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1 \input texinfo.tex
2
3 @c %**start of header
4 @setfilename ../info/widget
5 @settitle The Emacs Widget Library
6 @syncodeindex fn cp
7 @syncodeindex vr cp
8 @syncodeindex ky cp
9 @afourpaper
10 @c %**end of header
11
12 @copying
13 Copyright @copyright{} 2000, 2002, 2003 Free Software Foundation, Inc.
14
15 @quotation
16 Permission is granted to copy, distribute and/or modify this document
17 under the terms of the GNU Free Documentation License, Version 1.1 or
18 any later version published by the Free Software Foundation; with the
19 Invariant Sections being ``The GNU Manifesto'', ``Distribution'' and
20 ``GNU GENERAL PUBLIC LICENSE'', with the Front-Cover texts being ``A GNU
21 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
22 license is included in the section entitled ``GNU Free Documentation
23 License'' in the Emacs manual.
24
25 This document is part of a collection distributed under the GNU Free
26 Documentation License. If you want to distribute this document
27 separately from the collection, you can do so by adding a copy of the
28 license to the document, as described in section 6 of the license.
29
30 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
31 this GNU Manual, like GNU software. Copies published by the Free
32 Software Foundation raise funds for GNU development.''
33 @end quotation
34 @end copying
35
36 @dircategory Emacs
37 @direntry
38 * Widget: (widget). The "widget" package used by the Emacs Customization
39 facility.
40 @end direntry
41
42 @node Top, Introduction, (dir), (dir)
43 @comment node-name, next, previous, up
44 @top The Emacs Widget Library
45
46 @menu
47 * Introduction::
48 * User Interface::
49 * Programming Example::
50 * Setting Up the Buffer::
51 * Basic Types::
52 * Sexp Types::
53 * Widget Properties::
54 * Defining New Widgets::
55 * Widget Browser::
56 * Widget Minor Mode::
57 * Utilities::
58 * Widget Wishlist::
59 * Index::
60 @end menu
61
62 @node Introduction, User Interface, Top, Top
63 @comment node-name, next, previous, up
64 @section Introduction
65
66 Most graphical user interface toolkits provide a number of standard
67 user interface controls (sometimes known as `widgets' or `gadgets').
68 Emacs doesn't really support anything like this, except for an
69 incredibly powerful text ``widget.'' On the other hand, Emacs does
70 provide the necessary primitives to implement many other widgets
71 within a text buffer. The @code{widget} package simplifies this task.
72
73 @cindex basic widgets
74 @cindex widgets, basic types
75 The basic widgets are:
76
77 @table @code
78 @item link
79 Areas of text with an associated action. Intended for hypertext links
80 embedded in text.
81 @item push-button
82 Like link, but intended for stand-alone buttons.
83 @item editable-field
84 An editable text field. It can be either variable or fixed length.
85 @item menu-choice
86 Allows the user to choose one of multiple options from a menu, each
87 option is itself a widget. Only the selected option will be visible in
88 the buffer.
89 @item radio-button-choice
90 Allows the user to choose one of multiple options by activating radio
91 buttons. The options are implemented as widgets. All options will be
92 visible in the buffer.
93 @item item
94 A simple constant widget intended to be used in the @code{menu-choice} and
95 @code{radio-button-choice} widgets.
96 @item choice-item
97 A button item only intended for use in choices. When invoked, the user
98 will be asked to select another option from the choice widget.
99 @item toggle
100 A simple @samp{on}/@samp{off} switch.
101 @item checkbox
102 A checkbox (@samp{[ ]}/@samp{[X]}).
103 @item editable-list
104 Create an editable list. The user can insert or delete items in the
105 list. Each list item is itself a widget.
106 @end table
107
108 Now, of what possible use can support for widgets be in a text editor?
109 I'm glad you asked. The answer is that widgets are useful for
110 implementing forms. A @dfn{form} in Emacs is a buffer where the user is
111 supposed to fill out a number of fields, each of which has a specific
112 meaning. The user is not supposed to change or delete any of the text
113 between the fields. Examples of forms in Emacs are the @file{forms}
114 package (of course), the customize buffers, the mail and news compose
115 modes, and the @acronym{HTML} form support in the @file{w3} browser.
116
117 @cindex widget library, why use it
118 The advantages for a programmer of using the @code{widget} package to
119 implement forms are:
120
121 @enumerate
122 @item
123 More complex fields than just editable text are supported.
124 @item
125 You can give the users immediate feedback if they enter invalid data in a
126 text field, and sometimes prevent entering invalid data.
127 @item
128 You can have fixed sized fields, thus allowing multiple fields to be
129 lined up in columns.
130 @item
131 It is simple to query or set the value of a field.
132 @item
133 Editing happens in the buffer, not in the mini-buffer.
134 @item
135 Packages using the library get a uniform look, making them easier for
136 the user to learn.
137 @item
138 As support for embedded graphics improve, the widget library will be
139 extended to use the GUI features. This means that your code using the
140 widget library will also use the new graphic features automatically.
141 @end enumerate
142
143 In order to minimize the code that is loaded by users who does not
144 create any widgets, the code has been split in two files:
145
146 @cindex widget library, files
147 @table @file
148 @item widget.el
149 This will declare the user variables, define the function
150 @code{define-widget}, and autoload the function @code{widget-create}.
151 @item wid-edit.el
152 Everything else is here, there is no reason to load it explicitly, as
153 it will be autoloaded when needed.
154 @end table
155
156 @node User Interface, Programming Example, Introduction, Top
157 @comment node-name, next, previous, up
158 @section User Interface
159
160 A form consist of read only text for documentation and some fields,
161 where each field contains two parts, a tag and a value. The tags are
162 used to identify the fields, so the documentation can refer to the
163 @samp{foo field}, meaning the field tagged with @samp{Foo}. Here is an
164 example form:
165
166 @example
167 Here is some documentation.
168
169 Name: @i{My Name} @strong{Choose}: This option
170 Address: @i{Some Place
171 In some City
172 Some country.}
173
174 See also @b{_other work_} for more information.
175
176 Numbers: count to three below
177 @b{[INS]} @b{[DEL]} @i{One}
178 @b{[INS]} @b{[DEL]} @i{Eh, two?}
179 @b{[INS]} @b{[DEL]} @i{Five!}
180 @b{[INS]}
181
182 Select multiple:
183
184 @b{[X]} This
185 @b{[ ]} That
186 @b{[X]} Thus
187
188 Select one:
189
190 @b{(*)} One
191 @b{( )} Another One.
192 @b{( )} A Final One.
193
194 @b{[Apply Form]} @b{[Reset Form]}
195 @end example
196
197 The top level widgets in is example are tagged @samp{Name},
198 @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers},
199 @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and
200 @samp{[Reset Form]}. There are basically two things the user can do
201 within a form, namely editing the editable text fields and activating
202 the buttons.
203
204 @subsection Editable Text Fields
205
206 In the example, the value for the @samp{Name} is most likely displayed
207 in an editable text field, and so are values for each of the members of
208 the @samp{Numbers} list. All the normal Emacs editing operations are
209 available for editing these fields. The only restriction is that each
210 change you make must be contained within a single editable text field.
211 For example, capitalizing all text from the middle of one field to the
212 middle of another field is prohibited.
213
214 Editable text fields are created by the @code{editable-field} widget.
215
216 @strong{Warning:} In an @code{editable-field} widget, the editable
217 field must not be adjacent to another widget---that won't work.
