grid(3)
NAME
Tk::grid - Geometry manager that arranges widgets in a
grid
SYNOPSIS
$widget->grid?(?widget ...,? ?arg ?...>?)? $widget->gridOption?(arg ?,arg ...?)?
DESCRIPTION
The grid method is used to communicate with the grid geom
etry manager that arranges widgets in rows and columns
inside of another window, called the geometry master (or
master window). The grid method can have any of several
forms, depending on the option argument:
- $slave->grid(?$slave, ...??, options?)
- The arguments consist of the optional references to
more slave windows followed by pairs of arguments that
specify how to manage the slaves. The characters -,
x and ^, can be specified instead of a window refer
ence to alter the default location of a $slave, as
described in "RELATIVE PLACEMENT", below. - If any of the slaves are already managed by the geome
try manager then any unspecified options for them
retain their previous values rather than receiving
default values. - The following options are supported:
- -column => n
Insert the $slave so that it occupies the nth column in the grid. Column numbers start with
0. If this option is not supplied, then the
$slave is arranged just to the right of previ
ous slave specified on this call to grid, or
column "0" if it is the first slave. For each
x that immediately precedes the $slave, the
column position is incremented by one. Thus
the x represents a blank column for this row
in the grid. - -columnspan => n
Insert the slave so that it occupies n columns
in the grid. The default is one column,
unless the window name is followed by a -, in
which case the columnspan is incremented once
for each immediately following -. - -in => $other
Insert the slave(s) in the master window given
by $other. The default is the first slave's
parent window. - -ipadx => amount
The amount specifies how much horizontal
internal padding to leave on each side of the
slave(s). This is space is added inside the
slave(s) border. The amount must be a valid
screen distance, such as 2 or '.5c'. It
defaults to 0. - -ipady => amount
The amount specifies how much vertical inter
nal padding to leave on on the top and bottom
of the slave(s). This space is added inside
the slave(s) border. The amount defaults to
0. - -padx => amount
The amount specifies how much horizontal
external padding to leave on each side of the
slave(s), in screen units. The amount
defaults to 0. This space is added outside
the slave(s) border. - -pady => amount
The amount specifies how much vertical exter
nal padding to leave on the top and bottom of
the slave(s), in screen units. The amount
defaults to 0. This space is added outside
the slave(s) border. - -row => n
Insert the slave so that it occupies the nth
row in the grid. Row numbers start with 0.
If this option is not supplied, then the slave
is arranged on the same row as the previous
slave specified on this call to grid, or the
first unoccupied row if this is the first
slave. - -rowspan => n
Insert the slave so that it occupies n rows in
the grid. The default is one row. If the
next grid method contains ^ characters instead
of $slaves that line up with the columns of
this $slave, then the rowspan of this $slave is extended by one. - -sticky => style
If a slave's cell is larger than its requested
dimensions, this option may be used to posi
tion (or stretch) the slave within its cell.
Style is a string that contains zero or more
of the characters n, s, e or w. The string
can optionally contain spaces or commas, but
they are ignored. Each letter refers to a
side (north, south, east, or west) that the
slave will "stick" to. If both n and s (or e
and w) are specified, the slave will be
stretched to fill the entire height (or width)
of its cavity. The sticky option subsumes the combination of -anchor and -fill that is used by pack. The default is '', which causes the
slave to be centered in its cavity, at its
requested size. - $master->gridBbox(?column, row,? ?column2, row2?)
With no arguments, the bounding box (in pixels) of the
grid is returned. The return value consists of 4
integers. The first two are the pixel offset from the
master window (x then y) of the top-left corner of the
grid, and the second two integers are the width and
height of the grid, also in pixels. If a single col_
umn and row is specified on the command line, then the bounding box for that cell is returned, where the top
left cell is numbered from zero. If both column and
row arguments are specified, then the bounding box
spanning the rows and columns indicated is returned. - $master->gridColumnconfigure(index?, -option=>value, ...?)
Query or set the column properties of the index column
of the geometry master, $master. The valid options
are -minsize, -weight and -pad. If one or more options are provided, then index may be given as a
list of column indices to which the configuration
options will operate on. The -minsize option sets the minimum size, in screen units, that will be permitted
for this column. The -weight option (an integer
value) sets the relative weight for apportioning any
extra spaces among columns. A weight of zero (0)
indicates the column will not deviate from its
requested size. A column whose weight is two will
grow at twice the rate as a column of weight one when
extra space is allocated to the layout. The -pad
option specifies the number of screen units that will
be added to the largest window contained completely in
that column when the grid geometry manager requests a
size from the containing window. If only an option is
specified, with no value, the current value of that
option is returned. If only the master window and
index is specified, all the current settings are
returned in an list of "-option value" pairs. - $slave->gridConfigure(?$slave, ...?, options?) The same as grid method.
- $slave->gridForget?($slave, ...)?
