grid
Section: Tk Built-In Commands (n)
Updated: 8.5
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NAME
grid - Geometry manager that arranges widgets in a grid
SYNOPSIS
grid 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 suitable as the first slave
argument to grid configure, either a window name (any value
starting with .) or one of the characters x or ^
(see the RELATIVE PLACEMENT section below), then the command is
processed in the same way as grid configure.
- grid anchor master ?anchor?
-
The anchor value controls how to place the grid within the master
when no row/column has any weight. See THE GRID ALGORITHM below
for further details. The default anchor is nw.
- 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 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.
- 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, -uniform
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.
Indices may be integers, window names or the keyword all. For all
the options apply to all columns currently occupied be slave windows. For
a window name, that window must be a slave of this master and the options
apply to all columns currently occupied be the slave.
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 -uniform option, when a non-empty value is supplied, places
the column in a uniform group with other columns that have the
same value for -uniform. The space for columns belonging to a
uniform group is allocated so that their sizes are always in strict
proportion to their -weight values. See
THE GRID ALGORITHM below for further details.
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 a 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 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 internal padding to
leave 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.
Amount may be a list
of two values to specify padding for left and right separately.
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.
Amount may be a list
of two values to specify padding for top and bottom separately.
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 next row after the highest occupied 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 contains 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.
- 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 forgotten, 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 configuration 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 master.
- 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, -uniform
and -pad.
If one or more options are provided, then index may be given as
a list of row indices to which the configuration options will operate on.
Indices may be integers, window names or the keyword all. For all
the options apply to all rows currently occupied be slave windows. For
a window name, that window must be a slave of this master and the options
apply to all rows currently occupied be the slave.
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 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 -uniform option, when a non-empty value is supplied, places
the row in a uniform group with other rows that have the
same value for -uniform. The space for rows belonging to a
uniform group is allocated so that their sizes are always in strict
proportion to their -weight values. See
THE GRID ALGORITHM below for further details.
The -pad option specifies the number of screen units that will be
added to the largest window contained completely 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 settings
are returned in a 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 previous
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 manages 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 characters -, x, 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 successively increase the number of columns spanned. A -
may not follow a ^ or a x, nor may it be the first slave
argument to grid configure.
- 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 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. After that
the rows or columns in each uniform group adapt to each other. Then
the slaves whose row-spans or column-spans 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.
When multiple rows or columns belong to a uniform group, the space
allocated to them is always in proportion to their weights. (A weight
of zero is considered to be 1.) In other words, a row or column
configured with -weight 1 -uniform a will have exactly the same
size as any other row or column configured with -weight 1 -uniform
a. A row or column configured with -weight 2 -uniform b will
be exactly twice as large as one that is configured with -weight 1
-uniform b.
More technically, each row or column in the group will have a size
equal to k*weight for some constant k. The constant
k is chosen so that no row or column becomes smaller than its
minimum size. For example, if all rows or columns in a group have the
same weight, then each row or column will have the same size as the
largest row or column in the group.
For masters whose size is larger than the requested layout, the additional
space is apportioned according to the row and column weights. If all of
the weights are zero, the layout is placed within its master according to
the anchor value.
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 their minimum sizes, the layout is
placed and clipped according to the anchor value.
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 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 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.
RESTRICTIONS ON MASTER WINDOWS
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.
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 has not been managed 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.
EXAMPLES
A toplevel window containing a text widget and two scrollbars:
-
# Make the widgets
toplevel .t
text .t.txt -wrap none -xscroll {.t.h set} -yscroll {.t.v set}
scrollbar .t.v -orient vertical -command {.t.txt yview}
scrollbar .t.h -orient horizontal -command {.t.txt xview}
# Lay them out
grid .t.txt .t.v -sticky nsew
grid .t.h -sticky nsew
# Tell the text widget to take all the extra room
grid rowconfigure .t .t.txt -weight 1
grid columnconfigure .t .t.txt -weight 1
Three widgets of equal width, despite their different
``natural''
widths:
-
button .b -text "Foo"
entry .e -textvariable foo ; set foo "Hello World!"
label .l -text "This is a fairly long piece of text"
grid .b .e .l -sticky ew
grid columnconfigure . "all" -uniform allTheSame
SEE ALSO
pack(n),
place(n)
KEYWORDS
geometry manager, location, grid, cell, propagation, size, pack