218 You must put some text in between. Either make this text part of
219 the @code{editable-field} widget itself, or insert it with
220 @code{widget-insert}.
221
222 The @code{:format} keyword is useful for generating the necessary
223 text; for instance, if you give it a value of @code{"Name: %v "},
224 the @samp{Name: } part will provide the necessary separating text
225 before the field and the trailing space will provide the
226 separating text after the field. If you don't include the
227 @code{:size} keyword, the field will extend to the end of the
228 line, and the terminating newline will provide separation after.
229
230 The editing text fields are highlighted with the
231 @code{widget-field-face} face, making them easy to find.
232
233 @deffn Face widget-field-face
234 Face used for other editing fields.
235 @end deffn
236
237 @subsection Buttons
238
239 @cindex widget buttons
240 @cindex button widgets
241 Some portions of the buffer have an associated @dfn{action}, which can
242 be @dfn{invoked} by a standard key or mouse command. These portions
243 are called @dfn{buttons}. The default commands for activating a button
244 are:
245
246 @table @kbd
247 @item @key{RET}
248 @deffn Command widget-button-press @var{pos} &optional @var{event}
249 Invoke the button at @var{pos}, defaulting to point.
250 If point is not located on a button, invoke the binding in
251 @code{widget-global-map} (by default the global map).
252 @end deffn
253
254 @kindex Mouse-2 @r{(on button widgets})
255 @item Mouse-2
256 @deffn Command widget-button-click @var{event}
257 Invoke the button at the location of the mouse pointer. If the mouse
258 pointer is located in an editable text field, invoke the binding in
259 @code{widget-global-map} (by default the global map).
260 @end deffn
261 @end table
262
263 There are several different kind of buttons, all of which are present in
264 the example:
265
266 @table @emph
267 @cindex option field tag
268 @item The Option Field Tags
269 When you invoke one of these buttons, you will be asked to choose
270 between a number of different options. This is how you edit an option
271 field. Option fields are created by the @code{menu-choice} widget. In
272 the example, @samp{@b{Choose}} is an option field tag.
273 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons
274 Activating these will insert or delete elements from an editable list.
275 The list is created by the @code{editable-list} widget.
276 @cindex embedded buttons
277 @item Embedded Buttons
278 The @samp{@b{_other work_}} is an example of an embedded
279 button. Embedded buttons are not associated with a fields, but can serve
280 any purpose, such as implementing hypertext references. They are
281 usually created by the @code{link} widget.
282 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons
283 Activating one of these will convert it to the other. This is useful
284 for implementing multiple-choice fields. You can create it with the
285 @code{checkbox} widget.
286 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons
287 Only one radio button in a @code{radio-button-choice} widget can be
288 selected at any time. When you invoke one of the unselected radio
289 buttons, it will be selected and the previous selected radio button will
290 become unselected.
291 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons
292 These are explicit buttons made with the @code{push-button} widget. The
293 main difference from the @code{link} widget is that the buttons will be
294 displayed as GUI buttons when possible.
295 @end table
296
297 To make them easier to locate, buttons are emphasized in the buffer.
298
299 @deffn Face widget-button-face
300 Face used for buttons.
301 @end deffn
302
303 @defopt widget-mouse-face
304 Face used for highlighting a button when the mouse pointer moves across
305 it.
306 @end defopt
307
308 @subsection Navigation
309
310 You can use all the normal Emacs commands to move around in a form
311 buffer, plus you will have these additional commands:
312
313 @table @kbd
314 @item @key{TAB}
315 @deffn Command widget-forward &optional count
316 Move point @var{count} buttons or editing fields forward.
317 @end deffn
318 @item @key{M-TAB}
319 @deffn Command widget-backward &optional count
320 Move point @var{count} buttons or editing fields backward.
321 @end deffn
322 @end table
323
324 @node Programming Example, Setting Up the Buffer, User Interface, Top
325 @comment node-name, next, previous, up
326 @section Programming Example
327
328 @cindex widgets, programming example
329 @cindex example of using widgets
330 Here is the code to implement the user interface example (@pxref{User
331 Interface}).
332
333 @lisp
334 (require 'widget)
335
336 (eval-when-compile
337 (require 'wid-edit))
338
339 (defvar widget-example-repeat)
340
341 (defun widget-example ()
342 "Create the widgets from the Widget manual."
343 (interactive)
344 (switch-to-buffer "*Widget Example*")
345 (kill-all-local-variables)
346 (make-local-variable 'widget-example-repeat)
347 (let ((inhibit-read-only t))
348 (erase-buffer))
349 (remove-overlays)
350 (widget-insert "Here is some documentation.\n\nName: ")
351 (widget-create 'editable-field
352 :size 13
353 :format "%v " ; Text after the field!
354 "My Name")
355 (widget-create 'menu-choice
356 :tag "Choose"
357 :value "This"
358 :help-echo "Choose me, please!"
359 :notify (lambda (widget &rest ignore)
360 (message "%s is a good choice!"
361 (widget-value widget)))
362 '(item :tag "This option" :value "This")
363 '(choice-item "That option")
364 '(editable-field :menu-tag "No option" "Thus option"))
365 (widget-insert "Address: ")
366 (widget-create 'editable-field
367 "Some Place\nIn some City\nSome country.")
368 (widget-insert "\nSee also ")
369 (widget-create 'link
370 :notify (lambda (&rest ignore)
371 (widget-value-set widget-example-repeat
372 '("En" "To" "Tre"))
373 (widget-setup))
374 "other work")
375 (widget-insert
376 " for more information.\n\nNumbers: count to three below\n")
377 (setq widget-example-repeat
378 (widget-create 'editable-list
379 :entry-format "%i %d %v"
380 :notify (lambda (widget &rest ignore)
381 (let ((old (widget-get widget
382 ':example-length))
383 (new (length (widget-value widget))))
384 (unless (eq old new)
385 (widget-put widget ':example-length new)
386 (message "You can count to %d." new))))
387 :value '("One" "Eh, two?" "Five!")
388 '(editable-field :value "three")))
389 (widget-insert "\n\nSelect multiple:\n\n")
390 (widget-create 'checkbox t)
391 (widget-insert " This\n")
392 (widget-create 'checkbox nil)
393 (widget-insert " That\n")
394 (widget-create 'checkbox
395 :notify (lambda (&rest ignore) (message "Tickle"))
396 t)
397 (widget-insert " Thus\n\nSelect one:\n\n")
398 (widget-create 'radio-button-choice
399 :value "One"
400 :notify (lambda (widget &rest ignore)
401 (message "You selected %s"
402 (widget-value widget)))
403 '(item "One") '(item "Another One.") '(item "A Final One."))
404 (widget-insert "\n")
405 (widget-create 'push-button
406 :notify (lambda (&rest ignore)
407 (if (= (length (widget-value widget-example-repeat))
408 3)
409 (message "Congratulation!")
410 (error "Three was the count!")))
411 "Apply Form")
412 (widget-insert " ")
413 (widget-create 'push-button
414 :notify (lambda (&rest ignore)
415 (widget-example))
416 "Reset Form")
417 (widget-insert "\n")
418 (use-local-map widget-keymap)
419 (widget-setup))
420 @end lisp
421
422 @node Setting Up the Buffer, Basic Types, Programming Example, Top
423 @comment node-name, next, previous, up
424 @section Setting Up the Buffer
425
426 Widgets are created with @code{widget-create}, which returns a
427 @dfn{widget} object. This object can be queried and manipulated by
428 other widget functions, until it is deleted with @code{widget-delete}.
