4 @setfilename ../info/widget
5 @settitle The Emacs Widget Library
13 Copyright @copyright{} 2000, 2002, 2003 Free Software Foundation, Inc.
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.
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.
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.''
38 * Widget: (widget). The "widget" package used by the Emacs Customization
42 @node Top, Introduction, (dir), (dir)
43 @comment node-name, next, previous, up
44 @top The Emacs Widget Library
49 * Programming Example::
50 * Setting Up the Buffer::
54 * Defining New Widgets::
62 @node Introduction, User Interface, Top, Top
63 @comment node-name, next, previous, up
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.
74 @cindex widgets, basic types
75 The basic widgets are:
79 Areas of text with an associated action. Intended for hypertext links
82 Like link, but intended for stand-alone buttons.
84 An editable text field. It can be either variable or fixed length.
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
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.
94 A simple constant widget intended to be used in the @code{menu-choice} and
95 @code{radio-button-choice} widgets.
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.
100 A simple @samp{on}/@samp{off} switch.
102 A checkbox (@samp{[ ]}/@samp{[X]}).
104 Create an editable list. The user can insert or delete items in the
105 list. Each list item is itself a widget.
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 @sc{html} form support in the @file{w3} browser.
117 @cindex widget library, why use it
118 The advantages for a programmer of using the @code{widget} package to
123 More complex fields than just editable text are supported.
125 You can give the users immediate feedback if they enter invalid data in a
126 text field, and sometimes prevent entering invalid data.
128 You can have fixed sized fields, thus allowing multiple fields to be
131 It is simple to query or set the value of a field.
133 Editing happens in the buffer, not in the mini-buffer.
135 Packages using the library get a uniform look, making them easier for
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.
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:
146 @cindex widget library, files
149 This will declare the user variables, define the function
150 @code{define-widget}, and autoload the function @code{widget-create}.
152 Everything else is here, there is no reason to load it explicitly, as
153 it will be autoloaded when needed.
156 @node User Interface, Programming Example, Introduction, Top
157 @comment node-name, next, previous, up
158 @section User Interface
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
167 Here is some documentation.
169 Name: @i{My Name} @strong{Choose}: This option
170 Address: @i{Some Place
174 See also @b{_other work_} for more information.
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!}
194 @b{[Apply Form]} @b{[Reset Form]}
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
204 @subsection Editable Text Fields
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.
214 Editable text fields are created by the @code{editable-field} widget.
216 An editable fields must be surrounded by static text on both sides, that
217 is, text that does not change in the lifetime of the widget. If the
218 field extend to the end of the line, the terminating line-feed character
219 will count as the necessary static text on that end, but you will have
220 to provide the static text before the field yourself. The
221 @code{:format} keyword is useful for generating the static text; for
222 instance, if you give it a value of @code{"Name: %v"}, the "Name: " part
223 will count as the static text.
225 The editing text fields are highlighted with the
226 @code{widget-field-face} face, making them easy to find.
228 @deffn Face widget-field-face
229 Face used for other editing fields.
234 @cindex widget buttons
235 @cindex button widgets
236 Some portions of the buffer have an associated @dfn{action}, which can
237 be @dfn{invoked} by a standard key or mouse command. These portions
238 are called @dfn{buttons}. The default commands for activating a button
243 @deffn Command widget-button-press @var{pos} &optional @var{event}
244 Invoke the button at @var{pos}, defaulting to point.
245 If point is not located on a button, invoke the binding in
246 @code{widget-global-map} (by default the global map).
249 @kindex Mouse-2 @r{(on button widgets})
251 @deffn Command widget-button-click @var{event}
252 Invoke the button at the location of the mouse pointer. If the mouse
253 pointer is located in an editable text field, invoke the binding in
254 @code{widget-global-map} (by default the global map).
258 There are several different kind of buttons, all of which are present in
262 @cindex option field tag
263 @item The Option Field Tags
264 When you invoke one of these buttons, you will be asked to choose
265 between a number of different options. This is how you edit an option
266 field. Option fields are created by the @code{menu-choice} widget. In
267 the example, @samp{@b{Choose}} is an option field tag.
268 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons
269 Activating these will insert or delete elements from an editable list.
270 The list is created by the @code{editable-list} widget.
271 @cindex embedded buttons
272 @item Embedded Buttons
273 The @samp{@b{_other work_}} is an example of an embedded
274 button. Embedded buttons are not associated with a fields, but can serve
275 any purpose, such as implementing hypertext references. They are
276 usually created by the @code{link} widget.
277 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons
278 Activating one of these will convert it to the other. This is useful
279 for implementing multiple-choice fields. You can create it with the
280 @code{checkbox} widget.
