1Listbox(3)            User Contributed Perl Documentation           Listbox(3)
2
3
4

NAME

6       Tk::Listbox - Create and manipulate Listbox widgets
7

SYNOPSIS

9       $listbox = $parent->Listbox(?options?);
10

STANDARD OPTIONS

12       -background -borderwidth -cursor -disabledforeground -exportselection
13       -font -foreground -height -highlightbackground -highlightcolor
14       -highlightthickness -offset -relief -selectbackground
15       -selectborderwidth -selectforeground -setgrid -state -takefocus -tile
16       -width -xscrollcommand -yscrollcommand
17
18       See Tk::options for details of the standard options.
19

WIDGET-SPECIFIC OPTIONS

21       Name:     activeStyle
22       Class:    ActiveStyle
23       Switch:   -activestyle
24           Specifies the style in which to draw the active element. This must
25           be one of dotbox (show a focus ring around the active element),
26           none (no special indication of active element) or underline
27           (underline the active element). The default is underline.
28
29       Name:     height
30       Class:    Height
31       Switch:   -height
32           Specifies the desired height for the window, in lines.  If zero or
33           less, then the desired height for the window is made just large
34           enough to hold all the elements in the listbox.
35
36       Name:     listVariable
37       Class:    Variable
38       Switch:   -listvariable
39           The following is only partially implemented in Perl/Tk:
40
41           Specifies the reference of a variable. The value of the variable is
42           an array to be displayed inside the widget; if the variable value
43           changes then the widget will automatically update itself to reflect
44           the new value. Attempts to assign a variable with an invalid list
45           value to -listvariable will cause an error. Attempts to unset a
46           variable in use as a -listvariable will fail but will not generate
47           an error.
48
49       Name:     selectMode
50       Class:    SelectMode
51       Switch:   -selectmode
52           Specifies one of several styles for manipulating the selection.
53           The value of the option may be arbitrary, but the default bindings
54           expect it to be either single, browse, multiple, or extended;  the
55           default value is browse.
56
57       Name:     state
58       Class:    State
59       Switch:   -state
60           Specifies one of two states for the listbox: normal or disabled.
61           If the listbox is disabled then items may not be inserted or
62           deleted, items are drawn in the -disabledforeground color, and
63           selection cannot be modified and is not shown (though selection
64           information is retained).
65
66       Name:     width
67       Class:    Width
68       Switch:   -width
69           Specifies the desired width for the window in characters.  If the
70           font doesn't have a uniform width then the width of the character
71           ``0'' is used in translating from character units to screen units.
72           If zero or less, then the desired width for the window is made just
73           large enough to hold all the elements in the listbox.
74

DESCRIPTION

76       The Listbox method creates a new window (given by the $widget argument)
77       and makes it into a listbox widget.  Additional options, described
78       above, may be specified on the command line or in the option database
79       to configure aspects of the listbox such as its colors, font, text, and
80       relief.  The listbox command returns its $widget argument.  At the time
81       this command is invoked, there must not exist a window named $widget,
82       but $widget's parent must exist.
83
84       A listbox is a widget that displays a list of strings, one per line.
85       When first created, a new listbox has no elements.  Elements may be
86       added or deleted using methods described below.  In addition, one or
87       more elements may be selected as described below.  If a listbox is
88       exporting its selection (see exportSelection option), then it will
89       observe the standard X11 protocols for handling the selection.  Listbox
90       selections are available as type STRING; the value of the selection
91       will be the text of the selected elements, with newlines separating the
92       elements.
93
94       It is not necessary for all the elements to be displayed in the listbox
95       window at once;  commands described below may be used to change the
96       view in the window.  Listboxes allow scrolling in both directions using
97       the standard xScrollCommand and yScrollCommand options.  They also
98       support scanning, as described below.
99