429 After the widgets have been created, @code{widget-setup} must be called
430 to enable them.
431
432 @defun widget-create type [ keyword argument ]@dots{}
433 Create and return a widget of type @var{type}.
434 The syntax for the @var{type} argument is described in @ref{Basic Types}.
435
436 The keyword arguments can be used to overwrite the keyword arguments
437 that are part of @var{type}.
438 @end defun
439
440 @defun widget-delete widget
441 Delete @var{widget} and remove it from the buffer.
442 @end defun
443
444 @defun widget-setup
445 Set up a buffer to support widgets.
446
447 This should be called after creating all the widgets and before allowing
448 the user to edit them.
449 @refill
450 @end defun
451
452 If you want to insert text outside the widgets in the form, the
453 recommended way to do that is with @code{widget-insert}.
454
455 @defun widget-insert
456 Insert the arguments, either strings or characters, at point.
457 The inserted text will be read-only.
458 @end defun
459
460 There is a standard widget keymap which you might find useful.
461
462 @findex widget-button-press
463 @findex widget-button-click
464 @defvr Const widget-keymap
465 A keymap with the global keymap as its parent.@*
466 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
467 @code{widget-backward}, respectively. @key{RET} and @kbd{Mouse-2}
468 are bound to @code{widget-button-press} and
469 @code{widget-button-click}.@refill
470 @end defvr
471
472 @defvar widget-global-map
473 Keymap used by @code{widget-button-press} and @code{widget-button-click}
474 when not on a button. By default this is @code{global-map}.
475 @end defvar
476
477 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
478 @comment node-name, next, previous, up
479 @section Basic Types
480
481 The syntax of a type specification is given below:
482
483 @example
484 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
485 | NAME
486 @end example
487
488 Where, @var{name} is a widget name, @var{keyword} is the name of a
489 property, @var{argument} is the value of the property, and @var{args}
490 are interpreted in a widget specific way.
491
492 @cindex keyword arguments
493 The following keyword arguments that apply to all widgets:
494
495 @table @code
496 @vindex value@r{ keyword}
497 @item :value
498 The initial value for widgets of this type.
499
500 @vindex format@r{ keyword}
501 @item :format
502 This string will be inserted in the buffer when you create a widget.
503 The following @samp{%} escapes are available:
504
505 @table @samp
506 @item %[
507 @itemx %]
508 The text inside will be marked as a button.
509
510 By default, the text will be shown in @code{widget-button-face}, and
511 surrounded by brackets.
512
513 @defopt widget-button-prefix
514 String to prefix buttons.
515 @end defopt
516
517 @defopt widget-button-suffix
518 String to suffix buttons.
519 @end defopt
520
521 @item %@{
522 @itemx %@}
523 The text inside will be displayed with the face specified by
524 @code{:sample-face}.
525
526 @item %v
527 This will be replaced with the buffer representation of the widget's
528 value. What this is depends on the widget type.
529
530 @item %d
531 Insert the string specified by @code{:doc} here.
532
533 @item %h
534 Like @samp{%d}, with the following modifications: If the documentation
535 string is more than one line, it will add a button which will toggle
536 between showing only the first line, and showing the full text.
537 Furthermore, if there is no @code{:doc} property in the widget, it will
538 instead examine the @code{:documentation-property} property. If it is a
539 lambda expression, it will be called with the widget's value as an
540 argument, and the result will be used as the documentation text.
541
542 @item %t
543 Insert the string specified by @code{:tag} here, or the @code{princ}
544 representation of the value if there is no tag.
545
546 @item %%
547 Insert a literal @samp{%}.
548 @end table
549
550 @vindex button-face@r{ keyword}
551 @item :button-face
552 Face used to highlight text inside %[ %] in the format.
553
554 @vindex button-prefix@r{ keyword}
555 @vindex button-suffix@r{ keyword}
556 @item :button-prefix
557 @itemx :button-suffix
558 Text around %[ %] in the format.
559
560 These can be
561 @table @emph
562 @item nil
563 No text is inserted.
564
565 @item a string
566 The string is inserted literally.
567
568 @item a symbol
569 The value of the symbol is expanded according to this table.
570 @end table
571
572 @vindex doc@r{ keyword}
573 @item :doc
574 The string inserted by the @samp{%d} escape in the format
575 string.
576
577 @vindex tag@r{ keyword}
578 @item :tag
579 The string inserted by the @samp{%t} escape in the format
580 string.
581
582 @vindex tag-glyph@r{ keyword}
583 @item :tag-glyph
584 Name of image to use instead of the string specified by @code{:tag} on
585 Emacsen that supports it.
586
587 @vindex help-echo@r{ keyword}
588 @item :help-echo
589 Specifies how to display a message whenever you move to the widget with
590 either @code{widget-forward} or @code{widget-backward} or move the mouse
591 over it (using the standard @code{help-echo} mechanism). The argument
592 is either a string to display, a function of one argument, the widget,
593 which should return a string to display, or a form that evaluates to
594 such a string.
595
596 @vindex indent@r{ keyword}
597 @item :indent
598 An integer indicating the absolute number of spaces to indent children
599 of this widget.
600
601 @vindex offset@r{ keyword}
602 @item :offset
603 An integer indicating how many extra spaces to add to the widget's
604 grandchildren compared to this widget.
605
606 @vindex extra-offset@r{ keyword}
607 @item :extra-offset
608 An integer indicating how many extra spaces to add to the widget's
609 children compared to this widget.
610
611 @vindex notify@r{ keyword}
612 @item :notify
613 A function called each time the widget or a nested widget is changed.
614 The function is called with two or three arguments. The first argument
615 is the widget itself, the second argument is the widget that was
616 changed, and the third argument is the event leading to the change, if
617 any.
618
619 @vindex menu-tag@r{ keyword}
620 @item :menu-tag
621 Tag used in the menu when the widget is used as an option in a
622 @code{menu-choice} widget.
623
624 @vindex menu-tag-get@r{ keyword}
625 @item :menu-tag-get
626 Function used for finding the tag when the widget is used as an option
627 in a @code{menu-choice} widget. By default, the tag used will be either the
628 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
629 representation of the @code{:value} property if not.
630
631 @vindex match@r{ keyword}
632 @item :match
633 Should be a function called with two arguments, the widget and a value,
634 and returning non-@code{nil} if the widget can represent the specified value.
635
636 @vindex validate@r{ keyword}
637 @item :validate
638 A function which takes a widget as an argument, and returns @code{nil}
639 if the widget's current value is valid for the widget. Otherwise it
640 should return the widget containing the invalid data, and set that
641 widget's @code{:error} property to a string explaining the error.
642
643 The following predefined function can be used:
644
645 @defun widget-children-validate widget
646 All the @code{:children} of @var{widget} must be valid.
647 @end defun
648
649 @vindex tab-order@r{ keyword}
650 @item :tab-order
651 Specify the order in which widgets are traversed with
652 @code{widget-forward} or @code{widget-backward}. This is only partially
653 implemented.
654
655 @enumerate a
656 @item
657 Widgets with tabbing order @code{-1} are ignored.
658
659 @item
660 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
661 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
662 whichever comes first.
