grid(n) Tk Built-In Commands grid(n)
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NAME
grid - Geometry manager that arranges widgets in a grid
SYNOPSIS
grid option arg ?arg ...?
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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 com-mand command
mand 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 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 col-umns columns
umns 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 indeces to which the configuration options will
operate on. The -minsize option sets the minimum size, in screen units, that will be permit-ted permitted
ted 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 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 incremented
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 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 on the top and bot-tom bottom
tom 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 pad-ding padding
ding 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 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 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 ele-ments elements
ments 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 indeces to which the configuration options will operate
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 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 -uni- |
form. 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 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 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 pres-ence presence
ence 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 suc-cessively successively
cessively increase the columnspan. 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 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.
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 col-umn column
umn 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 con-stant constant
stant 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 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 min-size, minsize,
size, 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 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 addi-tion, addition,
tion, 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 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.
KEYWORDS
geometry manager, location, grid, cell, propagation, size, pack
Tk 8.4 grid(n)
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