grid(n) Tk Built-In Commands grid(n)_________________________________________________________________NAMEgrid - Geometry manager that arranges widgets in a gridSYNOPSISgrid option arg ?arg ...?
_________________________________________________________________DESCRIPTION
The grid command is used to communicate with the grid
geometry manager that arranges widgets in rows and columns
inside of another window, called the geometry master (or
master window). The grid command can have any of several
forms, depending on the option argument:
grid slave ?slave ...? ?options?
If the first argument to grid is a window name (any
value starting with ``.''), then the command is
processed in the same way as grid configure.
grid bbox master ?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 column and row is specified on the com- |
mand 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 speci- |
fied, then the bounding box spanning the rows and |
columns indicated is returned.
grid columnconfigure master 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. The -min-
size 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 allo-
cated 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 speci-
fied, with no value, the current value of that
Tk 4.1 1
grid(n) Tk Built-In Commands grid(n)
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.
grid configure slave ?slave ...? ?options?
The arguments consist of the names of one or 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
name to alter the default location of a slave, as
described in the ``RELATIVE PLACEMENT'' section,
below. 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 previous 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 incre-
mented 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 fol-
lowing -.
-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
internal 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.
Tk 4.1 2
grid(n) Tk Built-In Commands grid(n)-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
external 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 command 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 position (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 con-
tains 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.
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.
Tk 4.1 3
grid(n) Tk Built-In Commands grid(n)grid forget slave ?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 configuration options for that window are for-
gotten, so that if the slave is managed once more
by the grid geometry manager, the initial default
settings are used.
grid info slave
Returns a list whose elements are the current con-
figuration state of the slave given by slave in the
same option-value form that might be specified to
grid configure. The first two elements of the list
are ``-in master'' where master is the slave's mas-
ter.
grid location master 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.
grid propagate master ?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 command returns 0 or 1
to indicate whether propagation is currently
enabled for master. Propagation is enabled by
default.
grid rowconfigure master 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. 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 relative weight for appor-
tioning 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
Tk 4.1 4
grid(n) Tk Built-In Commands grid(n)
the master window and index is specified, all the
current settings are returned in an list of
"-option value" pairs.
grid remove slave ?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 previ-
ous values are retained.
grid size master
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.
grid slaves master ?-option value?
If no options are supplied, a list of all of the
slaves in master are returned, most recently man-
ages first. Option can be either -row or -column
which causes only the slaves in the row (or column)
specified by value to be returned.
RELATIVE PLACEMENT
The grid command 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 managed.
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 command, and the presence of the charac-
ters -, ^, and ^ in grid command where slave names are
normally expected.
- This increases the columnspan of the slave
to the left. Several -'s in a row will suc-
cessively 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
Tk 4.1 5
grid(n) Tk Built-In Commands grid(n)
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 spaces 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 top-
level window so that the entire sub-tree sizes itself to
fit the needs of the leaf windows. However, the grid
propagate command 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.
Tk 4.1 6
grid(n) Tk Built-In Commands grid(n)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 command is based on ideas taken from the GridBag
geometry manager written by Doug. Stein, and the blt_table
geometry manager, written by George Howlett.
KEYWORDS
geometry manager, location, grid, cell, propagation, size,
pack
Tk 4.1 7