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 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 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
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 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 -variable foo
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(3tk), place(3tk)
KEYWORDS¶
geometry manager, location, grid, cell, propagation, size, pack
