1pack(3) User Contributed Perl Documentation pack(3)
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6 Tk::pack - Geometry manager that packs around edges of cavity
7
9 $widget->pack?(args)?
10 $widget->packOption?(args)?
12
14 The pack method is used to communicate with the packer, a geometry
15 manager that arranges the children of a parent by packing them in order
16 around the edges of the parent.
17 In this perl port of Tk it is normal to pack widgets one-at-a-time
19 using the widget object to be packed to invoke a method call. This is
20 a slight distortion of underlying Tk interface (which can handle lists
21 of windows to one pack method call) but has proven effective in
22 practice.
23 The pack method can have any of several forms, depending on Option:
25 $slave->pack?(options)?
27 The options consist of pairs of arguments that specify how to
28 manage the slave. See "THE PACKER ALGORITHM" below for details on
29 how the options are used by the packer. The following options are
30 supported:
31 -after => $other
33 $other must be another window. Use its master as the
34 master for the slave, and insert the slave just after
35 $other in the packing order.
36 -anchor => anchor
38 Anchor must be a valid anchor position such as n or sw; it
39 specifies where to position each slave in its parcel.
40 Defaults to center.
41 -before => $other
43 $other must be another window. Use its master as the
44 master for the slave, and insert the slave just before
45 $other in the packing order.
46 -expand => boolean
48 Specifies whether the slave should be expanded to consume
49 extra space in their master. Boolean may have any proper
50 boolean value, such as 1 or no. Defaults to 0.
51 -fill => style
53 If a slave's parcel is larger than its requested
54 dimensions, this option may be used to stretch the slave.
55 Style must have one of the following values:
56 none Give the slave its requested dimensions plus
58 any internal padding requested with -ipadx or
59 -ipady. This is the default.
60 x Stretch the slave horizontally to fill the
62 entire width of its parcel (except leave
63 external padding as specified by -padx).
64 y Stretch the slave vertically to fill the entire
66 height of its parcel (except leave external
67 padding as specified by -pady).
68 both Stretch the slave both horizontally and
70 vertically.
71 -in => $master
73 Insert the slave(s) at the end of the packing order for the
74 master window given by $master.
75 -ipadx => amount
77 Amount specifies how much horizontal internal padding to
78 leave on each side of the slave(s). Amount must be a valid
79 screen distance, such as 2 or .5c. It defaults to 0.
80 -ipady => amount
82 Amount specifies how much vertical internal padding to
83 leave on each side of the slave(s). Amount defaults to 0.
84 -padx => amount
86 Amount specifies how much horizontal external padding to
87 leave on each side of the slave(s). Amount defaults to 0.
88 -pady => amount
90 Amount specifies how much vertical external padding to
91 leave on each side of the slave(s). Amount defaults to 0.
92 -side => side
94 Specifies which side of the master the slave(s) will be
95 packed against. Must be left, right, top, or bottom.
96 Defaults to top.
97 If no -in, -after or -before option is specified then slave will be
99 inserted at the end of the packing list for its parent unless it is
100 already managed by the packer (in which case it will be left where it
101 is). If one of these options is specified then slave will be inserted
102 at the specified point. If the slave are already managed by the
103 geometry manager then any unspecified options for them retain their
104 previous values rather than receiving default values.
105 $slave->packConfigure?(options)?
107 Same as pack.
108 $slave->packForget
110 Removes slave from the packing order for its master and unmaps its
111 window. The slave will no longer be managed by the packer.
112 $slave->packInfo
114 Returns a list whose elements are the current configuration state
115 of the slave given by $slave in the same option-value form that
116 might be specified to packConfigure. The first two elements of the
117 list are ``-in=>$master'' where $master is the slave's master.
118 $master->packPropagate?(boolean)?
120 If boolean has a true boolean value such as 1 or on then
121 propagation is enabled for $master, (see "GEOMETRY PROPAGATION"
122 below). If boolean has a false boolean value then propagation is
123 disabled for $master. In either of these cases an empty string is
124 returned. If boolean is omitted then the method returns 0 or 1 to
125 indicate whether propagation is currently enabled for $master.
