table(n) BLT Built-In Commands table(n)______________________________________________________________________________NAME
table - Arranges widgets in a table
SYNOPSIS
table container ?widget index option value?...
table arrange container
table cget container ?item? option
table configure container ?item?... ?option value?...
table extents container item
table forget widget ?widget?...
table info container item
table locate container x y
table containers ?switch? ?arg?
table save container
table search container ?switch arg?...
_________________________________________________________________DESCRIPTION
The table command arranges widgets in a table. The alignment of wid‐
gets is detemined by their row and column positions and the number of
rows or columns that they span.
INTRODUCTION
Probably the most painstaking aspect of building a graphical applica‐
tion is getting the placement and size of the widgets just right. It
usually takes many iterations to align widgets and adjust their spac‐
ing. That's because managing the geometry of widgets is simply not a
packing problem, but also graphical design problem. Attributes such as
alignment, symmetry, and balance are more important than minimizing the
amount of space used for packing.
The table geometry manager arranges widgets in a table. It's easy to
align widgets (horizontally and vertically) or to create empty space to
balance the arrangement of the widgets. Widgets (called slaves in the
Tk parlance) are arranged inside a containing widget (called the mas‐
ter). Widgets are positioned at row,column locations and may span any
number of rows or columns. More than one widget can occupy a single
location.
The placement of widget windows determines both the size and arrange‐
ment of the table. The table queries the requested size of each wid‐
get. The requested size of a widget is the natural size of the widget
(before the widget is shrunk or expanded). The height of each row and
the width of each column is the largest widget spanning that row or
column. The size of the table is in turn the sum of the row and column
sizes. This is the table's normal size.
The total number of rows and columns in a table is determined from the
indices specified. The table grows dynamically as windows are added at
larger indices.
EXAMPLE
The table geometry manager is created by invoking the table command.
# Create a table in the root window
table .
The window . is now the container of the table. Widgets are packed
into the table and displayed within the confines of the container.
You add widgets to the table by row and column location. Row and col‐
umn indices start from zero.
label .title -text "This is a title"
# Add a label to the table
table . .title 0,0
The label .title is added to the table. We can add more widgets in the
same way.
button .ok -text "Ok"
button .cancel -text "Cancel"
# Add two buttons
table . .ok 1,0
table . .cancel 1,1
Two buttons .ok and .cancel are now packed into the second row of the
table. They each occupy one cell of the table. By default, widgets
span only a single row and column.
The first column contains two widgets, .title and .ok. By default, the
widest of the two widgets will define the width of the column. How‐
ever, we want .title to be centered horizontally along the top of the
table. We can make .title span two columns using the configure opera‐
tion.
# Make the label span both columns
table configure . .title -cspan 2
The label .title will now be centered along the top row of the table.
In the above example, we've create and arranged the layout for the ta‐
ble invoking the table command several times. Alternately, we could
have used a single table command.
label .title -text "This is a title"
button .ok -text "Ok"
button .cancel -text "Cancel"
# Create and pack the table
table . \
.title 0,0 -cspan 2 \
.ok 1,0 \
.cancel 1,1
The table will override the requested width and height of the container
so that the window fits the table exactly. This also means that any
change to the size of table will be propagated up through the Tk window
hierarchy. This feature can be turned off using the configure opera‐
tion again.
table configure . -propagate no
You can also set the width of height of the table to a specific value.
This supersedes the calculated table size.
# Make the container 4 inches wide, 3 inches high
table configure . -reqwidth 4i -reqheight 3i
If a widget is smaller than the cell(s) it occupies, the widget will
float within the extra space. By default, the widget will be centered
within the space, but you can anchor the widget to any side of cell
using the -anchor configuration option.
table configure . .ok -anchor w
The -fill option expands the widget to fill the extra space either ver‐
tically or horizontally (or both).
# Make the title label fill the entire top row
table configure . .title -cspan 2 -fill x
# Each button will be as height of the 2nd row.
table configure . .ok .cancel -fill y
The width of .title will be the combined widths of both columns. Both
.ok and .cancel will become as tall as the second row.
