table
Section: BLT Built-In Commands (n)
Updated: 2.4
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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
widgets is determined 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
application is getting the placement and size of the widgets just right.
It usually takes many iterations to align widgets and adjust their spacing.
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 master). 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
arrangement of the table. The table queries the requested size of
each widget. 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
column 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. However, we want .title to be centered horizontally
along the top of the table. We can make .title span two columns
using the configure operation.
-
# 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
table 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 operation 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 vertically 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 bottom
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
window. 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 determines 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 column numbers, starting from zero (0,0 is the
upper leftmost position). 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 provided, then the configuration option is
for the table itself. Option may be any one of the options
described in the appropriate 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
describing 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 column. 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.
Widget is the pathname of the window currently
managed by some table. 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 column.
- 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 criteria (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 managing 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 container 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 exteriors of the table.
Pad can be a list of one or two numbers. If pad
has two elements, the left side of the table 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 exteriors of the table.
Pad can be a list of one or two numbers. 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 invoking 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 available 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 centered 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 horizontally.
- 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 exteriors of widget.
Pad can be a list of one or two numbers. 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 exteriors of
widget. Pad can be a list of one or two numbers. If
pad has two elements, the area above widget 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.
- -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 values. 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 values. 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 number, 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
altogether. Similar to the way the wm command lets you specify
a minsize and maxsize for a toplevel window, you can bound
the sizes the container, 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 resizing,
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
number 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 calculated 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 widget.
-
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
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- INTRODUCTION
-
- EXAMPLE
-
- OPERATIONS
-
- TABLE OPTIONS
-
- WIDGET OPTIONS
-
- COLUMN OPTIONS
-
- ROW OPTIONS
-
- BOUNDING SIZES
-
- MISCELLANEOUS
-
- LIMITATIONS
-
- KEYWORDS
-
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Time: 19:49:25 GMT, April 27, 2011