126 Propagation is enabled by default.
127 $master->packSlaves
129 Returns a list of all of the slaves in the packing order for
130 $master. The order of the slaves in the list is the same as their
131 order in the packing order. If $master has no slaves then an empty
132 list/string is returned in array/scalar context, respectively
133
135 For each master the packer maintains an ordered list of slaves called
136 the packing list. The -in, -after, and -before configuration options
137 are used to specify the master for each slave and the slave's position
138 in the packing list. If none of these options is given for a slave
139 then the slave is added to the end of the packing list for its parent.
140 The packer arranges the slaves for a master by scanning the packing
142 list in order. At the time it processes each slave, a rectangular area
143 within the master is still unallocated. This area is called the
144 cavity; for the first slave it is the entire area of the master.
145 For each slave the packer carries out the following steps:
147 [1] The packer allocates a rectangular parcel for the slave along the
149 side of the cavity given by the slave's -side option. If the side
150 is top or bottom then the width of the parcel is the width of the
151 cavity and its height is the requested height of the slave plus the
152 -ipady and -pady options. For the left or right side the height of
153 the parcel is the height of the cavity and the width is the
154 requested width of the slave plus the -ipadx and -padx options.
155 The parcel may be enlarged further because of the -expand option
156 (see "EXPANSION" below)
157 [2] The packer chooses the dimensions of the slave. The width will
159 normally be the slave's requested width plus twice its -ipadx
160 option and the height will normally be the slave's requested height
161 plus twice its -ipady option. However, if the -fill option is x or
162 both then the width of the slave is expanded to fill the width of
163 the parcel, minus twice the -padx option. If the -fill option is y
164 or both then the height of the slave is expanded to fill the width
165 of the parcel, minus twice the -pady option.
166 [3] The packer positions the slave over its parcel. If the slave is
168 smaller than the parcel then the -anchor option determines where in
169 the parcel the slave will be placed. If -padx or -pady is non-
170 zero, then the given amount of external padding will always be left
171 between the slave and the edges of the parcel.
172 Once a given slave has been packed, the area of its parcel is
174 subtracted from the cavity, leaving a smaller rectangular cavity
175 for the next slave. If a slave doesn't use all of its parcel, the
176 unused space in the parcel will not be used by subsequent slaves.
177 If the cavity should become too small to meet the needs of a slave
178 then the slave will be given whatever space is left in the cavity.
179 If the cavity shrinks to zero size, then all remaining slaves on
180 the packing list will be unmapped from the screen until the master
181 window becomes large enough to hold them again.
182
184 If a master window is so large that there will be extra space left over
185 after all of its slaves have been packed, then the extra space is
186 distributed uniformly among all of the slaves for which the -expand
187 option is set. Extra horizontal space is distributed among the
188 expandable slaves whose -side is left or right, and extra vertical
189 space is distributed among the expandable slaves whose -side is top or
190 bottom.
191
193 The packer normally computes how large a master must be to just exactly
194 meet the needs of its slaves, and it sets the requested width and
195 height of the master to these dimensions. This causes geometry
196 information to propagate up through a window hierarchy to a top-level
197 window so that the entire sub-tree sizes itself to fit the needs of the
198 leaf windows. However, the packPropagate method may be used to turn
199 off propagation for one or more masters. If propagation is disabled
200 then the packer will not set the requested width and height of the
201 packer. This may be useful if, for example, you wish for a master
202 window to have a fixed size that you specify.
203
205 The master for each slave must either be the slave's parent (the
206 default) or a descendant of the slave's parent. This restriction is
207 necessary to guarantee that the slave can be placed over any part of
208 its master that is visible without danger of the slave being clipped by
209 its parent.
210
212 If the master for a slave is not its parent then you must make sure
213 that the slave is higher in the stacking order than the master.
214 Otherwise the master will obscure the slave and it will appear as if
215 the slave hasn't been packed correctly. The easiest way to make sure
216 the slave is higher than the master is to create the master window
217 first: the most recently created window will be highest in the
218 stacking order. Or, you can use the raise and lower methods to change
219 the stacking order of either the master or the slave.
220
222 Tk::form Tk::grid Tk::place
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225 geometry manager, location, packer, parcel, propagation, size
226perl v5.16.3 2014-06-10 pack(3)