281 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons
282 Only one radio button in a @code{radio-button-choice} widget can be
283 selected at any time. When you invoke one of the unselected radio
284 buttons, it will be selected and the previous selected radio button will
286 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons
287 These are explicit buttons made with the @code{push-button} widget. The
288 main difference from the @code{link} widget is that the buttons will be
289 displayed as GUI buttons when possible.
292 To make them easier to locate, buttons are emphasized in the buffer.
294 @deffn Face widget-button-face
295 Face used for buttons.
298 @defopt widget-mouse-face
299 Face used for highlighting a button when the mouse pointer moves across
303 @subsection Navigation
305 You can use all the normal Emacs commands to move around in a form
306 buffer, plus you will have these additional commands:
310 @deffn Command widget-forward &optional count
311 Move point @var{count} buttons or editing fields forward.
314 @deffn Command widget-backward &optional count
315 Move point @var{count} buttons or editing fields backward.
319 @node Programming Example, Setting Up the Buffer, User Interface, Top
320 @comment node-name, next, previous, up
321 @section Programming Example
323 @cindex widgets, programming example
324 @cindex example of using widgets
325 Here is the code to implement the user interface example (@pxref{User
334 (defvar widget-example-repeat)
336 (defun widget-example ()
337 "Create the widgets from the Widget manual."
339 (switch-to-buffer "*Widget Example*")
340 (kill-all-local-variables)
341 (make-local-variable 'widget-example-repeat)
342 (let ((inhibit-read-only t))
344 (widget-insert "Here is some documentation.\n\nName: ")
345 (widget-create 'editable-field
348 (widget-create 'menu-choice
351 :help-echo "Choose me, please!"
352 :notify (lambda (widget &rest ignore)
353 (message "%s is a good choice!"
354 (widget-value widget)))
355 '(item :tag "This option" :value "This")
356 '(choice-item "That option")
357 '(editable-field :menu-tag "No option" "Thus option"))
358 (widget-insert "Address: ")
359 (widget-create 'editable-field
360 "Some Place\nIn some City\nSome country.")
361 (widget-insert "\nSee also ")
363 :notify (lambda (&rest ignore)
364 (widget-value-set widget-example-repeat
369 " for more information.\n\nNumbers: count to three below\n")
370 (setq widget-example-repeat
371 (widget-create 'editable-list
372 :entry-format "%i %d %v"
373 :notify (lambda (widget &rest ignore)
374 (let ((old (widget-get widget
376 (new (length (widget-value widget))))
378 (widget-put widget ':example-length new)
379 (message "You can count to %d." new))))
380 :value '("One" "Eh, two?" "Five!")
381 '(editable-field :value "three")))
382 (widget-insert "\n\nSelect multiple:\n\n")
383 (widget-create 'checkbox t)
384 (widget-insert " This\n")
385 (widget-create 'checkbox nil)
386 (widget-insert " That\n")
387 (widget-create 'checkbox
388 :notify (lambda (&rest ignore) (message "Tickle"))
390 (widget-insert " Thus\n\nSelect one:\n\n")
391 (widget-create 'radio-button-choice
393 :notify (lambda (widget &rest ignore)
394 (message "You selected %s"
395 (widget-value widget)))
396 '(item "One") '(item "Another One.") '(item "A Final One."))
398 (widget-create 'push-button
399 :notify (lambda (&rest ignore)
400 (if (= (length (widget-value widget-example-repeat))
402 (message "Congratulation!")
403 (error "Three was the count!")))
406 (widget-create 'push-button
407 :notify (lambda (&rest ignore)
411 (use-local-map widget-keymap)
415 @node Setting Up the Buffer, Basic Types, Programming Example, Top
416 @comment node-name, next, previous, up
417 @section Setting Up the Buffer
419 Widgets are created with @code{widget-create}, which returns a
420 @dfn{widget} object. This object can be queried and manipulated by
421 other widget functions, until it is deleted with @code{widget-delete}.
422 After the widgets have been created, @code{widget-setup} must be called
425 @defun widget-create type [ keyword argument ]@dots{}
426 Create and return a widget of type @var{type}.
427 The syntax for the @var{type} argument is described in @ref{Basic Types}.
429 The keyword arguments can be used to overwrite the keyword arguments
430 that are part of @var{type}.
433 @defun widget-delete widget
434 Delete @var{widget} and remove it from the buffer.
438 Set up a buffer to support widgets.
440 This should be called after creating all the widgets and before allowing
441 the user to edit them.
445 If you want to insert text outside the widgets in the form, the
446 recommended way to do that is with @code{widget-insert}.
449 Insert the arguments, either strings or characters, at point.
450 The inserted text will be read-only.
453 There is a standard widget keymap which you might find useful.
455 @findex widget-button-press
456 @findex widget-button-click
457 @defvr Const widget-keymap
458 A keymap with the global keymap as its parent.@*
459 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
460 @code{widget-backward}, respectively. @key{RET} and @kbd{Mouse-2}
461 are bound to @code{widget-button-press} and
462 @code{widget-button-click}.@refill
465 @defvar widget-global-map
466 Keymap used by @code{widget-button-press} and @code{widget-button-click}
467 when not on a button. By default this is @code{global-map}.
