Dmitry Karasik > Prima > Prima::Widget::pack

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NAME ^

Prima::Widget::pack - Geometry manager that packs around edges of cavity

SYNOPSIS ^

  $widget-> pack( args);

  $widget-> packInfo( args);
  $widget-> geometry( gt::Pack);

DESCRIPTION ^

The pack method is used to communicate with the packer, a geometry manager that arranges the children of a owner by packing them in order around the edges of the owner.

In this port of Tk::pack it is normal to pack widgets one-at-a-time using the widget object to be packed to invoke a method call. This is a slight distortion of the original Tcl-Tk interface (which can handle lists of windows to one pack method call) but Tk reports that it has proven effective in practice.

The pack method can have any of several forms, depending on Option:

pack %OPTIONS

The options consist of pairs of arguments that specify how to manage the slave. 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 another window. Use its master as the master for the slave, and insert the slave 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 another window. Use its master as the master for the slave, and insert the slave just before $other in the packing order.

expand => boolean

Specifies whether the slave 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 => $master

Insert the slave(s) at the end of the packing order for the master window given by $master. Currently, only the immediate owner can be accepted as master.

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 in, after or before option is specified then slave will be inserted at the end of the packing list for its owner 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 slave will be inserted at the specified point. If the slave are already managed by the geometry manager then any unspecified options for them retain their previous values rather than receiving default values.

packForget

Removes slave from the packing order for its master and unmaps its window. The slave will no longer be managed by the packer.

packInfo [ %OPTIONS ]

In get-mode, returns a list whose elements are the current configuration state of the slave given by $slave. The first two elements of the list are ``in=>$master'' where $master is the slave's master.

In set-mode, sets all pack parameters, but does not set widget geometry property to gt::Pack.

packPropagate BOOLEAN

If boolean has a true boolean value then propagation is enabled for $master, (see "Geometry propagation" below). If boolean has a false boolean value then propagation is disabled for $master. If boolean is omitted then the method returns 0 or 1 to indicate whether propagation is currently enabled for $master.

Propagation is enabled by default.

packSlaves

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 list/string is returned in array/scalar context, respectively

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 owner.

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:

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 geometryPropagate method 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 not be a child of the slave, and must not be present in any other list of slaves that directly or indirectly refers to the slave.

Packing order ^

If the master for a slave is not its owner 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 bring_to_front and send_to_back methods to change the stacking order of either the master or the slave.

SEE ALSO ^

Prima, Prima::Widget

Tk::pack Tk::place

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