The -padx and -pady options control the amount of padding around the
widget. Both options take a list of one or two values.
# Pad the title by two pixels above and below.
table configure . .title -pady 2
# Pad each button 2 pixels on the left, and 4 on the right.
table configure . .ok .cancel -padx { 2 4 }
If the list has only one value, then both exterior sides (top and bot‐
tom or left and right) of the widget are padded by that amount. If the
list has two elements, the first specifies padding for the top or left
side and the second for the bottom or right side.
Like the container, you can also override the requested widths and
heights of widgets using the -reqwidth and -reqheight options. This is
especially useful with character-based widgets (such as buttons,
labels, text, listbox, etc) that let you specify their size only in
units of characters and lines, instead of pixels.
# Make all buttons one inch wide
table configure . .ok .cancel -reqwidth 1i
Each row and column of the table can be configured, again using the
configure operation. Rows are and columns are designated by Ri and Ci
respectively, where i is the index of the row or column.
For example, you can set the size of a row or column.
# Make the 1st column 2 inches wide
table configure . c0 -width 2.0i
# Make the 2nd row 1/2 inch high.
table configure . r1 -height 0.5i
The new size for the row or column overrides its calculated size. If
no widgets span the row or column, its height or width is zero. So you
can use the -width and -height options to create empty spaces in the
table.
# Create an empty row and column
table configure . r2 c2 -width 1i
The -pady option lets you add padding to the top and bottom sides of
rows. The -padx option adds padding to the left and right sides of
columns. Both options take a list of one or two values.
# Pad above the title by two pixels
table configure . r0 -pady { 2 0 }
# Pad each column 4 pixels on the left, and 2 on the right.
table configure . c* -padx { 2 4 }
Notice that you can configure all the rows and columns using either R*
or C*.
When the container is resized, the rows and columns of the table are
also resized. Only the rows or columns that contain widgets (a widget
spans the row or column) grow or shrink. The -resize option indicates
whether the row or column can be shrunk or stretched. If the value is
shrink, the row or column can only be resized smaller. If expand, it
can only be resized larger. If none, the row or column is frozen at
its requested size.
# Let the 1st column get smaller, but not bigger
table configure . c0 -resize shrink
# Let the 2nd column get bigger, not smaller
table configure . c1 -resize expand
# Don't resize the first row
table configure . r0 -resize none
The following example packs a canvas, two scrollbars, and a title. The
rows and columns containing the scrollbars are frozen at their
requested size, so that even if the frame is resized, the scrollbars
will remain the same width.
table . \
.title 0,0 -cspan 3 \
.canvas 1,1 -fill both \
.vscroll 1,2 -fill y \
.hscroll 2,1 -fill x
# Don't let the scrollbars resize
table configure . c2 r2 -resize none
# Create an empty space to balance the scrollbar
table configure . c0 -width .vscroll
Note that the value of the -width option is the name of a widget win‐
dow. This indicates that the width of the column should be the same as
the requested width of .vscroll.
Finally, the forget operation removes widgets from the table.
# Remove the windows from the table
table forget .quit .frame
It's not necessary to specify the container. The table command deter‐
mines the container from the widget name.
OPERATIONS
The following operations are available for the table:
table container ?widget index option value?...
Adds the widget widget to the table at index. Index is a
row,column position in the table. It must be in the form
row,column where row and column are the respective row and col‐
umn numbers, starting from zero (0,0 is the upper leftmost posi‐
tion). Row and column may also be numeric expressions that are
recursively evaluated. If a table doesn't exist for container,
one is created. Widget is the path name of the window, that
must already exist, to be arranged inside of container. Option
and value are described in the WIDGET OPTIONS section.
table arrange container
Forces the table to compute its layout immediately. Normally,
the table geometry manager will wait until the next idle point,
before calculating the size of its rows and columns. This is
useful for collecting the normal sizes of rows and columns, that
are based upon the requested widget sizes.
table cget container ?item? option
Returns the current value of the configuration option specific
to item given by option. Item is either a row or column index,
or the path name of a widget. Item can be in any form describe
in the configure operation below. If no item argument is pro‐
vided, then the configuration option is for the table itself.