663
664 @item
665 When on a widget with no tabbing order specified, go to the next widget
666 in the buffer with a positive tabbing order, or @code{nil}
667 @end enumerate
668
669 @vindex parent@r{ keyword}
670 @item :parent
671 The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
672 element of a @code{editable-list} widget).
673
674 @vindex sibling-args@r{ keyword}
675 @item :sibling-args
676 This keyword is only used for members of a @code{radio-button-choice} or
677 @code{checklist}. The value should be a list of extra keyword
678 arguments, which will be used when creating the @code{radio-button} or
679 @code{checkbox} associated with this item.
680
681 @end table
682
683 @deffn {User Option} widget-glyph-directory
684 Directory where glyphs are found.
685 Widget will look here for a file with the same name as specified for the
686 image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
687 @end deffn
688
689 @deffn{User Option} widget-glyph-enable
690 If non-@code{nil}, allow glyphs to appear on displays where they are supported.
691 @end deffn
692
693
694 @menu
695 * link::
696 * url-link::
697 * info-link::
698 * push-button::
699 * editable-field::
700 * text::
701 * menu-choice::
702 * radio-button-choice::
703 * item::
704 * choice-item::
705 * toggle::
706 * checkbox::
707 * checklist::
708 * editable-list::
709 * group::
710 @end menu
711
712 @node link, url-link, Basic Types, Basic Types
713 @comment node-name, next, previous, up
714 @subsection The @code{link} Widget
715 @findex link@r{ widget}
716
717 Syntax:
718
719 @example
720 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
721 @end example
722
723 The @var{value}, if present, is used to initialize the @code{:value}
724 property. The value should be a string, which will be inserted in the
725 buffer.
726
727 By default the link will be shown in brackets.
728
729 @defopt widget-link-prefix
730 String to prefix links.
731 @end defopt
732
733 @defopt widget-link-suffix
734 String to suffix links.
735 @end defopt
736
737 @node url-link, info-link, link, Basic Types
738 @comment node-name, next, previous, up
739 @subsection The @code{url-link} Widget
740 @findex url-link@r{ widget}
741
742 Syntax:
743
744 @example
745 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
746 @end example
747
748 @findex browse-url-browser-function@r{, and @code{url-link} widget}
749 When this link is invoked, the @acronym{WWW} browser specified by
750 @code{browse-url-browser-function} will be called with @var{url}.
751
752 @node info-link, push-button, url-link, Basic Types
753 @comment node-name, next, previous, up
754 @subsection The @code{info-link} Widget
755 @findex info-link@r{ widget}
756
757 Syntax:
758
759 @example
760 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
761 @end example
762
763 When this link is invoked, the built-in Info reader is started on
764 @var{address}.
765
766 @node push-button, editable-field, info-link, Basic Types
767 @comment node-name, next, previous, up
768 @subsection The @code{push-button} Widget
769 @findex push-button@r{ widget}
770
771 Syntax:
772
773 @example
774 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
775 @end example
776
777 The @var{value}, if present, is used to initialize the @code{:value}
778 property. The value should be a string, which will be inserted in the
779 buffer.
780
781 By default the tag will be shown in brackets.
782
783 @defopt widget-push-button-prefix
784 String to prefix push buttons.
785 @end defopt
786
787 @defopt widget-push-button-suffix
788 String to suffix push buttons.
789 @end defopt
790
791 @node editable-field, text, push-button, Basic Types
792 @comment node-name, next, previous, up
793 @subsection The @code{editable-field} Widget
794 @findex editable-field@r{ widget}
795
796 Syntax:
797
798 @example
799 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
800 @end example
801
802 The @var{value}, if present, is used to initialize the @code{:value}
803 property. The value should be a string, which will be inserted in
804 field. This widget will match all string values.
805
806 The following extra properties are recognized:
807
808 @table @code
809 @vindex size@r{ keyword}
810 @item :size
811 The width of the editable field.@*
812 By default the field will reach to the end of the line.
813
814 @vindex value-face@r{ keyword}
815 @item :value-face
816 Face used for highlighting the editable field. Default is
817 @code{widget-field-face}, see @ref{User Interface}.
818
819 @vindex secret@r{ keyword}
820 @item :secret
821 Character used to display the value. You can set this to e.g.@: @code{?*}
822 if the field contains a password or other secret information. By
823 default, this is @code{nil}, and the value is not secret.
824
825 @vindex valid-regexp@r{ keyword}
826 @item :valid-regexp
827 By default the @code{:validate} function will match the content of the
828 field with the value of this attribute. The default value is @code{""}
829 which matches everything.
830
831 @vindex keymap@r{ keyword}
832 @vindex widget-field-keymap
833 @item :keymap
834 Keymap used in the editable field. The default value is
835 @code{widget-field-keymap}, which allows you to use all the normal
836 editing commands, even if the buffer's major mode suppresses some of
837 them. Pressing @key{RET} invokes the function specified by
838 @code{:action}.
839 @end table
840
841 @node text, menu-choice, editable-field, Basic Types
842 @comment node-name, next, previous, up
843 @subsection The @code{text} Widget
844 @findex text@r{ widget}
845
846 @vindex widget-text-keymap
847 This is just like @code{editable-field}, but intended for multiline text
848 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
849 does not rebind the @key{RET} key.
850
851 @node menu-choice, radio-button-choice, text, Basic Types
852 @comment node-name, next, previous, up
853 @subsection The @code{menu-choice} Widget
854 @findex menu-choice@r{ widget}
855
856 Syntax:
857
858 @example
859 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
860 @end example
861
862 The @var{type} argument represents each possible choice. The widget's
863 value will be that of the chosen @var{type} argument. This widget will
864 match any value matching at least one of the specified @var{type}
865 arguments.
866
867 @table @code
868 @vindex void@r{ keyword}
869 @item :void
870 Widget type used as a fallback when the value does not match any of the
871 specified @var{type} arguments.
872
873 @vindex case-fold@r{ keyword}
874 @item :case-fold
875 Set this to @code{nil} if you don't want to ignore case when prompting for a
876 choice through the minibuffer.
877
878 @vindex children@r{ keyword}
879 @item :children
880 A list whose @sc{car} is the widget representing the currently chosen
881 type in the buffer.
882
883 @vindex choice@r{ keyword}
884 @item :choice
885 The current chosen type.
886
887 @vindex args@r{ keyword}
888 @item :args
889 The list of types.
890 @end table
891
892 @node radio-button-choice, item, menu-choice, Basic Types
893 @comment node-name, next, previous, up
894 @subsection The @code{radio-button-choice} Widget
895 @findex radio-button-choice@r{ widget}
896
897 Syntax:
898
899 @example
900 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
901 @end example
902
903 The @var{type} argument represents each possible choice. The widget's
904 value will be that of the chosen @var{type} argument. This widget will
905 match any value matching at least one of the specified @var{type}
906 arguments.
907
908 The following extra properties are recognized.
909
910 @table @code
911 @vindex entry-format@r{ keyword}
912 @item :entry-format
913 This string will be inserted for each entry in the list.
914 The following @samp{%} escapes are available:
915 @table @samp
916 @item %v
917 Replace with the buffer representation of the @var{type} widget.
918 @item %b
919 Replace with the radio button.
920 @item %%
921 Insert a literal @samp{%}.
922 @end table
923
924 @vindex button-args@r{ keyword}
925 @item :button-args
926 A list of keywords to pass to the radio buttons. Useful for setting
927 e.g.@: the @samp{:help-echo} for each button.