470 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
471 @comment node-name, next, previous, up
474 The syntax of a type specification is given below:
477 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
481 Where, @var{name} is a widget name, @var{keyword} is the name of a
482 property, @var{argument} is the value of the property, and @var{args}
483 are interpreted in a widget specific way.
485 @cindex keyword arguments
486 The following keyword arguments that apply to all widgets:
489 @vindex value@r{ keyword}
491 The initial value for widgets of this type.
493 @vindex format@r{ keyword}
495 This string will be inserted in the buffer when you create a widget.
496 The following @samp{%} escapes are available:
501 The text inside will be marked as a button.
503 By default, the text will be shown in @code{widget-button-face}, and
504 surrounded by brackets.
506 @defopt widget-button-prefix
507 String to prefix buttons.
510 @defopt widget-button-suffix
511 String to suffix buttons.
516 The text inside will be displayed with the face specified by
520 This will be replaced with the buffer representation of the widget's
521 value. What this is depends on the widget type.
524 Insert the string specified by @code{:doc} here.
527 Like @samp{%d}, with the following modifications: If the documentation
528 string is more than one line, it will add a button which will toggle
529 between showing only the first line, and showing the full text.
530 Furthermore, if there is no @code{:doc} property in the widget, it will
531 instead examine the @code{:documentation-property} property. If it is a
532 lambda expression, it will be called with the widget's value as an
533 argument, and the result will be used as the documentation text.
536 Insert the string specified by @code{:tag} here, or the @code{princ}
537 representation of the value if there is no tag.
540 Insert a literal @samp{%}.
543 @vindex button-face@r{ keyword}
545 Face used to highlight text inside %[ %] in the format.
547 @vindex button-prefix@r{ keyword}
548 @vindex button-suffix@r{ keyword}
550 @itemx :button-suffix
551 Text around %[ %] in the format.
559 The string is inserted literally.
562 The value of the symbol is expanded according to this table.
565 @vindex doc@r{ keyword}
567 The string inserted by the @samp{%d} escape in the format
570 @vindex tag@r{ keyword}
572 The string inserted by the @samp{%t} escape in the format
575 @vindex tag-glyph@r{ keyword}
577 Name of image to use instead of the string specified by @code{:tag} on
578 Emacsen that supports it.
580 @vindex help-echo@r{ keyword}
582 Specifies how to display a message whenever you move to the widget with
583 either @code{widget-forward} or @code{widget-backward} or move the mouse
584 over it (using the standard @code{help-echo} mechanism). The argument
585 is either a string to display, a function of one argument, the widget,
586 which should return a string to display, or a form that evaluates to
589 @vindex indent@r{ keyword}
591 An integer indicating the absolute number of spaces to indent children
594 @vindex offset@r{ keyword}
596 An integer indicating how many extra spaces to add to the widget's
597 grandchildren compared to this widget.
599 @vindex extra-offset@r{ keyword}
601 An integer indicating how many extra spaces to add to the widget's
602 children compared to this widget.
604 @vindex notify@r{ keyword}
606 A function called each time the widget or a nested widget is changed.
607 The function is called with two or three arguments. The first argument
608 is the widget itself, the second argument is the widget that was
609 changed, and the third argument is the event leading to the change, if
612 @vindex menu-tag@r{ keyword}
614 Tag used in the menu when the widget is used as an option in a
615 @code{menu-choice} widget.
617 @vindex menu-tag-get@r{ keyword}
619 Function used for finding the tag when the widget is used as an option
620 in a @code{menu-choice} widget. By default, the tag used will be either the
621 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
622 representation of the @code{:value} property if not.
624 @vindex match@r{ keyword}
626 Should be a function called with two arguments, the widget and a value,
627 and returning non-@code{nil} if the widget can represent the specified value.
629 @vindex validate@r{ keyword}
631 A function which takes a widget as an argument, and returns @code{nil}
632 if the widget's current value is valid for the widget. Otherwise it
633 should return the widget containing the invalid data, and set that
634 widget's @code{:error} property to a string explaining the error.
636 The following predefined function can be used:
638 @defun widget-children-validate widget
639 All the @code{:children} of @var{widget} must be valid.
642 @vindex tab-order@r{ keyword}
644 Specify the order in which widgets are traversed with
645 @code{widget-forward} or @code{widget-backward}. This is only partially
650 Widgets with tabbing order @code{-1} are ignored.
653 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
654 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
655 whichever comes first.
658 When on a widget with no tabbing order specified, go to the next widget
659 in the buffer with a positive tabbing order, or @code{nil}
662 @vindex parent@r{ keyword}
664 The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
665 element of a @code{editable-list} widget).
