grid - Geometry manager that arranges widgets in a grid
grid option arg ?arg ...?
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.
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 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.
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.
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.
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.
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.
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
geometry manager, location, grid, cell, propagation, size,
pack