path: root/doc/grid.n

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.TH grid n 8.5 Tk "Tk Built-In Commands"
.so man.macros
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
grid \- Geometry manager that arranges widgets in a grid
.SH SYNOPSIS
\fBgrid \fIoption arg \fR?\fIarg ...\fR?
.BE
.SH DESCRIPTION
.PP
The \fBgrid\fR command is used to communicate with the grid
geometry manager that arranges widgets in rows and columns inside
of another window, called the geometry container (or container window).
The \fBgrid\fR command can have any of several forms, depending
on the \fIoption\fR argument:
.TP
\fBgrid \fIwindow \fR?\fIwindow ...\fR? ?\fIoptions\fR?
.
If the first argument to \fBgrid\fR is suitable as the first window
argument to \fBgrid configure\fR, either a window name (any value
starting with \fB.\fR) or one of the characters \fBx\fR or \fB^\fR
(see the \fBRELATIVE PLACEMENT\fR section below), then the command is
processed in the same way as \fBgrid configure\fR.
.TP
\fBgrid anchor \fIwindow\fR ?\fIanchor\fR?
.
The anchor value controls how to place the grid within the container window
when no row/column has any weight.  See \fBTHE GRID ALGORITHM\fR below
for further details.  The default \fIanchor\fR is \fInw\fR.
.TP
\fBgrid bbox \fIwindow\fR ?\fIcolumn row\fR? ?\fIcolumn2 row2\fR?
.
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 container 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 \fIcolumn\fR and \fIrow\fR 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 \fIcolumn\fR and \fIrow\fR
arguments are specified, then the bounding box spanning the rows and columns
indicated is returned.
.TP
\fBgrid columnconfigure \fIwindow index \fR?\fI\-option value...\fR?
.
Query or set the column properties of the \fIindex\fR column of the
geometry container, \fIwindow\fR.
The valid options are \fB\-minsize\fR, \fB\-weight\fR, \fB\-uniform\fR
and \fB\-pad\fR.
If one or more options are provided, then \fIindex\fR 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 \fIall\fR. For \fIall\fR
the options apply to all columns currently occupied be content windows. For
a window name, that window must be a content of this container and the options
apply to all columns currently occupied be the content.
The \fB\-minsize\fR option sets the minimum size, in screen units,
that will be permitted for this column.
The \fB\-weight\fR 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 \fB\-uniform\fR option, when a non-empty value is supplied, places
the column in a \fIuniform group\fR with other columns that have the
same value for \fB\-uniform\fR.  The space for columns belonging to a
uniform group is allocated so that their sizes are always in strict
proportion to their \fB\-weight\fR values.  See
\fBTHE GRID ALGORITHM\fR below for further details.
The \fB\-pad\fR 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 container window and index is specified, all the current settings
are returned in a list of
.QW "\-option value"
pairs.
.TP
\fBgrid configure \fIwindow \fR?\fIwindow ...\fR? ?\fIoptions\fR?
.
The arguments consist of the names of one or more content windows
followed by pairs of arguments that specify how
to manage the content.
The characters \fB\-\fR,  \fBx\fR and \fB^\fR,
can be specified instead of a window name to alter the default
location of a \fIwindow\fR, as described in the \fBRELATIVE PLACEMENT\fR
section, below.
The following options are supported:
.RS
.TP
\fB\-column \fIn\fR
.
Insert the window so that it occupies the \fIn\fRth column in the grid.
Column numbers start with 0.  If this option is not supplied, then the
window is arranged just to the right of previous window specified on this
call to \fBgrid\fR, or column
.QW 0
if it is the first window.  For each
\fBx\fR that immediately precedes the \fIwindow\fR, the column position
is incremented by one.  Thus the \fBx\fR represents a blank column
for this row in the grid.
.TP
\fB\-columnspan \fIn\fR
.
Insert the window so that it occupies \fIn\fR columns in the grid.
The default is one column, unless the window name is followed by a
\fB\-\fR, in which case the columnspan is incremented once for each immediately
following \fB\-\fR.
.TP
\fB\-in \fIcontainer\fR
.
Insert the window(s) in the container
window given by \fIcontainer\fR.  The default is the first window's
parent window.
