listbox(n) - phpMan

listbox(n) Tk Built-In Commands listbox(n)

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NAME
listbox - Create and manipulate listbox widgets

SYNOPSIS
listbox pathName ?options?

STANDARD OPTIONS
-background -borderwidth -cursor
-disabledforeground -exportselection -font
-foreground -highlightbackground -highlightcolor
-highlightthickness -relief -selectbackground
-selectborderwidth -selectforeground -setgrid
-takefocus -xscrollcommand -yscrollcommand

See the options manual entry for details on the standard options.

WIDGET-SPECIFIC OPTIONS
[-activestyle activeStyle] 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 on Windows, and dotbox elsewhere. [-height 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. [-listvariable listVariable]
Specifies the name of a global variable. The value of the variable is a list to be dis-
played inside the widget; if the variable 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. [-selectmode selectMode] Speci-
fies 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. [-state state] 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 can-
not be modified and is not shown (though selection information is retained).
[-width width] Specifies the desired width for the window in characters. If the font does
not 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.
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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 com-
mand line or in the option database to configure aspects of the listbox such as its col-
ors, 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 dis-
played 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 ele-
ment given by index. The first two elements of the list give the x and y coordi-
nates 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 widget. If no option is speci-
fied, 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 speci-
fied 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 list-
box 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 is not 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 speci-
fied, 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 stan-
dard 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 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
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 speci-
fied, 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 displaying the item. It may
have any of the forms accepted by Tk_GetColor.

-foreground color
Color specifies the foreground color to use when displaying the item. It may
have any of the forms accepted by Tk_GetColor.

-selectbackground color
color specifies the background color to use when displaying 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 displaying 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, depend-
ing on option:

pathName scan mark x y
Records x and y and the current view in the listbox window; used in con-
junction with later scan dragto commands. Typically this command is associ-
ated 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 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
is not.

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 character) on the dis-
play; 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?
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 ele-
ment 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 dis-
played 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 indi-
cates 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. On button 1, the listbox will also take focus if it has a normal state and |
-takefocus is true.

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 selec-
tion 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 <<ListboxSelect>> 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 oper-
ation: the anchor is set to the element under the mouse, and its selection state is
reversed. The selection state of other elements is not 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 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 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 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 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.