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pack(3tk) Tk Built-In Commands pack(3tk) 





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:



  

  
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.

  

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







  

  
Other must the name of another window. Use its container as the
      container for the content, and insert the content just after other
      in the packing order.

  

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

  

  
Other must the name of another window. Use its container as the
      container for the content, and insert the content just before other
      in the packing order.

  

  
Specifies whether the content should be expanded to consume extra space in
      their container. Boolean may have any proper boolean value, such as
      1 or no. Defaults to 0.

  

  
If a content's parcel is larger than its requested dimensions, this option
      may be used to stretch the content. Style must have one of the
      following values:







  

  
Give the content its requested dimensions plus any internal padding
      requested with -ipadx or -ipady. This is the default.

  

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

  

  
Stretch the content vertically to fill the entire height of its parcel
      (except leave external padding as specified by -pady).

  

  
Stretch the content both horizontally and vertically.







  

  
Insert the window at the end of the packing order for the container window
      given by container.

  

  
Amount specifies how much horizontal internal padding to leave on
      each side of the content. Amount must be a valid screen distance,
      such as 2 or .5c. It defaults to 0.

  

  
Amount specifies how much vertical internal padding to leave on
      each side of the content. Amount defaults to 0.

  

  
Amount specifies how much horizontal external padding to leave on
      each side of the content. Amount may be a list of two values to
      specify padding for left and right separately. Amount defaults to
      0.

  

  
Amount specifies how much vertical external padding to leave on
      each side of the content. Amount may be a list of two values to
      specify padding for top and bottom separately. Amount defaults to
      0.

  

  
Specifies which side of the container the content 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 content 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 content will be inserted at the specified point. If
    any of the content are already managed by the geometry manager then any
    unspecified options for them retain their previous values rather than
    receiving default values.





  

  
Removes each of the windows from the packing order for its
      container and unmaps their windows. The content will no longer be managed
      by the packer.

  

  
Returns a list whose elements are the current configuration state of the
      window given by window in the same option-value form that might be
      specified to pack configure. The first two elements of the list are
      “-in container” where container is the
      window's container.

  

  
If boolean has a true boolean value such as 1 or on
      then propagation is enabled for container, which must be a window
      name (see GEOMETRY PROPAGATION below). If boolean has a
      false boolean value then propagation is disabled for container. 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 container. Propagation is
      enabled by default.

  

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

  

  
Synonym for pack slaves window.








THE PACKER ALGORITHM


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


The packer arranges the content windows for a container by
    scanning the packing list in order. At the time it processes each content, a
    rectangular area within the container is still unallocated. This area is
    called the cavity; for the first content it is the entire area of the
    container.


For each content the packer carries out the following steps:



  
[1]

  
The packer allocates a rectangular parcel for the content along the
      side of the cavity given by the content'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 content 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 content 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 content. The width will normally
      be the content's requested width plus twice its -ipadx option and
      the height will normally be the content's requested height plus twice its
      -ipady option. However, if the -fill option is x or
      both then the width of the content 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 content is
      expanded to fill the width of the parcel, minus twice the -pady
      option.

  
[3]

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




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




EXPANSION


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






GEOMETRY PROPAGATION


The packer normally computes how large a container must be to just
    exactly meet the needs of its content, and it sets the requested width and
    height of the container 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 containers. 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 container window to have a fixed
    size that you specify.








RESTRICTIONS ON CONTAINER WINDOWS


The container for each content must either be the content's parent
    (the default) or a descendant of the content's parent. This restriction is
    necessary to guarantee that the content can be placed over any part of its
    container that is visible without danger of the content being clipped by its
    parent.






PACKING ORDER


If the container for a content is not its parent then you must
    make sure that the content is higher in the stacking order than the
    container. Otherwise the container will obscure the content and it will
    appear as if the content has not been packed correctly. The easiest way to
    make sure the content is higher than the container is to create the
    container 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 container or the
    content.






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
.mid insert end "This layout is like Java's BorderLayout"
# 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







  

    4.0
    Tk