PACK(9) PACK(9)
NAME
pack - Geometry manager that packs around edges of cavity
SYNOPSIS
pack option arg ?arg ...?
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 be 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 be 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
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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 dist
Dist specifies how much horizontal internal
padding to leave on each side of the slave(s).
Dist must be a valid screen distance, such as 2 or
.5c. It defaults to 0.
-ipady dist
Dist specifies how much vertical internal padding
to leave on each side of the slave(s). Dist
defaults to 0.
-padx dist
Dist specifies how much horizontal external
padding to leave on each side of the slave(s).
Dist defaults to 0.
-pady dist
Dist specifies how much vertical external padding
to leave on each side of the slave(s). Dist
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
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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 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
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PACK(9) PACK(9)
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
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PACK(9) PACK(9)
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 a frame widget or the
top-level window (``.''). Widgets of other types can be
specifed as the master window but will give rise to
unpredictable results.
SEE ALSO
types(9)
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