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listbox(n) Tk Built-In Commands listbox(n)
NAME
listbox - Create and manipulate listbox widgets
SYNOPSIS
listbox pathName ?options? -activestyle -height -selectforeground
-background -highlightbackground -setgrid -borderwidth -high-
lightcolor -state -cursor -highlightthickness -takefocus -dis-
abledforeground -relief -width -exportselection -selectback-
ground -xscrollcommand -font -selectborderwidth -yscrollcommand
-foreground
WIDGET-SPECIFIC OPTIONS
Specifies the style in which to draw the active element. This must be
one of dotbox (show a focus ring around the active element), none (no
special indication of active element) or underline (underline the
active element). The default is underline. Specifies the desired
height for the window, in lines. If zero or less, then the desired
height for the window is made just large enough to hold all the ele-
ments in the listbox. Specifies the name of a variable. The value of
the variable is a list to be displayed inside the widget; if the vari-
able value changes then the widget will automatically update itself to
reflect the new value. Attempts to assign a variable with an invalid
list value to -listvariable will cause an error. Attempts to unset a
variable in use as a -listvariable will fail but will not generate an
error. Specifies one of several styles for manipulating the selection.
The value of the option may be arbitrary, but the default bindings
expect it to be either single, browse, multiple, or extended; the
default value is browse. Specifies one of two states for the listbox:
normal or disabled. If the listbox is disabled then items may not be
inserted or deleted, items are drawn in the -disabledforeground color,
and selection cannot be modified and is not shown (though selection
information is retained). Specifies the desired width for the window
in characters. If the font doesn't have a uniform width then the width
of the character ``0'' is used in translating from character units to
screen units. If zero or less, then the desired width for the window
is made just large enough to hold all the elements in the listbox.
DESCRIPTION
The listbox command creates a new window (given by the pathName argu-
ment) and makes it into a listbox widget. Additional options,
described above, may be specified on the command line or in the option
database to configure aspects of the listbox such as its colors, font,
text, and relief. The listbox command returns its pathName argument.
At the time this command is invoked, there must not exist a window
named pathName, but pathName's parent must exist.
A listbox is a widget that displays a list of strings, one per line.
When first created, a new listbox has no elements. Elements may be
added or deleted using widget commands described below. In addition,
one or more elements may be selected as described below. If a listbox
is exporting its selection (see exportSelection option), then it will
observe the standard X11 protocols for handling the selection. Listbox
selections are available as type STRING; the value of the selection
will be the text of the selected elements, with newlines separating the
elements.
It is not necessary for all the elements to be displayed in the listbox
window at once; commands described below may be used to change the
view in the window. Listboxes allow scrolling in both directions using
the standard xScrollCommand and yScrollCommand options. They also sup-
port scanning, as described below.
INDICES
Many of the widget commands for listboxes take one or more indices as
arguments. An index specifies a particular element of the listbox, in
any of the following ways:
number Specifies the element as a numerical index, where 0 corre-
sponds to the first element in the listbox.
active Indicates the element that has the location cursor. This
element will be displayed as specified by -activestyle when
the listbox has the keyboard focus, and it is specified
with the activate widget command.
anchor Indicates the anchor point for the selection, which is set
with the selection anchor widget command.
end Indicates the end of the listbox. For most commands this
refers to the last element in the listbox, but for a few
commands such as index and insert it refers to the element
just after the last one.
@x,y Indicates the element that covers the point in the listbox
window specified by x and y (in pixel coordinates). If no
element covers that point, then the closest element to that
point is used.
In the widget command descriptions below, arguments named index, first,
and last always contain text indices in one of the above forms.
WIDGET COMMAND
The listbox command creates a new Tcl command whose name is pathName.
This command may be used to invoke various operations on the widget.
It has the following general form: pathName option ?arg arg ...?