928
929 @vindex buttons@r{ keyword}
930 @item :buttons
931 The widgets representing the radio buttons.
932
933 @vindex children@r{ keyword}
934 @item :children
935 The widgets representing each type.
936
937 @vindex choice@r{ keyword}
938 @item :choice
939 The current chosen type
940
941 @vindex args@r{ keyword}
942 @item :args
943 The list of types.
944 @end table
945
946 You can add extra radio button items to a @code{radio-button-choice}
947 widget after it has been created with the function
948 @code{widget-radio-add-item}.
949
950 @defun widget-radio-add-item widget type
951 Add to @code{radio-button-choice} widget @var{widget} a new radio button
952 item of type @var{type}.
953 @end defun
954
955 Please note that such items added after the @code{radio-button-choice}
956 widget has been created will @strong{not} be properly destructed when
957 you call @code{widget-delete}.
958
959 @node item, choice-item, radio-button-choice, Basic Types
960 @comment node-name, next, previous, up
961 @subsection The @code{item} Widget
962 @findex item@r{ widget}
963
964 Syntax:
965
966 @example
967 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
968 @end example
969
970 The @var{value}, if present, is used to initialize the @code{:value}
971 property. The value should be a string, which will be inserted in the
972 buffer. This widget will only match the specified value.
973
974 @node choice-item, toggle, item, Basic Types
975 @comment node-name, next, previous, up
976 @subsection The @code{choice-item} Widget
977 @findex choice-item@r{ widget}
978
979 Syntax:
980
981 @example
982 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
983 @end example
984
985 The @var{value}, if present, is used to initialize the @code{:value}
986 property. The value should be a string, which will be inserted in the
987 buffer as a button. Activating the button of a @code{choice-item} is
988 equivalent to activating the parent widget. This widget will only match
989 the specified value.
990
991 @node toggle, checkbox, choice-item, Basic Types
992 @comment node-name, next, previous, up
993 @subsection The @code{toggle} Widget
994 @findex toggle@r{ widget}
995
996 Syntax:
997
998 @example
999 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
1000 @end example
1001
1002 The widget has two possible states, @samp{on} and @samp{off}, which
1003 correspond to a @code{t} or @code{nil} value, respectively.
1004
1005 The following extra properties are recognized:
1006
1007 @table @code
1008 @item :on
1009 A string representing the @samp{on} state. By default the string
1010 @samp{on}.
1011 @item :off
1012 A string representing the @samp{off} state. By default the string
1013 @samp{off}.
1014 @vindex on-glyph@r{ keyword}
1015 @item :on-glyph
1016 Name of a glyph to be used instead of the @samp{:on} text string, on
1017 emacsen that supports this.
1018 @vindex off-glyph@r{ keyword}
1019 @item :off-glyph
1020 Name of a glyph to be used instead of the @samp{:off} text string, on
1021 emacsen that supports this.
1022 @end table
1023
1024 @node checkbox, checklist, toggle, Basic Types
1025 @comment node-name, next, previous, up
1026 @subsection The @code{checkbox} Widget
1027 @findex checkbox@r{ widget}
1028
1029 This widget has two possible states, @samp{selected} and
1030 @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
1031
1032 Syntax:
1033
1034 @example
1035 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
1036 @end example
1037
1038 @node checklist, editable-list, checkbox, Basic Types
1039 @comment node-name, next, previous, up
1040 @subsection The @code{checklist} Widget
1041 @findex checklist@r{ widget}
1042
1043 Syntax:
1044
1045 @example
1046 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
1047 @end example
1048
1049 The @var{type} arguments represent each checklist item. The widget's
1050 value will be a list containing the values of all checked @var{type}
1051 arguments. The checklist widget will match a list whose elements all
1052 match at least one of the specified @var{type} arguments.
1053
1054 The following extra properties are recognized:
1055
1056 @table @code
1057 @vindex entry-format@r{ keyword}
1058 @item :entry-format
1059 This string will be inserted for each entry in the list.
1060 The following @samp{%} escapes are available:
1061 @table @samp
1062 @item %v
1063 Replaced with the buffer representation of the @var{type} widget.
1064 @item %b
1065 Replace with the checkbox.
1066 @item %%
1067 Insert a literal @samp{%}.
1068 @end table
1069
1070 @vindex greedy@r{ keyword}
1071 @item :greedy
1072 Usually a checklist will only match if the items are in the exact
1073 sequence given in the specification. By setting @code{:greedy} to
1074 non-@code{nil}, it will allow the items to come in any sequence.
1075 However, if you extract the value they will be in the sequence given
1076 in the checklist, i.e.@: the original sequence is forgotten.
1077
1078 @vindex button-args@r{ keyword}
1079 @item :button-args
1080 A list of keywords to pass to the checkboxes. Useful for setting
1081 e.g.@: the @samp{:help-echo} for each checkbox.
1082
1083 @vindex buttons@r{ keyword}
1084 @item :buttons
1085 The widgets representing the checkboxes.
1086
1087 @vindex children@r{ keyword}
1088 @item :children
1089 The widgets representing each type.
1090
1091 @vindex args@r{ keyword}
1092 @item :args
1093 The list of types.
1094 @end table
1095
1096 @node editable-list, group, checklist, Basic Types
1097 @comment node-name, next, previous, up
1098 @subsection The @code{editable-list} Widget
1099 @findex editable-list@r{ widget}
1100
1101 Syntax:
1102
1103 @example
1104 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
1105 @end example
1106
1107 The value is a list, where each member represents one widget of type
1108 @var{type}.
1109
1110 The following extra properties are recognized:
1111
1112 @table @code
1113 @vindex entry-format@r{ keyword}
1114 @item :entry-format
1115 This string will be inserted for each entry in the list.
1116 The following @samp{%} escapes are available:
1117 @table @samp
1118 @item %v
1119 This will be replaced with the buffer representation of the @var{type}
1120 widget.
1121 @item %i
1122 Insert the @b{[INS]} button.
1123 @item %d
1124 Insert the @b{[DEL]} button.
1125 @item %%
1126 Insert a literal @samp{%}.
1127 @end table
1128
1129 @vindex insert-button-args@r{ keyword}
1130 @item :insert-button-args
1131 A list of keyword arguments to pass to the insert buttons.
1132
1133 @vindex delete-button-args@r{ keyword}
1134 @item :delete-button-args
1135 A list of keyword arguments to pass to the delete buttons.
1136
1137 @vindex append-button-args@r{ keyword}
1138 @item :append-button-args
1139 A list of keyword arguments to pass to the trailing insert button.
1140
1141 @vindex buttons@r{ keyword}
1142 @item :buttons
1143 The widgets representing the insert and delete buttons.
1144
1145 @vindex children@r{ keyword}
1146 @item :children
1147 The widgets representing the elements of the list.
1148
1149 @vindex args@r{ keyword}
1150 @item :args
1151 List whose @sc{car} is the type of the list elements.
1152 @end table
1153
1154 @node group, , editable-list, Basic Types
1155 @comment node-name, next, previous, up
1156 @subsection The @code{group} Widget
1157 @findex group@r{ widget}
1158
1159 This widget simply group other widgets together.
1160
1161 Syntax:
1162
1163 @example
1164 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1165 @end example
1166
1167 The value is a list, with one member for each @var{type}.
1168
1169 @node Sexp Types, Widget Properties, Basic Types, Top
1170 @comment
1171 @section Sexp Types
1172 @cindex sexp types
1173
1174 A number of widgets for editing @dfn{s-expressions} (Lisp types), sexp
1175 for short, are also available. These basically fall in several
1176 categories described in this section.