Option may be any one of the options described in the appropiate
section for item.
table configure container item... ?option value?...
Queries or modifies the configuration options specific to item.
If no option is specified, this command returns a list describ‐
ing all of the available options for item If the argument item
is omitted, then the specified configuration options are for the
table itself. Otherwise item must be either a row or column
specification, or the path name of a widget. The following item
types are available.
Ci Specifies the column of container to be configured. Item
must be in the form Cn, where i is the index of the col‐
umn. See the COLUMN OPTIONS section.
Ri Specifies the row of container to be configured. Item
must be in the form Ri, where i is the index of the row.
See the ROW OPTIONS section.
widget Specifies a widget of container to be queried. Widget is
the path name of a widget packed in container. See the
WIDGET OPTIONS section.
No argument
Specifies that the table itself is to be queried. See
the TABLE OPTIONS section for a description of the
option-value pairs for the table.
The option and value pairs are specific to item. If option is
specified with no value, then the command returns a list
describing the one named option (this list will be identical to
the corresponding sublist of the value returned if no option is
specified). If one or more option-value pairs are specified,
then the command modifies the given option(s) to have the given
value(s); in this case the command returns the empty string.
table extents container index
Queries the location and dimensions of row and columns in the
table. Index can be either a row or column index or a table
index. Returns a list of the x,y coordinates (upperleft corner)
and dimensions (width and height) of the cell, row, or column.
table forget widget ?widget?...
Requests that widget no longer have its geometry managed. Wid‐
get is the pathname of the window currently managed by some ta‐
ble. The window will be unmapped so that it no longer appears on
the screen. If widget is not currently managed by any table, an
error message is returned, otherwise the empty string.
table info container item
Returns a list of the current configuration options for item.
The list returned is exactly in the form that might be specified
to the table command. It can be used to save and reset table
configurations. Item must be one of the following.
Ci Specifies the column of container to be queried. Item
must be in the form Cn, where n is the index of the col‐
umn.
Ri Specifies the row of container to be queried. Item must
be in the form Ri, where i is the index of the row.
widget Specifies a widget of container to be queried. Widget is
the path name of a widget packed in container.
No argument
Specifies that the table itself is to be queried.
table locate container x y
Returns the table index (row,column) of the cell containing the
given screen coordinates. The x and y arguments represent the x
and y coordinates of the sample point to be tested.
table containers ?switch arg?
Returns a list of all container windows matching a given crite‐
ria (using switch and arg). If no switch and arg arguments are
given, the names of all container windows (only those using the
table command) are returned. The following are valid switches:
-pattern pattern
Returns a list of pathnames of all container windows
matching pattern.
-slave window
Returns the name of the container window of table manag‐
ing window. Window must be the path name of widget. If
window is not managed by any table, the empty string is
returned.
table search container ?switch arg?...
Returns the names of all the widgets in container matching the
criteria given by switch and arg. Container is name of the con‐
tainer window associated with the table to be searched. The
name of the widget is returned if any one switch-arg criteria
matches. If no switch-arg arguments are given, the names of all
widgets managed by container are returned. The following are
switches are available:
-pattern pattern
Returns the names of any names of the widgets matching
pattern.
-span index
Returns the names of widgets that span index. A widget
does not need to start at index to be included. Index
must be in the form row,column, where row and column are
valid row and column numbers.
-start index
Returns the names of widgets that start at index. Index
must be in the form row,column, where row and column are
valid row and column numbers.
TABLE OPTIONS
To configure the table itself, you omit the item argument when invoking
the configure operation.
table configure container ?option value?...
The following options are available for the table:
-padx pad
Sets how much padding to add to the left and right exte‐
riors of the table. Pad can be a list of one or two num‐
bers. If pad has two elements, the left side of the ta‐
ble is padded by the first value and the right side by
the second value. If pad has just one value, both the
left and right sides are padded evenly by the value. The
default is 0.