Option and the args determine the exact behavior of the command. The
following commands are possible for listbox widgets:
pathName activate index
Sets the active element to the one indicated by index. If index
is outside the range of elements in the listbox then the closest
element is activated. The active element is drawn as specified
by -activestyle when the widget has the input focus, and its
index may be retrieved with the index active.
pathName bbox index
Returns a list of four numbers describing the bounding box of
the text in the element given by index. The first two elements
of the list give the x and y coordinates of the upper-left cor-
ner of the screen area covered by the text (specified in pixels
relative to the widget) and the last two elements give the width
and height of the area, in pixels. If no part of the element
given by index is visible on the screen, or if index refers to a
non-existent element, then the result is an empty string; if
the element is partially visible, the result gives the full area
of the element, including any parts that are not visible.
pathName cget option
Returns the current value of the configuration option given by
option. Option may have any of the values accepted by the list-
box command.
pathName configure ?option? ?value option value ...?
Query or modify the configuration options of the widget. If no
option is specified, returns a list describing all of the avail-
able options for pathName (see Tk_ConfigureInfo for information
on the format of this list). 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 widget option(s) to have the given value(s); in this
case the command returns an empty string. Option may have any
of the values accepted by the listbox command.
pathName curselection
Returns a list containing the numerical indices of all of the
elements in the listbox that are currently selected. If there
are no elements selected in the listbox then an empty string is
returned.
pathName delete first ?last?
Deletes one or more elements of the listbox. First and last are
indices specifying the first and last elements in the range to
delete. If last isn't specified it defaults to first, i.e. a
single element is deleted.
pathName get first ?last?
If last is omitted, returns the contents of the listbox element
indicated by first, or an empty string if first refers to a non-
existent element. If last is specified, the command returns a
list whose elements are all of the listbox elements between
first and last, inclusive. Both first and last may have any of
the standard forms for indices.
pathName index index
Returns the integer index value that corresponds to index. If
index is end the return value is a count of the number of ele-
ments in the listbox (not the index of the last element).
pathName insert index ?element element ...?
Inserts zero or more new elements in the list just before the
element given by index. If index is specified as end then the
new elements are added to the end of the list. Returns an empty
string.
pathName itemcget index option
Returns the current value of the item configuration option given
by option. Option may have any of the values accepted by the
listbox itemconfigure command.
pathName itemconfigure index ?option? ?value? ?option value ...?
Query or modify the configuration options of an item in the
listbox. If no option is specified, returns a list describing
all of the available options for the item (see Tk_ConfigureInfo
for information on the format of this list). If option is spec-
ified with no value, then the command returns a list describing
the one named option (this list will be identical to the corre-
sponding sublist of the value returned if no option is speci-
fied). If one or more option-value pairs are specified, then
the command modifies the given widget option(s) to have the
given value(s); in this case the command returns an empty
string. The following options are currently supported for items:
-background color
Color specifies the background color to use when display-
ing the item. It may have any of the forms accepted by
Tk_GetColor.
-foreground color
Color specifies the foreground color to use when display-
ing the item. It may have any of the forms accepted by
Tk_GetColor.
-selectbackground color
color specifies the background color to use when display-
ing the item while it is selected. It may have any of the
forms accepted by Tk_GetColor.
-selectforeground color
color specifies the foreground color to use when display-
ing the item while it is selected. It may have any of the
forms accepted by Tk_GetColor.
pathName nearest y
Given a y-coordinate within the listbox window, this command
returns the index of the (visible) listbox element nearest to
that y-coordinate.
pathName scan option args
This command is used to implement scanning on listboxes. It has
two forms, depending on option:
pathName scan mark x y
Records x and y and the current view in the listbox win-
dow; used in conjunction with later scan dragto com-
mands. Typically this command is associated with a mouse
button press in the widget. It returns an empty string.
pathName scan dragto x y.