1177
1178 @menu
1179 * constants::
1180 * generic::
1181 * atoms::
1182 * composite::
1183 @end menu
1184
1185 @node constants, generic, Sexp Types, Sexp Types
1186 @comment node-name, next, previous, up
1187 @subsection The Constant Widgets
1188 @cindex constant widgets
1189
1190 The @code{const} widget can contain any Lisp expression, but the user is
1191 prohibited from editing it, which is mainly useful as a component of one
1192 of the composite widgets.
1193
1194 The syntax for the @code{const} widget is:
1195
1196 @example
1197 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1198 @end example
1199
1200 The @var{value}, if present, is used to initialize the @code{:value}
1201 property and can be any s-expression.
1202
1203 @deffn Widget const
1204 This will display any valid s-expression in an immutable part of the
1205 buffer.
1206 @end deffn
1207
1208 There are two variations of the @code{const} widget, namely
1209 @code{variable-item} and @code{function-item}. These should contain a
1210 symbol with a variable or function binding. The major difference from
1211 the @code{const} widget is that they will allow the user to see the
1212 variable or function documentation for the symbol.
1213
1214 @deffn Widget variable-item
1215 An immutable symbol that is bound as a variable.
1216 @end deffn
1217
1218 @deffn Widget function-item
1219 An immutable symbol that is bound as a function.
1220 @end deffn
1221
1222 @node generic, atoms, constants, Sexp Types
1223 @comment node-name, next, previous, up
1224 @subsection Generic Sexp Widget
1225 @cindex generic sexp widget
1226
1227 The @code{sexp} widget can contain any Lisp expression, and allows the
1228 user to edit it inline in the buffer.
1229
1230 The syntax for the @code{sexp} widget is:
1231
1232 @example
1233 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1234 @end example
1235
1236 @deffn Widget sexp
1237 This will allow you to edit any valid s-expression in an editable buffer
1238 field.
1239
1240 The @code{sexp} widget takes the same keyword arguments as the
1241 @code{editable-field} widget. @xref{editable-field}.
1242 @end deffn
1243
1244 @node atoms, composite, generic, Sexp Types
1245 @comment node-name, next, previous, up
1246 @subsection Atomic Sexp Widgets
1247 @cindex atomic sexp widget
1248
1249 The atoms are s-expressions that do not consist of other s-expressions.
1250 For example, a string, a file name, or a symbol are atoms, while a list
1251 is a composite type. You can edit the value of an atom with the
1252 following widgets.
1253
1254 The syntax for all the atoms are:
1255
1256 @example
1257 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1258 @end example
1259
1260 The @var{value}, if present, is used to initialize the @code{:value}
1261 property and must be an expression of the same type as the widget.
1262 That is, the string widget can only be initialized with a string.
1263
1264 All the atom widgets take the same keyword arguments as the
1265 @code{editable-field} widget. @xref{editable-field}.
1266
1267 @deffn Widget string
1268 Allows you to edit a string in an editable field.
1269 @end deffn
1270
1271 @deffn Widget regexp
1272 Allows you to edit a regular expression in an editable field.
1273 @end deffn
1274
1275 @deffn Widget character
1276 Allows you to enter a character in an editable field.
1277 @end deffn
1278
1279 @deffn Widget file
1280 Allows you to edit a file name in an editable field. If you invoke
1281 the tag button, you can edit the file name in the mini-buffer with
1282 completion.
1283
1284 Keywords:
1285 @table @code
1286 @vindex must-match@r{ keyword}
1287 @item :must-match
1288 If this is set to non-@code{nil}, only existing file names will be
1289 allowed in the minibuffer.
1290 @end table
1291 @end deffn
1292
1293 @deffn Widget directory
1294 Allows you to edit a directory name in an editable field.
1295 Similar to the @code{file} widget.
1296 @end deffn
1297
1298 @deffn Widget symbol
1299 Allows you to edit a Lisp symbol in an editable field.
1300 @end deffn
1301
1302 @deffn Widget function
1303 Allows you to edit a lambda expression, or a function name with completion.
1304 @end deffn
1305
1306 @deffn Widget variable
1307 Allows you to edit a variable name, with completion.
1308 @end deffn
1309
1310 @deffn Widget integer
1311 Allows you to edit an integer in an editable field.
1312 @end deffn
1313
1314 @deffn Widget number
1315 Allows you to edit a number in an editable field.
1316 @end deffn
1317
1318 @deffn Widget boolean
1319 Allows you to edit a boolean. In Lisp this means a variable which is
1320 either @code{nil} meaning false, or non-@code{nil} meaning true.
1321 @end deffn
1322
1323
1324 @node composite, , atoms, Sexp Types
1325 @comment node-name, next, previous, up
1326 @subsection Composite Sexp Widgets
1327 @cindex composite sexp widgets
1328
1329 The syntax for the composite widget is:
1330
1331 @example
1332 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1333 @end example
1334
1335 @noindent
1336 where each @var{component} must be a widget type. Each component widget
1337 will be displayed in the buffer, and will be editable by the user.
1338
1339 @deffn Widget cons
1340 The value of a @code{cons} widget is a cons-cell where the @sc{car} is
1341 the value of the first component and the @sc{cdr} is the value of the
1342 second component. There must be exactly two components.
1343 @end deffn
1344
1345 @deffn Widget list
1346 The value of a @code{list} widget is a list containing the value of
1347 each of its component.
1348 @end deffn
1349
1350 @deffn Widget vector
1351 The value of a @code{vector} widget is a vector containing the value of
1352 each of its component.
1353 @end deffn
1354
1355 The above suffice for specifying fixed size lists and vectors. To get
1356 variable length lists and vectors, you can use a @code{choice},
1357 @code{set}, or @code{repeat} widgets together with the @code{:inline}
1358 keywords. If any component of a composite widget has the @code{:inline}
1359 keyword set, its value must be a list which will then be spliced into
1360 the composite. For example, to specify a list whose first element must
1361 be a file name, and whose remaining arguments should either by the
1362 symbol @code{t} or two files, you can use the following widget
1363 specification:
1364
1365 @example
1366 (list file
1367 (choice (const t)
1368 (list :inline t
1369 :value ("foo" "bar")
1370 string string)))
1371 @end example
1372
1373 The value of a widget of this type will either have the form
1374 @code{(file t)} or @code{(file string string)}.
1375
1376 This concept of inline is probably hard to understand. It was certainly
1377 hard to implement, so instead of confusing you more by trying to explain
1378 it here, I'll just suggest you meditate over it for a while.
1379
1380 @deffn Widget choice
1381 Allows you to edit a sexp which may have one of a fixed set of types.
1382 It is currently implemented with the @code{choice-menu} basic widget,
1383 and has a similar syntax.
1384 @end deffn
1385
1386 @deffn Widget set
1387 Allows you to specify a type which must be a list whose elements all
1388 belong to given set. The elements of the list are not significant.
1389 This is implemented on top of the @code{checklist} basic widget, and has
1390 a similar syntax.