.TP
\fB\-ipadx \fIamount\fR
.
The \fIamount\fR specifies how much horizontal internal padding to
leave on each side of the content.  This is space is added
inside the content border.
The \fIamount\fR must be a valid screen distance, such as \fB2\fR or \fB.5c\fR.
It defaults to 0.
.TP
\fB\-ipady \fIamount\fR
.
The \fIamount\fR specifies how much vertical internal padding to
leave on the top and bottom of the content.
This space is added inside the content border.
The \fIamount\fR  defaults to 0.
.TP
\fB\-padx \fIamount\fR
.
The \fIamount\fR specifies how much horizontal external padding to
leave on each side of the content, in screen units.
\fIAmount\fR may be a list
of two values to specify padding for left and right separately.
The \fIamount\fR defaults to 0.
This space is added outside the content border.
.TP
\fB\-pady \fIamount\fR
.
The \fIamount\fR specifies how much vertical external padding to
leave on the top and bottom of the content, in screen units.
\fIAmount\fR may be a list
of two values to specify padding for top and bottom separately.
The \fIamount\fR defaults to 0.
This space is added outside the content border.
.TP
\fB\-row \fIn\fR
.
Insert the content so that it occupies the \fIn\fRth row in the grid.
Row numbers start with 0.  If this option is not supplied, then the
content is arranged on the same row as the previous content specified on this
call to \fBgrid\fR, or the next row after the highest occupied row
if this is the first content.
.TP
\fB\-rowspan \fIn\fR
.
Insert the content so that it occupies \fIn\fR rows in the grid.
The default is one row.  If the next \fBgrid\fR command contains
\fB^\fR characters instead of \fIcontent\fR that line up with the columns
of this \fIcontent\fR, then the \fBrowspan\fR of this \fIcontent\fR is
extended by one.
.TP
\fB\-sticky \fIstyle\fR
.
If a content's cell is larger than its requested dimensions, this
option may be used to position (or stretch) the content within its cell.
\fIStyle\fR  is a string that contains zero or more of the characters
\fBn\fR, \fBs\fR, \fBe\fR or \fBw\fR.
The string can optionally contain spaces or
commas, but they are ignored.  Each letter refers to a side (north, south,
east, or west) that the content will
.QW stick
to.  If both \fBn\fR and \fBs\fR (or \fBe\fR and \fBw\fR) are
specified, the content will be stretched to fill the entire
height (or width) of its cavity.  The \fB\-sticky\fR option subsumes the
combination of \fB\-anchor\fR and \fB\-fill\fR that is used by \fBpack\fR.
The default is
.QW "" ,
which causes the content to be centered in its cavity, at its requested size.
.LP
If any of the content is already managed by the geometry manager
then any unspecified options for them retain their previous values rather
than receiving default values.
.RE
.TP
\fBgrid forget \fIwindow \fR?\fIwindow ...\fR?
.
Removes each of the \fIwindow\fRs from grid for its
container and unmaps their windows.
The content will no longer be managed by the grid geometry manager.
The configuration options for that window are forgotten, so that if the
window is managed once more by the grid geometry manager, the initial
default settings are used.
.RS
.PP
.VS "TIP 518"
If the last content window of the container becomes unmanaged, this will also send
the virtual event \fB<<NoManagedChild>>\fR to the container; the container
may choose to resize itself (or otherwise respond) to such a change.
.VE "TIP 518"
.RE
.TP
\fBgrid info \fIwindow\fR
.
Returns a list whose elements are the current configuration state of
the content given by \fIwindow\fR in the same option-value form that
might be specified to \fBgrid configure\fR.
The first two elements of the list are
.QW "\fB\-in \fIcontainer\fR"
where \fIcontainer\fR is the windows's container window.
.TP
\fBgrid location \fIwindow x y\fR
.
Given  \fIx\fR and \fIy\fR values in screen units relative to the container window,
the column and row number at that \fIx\fR and \fIy\fR location is returned.
For locations that are above or to the left of the grid, \fB\-1\fR is
returned.
.TP
\fBgrid propagate \fIwindow\fR ?\fIboolean\fR?
.
If \fIboolean\fR has a true boolean value such as \fB1\fR or \fBon\fR
then propagation is enabled for \fIwindow\fR, which must be a window
name (see \fBGEOMETRY PROPAGATION\fR below).
