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Listbox(3)            User Contributed Perl Documentation           Listbox(3)




NAME

       Tk::Listbox - Create and manipulate Listbox widgets


SYNOPSIS

       $listbox = $parent->Listbox(?options?);


STANDARD OPTIONS

       -background -borderwidth -cursor -disabledforeground -exportselection
       -font -foreground -height -highlightbackground -highlightcolor
       -highlightthickness -offset -relief -selectbackground
       -selectborderwidth -selectforeground -setgrid -state -takefocus -tile
       -width -xscrollcommand -yscrollcommand

       See Tk::options for details of the standard options.


WIDGET-SPECIFIC OPTIONS

       Name:     activeStyle
       Class:    ActiveStyle
       Switch:   -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.

       Name:     height
       Class:    Height
       Switch:   -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.

       Name:     listVariable
       Class:    Variable
       Switch:   -listvariable
           The following is only partially implemented in Perl/Tk:

           Specifies the reference of a variable. The value of the variable is
           an array to be displayed 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.

       Name:     selectMode
       Class:    SelectMode
       Switch:   -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.

       Name:     state
       Class:    State
       Switch:   -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 cannot be modified and is not shown (though selection
           information is retained).

       Name:     width
       Class:    Width
       Switch:   -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 method creates a new window (given by the $widget 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 $widget argument.  At the time
       this command is invoked, there must not exist a window named $widget,
       but $widget'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 methods 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 methods 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 method.

       anchor
           Indicates the anchor point for the selection, which is set with the
           selection anchor method.

       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 method descriptions below, arguments named index, first, and
       last always contain text indices in one of the above forms.


WIDGET METHODS

       The Listbox method creates a widget object.  This object supports the
       configure and cget methods described in Tk::options which can be used
       to enquire and modify the options described above.  The widget also
       inherits all the methods provided by the generic Tk::Widget class.

       The following additional methods are available for listbox widgets:

       $listbox->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.

       $listbox->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.

       $listbox->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.

       $listbox->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.

       $listbox->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.

       $listbox->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).

       $listbox->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.

       $listbox->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.

       $listbox->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 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 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.

       $listbox->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.

       $listbox->scan(option, args)
           This command is used to implement scanning on listboxes.  It has
           two forms, depending on option:

           $listbox->scanMark(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.

           $listbox->scanDragto(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.

       $listbox->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.

       $listbox->selection(option, arg)
           This command is used to adjust the selection within a listbox.  It
           has several forms, depending on option:

           $listbox->selectionAnchor(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.

           $listbox->selectionClear(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.

           $listbox->selectionIncludes(index)
                   Returns 1 if the element indicated by index is currently
                   selected, 0 if it isn't.

           $listbox->selectionSet(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.

       $listbox->size
           Returns a decimal string indicating the total number of elements in
           the listbox.

       $listbox->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:

           $listbox->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.

           $listbox->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.

           $listbox->xviewMoveto( 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.

           $listbox->xviewScroll( 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.

       $listbox->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:

           $listbox->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.

           $listbox->yview(index)
                   Adjusts the view in the window so that the element given by
                   index is displayed at the top of the window.

           $listbox->yviewMoveto( 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.

           $listbox->yviewScroll( 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
       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.

       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 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.


TIED INTERFACE

       The Tk::Listbox widget can also be tied to a scalar or array variable,
       with different behaviour depending on the variable type, with the
       following tie commands:

          use Tk;

          my ( @array, $scalar, $other );
          my %options = ( ReturnType => "index" );

          my $MW = MainWindow->new();
          my $lbox = $MW->Listbox()->pack();

          my @list = ( "a", "b", "c", "d", "e", "f" );
          $lbox->insert('end', @list );

          tie @array, "Tk::Listbox", $lbox
          tie $scalar, "Tk::Listbox", $lbox;
          tie $other, "Tk::Listbox", $lbox, %options;

       currently only one modifier is implemented, a 3 way flag for tied
       scalars "ReturnType" which can have values "element", "index" or
       "both". The default is "element".

       Tied Arrays
           If you tie an array to the Listbox you can manipulate the items
           currently contained by the box in the same manner as a normal
           array, e.g.

               print @array;
               push(@array, @list);
               my $popped = pop(@array);
               my $shifted = shift(@array);
               unshift(@array, @list);
               delete $array[$index];
               print $string if exists $array[$i];
               @array = ();
               splice @array, $offset, $length, @list

           The delete function is implemented slightly differently from the
           standard array implementation. Instead of setting the element at
           that index to undef it instead physically removes it from the
           Listbox. This has the effect of changing the array indices, so for
           instance if you had a list on non-continuous indices you wish to
           remove from the Listbox you should reverse sort the list and then
           apply the delete function, e.g.

                my @list = ( 1, 2, 4, 12, 20 );
                my @remove = reverse sort { $a <=> $b } @list;
                delete @array[@remove];

           would safely remove indices 20, 12, 4, 2 and 1 from the Listbox
           without problems. It should also be noted that a similar warning
           applies to the splice function (which would normally be used in
           this context to perform the same job).

       Tied Scalars
           Unlike tied arrays, if you tie a scalar to the Listbox you can
           retrieve the currently selected elements in the box as an array
           referenced by the scalar, for instance

               my @list = ( "a", "b", "c", "d", "e", "f" );
               $lbox->insert('end', sort @list );
               $lbox->selectionSet(1);

           inserts @list as elements in an already existing listbox and
           selects the element at index 1, which is "b". If we then

                print @$selected;

           this will return the currently selected elements, in this case "b".

           However, if the "ReturnType" arguement is passed when tying the
           Listbox to the scalar with value "index" then the indices of the
           selected elements will be returned instead of the elements
           themselves, ie in this case "1". This can be useful when
           manipulating both contents and selected elements in the Listbox at
           the same time.

           Importantly, if a value "both" is given the scalar will not be tied
           to an array, but instead to a hash, with keys being the indices and
           values being the elements at those indices

           You can also manipulate the selected items using the scalar.
           Equating the scalar to an array reference will select any elements
           that match elements in the Listbox, non-matching array items are
           ignored, e.g.

               my @list = ( "a", "b", "c", "d", "e", "f" );
               $lbox->insert('end', sort @list );
               $lbox->selectionSet(1);

           would insert the array @list into an already existing Listbox and
           select element at index 1, i.e. "b"

               @array = ( "a", "b", "f" );
               $selected = \@array;

           would select elements "a", "b" and "f" in the Listbox.

           Again, if the "index" we indicate we want to use indices in the
           options hash then the indices are use instead of elements, e.g.

               @array = ( 0, 1, 5 );
               $selected = \@array;

           would have the same effect, selecting elements "a", "b" and "f" if
           the $selected variable was tied with %options = ( ReturnType =>
           "index" ).

           If we are returning "both", i.e. the tied scalar points to a hash,
           both key and value must match, e.g.

               %hash = ( 0 => "a", 1 => "b", 5 => "f" );
               $selected = \%hash;

           would have the same effect as the previous examples.

           It should be noted that, despite being a reference to an array (or
           possibly a has), you still can not copy the tied variable without
           it being untied, instead you must pass a reference to the tied
           scalar between subroutines.


KEYWORDS

       listbox, widget, tied


SEE ALSO

       Tk::HList, Tk::TextList.



perl v5.18.0                      2012-01-16                        Listbox(3)

perl-Tk 804.030_502 - Generated Wed Aug 14 18:35:34 CDT 2013
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