667 @vindex sibling-args@r{ keyword}
669 This keyword is only used for members of a @code{radio-button-choice} or
670 @code{checklist}. The value should be a list of extra keyword
671 arguments, which will be used when creating the @code{radio-button} or
672 @code{checkbox} associated with this item.
676 @deffn {User Option} widget-glyph-directory
677 Directory where glyphs are found.
678 Widget will look here for a file with the same name as specified for the
679 image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
682 @deffn{User Option} widget-glyph-enable
683 If non-nil, allow glyphs to appear on displays where they are supported.
695 * radio-button-choice::
705 @node link, url-link, Basic Types, Basic Types
706 @comment node-name, next, previous, up
707 @subsection The @code{link} Widget
708 @findex link@r{ widget}
713 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
716 The @var{value}, if present, is used to initialize the @code{:value}
717 property. The value should be a string, which will be inserted in the
720 By default the link will be shown in brackets.
722 @defopt widget-link-prefix
723 String to prefix links.
726 @defopt widget-link-suffix
727 String to suffix links.
730 @node url-link, info-link, link, Basic Types
731 @comment node-name, next, previous, up
732 @subsection The @code{url-link} Widget
733 @findex url-link@r{ widget}
738 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
741 @findex browse-url-browser-function@r{, and @code{url-link} widget}
742 When this link is invoked, the @sc{www} browser specified by
743 @code{browse-url-browser-function} will be called with @var{url}.
745 @node info-link, push-button, url-link, Basic Types
746 @comment node-name, next, previous, up
747 @subsection The @code{info-link} Widget
748 @findex info-link@r{ widget}
753 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
756 When this link is invoked, the built-in Info reader is started on
759 @node push-button, editable-field, info-link, Basic Types
760 @comment node-name, next, previous, up
761 @subsection The @code{push-button} Widget
762 @findex push-button@r{ widget}
767 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
770 The @var{value}, if present, is used to initialize the @code{:value}
771 property. The value should be a string, which will be inserted in the
774 By default the tag will be shown in brackets.
776 @defopt widget-push-button-prefix
777 String to prefix push buttons.
780 @defopt widget-push-button-suffix
781 String to suffix push buttons.
784 @node editable-field, text, push-button, Basic Types
785 @comment node-name, next, previous, up
786 @subsection The @code{editable-field} Widget
787 @findex editable-field@r{ widget}
792 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
795 The @var{value}, if present, is used to initialize the @code{:value}
796 property. The value should be a string, which will be inserted in
797 field. This widget will match all string values.
799 The following extra properties are recognized:
802 @vindex size@r{ keyword}
804 The width of the editable field.@*
805 By default the field will reach to the end of the line.
807 @vindex value-face@r{ keyword}
809 Face used for highlighting the editable field. Default is
810 @code{widget-field-face}, see @ref{User Interface}.
812 @vindex secret@r{ keyword}
814 Character used to display the value. You can set this to e.g.@: @code{?*}
815 if the field contains a password or other secret information. By
816 default, this is nil, and the value is not secret.
818 @vindex valid-regexp@r{ keyword}
820 By default the @code{:validate} function will match the content of the
821 field with the value of this attribute. The default value is @code{""}
822 which matches everything.
824 @vindex keymap@r{ keyword}
825 @vindex widget-field-keymap
827 Keymap used in the editable field. The default value is
828 @code{widget-field-keymap}, which allows you to use all the normal
829 editing commands, even if the buffer's major mode suppresses some of
830 them. Pressing @key{RET} invokes the function specified by
834 @node text, menu-choice, editable-field, Basic Types
835 @comment node-name, next, previous, up
836 @subsection The @code{text} Widget
837 @findex text@r{ widget}
839 @vindex widget-text-keymap
840 This is just like @code{editable-field}, but intended for multiline text
841 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
842 does not rebind the @key{RET} key.
844 @node menu-choice, radio-button-choice, text, Basic Types
845 @comment node-name, next, previous, up
846 @subsection The @code{menu-choice} Widget
847 @findex menu-choice@r{ widget}
852 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
855 The @var{type} argument represents each possible choice. The widget's
856 value will be that of the chosen @var{type} argument. This widget will
857 match any value matching at least one of the specified @var{type}
861 @vindex void@r{ keyword}
863 Widget type used as a fallback when the value does not match any of the
864 specified @var{type} arguments.
866 @vindex case-fold@r{ keyword}
868 Set this to nil if you don't want to ignore case when prompting for a
869 choice through the minibuffer.
