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



NAME
       listbox - Create and manipulate listbox widgets

SYNOPSIS
       (listbox widget-name ?options?)
       :background    :foreground    :relief   :takefocus
       :borderwidth   :height   :selectbackground   :width
       :cursor   :highlightbackground     :selectborderwidth  :xscrollcommand
       :exportselection    :highlightcolor     :selectforeground   :yscrollcommand
       :font     :highlightthickness :setgrid

WIDGET-SPECIFIC OPTIONS
       [: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.
       [:selectmode selectMode] Speifies 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.  [:width 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.


DESCRIPTION
       The listbox procedure creates a new window (given by the widget-name
       argument) and makes it into a listbox widget.  Additional options,
       described above, may be specified on the procedure line or in the
       option database to configure aspects of the listbox such as its colors,
       font, text, and relief.  The listbox procedure returns its widget-name
       argument.  At the time this procedure is invoked, there must not exist
       a window named widget-name, but widget-name'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 procedures 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;  procedures described below may be used to change the
       view in the window.  Listboxes allow scrolling in both directions using
       the standard xScrollProcedure and yScrollProcedure options.  They also
       support scanning, as described below.


INDICES
       Many of the widget procedures 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 procedure.

       anchor      Indicates the anchor point for the selection, which is set
                   with the ``selection anchor'' widget procedure.

       end         Indicates the end of the listbox.  For most procedure this
                   refers to the last element in the listbox, but for a few
                   procedure 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 procedure descriptions below, arguments named index,
       first, and last always contain text indices in one of the above forms.


WIDGET PROCEDURE
       The listbox procedure creates a new STk procedure whose name is
       widget-name.  This procedure may be used to invoke various operations
       on the widget.  It has the following general form: (widget-name option
       ?arg arg ...?)  Option and the args determine the exact behavior of the
       procedure.  The following procedures are possible for listbox widgets:

       (widget-name '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.

       (widget-name '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
              list;  if the element is partially visible, the result gives the
              full area of the element, including any parts that are not
              visible.

       (widget-name 'cget option)
              Returns the current value of the configuration option given by
              option.  Option may have any of the values accepted by the
              listbox procedure.

       (widget-name '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
              available options for widget-name (see Tk_ConfigureInfo for
              information on the format of this list).  If option is specified
              with no value, then the procedure 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 procedure modifies the given widget option(s) to have
              the given value(s);  in this case the procedure returns an empty
              list.  Option may have any of the values accepted by the listbox
              procedure.

       (widget-name '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 #f is returned.

       (widget-name 'delete first)

       (widget-name '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.

       (widget-name 'get first)

       (widget-name 'get first last)
              If last is omitted, returns the contents of the listbox element
              indicated by first, or an empty list if first refers to a non-
              existent element.  If last is specified, the procedure 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.

       (widget-name '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).

       (widget-name '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
              list.

       (widget-name 'nearest y)
              Given a y-coordinate within the listbox window, this procedure
              returns the index of the (visible) listbox element nearest to
              that y-coordinate.

       (widget-name 'scan option args)
              This procedure is used to implement scanning on listboxes.  It
              has two forms, depending on option:

              (widget-name 'scan 'mark x y)
                     Records x and y and the current view in the listbox
                     window;  used in conjunction with later scan dragto
                     procedures.  Typically this procedure is associated with
                     a mouse button press in the widget.  It returns an empty
                     list.

              (widget-name 'scan 'dragto x y)
                     This procedure computes the difference between its x and
                     y arguments and the x and y arguments to the last scan
                     mark procedure for the widget.  It then adjusts the view
                     by 10 times the difference in coordinates.  This
                     procedure 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 list.

       (widget-name '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
              procedure 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.

       (widget-name 'selection option arg)
              This procedure is used to adjust the selection within a listbox.
              It has several forms, depending on option:

              (widget-name '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.

              (widget-name 'selection 'clear first)

              (widget-name '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.

              (widget-name 'selection 'includes index)
                     Returns #t if the element indicated by index is currently
                     selected, #f if it isn't.

              (widget-name 'selection 'set first)

              (widget-name '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.

       (widget-name 'size)
              Returns a decimal string indicating the total number of elements
              in the listbox.

       (widget-name 'xview args)
              This procedure 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:

              (widget-name '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
                     :xscrollprocedure option.

              (widget-name '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.

              (widget-name '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.

              (widget-name 'xview 'scroll number what)
                     This procedure 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.

       (widget-name 'yview ?args?)
              This procedure 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:

              (widget-name '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 :yscrollprocedure option.

              (widget-name 'yview index)
                     Adjusts the view in the window so that the element given
                     by index is displayed at the top of the window.

              (widget-name '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.

              (widget-name 'yview 'scroll number what)
                     This procedure 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
       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 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 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.


EXAMPLE
       Herafter is an example of a listbox connected to a scrollbar ;; Create
       list box and scrollbar (listbox   '.l :height 5             :yscroll
       (lambda l (apply .s 'set l))) (scrollbar '.s :command (lambda l (apply
       .l 'yview l)))

       ;; Set some elements in the listbox (.l 'insert 0 'one 'two 'three
       'four 'five 'six 'seven 'eight)

       ;; Pack elements (pack .l :side "left" :expand #t  :fill "both") (pack
       .s :side "right" :expand #f :fill "y")


SEE ALSO
       scrollbar



STk                                   3.1                           listbox(n)