INDICES

101       Many of the methods for listboxes take one or more indices as
102       arguments.  An index specifies a particular element of the listbox, in
103       any of the following ways:
104
105       number
106           Specifies the element as a numerical index, where 0 corresponds to
107           the first element in the listbox.
108
109       active
110           Indicates the element that has the location cursor.  This element
111           will be displayed with an underline when the listbox has the
112           keyboard focus, and it is specified with the activate method.
113
114       anchor
115           Indicates the anchor point for the selection, which is set with the
116           selection anchor method.
117
118       end Indicates the end of the listbox.  For most commands this refers to
119           the last element in the listbox, but for a few commands such as
120           index and insert it refers to the element just after the last one.
121
122       @x,y
123           Indicates the element that covers the point in the listbox window
124           specified by x and y (in pixel coordinates).  If no element covers
125           that point, then the closest element to that point is used.
126
127       In the method descriptions below, arguments named index, first, and
128       last always contain text indices in one of the above forms.
129

WIDGET METHODS

131       The Listbox method creates a widget object.  This object supports the
132       configure and cget methods described in Tk::options which can be used
133       to enquire and modify the options described above.  The widget also
134       inherits all the methods provided by the generic Tk::Widget class.
135
136       The following additional methods are available for listbox widgets:
137
138       $listbox->activate(index)
139           Sets the active element to the one indicated by index.  If index is
140           outside the range of elements in the listbox then the closest
141           element is activated.  The active element is drawn with an
142           underline when the widget has the input focus, and its index may be
143           retrieved with the index active.
144
145       $listbox->bbox(index)
146           Returns a list of four numbers describing the bounding box of the
147           text in the element given by index.  The first two elements of the
148           list give the x and y coordinates of the upper-left corner of the
149           screen area covered by the text (specified in pixels relative to
150           the widget) and the last two elements give the width and height of
151           the area, in pixels.  If no part of the element given by index is
152           visible on the screen, or if index refers to a non-existent
153           element, then the result is an empty string;  if the element is
154           partially visible, the result gives the full area of the element,
155           including any parts that are not visible.
156
157       $listbox->curselection
158           Returns a list containing the numerical indices of all of the
159           elements in the listbox that are currently selected.  If there are
160           no elements selected in the listbox then an empty string is
161           returned.
162
163       $listbox->delete(first, ?last?)
164           Deletes one or more elements of the listbox.  First and last are
165           indices specifying the first and last elements in the range to
166           delete.  If last isn't specified it defaults to first, i.e. a
167           single element is deleted.
168
169       $listbox->get(first, ?last?)
170           If last is omitted, returns the contents of the listbox element
171           indicated by first, or an empty string if first refers to a non-
172           existent element.  If last is specified, the command returns a list
173           whose elements are all of the listbox elements between first and
174           last, inclusive.  Both first and last may have any of the standard
175           forms for indices.
176
177       $listbox->index(index)
178           Returns the integer index value that corresponds to index.  If
179           index is end the return value is a count of the number of elements
180           in the listbox (not the index of the last element).
181
182       $listbox->insert(index, ?element, element, ...?)
183           Inserts zero or more new elements in the list just before the
184           element given by index.  If index is specified as end then the new
185           elements are added to the end of the list.  Returns an empty
186           string.
187
188       $listbox->itemcget(index, option)
189           Returns the current value of the item configuration option given by