If \fIboolean\fR has a false boolean value then propagation is
disabled for \fIwindow\fR.
In either of these cases an empty string is returned.
If \fIboolean\fR is omitted then the command returns \fB0\fR or
\fB1\fR to indicate whether propagation is currently enabled
for \fIwindow\fR.
Propagation is enabled by default.
.TP
\fBgrid rowconfigure \fIwindow index \fR?\fI\-option value...\fR?
.
Query or set the row properties of the \fIindex\fR row of the
geometry container, \fIwindow\fR.
The valid options are \fB\-minsize\fR, \fB\-weight\fR, \fB\-uniform\fR
and \fB\-pad\fR.
If one or more options are provided, then \fIindex\fR 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 \fIall\fR. For \fIall\fR
the options apply to all rows currently occupied by content windows. For
a window name, that window must be a content window of this container and the options
apply to all rows currently occupied by the container window.
The \fB\-minsize\fR option sets the minimum size, in screen units,
that will be permitted for this row.
The \fB\-weight\fR 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 \fB\-uniform\fR option, when a non-empty value is supplied, places
the row in a \fIuniform group\fR with other rows that have the
same value for \fB\-uniform\fR.  The space for rows belonging to a
uniform group is allocated so that their sizes are always in strict
proportion to their \fB\-weight\fR values.  See
\fBTHE GRID ALGORITHM\fR below for further details.
The \fB\-pad\fR 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 container window and index is specified, all the current settings
are returned in a list of
.QW "-option value"
pairs.
.TP
\fBgrid remove \fIwindow \fR?\fIwindow ...\fR?
.
Removes each of the \fIwindow\fRs from grid for its
container and unmaps their windows.
The content will no longer be managed by the grid geometry manager.
However, the configuration options for that window are remembered,
so that if the content window is managed once more by the grid
geometry manager, the previous values are retained.
.RS
.PP
.VS "TIP 518"
If the last content window of the container becomes unmanaged, this will also send
the virtual event \fB<<NoManagedChild>>\fR to the container; the container
may choose to resize itself (or otherwise respond) to such a change.
.VE "TIP 518"
.RE
.TP
\fBgrid size \fIcontainer\fR
.
Returns the size of the grid (in columns then rows) for \fIcontainer\fR.
The size is determined either by the \fIcontent\fR occupying the largest
row or column, or the largest column or row with a \fB\-minsize\fR,
\fB\-weight\fR, or \fB\-pad\fR that is non-zero.
.TP
\fBgrid content fI\window\fR ?\fI\-option value\fR?
.
If no options are supplied, a list of all of the content in \window\fR
is returned, most recently managed first.
\fIOption\fR can be either \fB\-row\fR or \fB\-column\fR which
causes only the content in the row (or column) specified by \fIvalue\fR
to be returned.
.TP
\fBgrid slaves \fIwindow\fR ?\fI\-option value\fR?
.
Synonym for . \fBgrid content \fIwindow\fR ?\fI\-option value\fR?
.SH "RELATIVE PLACEMENT"
.PP
The \fBgrid\fR command contains a limited set of capabilities that
permit layouts to be created without specifying the row and column
information for each content.  This permits content 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 \fIcontent\fR,
default values are chosen for
\fB\-column\fR, \fB\-row\fR, \fB\-columnspan\fR and \fB\-rowspan\fR
at the time the \fIcontent\fR is managed. The values are chosen
based upon the current layout of the grid, the position of the \fIcontent\fR
relative to other \fIcontent\fRs in the same grid command, and the presence
of the characters \fB\-\fR, \fBx\fR, and \fB^\fR in \fBgrid\fR
command where \fIcontent\fR names are normally expected.
.RS
.TP
\fB\-\fR
.
This increases the \fB\-columnspan\fR of the \fIcontent\fR to the left.  Several
\fB\-\fR's in a row will successively increase the number of columns spanned. A \fB\-\fR
may not follow a \fB^\fR or a \fBx\fR, nor may it be the first \fIcontent\fR
argument to \fBgrid configure\fR.
.TP
\fBx\fR
.