871 @vindex children@r{ keyword}
873 A list whose @code{car} is the widget representing the currently chosen
876 @vindex choice@r{ keyword}
878 The current chosen type.
880 @vindex args@r{ keyword}
885 @node radio-button-choice, item, menu-choice, Basic Types
886 @comment node-name, next, previous, up
887 @subsection The @code{radio-button-choice} Widget
888 @findex radio-button-choice@r{ widget}
893 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
896 The @var{type} argument represents each possible choice. The widget's
897 value will be that of the chosen @var{type} argument. This widget will
898 match any value matching at least one of the specified @var{type}
901 The following extra properties are recognized.
904 @vindex entry-format@r{ keyword}
906 This string will be inserted for each entry in the list.
907 The following @samp{%} escapes are available:
910 Replace with the buffer representation of the @var{type} widget.
912 Replace with the radio button.
914 Insert a literal @samp{%}.
917 @vindex button-args@r{ keyword}
919 A list of keywords to pass to the radio buttons. Useful for setting
920 e.g.@: the @samp{:help-echo} for each button.
922 @vindex buttons@r{ keyword}
924 The widgets representing the radio buttons.
926 @vindex children@r{ keyword}
928 The widgets representing each type.
930 @vindex choice@r{ keyword}
932 The current chosen type
934 @vindex args@r{ keyword}
939 You can add extra radio button items to a @code{radio-button-choice}
940 widget after it has been created with the function
941 @code{widget-radio-add-item}.
943 @defun widget-radio-add-item widget type
944 Add to @code{radio-button-choice} widget @var{widget} a new radio button
945 item of type @var{type}.
948 Please note that such items added after the @code{radio-button-choice}
949 widget has been created will @strong{not} be properly destructed when
950 you call @code{widget-delete}.
952 @node item, choice-item, radio-button-choice, Basic Types
953 @comment node-name, next, previous, up
954 @subsection The @code{item} Widget
955 @findex item@r{ widget}
960 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
963 The @var{value}, if present, is used to initialize the @code{:value}
964 property. The value should be a string, which will be inserted in the
965 buffer. This widget will only match the specified value.
967 @node choice-item, toggle, item, Basic Types
968 @comment node-name, next, previous, up
969 @subsection The @code{choice-item} Widget
970 @findex choice-item@r{ widget}
975 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
978 The @var{value}, if present, is used to initialize the @code{:value}
979 property. The value should be a string, which will be inserted in the
980 buffer as a button. Activating the button of a @code{choice-item} is
981 equivalent to activating the parent widget. This widget will only match
984 @node toggle, checkbox, choice-item, Basic Types
985 @comment node-name, next, previous, up
986 @subsection The @code{toggle} Widget
987 @findex toggle@r{ widget}
992 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
995 The widget has two possible states, @samp{on} and @samp{off}, which
996 correspond to a @code{t} or @code{nil} value, respectively.
998 The following extra properties are recognized:
1002 A string representing the @samp{on} state. By default the string
1005 A string representing the @samp{off} state. By default the string
1007 @vindex on-glyph@r{ keyword}
1009 Name of a glyph to be used instead of the @samp{:on} text string, on
1010 emacsen that supports this.
1011 @vindex off-glyph@r{ keyword}
1013 Name of a glyph to be used instead of the @samp{:off} text string, on
1014 emacsen that supports this.
1017 @node checkbox, checklist, toggle, Basic Types
1018 @comment node-name, next, previous, up
1019 @subsection The @code{checkbox} Widget
1020 @findex checkbox@r{ widget}
1022 This widget has two possible states, @samp{selected} and
1023 @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
1028 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
1031 @node checklist, editable-list, checkbox, Basic Types
1032 @comment node-name, next, previous, up
1033 @subsection The @code{checklist} Widget
1034 @findex checklist@r{ widget}
1039 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
1042 The @var{type} arguments represent each checklist item. The widget's
1043 value will be a list containing the values of all checked @var{type}
1044 arguments. The checklist widget will match a list whose elements all
1045 match at least one of the specified @var{type} arguments.
1047 The following extra properties are recognized:
1050 @vindex entry-format@r{ keyword}
1052 This string will be inserted for each entry in the list.
1053 The following @samp{%} escapes are available:
1056 Replaced with the buffer representation of the @var{type} widget.
1058 Replace with the checkbox.
1060 Insert a literal @samp{%}.
1063 @vindex greedy@r{ keyword}
1065 Usually a checklist will only match if the items are in the exact
1066 sequence given in the specification. By setting @code{:greedy} to
1067 non-nil, it will allow the items to come in any sequence. However, if
1068 you extract the value they will be in the sequence given in the
1069 checklist, i.e.@: the original sequence is forgotten.
1071 @vindex button-args@r{ keyword}
1073 A list of keywords to pass to the checkboxes. Useful for setting
1074 e.g.@: the @samp{:help-echo} for each checkbox.