190           option. Option may have any of the values accepted by the listbox
191           itemconfigure command.
192
193       $listbox->itemconfigure(index, ?option, value, option, value, ...?)
194           Query or modify the configuration options of an item in the
195           listbox.  If no option is specified, returns a list describing all
196           of the available options for the item (see Tk_ConfigureInfo for
197           information on the format of this list). If option is specified
198           with no value, then the command returns a list describing the one
199           named option (this list will be identical to the corresponding
200           sublist of the value returned if no option is specified). If one or
201           more option-value pairs are specified, then the command modifies
202           the given widget option(s) to have the given value(s); in this case
203           the command returns an empty string. The following options are
204           currently supported for items:
205
206           -background => color
207               Color specifies the background color to use when displaying the
208               item. It may have any of the forms accepted by Tk_GetColor.
209
210           -foreground => color
211               Color specifies the foreground color to use when displaying the
212               item. It may have any of the forms accepted by Tk_GetColor.
213
214           -selectbackground => color
215               Color specifies the background color to use when displaying the
216               item while it is selected. It may have any of the forms
217               accepted by Tk_GetColor.
218
219           -selectforeground => color
220               Color specifies the foreground color to use when displaying the
221               item while it is selected. It may have any of the forms
222               accepted by Tk_GetColor.
223
224       $listbox->nearest(y)
225           Given a y-coordinate within the listbox window, this command
226           returns the index of the (visible) listbox element nearest to that
227           y-coordinate.
228
229       $listbox->scan(option, args)
230           This command is used to implement scanning on listboxes.  It has
231           two forms, depending on option:
232
233           $listbox->scanMark(x, y)
234                   Records x and y and the current view in the listbox window;
235                   used in conjunction with later scan dragto commands.
236                   Typically this command is associated with a mouse button
237                   press in the widget.  It returns an empty string.
238
239           $listbox->scanDragto(x, y.)
240                   This command computes the difference between its x and y
241                   arguments and the x and y arguments to the last scan mark
242                   command for the widget.  It then adjusts the view by 10
243                   times the difference in coordinates.  This command is
244                   typically associated with mouse motion events in the
245                   widget, to produce the effect of dragging the list at high
246                   speed through the window.  The return value is an empty
247                   string.
248
249       $listbox->see(index)
250           Adjust the view in the listbox so that the element given by index
251           is visible.  If the element is already visible then the command has
252           no effect; if the element is near one edge of the window then the
253           listbox scrolls to bring the element into view at the edge;
254           otherwise the listbox scrolls to center the element.
255
256       $listbox->selection(option, arg)
257           This command is used to adjust the selection within a listbox.  It
258           has several forms, depending on option:
259
260           $listbox->selectionAnchor(index)
261                   Sets the selection anchor to the element given by index.
262                   If index refers to a non-existent element, then the closest
263                   element is used.  The selection anchor is the end of the
264                   selection that is fixed while dragging out a selection with
265                   the mouse.  The index anchor may be used to refer to the
266                   anchor element.
267
268           $listbox->selectionClear(first, ?last?)
269                   If any of the elements between first and last (inclusive)
270                   are selected, they are deselected.  The selection state is
271                   not changed for elements outside this range.
272
273           $listbox->selectionIncludes(index)
274                   Returns 1 if the element indicated by index is currently
275                   selected, 0 if it isn't.
276
