Provided by: tk8.4-doc_8.4.19-4_all bug

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 values 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 ``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 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 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 distributed 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
       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
       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 either be the slave's parent (the default) or a  descendant
       of  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.

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.  Otherwise the master will obscure the slave
       and  it will appear as if the slave hasn't 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\nHand\nSide"
              label .r -text "Right\nHand\nSide"
              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(3tk), place(3tk)

KEYWORDS

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