1076 @vindex buttons@r{ keyword}
1078 The widgets representing the checkboxes.
1080 @vindex children@r{ keyword}
1082 The widgets representing each type.
1084 @vindex args@r{ keyword}
1089 @node editable-list, group, checklist, Basic Types
1090 @comment node-name, next, previous, up
1091 @subsection The @code{editable-list} Widget
1092 @findex editable-list@r{ widget}
1097 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
1100 The value is a list, where each member represents one widget of type
1103 The following extra properties are recognized:
1106 @vindex entry-format@r{ keyword}
1108 This string will be inserted for each entry in the list.
1109 The following @samp{%} escapes are available:
1112 This will be replaced with the buffer representation of the @var{type}
1115 Insert the @b{[INS]} button.
1117 Insert the @b{[DEL]} button.
1119 Insert a literal @samp{%}.
1122 @vindex insert-button-args@r{ keyword}
1123 @item :insert-button-args
1124 A list of keyword arguments to pass to the insert buttons.
1126 @vindex delete-button-args@r{ keyword}
1127 @item :delete-button-args
1128 A list of keyword arguments to pass to the delete buttons.
1130 @vindex append-button-args@r{ keyword}
1131 @item :append-button-args
1132 A list of keyword arguments to pass to the trailing insert button.
1134 @vindex buttons@r{ keyword}
1136 The widgets representing the insert and delete buttons.
1138 @vindex children@r{ keyword}
1140 The widgets representing the elements of the list.
1142 @vindex args@r{ keyword}
1144 List whose @code{car} is the type of the list elements.
1147 @node group, , editable-list, Basic Types
1148 @comment node-name, next, previous, up
1149 @subsection The @code{group} Widget
1150 @findex group@r{ widget}
1152 This widget simply group other widgets together.
1157 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1160 The value is a list, with one member for each @var{type}.
1162 @node Sexp Types, Widget Properties, Basic Types, Top
1167 A number of widgets for editing @dfn{s-expressions} (lisp types), sexp
1168 for short, are also available. These basically fall in several
1169 categories described in this section.
1178 @node constants, generic, Sexp Types, Sexp Types
1179 @comment node-name, next, previous, up
1180 @subsection The Constant Widgets
1181 @cindex constant widgets
1183 The @code{const} widget can contain any lisp expression, but the user is
1184 prohibited from editing it, which is mainly useful as a component of one
1185 of the composite widgets.
1187 The syntax for the @code{const} widget is:
1190 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1193 The @var{value}, if present, is used to initialize the @code{:value}
1194 property and can be any s-expression.
1197 This will display any valid s-expression in an immutable part of the
1201 There are two variations of the @code{const} widget, namely
1202 @code{variable-item} and @code{function-item}. These should contain a
1203 symbol with a variable or function binding. The major difference from
1204 the @code{const} widget is that they will allow the user to see the
1205 variable or function documentation for the symbol.
1207 @deffn Widget variable-item
1208 An immutable symbol that is bound as a variable.
1211 @deffn Widget function-item
1212 An immutable symbol that is bound as a function.
1215 @node generic, atoms, constants, Sexp Types
1216 @comment node-name, next, previous, up
1217 @subsection Generic Sexp Widget
1218 @cindex generic sexp widget
1220 The @code{sexp} widget can contain any lisp expression, and allows the
1221 user to edit it inline in the buffer.
1223 The syntax for the @code{sexp} widget is:
1226 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1230 This will allow you to edit any valid s-expression in an editable buffer
1233 The @code{sexp} widget takes the same keyword arguments as the
1234 @code{editable-field} widget. @xref{editable-field}.
1237 @node atoms, composite, generic, Sexp Types
1238 @comment node-name, next, previous, up
1239 @subsection Atomic Sexp Widgets
1240 @cindex atomic sexp widget
1242 The atoms are s-expressions that do not consist of other s-expressions.
1243 For example, a string, a file name, or a symbol are atoms, while a list
1244 is a composite type. You can edit the value of an atom with the
1247 The syntax for all the atoms are:
1250 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1253 The @var{value}, if present, is used to initialize the @code{:value}
1254 property and must be an expression of the same type as the widget.
1255 That is, the string widget can only be initialized with a string.
1257 All the atom widgets take the same keyword arguments as the
1258 @code{editable-field} widget. @xref{editable-field}.
1260 @deffn Widget string
1261 Allows you to edit a string in an editable field.
1264 @deffn Widget regexp
1265 Allows you to edit a regular expression in an editable field.
1268 @deffn Widget character
1269 Allows you to enter a character in an editable field.
1273 Allows you to edit a file name in an editable field. If you invoke
1274 the tag button, you can edit the file name in the mini-buffer with
1279 @vindex must-match@r{ keyword}
1281 If this is set to non-nil, only existing file names will be allowed in
1286 @deffn Widget directory
1287 Allows you to edit a directory name in an editable field.
1288 Similar to the @code{file} widget.
1291 @deffn Widget symbol
1292 Allows you to edit a lisp symbol in an editable field.
1295 @deffn Widget function
1296 Allows you to edit a lambda expression, or a function name with completion.
1299 @deffn Widget variable
1300 Allows you to edit a variable name, with completion.
1303 @deffn Widget integer
1304 Allows you to edit an integer in an editable field.
1307 @deffn Widget number
1308 Allows you to edit a number in an editable field.
1311 @deffn Widget boolean
1312 Allows you to edit a boolean. In lisp this means a variable which is
1313 either nil meaning false, or non-nil meaning true.
