TkPack( SlaveWidgetName, [SlaveWidgetName]..., [Options]...)

Geometry manager that packs around edges of cavity.

Arguments:

SlaveWidgetName - a standard path-like name used to name the widget that names one or many "slave" widgets to be placed by the geometry manager.

Options - one or many descriptors for the options that are available to pack the widgets.

Options:

after - the name of another widget. Use its master as the master for the slaves, and insert the slaves just after it in the packing order.

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 - must the name of another widget. Use its master as the master for the slaves, and insert the slaves just before it in the packing order.

expand - Specifies whether the slaves should be expanded to consume extra space in their master. May have any proper boolean value, such as 1 or no. Defaults to 0.

fill - 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 - Insert the slave(s) at the end of the packing order for the master widget given by this value.

ipadx - specifies how much horizontal internal padding to leave on each side of the slave(s). The value must be a valid screen distance, such as 2 or .5c. It defaults to 0.

ipady - specifies how much vertical internal padding to leave on each side of the slave(s). The value defaults to 0.

padx - specifies how much horizontal external padding to leave on each side of the slave(s). Defaults to 0.

pady - specifies how much vertical external padding to leave on each side of the slave(s). Defaults to 0.

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.

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. Once a widget is packed, it is considered part of its parent window and is able to be displayed.

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 widget becomes large enough to hold them again.

RESTRICTIONS ON MASTER WIDGETS
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 widget first: the most recently created widget 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.