This command computes the difference between its x and y
arguments and the x and y arguments to the last scan mark
command for the widget. It then adjusts the view by 10
times the difference in coordinates. This command is
typically associated with mouse motion events in the wid-
get, to produce the effect of dragging the list at high
speed through the window. The return value is an empty
string.
pathName see index
Adjust the view in the listbox so that the element given by
index is visible. If the element is already visible then the
command has no effect; if the element is near one edge of the
window then the listbox scrolls to bring the element into view
at the edge; otherwise the listbox scrolls to center the ele-
ment.
pathName selection option arg
This command is used to adjust the selection within a listbox.
It has several forms, depending on option:
pathName selection anchor index
Sets the selection anchor to the element given by index.
If index refers to a non-existent element, then the clos-
est element is used. The selection anchor is the end of
the selection that is fixed while dragging out a selec-
tion with the mouse. The index anchor may be used to
refer to the anchor element.
pathName selection clear first ?last?
If any of the elements between first and last (inclusive)
are selected, they are deselected. The selection state
is not changed for elements outside this range.
pathName selection includes index
Returns 1 if the element indicated by index is currently
selected, 0 if it isn't.
pathName selection set first ?last?
Selects all of the elements in the range between first
and last, inclusive, without affecting the selection
state of elements outside that range.
pathName size
Returns a decimal string indicating the total number of elements
in the listbox.
pathName xview args
This command is used to query and change the horizontal position
of the information in the widget's window. It can take any of
the following forms:
pathName xview
Returns a list containing two elements. Each element is
a real fraction between 0 and 1; together they describe
the horizontal span that is visible in the window. For
example, if the first element is .2 and the second ele-
ment is .6, 20% of the listbox's text is off-screen to
the left, the middle 40% is visible in the window, and
40% of the text is off-screen to the right. These are
the same values passed to scrollbars via the -xscrollcom-
mand option.
pathName xview index
Adjusts the view in the window so that the character
position given by index is displayed at the left edge of
the window. Character positions are defined by the width
of the character 0.
pathName xview moveto fraction
Adjusts the view in the window so that fraction of the
total width of the listbox text is off-screen to the
left. fraction must be a fraction between 0 and 1.
pathName xview scroll number what
This command shifts the view in the window left or right
according to number and what. Number must be an integer.
What must be either units or pages or an abbreviation of
one of these. If what is units, the view adjusts left or
right by number character units (the width of the 0 char-
acter) on the display; if it is pages then the view
adjusts by number screenfuls. If number is negative then
characters farther to the left become visible; if it is
positive then characters farther to the right become vis-
ible.
pathName yview ?args?
This command is used to query and change the vertical position
of the text in the widget's window. It can take any of the fol-
lowing forms:
pathName yview
Returns a list containing two elements, both of which are
real fractions between 0 and 1. The first element gives
the position of the listbox element at the top of the
window, relative to the listbox as a whole (0.5 means it
is halfway through the listbox, for example). The second
element gives the position of the listbox element just
after the last one in the window, relative to the listbox
as a whole. These are the same values passed to scroll-
bars via the -yscrollcommand option.
pathName yview index
Adjusts the view in the window so that the element given
by index is displayed at the top of the window.
pathName yview moveto fraction
Adjusts the view in the window so that the element given
by fraction appears at the top of the window. Fraction
is a fraction between 0 and 1; 0 indicates the first
element in the listbox, 0.33 indicates the element one-
third the way through the listbox, and so on.
pathName yview scroll number what
This command adjusts the view in the window up or down
according to number and what. Number must be an integer.
What must be either units or pages. If what is units,
the view adjusts up or down by number lines; if it is
pages then the view adjusts by number screenfuls. If
number is negative then earlier elements become visible;
if it is positive then later elements become visible.
DEFAULT BINDINGS
Tk automatically creates class bindings for listboxes that give them
Motif-like behavior. Much of the behavior of a listbox is determined
by its selectMode option, which selects one of four ways of dealing
with the selection.
If the selection mode is single or browse, at most one element can be
selected in the listbox at once. In both modes, clicking button 1 on
an element selects it and deselects any other selected item. In browse
mode it is also possible to drag the selection with button 1.