1317 @node composite, , atoms, Sexp Types
1318 @comment node-name, next, previous, up
1319 @subsection Composite Sexp Widgets
1320 @cindex composite sexp widgets
1322 The syntax for the composite widget is:
1325 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1329 where each @var{component} must be a widget type. Each component widget
1330 will be displayed in the buffer, and will be editable by the user.
1333 The value of a @code{cons} widget is a cons-cell where the @code{car} is
1334 the value of the first component and the @code{cdr} is the value of the
1335 second component. There must be exactly two components.
1339 The value of a @code{list} widget is a list containing the value of
1340 each of its component.
1343 @deffn Widget vector
1344 The value of a @code{vector} widget is a vector containing the value of
1345 each of its component.
1348 The above suffice for specifying fixed size lists and vectors. To get
1349 variable length lists and vectors, you can use a @code{choice},
1350 @code{set}, or @code{repeat} widgets together with the @code{:inline}
1351 keywords. If any component of a composite widget has the @code{:inline}
1352 keyword set, its value must be a list which will then be spliced into
1353 the composite. For example, to specify a list whose first element must
1354 be a file name, and whose remaining arguments should either by the
1355 symbol @code{t} or two files, you can use the following widget
1362 :value ("foo" "bar")
1366 The value of a widget of this type will either have the form
1367 @code{(file t)} or @code{(file string string)}.
1369 This concept of inline is probably hard to understand. It was certainly
1370 hard to implement, so instead of confusing you more by trying to explain
1371 it here, I'll just suggest you meditate over it for a while.
1373 @deffn Widget choice
1374 Allows you to edit a sexp which may have one of a fixed set of types.
1375 It is currently implemented with the @code{choice-menu} basic widget,
1376 and has a similar syntax.
1380 Allows you to specify a type which must be a list whose elements all
1381 belong to given set. The elements of the list are not significant.
1382 This is implemented on top of the @code{checklist} basic widget, and has
1386 @deffn Widget repeat
1387 Allows you to specify a variable length list whose members are all of
1388 the same type. Implemented on top of the @code{editable-list} basic
1389 widget, and has a similar syntax.
1392 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1393 @comment node-name, next, previous, up
1395 @cindex properties of widgets
1396 @cindex widget properties
1398 You can examine or set the value of a widget by using the widget object
1399 that was returned by @code{widget-create}.
1401 @defun widget-value widget
1402 Return the current value contained in @var{widget}.
1403 It is an error to call this function on an uninitialized widget.
1406 @defun widget-value-set widget value
1407 Set the value contained in @var{widget} to @var{value}.
1408 It is an error to call this function with an invalid @var{value}.
1411 @strong{Important:} You @emph{must} call @code{widget-setup} after
1412 modifying the value of a widget before the user is allowed to edit the
1413 widget again. It is enough to call @code{widget-setup} once if you
1414 modify multiple widgets. This is currently only necessary if the widget
1415 contains an editing field, but may be necessary for other widgets in the
1418 If your application needs to associate some information with the widget
1419 objects, for example a reference to the item being edited, it can be
1420 done with @code{widget-put} and @code{widget-get}. The property names
1421 must begin with a @samp{:}.
1423 @defun widget-put widget property value
1424 In @var{widget} set @var{property} to @var{value}.
1425 @var{property} should be a symbol, while @var{value} can be anything.
1428 @defun widget-get widget property
1429 In @var{widget} return the value for @var{property}.
1430 @var{property} should be a symbol, the value is what was last set by
1431 @code{widget-put} for @var{property}.
1434 @defun widget-member widget property
1435 Non-nil if @var{widget} has a value (even nil) for property @var{property}.
1438 Occasionally it can be useful to know which kind of widget you have,
1439 i.e.@: the name of the widget type you gave when the widget was created.
1441 @defun widget-type widget
1442 Return the name of @var{widget}, a symbol.
1445 @cindex active widget
1446 @cindex inactive widget
1447 @cindex activate a widget
1448 @cindex deactivate a widget
1449 Widgets can be in two states: active, which means they are modifiable by
1450 the user, or inactive, which means they cannot be modified by the user.
1451 You can query or set the state with the following code:
1454 ;; Examine if @var{widget} is active or not.
1455 (if (widget-apply @var{widget} :active)
1456 (message "Widget is active.")
1457 (message "Widget is inactive.")
1459 ;; Make @var{widget} inactive.
1460 (widget-apply @var{widget} :deactivate)
1462 ;; Make @var{widget} active.
