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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 v5.24.1			  2013-11-15			    Listbox(3)

NAME | SYNOPSIS | STANDARD OPTIONS | WIDGET-SPECIFIC OPTIONS | DESCRIPTION | INDICES | WIDGET METHODS | DEFAULT BINDINGS | TIED INTERFACE | KEYWORDS | SEE ALSO

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