1391 @end deffn
1392
1393 @deffn Widget repeat
1394 Allows you to specify a variable length list whose members are all of
1395 the same type. Implemented on top of the @code{editable-list} basic
1396 widget, and has a similar syntax.
1397 @end deffn
1398
1399 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1400 @comment node-name, next, previous, up
1401 @section Properties
1402 @cindex properties of widgets
1403 @cindex widget properties
1404
1405 You can examine or set the value of a widget by using the widget object
1406 that was returned by @code{widget-create}.
1407
1408 @defun widget-value widget
1409 Return the current value contained in @var{widget}.
1410 It is an error to call this function on an uninitialized widget.
1411 @end defun
1412
1413 @defun widget-value-set widget value
1414 Set the value contained in @var{widget} to @var{value}.
1415 It is an error to call this function with an invalid @var{value}.
1416 @end defun
1417
1418 @strong{Important:} You @emph{must} call @code{widget-setup} after
1419 modifying the value of a widget before the user is allowed to edit the
1420 widget again. It is enough to call @code{widget-setup} once if you
1421 modify multiple widgets. This is currently only necessary if the widget
1422 contains an editing field, but may be necessary for other widgets in the
1423 future.
1424
1425 If your application needs to associate some information with the widget
1426 objects, for example a reference to the item being edited, it can be
1427 done with @code{widget-put} and @code{widget-get}. The property names
1428 must begin with a @samp{:}.
1429
1430 @defun widget-put widget property value
1431 In @var{widget} set @var{property} to @var{value}.
1432 @var{property} should be a symbol, while @var{value} can be anything.
1433 @end defun
1434
1435 @defun widget-get widget property
1436 In @var{widget} return the value for @var{property}.
1437 @var{property} should be a symbol, the value is what was last set by
1438 @code{widget-put} for @var{property}.
1439 @end defun
1440
1441 @defun widget-member widget property
1442 Non-@code{nil} if @var{widget} has a value (even @code{nil}) for
1443 property @var{property}.
1444 @end defun
1445
1446 Occasionally it can be useful to know which kind of widget you have,
1447 i.e.@: the name of the widget type you gave when the widget was created.
1448
1449 @defun widget-type widget
1450 Return the name of @var{widget}, a symbol.
1451 @end defun
1452
1453 @cindex active widget
1454 @cindex inactive widget
1455 @cindex activate a widget
1456 @cindex deactivate a widget
1457 Widgets can be in two states: active, which means they are modifiable by
1458 the user, or inactive, which means they cannot be modified by the user.
1459 You can query or set the state with the following code:
1460
1461 @lisp
1462 ;; Examine if @var{widget} is active or not.
1463 (if (widget-apply @var{widget} :active)
1464 (message "Widget is active.")
1465 (message "Widget is inactive.")
1466
1467 ;; Make @var{widget} inactive.
1468 (widget-apply @var{widget} :deactivate)
1469
1470 ;; Make @var{widget} active.
1471 (widget-apply @var{widget} :activate)
1472 @end lisp
1473
1474 A widget is inactive if it, or any of its ancestors (found by
1475 following the @code{:parent} link), have been deactivated. To make sure
1476 a widget is really active, you must therefore activate both it and
1477 all its ancestors.
1478
1479 @lisp
1480 (while widget
1481 (widget-apply widget :activate)
1482 (setq widget (widget-get widget :parent)))
1483 @end lisp
1484
1485 You can check if a widget has been made inactive by examining the value
1486 of the @code{:inactive} keyword. If this is non-@code{nil}, the widget itself
1487 has been deactivated. This is different from using the @code{:active}
1488 keyword, in that the latter tells you if the widget @strong{or} any of
1489 its ancestors have been deactivated. Do not attempt to set the
1490 @code{:inactive} keyword directly. Use the @code{:activate}
1491 @code{:deactivate} keywords instead.
1492
1493
1494 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1495 @comment node-name, next, previous, up
1496 @section Defining New Widgets
1497 @cindex new widgets
1498 @cindex defining new widgets
1499
1500 You can define specialized widgets with @code{define-widget}. It allows
1501 you to create a shorthand for more complex widgets, including specifying
1502 component widgets and new default values for the keyword
1503 arguments.
1504
1505 @defun define-widget name class doc &rest args
1506 Define a new widget type named @var{name} from @code{class}.
1507
1508 @var{name} and class should both be symbols, @code{class} should be one
1509 of the existing widget types.
1510
1511 The third argument @var{doc} is a documentation string for the widget.
1512
1513 After the new widget has been defined, the following two calls will
1514 create identical widgets:
1515
1516 @itemize @bullet
1517 @item
1518 @lisp
1519 (widget-create @var{name})
1520 @end lisp
1521
1522 @item
1523 @lisp
1524 (apply widget-create @var{class} @var{args})
1525 @end lisp
1526 @end itemize
1527
1528 @end defun
1529
1530 Using @code{define-widget} just stores the definition of the widget type
1531 in the @code{widget-type} property of @var{name}, which is what
1532 @code{widget-create} uses.
1533
1534 If you only want to specify defaults for keywords with no complex
1535 conversions, you can use @code{identity} as your conversion function.
1536
1537 The following additional keyword arguments are useful when defining new
1538 widgets:
1539 @table @code
1540 @vindex convert-widget@r{ keyword}
1541 @item :convert-widget
1542 Function to convert a widget type before creating a widget of that
1543 type. It takes a widget type as an argument, and returns the converted
1544 widget type. When a widget is created, this function is called for the
1545 widget type and all the widget's parent types, most derived first.
1546
1547 The following predefined functions can be used here:
1548
1549 @defun widget-types-convert-widget widget
1550 Convert @code{:args} as widget types in @var{widget}.
1551 @end defun
1552
1553 @defun widget-value-convert-widget widget
1554 Initialize @code{:value} from @code{:args} in @var{widget}.
1555 @end defun
1556
1557 @vindex copy@r{ keyword}
1558 @item :copy
1559 Function to deep copy a widget type. It takes a shallow copy of the
1560 widget type as an argument (made by @code{copy-sequence}), and returns a
1561 deep copy. The purpose of this is to avoid having different instances
1562 of combined widgets share nested attributes.
1563
1564 The following predefined functions can be used here:
1565
1566 @defun widget-types-copy widget
1567 Copy @code{:args} as widget types in @var{widget}.
1568 @end defun
1569
1570 @vindex value-to-internal@r{ keyword}
1571 @item :value-to-internal
1572 Function to convert the value to the internal format. The function
1573 takes two arguments, a widget and an external value, and returns the
1574 internal value. The function is called on the present @code{:value}
1575 when the widget is created, and on any value set later with
1576 @code{widget-value-set}.
1577
1578 @vindex value-to-external@r{ keyword}
1579 @item :value-to-external
1580 Function to convert the value to the external format. The function
1581 takes two arguments, a widget and an internal value, and returns the
1582 external value. The function is called on the present @code{:value}
1583 when the widget is created, and on any value set later with
1584 @code{widget-value-set}.
1585
1586 @vindex create@r{ keyword}
1587 @item :create
1588 Function to create a widget from scratch. The function takes one
1589 argument, a widget type, and creates a widget of that type, inserts it
1590 in the buffer, and returns a widget object.
1591
1592 @vindex delete@r{ keyword}
1593 @item :delete
1594 Function to delete a widget. The function takes one argument, a widget,
1595 and should remove all traces of the widget from the buffer.