277           $listbox->selectionSet(first, ?last?)
278                   Selects all of the elements in the range between first and
279                   last, inclusive, without affecting the selection state of
280                   elements outside that range.
281
282       $listbox->size
283           Returns a decimal string indicating the total number of elements in
284           the listbox.
285
286       $listbox->xview(args)
287           This command is used to query and change the horizontal position of
288           the information in the widget's window.  It can take any of the
289           following forms:
290
291           $listbox->xview
292                   Returns a list containing two elements.  Each element is a
293                   real fraction between 0 and 1;  together they describe the
294                   horizontal span that is visible in the window.  For
295                   example, if the first element is .2 and the second element
296                   is .6, 20% of the listbox's text is off-screen to the left,
297                   the middle 40% is visible in the window, and 40% of the
298                   text is off-screen to the right.  These are the same values
299                   passed to scrollbars via the -xscrollcommand option.
300
301           $listbox->xview(index)
302                   Adjusts the view in the window so that the character
303                   position given by index is displayed at the left edge of
304                   the window.  Character positions are defined by the width
305                   of the character 0.
306
307           $listbox->xviewMoveto( fraction );
308                   Adjusts the view in the window so that fraction of the
309                   total width of the listbox text is off-screen to the left.
310                   fraction must be a fraction between 0 and 1.
311
312           $listbox->xviewScroll( number, what );
313                   This command shifts the view in the window left or right
314                   according to number and what.  Number must be an integer.
315                   What must be either units or pages or an abbreviation of
316                   one of these.  If what is units, the view adjusts left or
317                   right by number character units (the width of the 0
318                   character) on the display;  if it is pages then the view
319                   adjusts by number screenfuls.  If number is negative then
320                   characters farther to the left become visible;  if it is
321                   positive then characters farther to the right become
322                   visible.
323
324       $listbox->yview(?args?)
325           This command is used to query and change the vertical position of
326           the text in the widget's window.  It can take any of the following
327           forms:
328
329           $listbox->yview
330                   Returns a list containing two elements, both of which are
331                   real fractions between 0 and 1.  The first element gives
332                   the position of the listbox element at the top of the
333                   window, relative to the listbox as a whole (0.5 means it is
334                   halfway through the listbox, for example).  The second
335                   element gives the position of the listbox element just
336                   after the last one in the window, relative to the listbox
337                   as a whole.  These are the same values passed to scrollbars
338                   via the -yscrollcommand option.
339
340           $listbox->yview(index)
341                   Adjusts the view in the window so that the element given by
342                   index is displayed at the top of the window.
343
344           $listbox->yviewMoveto( fraction );
345                   Adjusts the view in the window so that the element given by
346                   fraction appears at the top of the window.  Fraction is a
347                   fraction between 0 and 1;  0 indicates the first element in
348                   the listbox, 0.33 indicates the element one-third the way
349                   through the listbox, and so on.
350
351           $listbox->yviewScroll( number, what );
352                   This command adjusts the view in the window up or down
353                   according to number and what.  Number must be an integer.
354                   What must be either units or pages.  If what is units, the
355                   view adjusts up or down by number lines;  if it is pages
356                   then the view adjusts by number screenfuls.  If number is
357                   negative then earlier elements become visible;  if it is
358                   positive then later elements become visible.
359

