listbox(n) Tk (8.0) listbox(n)
_________________________________________________________________
NAME
listbox - Create and manipulate listbox widgets
SYNOPSIS
listbox pathName ?options?
STANDARD OPTIONS
-background-foreground-relief-takefocus
-borderwidth-height-selectbackground-width
-cursor-highlightbackground-selectborderwidth-xscrollcommand
-exportselection-highlightcolor -selectforeground-yscrollcommand
-font-highlightthickness-setgrid
See the options manual entry for details on the standard
options.
WIDGET-SPECIFIC OPTIONS
Command-Line Name:-height
Database Name: height
Database Class: Height
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 elements in
the listbox.
Command-Line Name:-selectmode
Database Name: selectMode
Database Class: SelectMode
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.
Command-Line Name:-width
Database Name: width
Database Class: Width
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.
_________________________________________________________________
Page 1 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
DESCRIPTION
The listbox command creates a new window (given by the
pathName argument) 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
support 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 corresponds to the first element in the
listbox.
active Indicates the element that has the location
cursor. This element will be displayed with an
underline 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 |
Page 2 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
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 with an underline 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 corner 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 listbox command.
pathName configure ?option? ?value option value ...?
Query or modify the configuration options of the
Page 3 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
widget. If no option is specified, returns a list
describing all of the available 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 elements 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 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.
Page 4 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
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 window; used in conjunction with later
scan dragto commands. 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 widget, 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 element.
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 closest element is used. The selection
anchor is the end of the selection that is fixed
while dragging out a selection 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.
Page 5 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
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 element 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
-xscrollcommand 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 character) 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 visible.
pathName yview ?args?
Page 6 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
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 following 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 scrollbars 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.
Page 7 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
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 without 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.
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 operation 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
Page 8 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
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 cursor (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 window. 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 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 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 cursor (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 selection and restores all the elements in the
selected range to their previous selection state.
[17] Control-slash selects everything in the widget, except
Page 9 (printed 2/26/99)
listbox(n) Tk (8.0) listbox(n)
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
Page 10 (printed 2/26/99)