-pady pad
Sets how much padding to add to the top and bottom exte‐
riors of the table. Pad can be a list of one or two num‐
bers. If pad has two elements, the area above the table
is padded by the first value and the area below by the
second value. If pad is just one number, both the top
and bottom areas are padded by the value. The default is
0.
-propagate boolean
Indicates if the table should override the requested
width and height of the container window. If boolean is
false, container will not be resized. Container will be
its requested size. The default is 1.
WIDGET OPTIONS
widgets are configured by specifying the name of the widget when invok‐
ing the configure operation. table configure container widget ?option
value?... Widget must be the path name of a window already packed in
the table associated with container. The following options are avail‐
able for widgets:
-anchor anchor
Anchors widget to a particular edge of the cell(s) it
resides. This option has effect only if the space of the
spans surrounding widget is larger than widget. Anchor
specifies how widget will be positioned in the space.
For example, if anchor is center then the window is cen‐
tered in the rows and columns it spans; if anchor is w
then the window will be aligned with the leftmost edge of
the span. The default is center.
-columnspan number
Sets the number of columns widget will span. The default
is 1.
-columncontrol control
Specifies how the width of widget should control the
width of the columns it spans. Control is either normal,
none, or full. The default is normal.
none The width of widget is not considered.
full Only the width of widget will be considered
when computing the widths of the columns.
normal Indicates that the widest widget spanning the
column will determine the width of the span.
-fill fill
Specifies if widget should be stretched to fill any free
space in the span surrounding widget. Fill is either
none, x, y, both. The default is none.
x The widget can grow horizontally.
y The widget can grow vertically.
both The widget can grow both vertically and hori‐
zontally.
none The widget does not grow along with the span.
-ipadx pixels
Sets how much horizontal padding to add internally on the
left and right sides of widget. Pixels must be a valid
screen distance like 2 or 0.3i. The default is 0.
-ipady pixels
Sets how much vertical padding to add internally on the
top and bottom of widget. Pixels must be a valid screen
distance like 2 or 0.3i. The default is 0.
-padx pad
Sets how much padding to add to the left and right exte‐
riors of widget. Pad can be a list of one or two num‐
bers. If pad has two elements, the left side of widget
is padded by the first value and the right side by the
second value. If pad has just one value, both the left
and right sides are padded evenly by the value. The
default is 0.
-pady pad
Sets how much padding to add to the top and bottom exte‐
riors of widget. Pad can be a list of one or two num‐
bers. If pad has two elements, the area above widget is
padded by the first value and the area below by the sec‐
ond value. If pad is just one number, both the top and
bottom areas are padded by the value. The default is 0.
-reqheight height
Specifies the limits of the requested height for widget.
Height is a list of bounding values. See the BOUNDING
SIZES section for a description of this list. By
default, the height of widget is its requested height
with its internal padding (see the -ipady option). The
bounds specified by height either override the height
completely, or bound the height between two sizes. The
default is "".
-reqwidth width
Specifies the limits of the requested width for widget.
Width is a list of bounding values. See the BOUNDING
SIZES section for a description of this list. By
default, the width of widget is its requested width with
its internal padding (set the -ipadx option). The bounds
specified by width either override the width completely,
or bound the height between two sizes. The default is
"".
-rowspan number
Sets the number of rows widget will span. The default is
1.
-rowcontrol control
Specifies how the height of widget should control the
height of the rows it spans. Control is either normal,
none, or full. The default is normal.
none The height of widget is not considered.
full Only the height of widget will be considered
when computing the heights of the rows.
normal Indicates that the tallest widget spanning the
row will determine the height of the span.
COLUMN OPTIONS
To configure a column in the table, specify the column index as Ci,
where i is the index of the column to be configured. table configure
container Ci ?option value?... If the index is specified as C*, then
all columns of the table will be configured. The following options are
available for table columns.
-padx pad
Sets the padding to the left and right of the column.
Pad can be a list of one or two numbers. If pad has two
elements, the left side of the column is padded by the
first value and the right side by the second value. If
pad has just one value, both the left and right sides are
padded evenly by the value. The default is 0.