DEFAULT BINDINGS

361       Tk automatically creates class bindings for listboxes that give them
362       Motif-like behavior.  Much of the behavior of a listbox is determined
363       by its selectMode option, which selects one of four ways of dealing
364       with the selection.
365
366       If the selection mode is single or browse, at most one element can be
367       selected in the listbox at once.  In both modes, clicking button 1 on
368       an element selects it and deselects any other selected item.  In browse
369       mode it is also possible to drag the selection with button 1.
370
371       If the selection mode is multiple or extended, any number of elements
372       may be selected at once, including discontiguous ranges.  In multiple
373       mode, clicking button 1 on an element toggles its selection state
374       without affecting any other elements.  In extended mode, pressing
375       button 1 on an element selects it, deselects everything else, and sets
376       the anchor to the element under the mouse;  dragging the mouse with
377       button 1 down extends the selection to include all the elements between
378       the anchor and the element under the mouse, inclusive.
379
380       Most people will probably want to use browse mode for single selections
381       and extended mode for multiple selections; the other modes appear to be
382       useful only in special situations.
383
384       Any time the selection changes in the listbox, the virtual event
385       <<ListboxSelect>> will be generated. It is easiest to bind to this
386       event to be made aware of any changes to listbox selection.
387
388       In addition to the above behavior, the following additional behavior is
389       defined by the default bindings:
390
391       [1] In extended mode, the selected range can be adjusted by pressing
392           button 1 with the Shift key down:  this modifies the selection to
393           consist of the elements between the anchor and the element under
394           the mouse, inclusive.  The un-anchored end of this new selection
395           can also be dragged with the button down.
396
397       [2] In extended mode, pressing button 1 with the Control key down
398           starts a toggle operation: the anchor is set to the element under
399           the mouse, and its selection state is reversed.  The selection
400           state of other elements isn't changed.  If the mouse is dragged
401           with button 1 down, then the selection state of all elements
402           between the anchor and the element under the mouse is set to match
403           that of the anchor element;  the selection state of all other
404           elements remains what it was before the toggle operation began.
405
406       [3] If the mouse leaves the listbox window with button 1 down, the
407           window scrolls away from the mouse, making information visible that
408           used to be off-screen on the side of the mouse.  The scrolling
409           continues until the mouse re-enters the window, the button is
410           released, or the end of the listbox is reached.
411
412       [4] Mouse button 2 may be used for scanning.  If it is pressed and
413           dragged over the listbox, the contents of the listbox drag at high
414           speed in the direction the mouse moves.
415
416       [5] If the Up or Down key is pressed, the location cursor (active
417           element) moves up or down one element.  If the selection mode is
418           browse or extended then the new active element is also selected and
419           all other elements are deselected.  In extended mode the new active
420           element becomes the selection anchor.
421
422       [6] In extended mode, Shift-Up and Shift-Down move the location cursor
423           (active element) up or down one element and also extend the
424           selection to that element in a fashion similar to dragging with
425           mouse button 1.
426
427       [7] The Left and Right keys scroll the listbox view left and right by
428           the width of the character 0.  Control-Left and Control-Right
429           scroll the listbox view left and right by the width of the window.
430           Control-Prior and Control-Next also scroll left and right by the
431           width of the window.
432
433       [8] The Prior and Next keys scroll the listbox view up and down by one
434           page (the height of the window).
435
436       [9] The Home and End keys scroll the listbox horizontally to the left
437           and right edges, respectively.
438
439       [10]
440           Control-Home sets the location cursor to the the first element in
441           the listbox, selects that element, and deselects everything else in
442           the listbox.
443
444       [11]
445           Control-End sets the location cursor to the the last element in the
446           listbox, selects that element, and deselects everything else in the
447           listbox.
448
449       [12]
450           In extended mode, Control-Shift-Home extends the selection to the
451           first element in the listbox and Control-Shift-End extends the
452           selection to the last element.
453
454       [13]
455           In multiple mode, Control-Shift-Home moves the location cursor to
456           the first element in the listbox and Control-Shift-End moves the
457           location cursor to the last element.
458
459       [14]
460           The space and Select keys make a selection at the location cursor
461           (active element) just as if mouse button 1 had been pressed over
462           this element.
463
464       [15]
465           In extended mode, Control-Shift-space and Shift-Select extend the
466           selection to the active element just as if button 1 had been
467           pressed with the Shift key down.
468
469       [16]
470           In extended mode, the Escape key cancels the most recent selection
471           and restores all the elements in the selected range to their
472           previous selection state.
473
474       [17]
475           Control-slash selects everything in the widget, except in single
476           and browse modes, in which case it selects the active element and
477           deselects everything else.
478
479       [18]
480           Control-backslash deselects everything in the widget, except in
481           browse mode where it has no effect.
482
483       [19]
484           The F16 key (labelled Copy on many Sun workstations) or Meta-w
485           copies the selection in the widget to the clipboard, if there is a
486           selection.
487
488           The behavior of listboxes can be changed by defining new bindings
489           for individual widgets or by redefining the class bindings.
490