If the selection mode is multiple or extended, any number of elements
may be selected at once, including discontiguous ranges. In multiple
mode, clicking button 1 on an element toggles its selection state with-
out affecting any other elements. In extended mode, pressing button 1
on an element selects it, deselects everything else, and sets the
anchor to the element under the mouse; dragging the mouse with button
1 down extends the selection to include all the elements between the
anchor and the element under the mouse, inclusive.
Most people will probably want to use browse mode for single selections
and extended mode for multiple selections; the other modes appear to be
useful only in special situations.
Any time the selection changes in the listbox, the virtual event
<> will be generated. It is easiest to bind to this
event to be made aware of any changes to listbox selection.
In addition to the above behavior, the following additional behavior is
defined by the default bindings:
[1] In extended mode, the selected range can be adjusted by pressing
button 1 with the Shift key down: this modifies the selection
to consist of the elements between the anchor and the element
under the mouse, inclusive. The un-anchored end of this new
selection can also be dragged with the button down.
[2] In extended mode, pressing button 1 with the Control key down
starts a toggle operation: the anchor is set to the element
under the mouse, and its selection state is reversed. The
selection state of other elements isn't changed. If the mouse
is dragged with button 1 down, then the selection state of all
elements between the anchor and the element under the mouse is
set to match that of the anchor element; the selection state of
all other elements remains what it was before the toggle opera-
tion began.
[3] If the mouse leaves the listbox window with button 1 down, the
window scrolls away from the mouse, making information visible
that used to be off-screen on the side of the mouse. The
scrolling continues until the mouse re-enters the window, the
button is released, or the end of the listbox is reached.
[4] Mouse button 2 may be used for scanning. If it is pressed and
dragged over the listbox, the contents of the listbox drag at
high speed in the direction the mouse moves.
[5] If the Up or Down key is pressed, the location cursor (active
element) moves up or down one element. If the selection mode is
browse or extended then the new active element is also selected
and all other elements are deselected. In extended mode the new
active element becomes the selection anchor.
[6] In extended mode, Shift-Up and Shift-Down move the location cur-
sor (active element) up or down one element and also extend the
selection to that element in a fashion similar to dragging with
mouse button 1.
[7] The Left and Right keys scroll the listbox view left and right
by the width of the character 0. Control-Left and Control-Right
scroll the listbox view left and right by the width of the win-
dow. Control-Prior and Control-Next also scroll left and right
by the width of the window.
[8] The Prior and Next keys scroll the listbox view up and down by
one page (the height of the window).
[9] The Home and End keys scroll the listbox horizontally to the
left and right edges, respectively.
[10] Control-Home sets the location cursor to the first element in
the listbox, selects that element, and deselects everything else
in the listbox.
[11] Control-End sets the location cursor to the last element in the
listbox, selects that element, and deselects everything else in
the listbox.
[12] In extended mode, Control-Shift-Home extends the selection to
the first element in the listbox and Control-Shift-End extends
the selection to the last element.
[13] In multiple mode, Control-Shift-Home moves the location cursor
to the first element in the listbox and Control-Shift-End moves
the location cursor to the last element.
[14] The space and Select keys make a selection at the location cur-
sor (active element) just as if mouse button 1 had been pressed
over this element.
[15] In extended mode, Control-Shift-space and Shift-Select extend
the selection to the active element just as if button 1 had been
pressed with the Shift key down.
[16] In extended mode, the Escape key cancels the most recent selec-
tion and restores all the elements in the selected range to
their previous selection state.
[17] Control-slash selects everything in the widget, except in single
and browse modes, in which case it selects the active element
and deselects everything else.
[18] Control-backslash deselects everything in the widget, except in
browse mode where it has no effect.
[19] The F16 key (labelled Copy on many Sun workstations) or Meta-w
copies the selection in the widget to the clipboard, if there is
a selection.
The behavior of listboxes can be changed by defining new bindings for
individual widgets or by redefining the class bindings.
KEYWORDS
listbox, widget
Tk 8.4 listbox(n)
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