space is distributed among the expand-
       able slaves whose -side is left or right, and extra vertical space is distributed 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 information to propagate up through a window hierarchy to a top-level  win-
       dow 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 either be the slave's parent (the default) or a descendant of the slave's parent.  This restriction is nec-
       essary 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.

PACKING ORDER

       If the master for a slave is not its parent then you must make sure that the slave is higher in the stacking order than the master.  Other-
       wise the master will obscure the slave and it will appear as if the slave has not been packed correctly.  The easiest way to make sure  the
       slave  is  higher  than	the master is to create the master window first:  the most recently created window will be highest in the stacking
       order.  Or, you can use the raise and lower commands to change the stacking order of either the master or the slave.

EXAMPLE

	      # Make the widgets
	      label .t -text "This widget is at the top"    -bg red
	      label .b -text "This widget is at the bottom" -bg green
	      label .l -text "Left
Hand
Side"
	      label .r -text "Right
Hand
Side"
	      text .mid
	      # Lay them out
	      pack .t	-side top    -fill x
	      pack .b	-side bottom -fill x
	      pack .l	-side left   -fill y
	      pack .r	-side right  -fill y
	      pack .mid -expand 1    -fill both

SEE ALSO

       grid(n), place(n)

KEYWORDS

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

Tk									4.0								   pack(n)