TIED INTERFACE

492       The Tk::Listbox widget can also be tied to a scalar or array variable,
493       with different behaviour depending on the variable type, with the
494       following tie commands:
495
496          use Tk;
497
498          my ( @array, $scalar, $other );
499          my %options = ( ReturnType => "index" );
500
501          my $MW = MainWindow->new();
502          my $lbox = $MW->Listbox()->pack();
503
504          my @list = ( "a", "b", "c", "d", "e", "f" );
505          $lbox->insert('end', @list );
506
507          tie @array, "Tk::Listbox", $lbox
508          tie $scalar, "Tk::Listbox", $lbox;
509          tie $other, "Tk::Listbox", $lbox, %options;
510
511       currently only one modifier is implemented, a 3 way flag for tied
512       scalars "ReturnType" which can have values "element", "index" or
513       "both". The default is "element".
514
515       Tied Arrays
516           If you tie an array to the Listbox you can manipulate the items
517           currently contained by the box in the same manner as a normal
518           array, e.g.
519
520               print @array;
521               push(@array, @list);
522               my $popped = pop(@array);
523               my $shifted = shift(@array);
524               unshift(@array, @list);
525               delete $array[$index];
526               print $string if exists $array[$i];
527               @array = ();
528               splice @array, $offset, $length, @list
529
530           The delete function is implemented slightly differently from the
531           standard array implementation. Instead of setting the element at
532           that index to undef it instead physically removes it from the
533           Listbox. This has the effect of changing the array indices, so for
534           instance if you had a list on non-continuous indices you wish to
535           remove from the Listbox you should reverse sort the list and then
536           apply the delete function, e.g.
537
538                my @list = ( 1, 2, 4, 12, 20 );
539                my @remove = reverse sort { $a <=> $b } @list;
540                delete @array[@remove];
541
542           would safely remove indices 20, 12, 4, 2 and 1 from the Listbox
543           without problems. It should also be noted that a similar warning
544           applies to the splice function (which would normally be used in
545           this context to perform the same job).
546
547       Tied Scalars
548           Unlike tied arrays, if you tie a scalar to the Listbox you can
549           retrieve the currently selected elements in the box as an array
550           referenced by the scalar, for instance
551
552               my @list = ( "a", "b", "c", "d", "e", "f" );
553               $lbox->insert('end', sort @list );
554               $lbox->selectionSet(1);
555
556           inserts @list as elements in an already existing listbox and
557           selects the element at index 1, which is "b". If we then
558
559                print @$selected;
560
561           this will return the currently selected elements, in this case "b".
562
563           However, if the "ReturnType" arguement is passed when tying the
564           Listbox to the scalar with value "index" then the indices of the
565           selected elements will be returned instead of the elements
566           themselves, ie in this case "1". This can be useful when
567           manipulating both contents and selected elements in the Listbox at
568           the same time.
569
570           Importantly, if a value "both" is given the scalar will not be tied
571           to an array, but instead to a hash, with keys being the indices and
572           values being the elements at those indices
573
574           You can also manipulate the selected items using the scalar.
575           Equating the scalar to an array reference will select any elements
576           that match elements in the Listbox, non-matching array items are
577           ignored, e.g.
578
579               my @list = ( "a", "b", "c", "d", "e", "f" );
580               $lbox->insert('end', sort @list );
581               $lbox->selectionSet(1);
582
583           would insert the array @list into an already existing Listbox and
584           select element at index 1, i.e. "b"
585
586               @array = ( "a", "b", "f" );
587               $selected = \@array;
588
589           would select elements "a", "b" and "f" in the Listbox.
590
591           Again, if the "index" we indicate we want to use indices in the
592           options hash then the indices are use instead of elements, e.g.
593
594               @array = ( 0, 1, 5 );
595               $selected = \@array;
596
597           would have the same effect, selecting elements "a", "b" and "f" if
598           the $selected variable was tied with %options = ( ReturnType =>
599           "index" ).
600
601           If we are returning "both", i.e. the tied scalar points to a hash,
602           both key and value must match, e.g.
603
604               %hash = ( 0 => "a", 1 => "b", 5 => "f" );
605               $selected = \%hash;
606
607           would have the same effect as the previous examples.
608
609           It should be noted that, despite being a reference to an array (or
610           possibly a has), you still can not copy the tied variable without
611           it being untied, instead you must pass a reference to the tied
612           scalar between subroutines.
613

KEYWORDS

615       listbox, widget, tied
616

SEE ALSO

618       Tk::HList, Tk::TextList.
619
620
621
622perl v5.30.1                      2020-01-30                        Listbox(3)
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