-resize mode
Indicates that the column can expand or shrink from its
requested width when the table is resized. Mode must be
one of the following: none, expand, shrink, or both. If
mode is expand the width of the column is expanded if
there is extra space in the container window. If mode is
shrink its width may be reduced beyond its requested
width if there is not enough space in the container. The
default is none.
-width width
Specifies the limits within that the width of the column
may expand or shrink. Width is a list of bounding val‐
ues. See the section BOUNDING SIZES for a description of
this list. By default there are no constraints.
ROW OPTIONS
To configure a row in the table, specify the row index as Ri, where i
is the index of the row to be configured. table configure container Ri
?option value?... If the index is specified as R*, then all rows of
the table will be configured. The following options are available for
table rows.
-height height
Specifies the limits of the height that the row may
expand or shrink to. Height is a list of bounding val‐
ues. See the section BOUNDING SIZES for a description of
this list. By default there are no constraints.
-pady pad
Sets the padding above and below the row. Pad can be a
list of one or two numbers. If pad has two elements, the
area above the row is padded by the first value and the
area below by the second value. If pad is just one num‐
ber, both the top and bottom areas are padded by the
value. The default is 0.
-resize mode
Indicates that the row can expand or shrink from its
requested height when the table is resized. Mode must be
one of the following: none, expand, shrink, or both. If
mode is expand the height of the row is expanded if there
is extra space in the container. If mode is shrink its
height may be reduced beyond its requested height if
there is not enough space in the container. The default
is none.
BOUNDING SIZES
Sometimes it's more useful to limit resizes to an acceptable range,
than to fix the size to a particular value or disallow resizing alto‐
gether. Similar to the way the wm command lets you specify a minsize
and maxsize for a toplevel window, you can bound the sizes the con‐
tainer, a widget, row, or column may take. The -width, -height,
-reqwidth, and -reqheight options, take a list of one, two, or three
values. We can take a previous example and instead preventing resiz‐
ing, bound the size of the scrollbars between two values.
table . \
.title 0,0 -cspan 3 \
.canvas 1,1 -fill both \
.vscroll 1,2 -fill y \
.hscroll 2,1 -fill x
# Bound the scrollbars between 1/8 and 1/2 inch
table configure . c2 -width { 0.125 0.5 }
table configure . r2 -height { 0.125 0.5 }
table configure . vscroll .hscroll -fill both
The scrollbars will get no smaller than 1/8 of an inch, or bigger than
1/2 inch. The initial size will be their requested size, so long as it
is within the specified bounds.
How the elements of the list are interpreted is dependent upon the num‐
ber of elements in the list.
{} Empty list. No bounds are set. The default sizing is
performed.
{ x } Fixes the size to x. The window or partition cannot
grow or shrink.
{ min max }
Sets up minimum and maximum limits for the size of the
window or partition. The window or partition can be
reduced less than min, nor can it be stretched beyond
max.
{ min max nom }
Specifies minimum and maximum size limits, but also
specifies a nominal size nom. This overrides the cal‐
culated size of the window or partition.
MISCELLANEOUS
Another feature is that you can put two widgets in the same cell of the
table. This is useful when you want to add decorations around a wid‐
get.
frame .frame -bd 1 -relief sunken
button .quit -text "Quit"
# Put both the frame and the button in the same cell.
table . \
.quit 1,0 -padx 2 -pady 2 \
.frame 1,0 -fill both
LIMITATIONS
A long standing bug in Tk (circa 1993), there is no way to detect if a
window is already a container of a different geometry manager. This is
usually done by accident, such as the following where all three widgets
are arranged in the same container ".", but using different geometry
managers.
table .f1
...
pack .f2
...
grid .f3
This leads to bizarre window resizing, as each geometry manager applies
its own brand of layout policies. When the container is a top level
window (such as "."), your window manager may become locked as it
responds to the never-ending stream of resize requests.
KEYWORDS
frame, geometry manager, location, table, size
BLT 2.4 table(n)