Removes each of the $slaves from grid for its master
and unmaps their windows. The slaves will no longer
be managed by the grid geometry manager. The configu
ration options for that window are forgotten, so that
if the slave is managed once more by the grid geometry
manager, the initial default settings are used. - $slave->gridInfo
Returns a list whose elements are the current configu
ration state of the slave given by $slave in the same
option-value form that might be specified to gridCon figure. The first two elements of the list are
``-in=>$master'' where $master is the slave's master. - $master->gridLocation(x, y)
Given x and y values in screen units relative to the
master window, the column and row number at that x and
y location is returned. For locations that are above
or to the left of the grid, -1 is returned. - $master->gridPropagate?(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 method returns 0 or 1 to indicate whether propaga
tion is currently enabled for $master. Propagation is enabled by default. - $master->gridRowconfigure(index?, -option=>value, ...?)
Query or set the row properties of the index row of
the geometry master, $master. The valid options are -minsize, -weight and -pad. If one or more options are provided, then index may be given as a list of row
indeces to which the configuration options will oper
ate on. The -minsize option sets the minimum size, in screen units, that will be permitted for this row.
The -weight option (an integer value) sets the rela
tive weight for apportioning any extra spaces among
rows. A weight of zero (0) indicates the row will not
deviate from its requested size. A row whose weight
is two will grow at twice the rate as a row of weight
one when extra space is allocated to the layout. The
-pad option specifies the number of screen units that
will be added to the largest window contained com
pletely in that row when the grid geometry manager
requests a size from the containing window. If only
an option is specified, with no value, the current
value of that option is returned. If only the master
window and index is specified, all the current set
tings are returned in an list of "option-value" pairs. - $slave->gridRemove?($slave, ...)?
Removes each of the $slaves from grid for its master
and unmaps their windows. The slaves will no longer
be managed by the grid geometry manager. However, the
configuration options for that window are remembered,
so that if the slave is managed once more by the grid
geometry manager, the previous values are retained. - $master->gridSize
Returns the size of the grid (in columns then rows)
for $master. The size is determined either by the
$slave occupying the largest row or column, or the
largest column or row with a -minsize, -weight, or -pad that is non-zero. - $master->gridSlaves?(-option=>value)?
If no options are supplied, a list of all of the
slaves in $master are returned, most recently manages first. -option can be either -row or -column which causes only the slaves in the row (or column) speci
fied by value to be returned.
RELATIVE PLACEMENT
The grid method contains a limited set of capabilities
that permit layouts to be created without specifying the
row and column information for each slave. This permits
slaves to be rearranged, added, or removed without the
need to explicitly specify row and column information.
When no column or row information is specified for a
$slave, default values are chosen for -column, -row,
-columnspan and -rowspan at the time the $slave is man
aged. The values are chosen based upon the current layout
of the grid, the position of the $slave relative to other
$slaves in the same grid method, and the presence of the
characters -, ^, and ^ in grid method where $slave names
are normally expected.
- - This increases the columnspan of the $slave to the
- left. Several -'s in a row will successively increase
the columnspan. A - may not follow a ^ or a x. - x This leaves an empty column between the $slave on the left and the $slave on the right.
- ^ This extends the -rowspan of the $slave above the ^'s
in the grid. The number of ^'s in a row must match
the number of columns spanned by the $slave above it.
THE GRID ALGORITHM
The grid geometry manager lays out its slaves in three
steps. In the first step, the minimum size needed to fit
all of the slaves is computed, then (if propagation is
turned on), a request is made of the master window to
become that size. In the second step, the requested size
is compared against the actual size of the master. If the
sizes are different, then space is added to or taken away
from the layout as needed. For the final step, each slave
is positioned in its row(s) and column(s) based on the
setting of its sticky flag.
To compute the minimum size of a layout, the grid geometry
manager first looks at all slaves whose columnspan and
rowspan values are one, and computes the nominal size of
each row or column to be either the minsize for that row
or column, or the sum of the padding plus the size of the
largest slave, whichever is greater. Then the slaves
whose rowspans or columnspans are greater than one are
examined. If a group of rows or columns need to be
increased in size in order to accommodate these slaves,
then extra space is added to each row or column in the
group according to its weight. For each group whose
weights are all zero, the additional space is apportioned
equally.
For masters whose size is larger than the requested lay
out, the additional space is apportioned according to the
row and column weights. If all of the weights are zero,
the layout is centered within its master. For masters
whose size is smaller than the requested layout, space is
taken away from columns and rows according to their
weights. However, once a column or row shrinks to its
minsize, its weight is taken to be zero. If more space
needs to be removed from a layout than would be permitted,
as when all the rows or columns are at there minimum
sizes, the layout is clipped on the bottom and right.
GEOMETRY PROPAGATION
The grid geometry manager 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 informa
tion to propagate up through a window hierarchy to a toplevel window so that the entire sub-tree sizes itself to
fit the needs of the leaf windows. However, the gridProp
agate method may be used to turn off propagation for one
or more masters. If propagation is disabled then grid
will not set the requested width and height of the master
window. 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 either be the slave's par
ent (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.
In addition, all slaves in one call to grid must have the
same master.
STACKING 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 man
aged 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.
CREDITS
The grid method is based on ideas taken from the GridBag
geometry manager written by Doug. Stein, and the blt_table
geometry manager, written by George Howlett.
SEE ALSO
Tk::form Tk::pack Tk::place
KEYWORDS
- geometry manager, location, grid, cell, propagation, size,
pack, master, slave