This leaves an empty column between the \fIcontent\fR on the left and
the \fIcontent\fR on the right.
.TP
\fB^\fR
.
This extends the \fB\-rowspan\fR of the \fIcontent\fR above the \fB^\fR's
in the grid.  The number of \fB^\fR's in a row must match the number of
columns spanned by the \fIcontent\fR above it.
.RE
.SH "THE GRID ALGORITHM"
.PP
The grid geometry manager lays out its content in three steps.
In the first step, the minimum size needed to fit all of the content
is computed, then (if propagation is turned on), a request is made
of the container window to become that size.
In the second step, the requested size is compared against the actual size
of the container.  If the sizes are different, then spaces is added to or taken
away from the layout as needed.
For the final step, each content is positioned in its row(s) and column(s)
based on the setting of its \fIsticky\fR flag.
.PP
To compute the minimum size of a layout, the grid geometry manager
first looks at all content whose \fB\-columnspan\fR and \fB\-rowspan\fR values are one,
and computes the nominal size of each row or column to be either the
\fIminsize\fR for that row or column, or the sum of the \fIpad\fRding
plus the size of the largest content, whichever is greater.  After that
the rows or columns in each uniform group adapt to each other.  Then
the content 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 content, then extra space is added to each
row or column in the group according to its \fIweight\fR.  For each
group whose weights are all zero, the additional space is apportioned
equally.
.PP
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 \fB\-weight 1 \-uniform a\fR will have exactly the same
size as any other row or column configured with \fB\-weight 1 \-uniform
a\fR.  A row or column configured with \fB\-weight 2 \-uniform b\fR will
be exactly twice as large as one that is configured with \fB\-weight 1
\-uniform b\fR.
.PP
More technically, each row or column in the group will have a size
equal to \fIk*weight\fR for some constant \fIk\fR.  The constant
\fIk\fR 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.
.PP
For containers 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 container according to
the \fIanchor\fR value.
For containers 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 \fIanchor\fR value.
.SH "GEOMETRY PROPAGATION"
.PP
The grid geometry manager normally computes how large a container must be to
just exactly meet the needs of its content, and it sets the
requested width and height of the container 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 \fBgrid propagate\fR command may be used to
turn off propagation for one or more containers.
If propagation is disabled then grid will not set
the requested width and height of the container window.
This may be useful if, for example, you wish for a container
window to have a fixed size that you specify.
.SH "RESTRICTIONS ON CONTAINER WINDOWS"
.PP
The container for each content must either be the content's parent
(the default) or a descendant of the content's parent.
This restriction is necessary to guarantee that the
content can be placed over any part of its container that is
visible without danger of the content being clipped by its parent.
In addition, all content in one call to \fBgrid\fR must have the same container.
.SH "STACKING ORDER"
.PP
If the container for a content is not its parent then you must make sure
that the content is higher in the stacking order than the container.
Otherwise the container will obscure the content and it will appear as
if the content has not been managed correctly.
The easiest way to make sure the content is higher than the container is
to create the container window first:  the most recently created window
will be highest in the stacking order.
.SH CREDITS
.PP
The \fBgrid\fR command is based on ideas taken from the \fIGridBag\fR
geometry manager written by Doug. Stein, and the \fBblt_table\fR geometry
manager, written by George Howlett.
.SH EXAMPLES
.PP
A toplevel window containing a text widget and two scrollbars:
.PP
.CS
# 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
\fBgrid\fR .t.txt .t.v \-sticky nsew
\fBgrid\fR .t.h        \-sticky nsew

# Tell the text widget to take all the extra room
\fBgrid rowconfigure\fR    .t .t.txt \-weight 1
\fBgrid columnconfigure\fR .t .t.txt \-weight 1
.CE
.PP
Three widgets of equal width, despite their different
.QW natural
widths:
.PP
.CS
button .b \-text "Foo"
entry .e \-textvariable foo ; set foo "Hello World!"
label .l \-text "This is a fairly long piece of text"

\fBgrid\fR .b .e .l \-sticky ew
\fBgrid columnconfigure\fR . "all" \-uniform allTheSame
.CE
.SH "SEE ALSO"
pack(n), place(n)
.SH KEYWORDS
geometry manager, location, grid, cell, propagation, size, pack
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