1596
1597 The default value is:
1598
1599 @defun widget-default-delete widget
1600 Remove @var{widget} from the buffer.
1601 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1602 @end defun
1603
1604 In most cases you should not change this value, but instead use
1605 @code{:value-delete} to make any additional cleanup.
1606
1607 @vindex value-create@r{ keyword}
1608 @item :value-create
1609 Function to expand the @samp{%v} escape in the format string. It will
1610 be called with the widget as its argument and should insert a
1611 representation of the widget's value in the buffer.
1612
1613 Nested widgets should be listed in @code{:children} or @code{:buttons}
1614 to make sure they are automatically deleted.
1615
1616 @vindex value-delete@r{ keyword}
1617 @item :value-delete
1618 Should remove the representation of the widget's value from the buffer.
1619 It will be called with the widget as its argument. It doesn't have to
1620 remove the text, but it should release markers and delete nested widgets
1621 if these are not listed in @code{:children} or @code{:buttons}.
1622
1623 @vindex value-get@r{ keyword}
1624 @item :value-get
1625 Function to extract the value of a widget, as it is displayed in the
1626 buffer.
1627
1628 The following predefined function can be used here:
1629
1630 @defun widget-value-value-get widget
1631 Return the @code{:value} property of @var{widget}.
1632 @end defun
1633
1634 @vindex format-handler@r{ keyword}
1635 @item :format-handler
1636 Function to handle unknown @samp{%} escapes in the format string. It
1637 will be called with the widget and the character that follows the
1638 @samp{%} as arguments. You can set this to allow your widget to handle
1639 non-standard escapes.
1640
1641 @findex widget-default-format-handler
1642 You should end up calling @code{widget-default-format-handler} to handle
1643 unknown escape sequences, which will handle the @samp{%h} and any future
1644 escape sequences, as well as give an error for unknown escapes.
1645
1646 @vindex action@r{ keyword}
1647 @item :action
1648 Function to handle user initiated events. By default, @code{:notify}
1649 the parent.
1650
1651 The following predefined function can be used here:
1652
1653 @defun widget-parent-action widget &optional event
1654 Tell @code{:parent} of @var{widget} to handle the @code{:action}.
1655 Optional @var{event} is the event that triggered the action.
1656 @end defun
1657
1658 @vindex prompt-value@r{ keyword}
1659 @item :prompt-value
1660 Function to prompt for a value in the minibuffer. The function should
1661 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1662 @var{unbound} and should return a value for widget entered by the user.
1663 @var{prompt} is the prompt to use. @var{value} is the default value to
1664 use, unless @var{unbound} is non-@code{nil}, in which case there is no default
1665 value. The function should read the value using the method most natural
1666 for this widget, and does not have to check that it matches.
1667 @end table
1668
1669 If you want to define a new widget from scratch, use the @code{default}
1670 widget as its base.
1671
1672 @deffn Widget default
1673 Widget used as a base for other widgets.
1674
1675 It provides most of the functionality that is referred to as ``by
1676 default'' in this text.
1677 @end deffn
1678
1679 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1680 @comment node-name, next, previous, up
1681 @section Widget Browser
1682 @cindex widget browser
1683
1684 There is a separate package to browse widgets. This is intended to help
1685 programmers who want to examine the content of a widget. The browser
1686 shows the value of each keyword, but uses links for certain keywords
1687 such as @samp{:parent}, which avoids printing cyclic structures.
1688
1689 @deffn Command widget-browse @var{widget}
1690 Create a widget browser for @var{widget}.
1691 When called interactively, prompt for @var{widget}.
1692 @end deffn
1693
1694 @deffn Command widget-browse-other-window @var{widget}
1695 Create a widget browser for @var{widget} and show it in another window.
1696 When called interactively, prompt for @var{widget}.
1697 @end deffn
1698
1699 @deffn Command widget-browse-at @var{pos}
1700 Create a widget browser for the widget at @var{pos}.
1701 When called interactively, use the position of point.
1702 @end deffn
1703
1704 @node Widget Minor Mode, Utilities, Widget Browser, Top
1705 @comment node-name, next, previous, up
1706 @section Widget Minor Mode
1707 @cindex widget minor mode
1708
1709 There is a minor mode for manipulating widgets in major modes that
1710 don't provide any support for widgets themselves. This is mostly
1711 intended to be useful for programmers doing experiments.
1712
1713 @deffn Command widget-minor-mode
1714 Toggle minor mode for traversing widgets.
1715 With arg, turn widget mode on if and only if arg is positive.
1716 @end deffn
1717
1718 @defvar widget-minor-mode-keymap
1719 Keymap used in @code{widget-minor-mode}.
1720 @end defvar
1721
1722 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1723 @comment node-name, next, previous, up
1724 @section Utilities.
1725 @cindex utility functions for widgets
1726
1727 @defun widget-prompt-value widget prompt [ value unbound ]
1728 Prompt for a value matching @var{widget}, using @var{prompt}.
1729 The current value is assumed to be @var{value}, unless @var{unbound} is
1730 non-@code{nil}.@refill
1731 @end defun
1732
1733 @defun widget-get-sibling widget
1734 Get the item which @var{widget} is assumed to toggle.
1735 This is only meaningful for radio buttons or checkboxes in a list.
1736 @end defun
1737
1738 @node Widget Wishlist, Index, Utilities, Top
1739 @comment node-name, next, previous, up
1740 @section Wishlist
1741 @cindex todo
1742
1743 @itemize @bullet
1744 @item
1745 It should be possible to add or remove items from a list with @kbd{C-k}
1746 and @kbd{C-o} (suggested by @sc{rms}).
1747
1748 @item
1749 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1750 dash (@samp{-}). The dash should be a button that, when invoked, asks
1751 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1752 the ugly buttons, the dash is my idea).
1753
1754 @item
1755 The @code{menu-choice} tag should be prettier, something like the abbreviated
1756 menus in Open Look.
1757
1758 @item
1759 Finish @code{:tab-order}.
1760
1761 @item
1762 Make indentation work with glyphs and proportional fonts.
1763
1764 @item
1765 Add commands to show overview of object and class hierarchies to the
1766 browser.
1767
1768 @item
1769 Find a way to disable mouse highlight for inactive widgets.
1770
1771 @item
1772 Find a way to make glyphs look inactive.
1773
1774 @item
1775 Add @code{property-list} widget.
1776
1777 @item
1778 Add @code{association-list} widget.
1779
1780 @item
1781 Add @code{key-binding} widget.
1782
1783 @item
1784 Add @code{widget} widget for editing widget specifications.
1785
1786 @item
1787 Find clean way to implement variable length list.
1788 See @code{TeX-printer-list} for an explanation.
1789
1790 @item
1791 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1792
1793 @item
1794 Add a @code{mailto} widget.
1795 @end itemize
1796
1797 @node Index, , Widget Wishlist, Top
1798 @comment node-name, next, previous, up
1799 @unnumbered Index
1800
1801 This is an alphabetical listing of all concepts, functions, commands,
1802 variables, and widgets described in this manual.
1803 @printindex cp
1804
1805 @setchapternewpage odd
1806 @contents
1807 @bye
1808
1809 @ignore
1810 arch-tag: 2b427731-4c61-4e72-85de-5ccec9c623f0
1811 @end ignore