1463 (widget-apply @var{widget} :activate)
1466 A widget is inactive if it, or any of its ancestors (found by
1467 following the @code{:parent} link), have been deactivated. To make sure
1468 a widget is really active, you must therefore activate both it and
1473 (widget-apply widget :activate)
1474 (setq widget (widget-get widget :parent)))
1477 You can check if a widget has been made inactive by examining the value
1478 of the @code{:inactive} keyword. If this is non-nil, the widget itself
1479 has been deactivated. This is different from using the @code{:active}
1480 keyword, in that the latter tells you if the widget @strong{or} any of
1481 its ancestors have been deactivated. Do not attempt to set the
1482 @code{:inactive} keyword directly. Use the @code{:activate}
1483 @code{:deactivate} keywords instead.
1486 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1487 @comment node-name, next, previous, up
1488 @section Defining New Widgets
1490 @cindex defining new widgets
1492 You can define specialized widgets with @code{define-widget}. It allows
1493 you to create a shorthand for more complex widgets, including specifying
1494 component widgets and new default values for the keyword
1497 @defun define-widget name class doc &rest args
1498 Define a new widget type named @var{name} from @code{class}.
1500 @var{name} and class should both be symbols, @code{class} should be one
1501 of the existing widget types.
1503 The third argument @var{DOC} is a documentation string for the widget.
1505 After the new widget has been defined, the following two calls will
1506 create identical widgets:
1511 (widget-create @var{name})
1516 (apply widget-create @var{class} @var{args})
1522 Using @code{define-widget} just stores the definition of the widget type
1523 in the @code{widget-type} property of @var{name}, which is what
1524 @code{widget-create} uses.
1526 If you only want to specify defaults for keywords with no complex
1527 conversions, you can use @code{identity} as your conversion function.
1529 The following additional keyword arguments are useful when defining new
1532 @vindex convert-widget@r{ keyword}
1533 @item :convert-widget
1534 Function to convert a widget type before creating a widget of that
1535 type. It takes a widget type as an argument, and returns the converted
1536 widget type. When a widget is created, this function is called for the
1537 widget type and all the widget's parent types, most derived first.
1539 The following predefined functions can be used here:
1541 @defun widget-types-convert-widget widget
1542 Convert @code{:args} as widget types in @var{widget}.
1545 @defun widget-value-convert-widget widget
1546 Initialize @code{:value} from @code{:args} in @var{widget}.
1549 @vindex copy@r{ keyword}
1551 Function to deep copy a widget type. It takes a shallow copy of the
1552 widget type as an argument (made by @code{copy-sequence}), and returns a
1553 deep copy. The purpose of this is to avoid having different instances
1554 of combined widgets share nested attributes.
1556 The following predefined functions can be used here:
1558 @defun widget-types-copy widget
1559 Copy @code{:args} as widget types in @var{widget}.
1562 @vindex value-to-internal@r{ keyword}
1563 @item :value-to-internal
1564 Function to convert the value to the internal format. The function
1565 takes two arguments, a widget and an external value, and returns the
1566 internal value. The function is called on the present @code{:value}
1567 when the widget is created, and on any value set later with
1568 @code{widget-value-set}.
1570 @vindex value-to-external@r{ keyword}
1571 @item :value-to-external
1572 Function to convert the value to the external format. The function
1573 takes two arguments, a widget and an internal value, and returns the
1574 external 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}.
1578 @vindex create@r{ keyword}
1580 Function to create a widget from scratch. The function takes one
1581 argument, a widget type, and creates a widget of that type, inserts it
1582 in the buffer, and returns a widget object.
1584 @vindex delete@r{ keyword}
1586 Function to delete a widget. The function takes one argument, a widget,
1587 and should remove all traces of the widget from the buffer.
1589 @vindex value-create@r{ keyword}
1591 Function to expand the @samp{%v} escape in the format string. It will
1592 be called with the widget as its argument and should insert a
1593 representation of the widget's value in the buffer.
1595 @vindex value-delete@r{ keyword}
1597 Should remove the representation of the widget's value from the buffer.
1598 It will be called with the widget as its argument. It doesn't have to
1599 remove the text, but it should release markers and delete nested widgets
1600 if such have been used.
1602 The following predefined function can be used here:
1604 @defun widget-children-value-delete widget
1605 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1608 @vindex value-get@r{ keyword}
1610 Function to extract the value of a widget, as it is displayed in the
1613 The following predefined function can be used here:
1615 @defun widget-value-value-get widget
1616 Return the @code{:value} property of @var{widget}.
1619 @vindex format-handler@r{ keyword}
1620 @item :format-handler
1621 Function to handle unknown @samp{%} escapes in the format string. It
1622 will be called with the widget and the character that follows the
1623 @samp{%} as arguments. You can set this to allow your widget to handle
1624 non-standard escapes.
1626 @findex widget-default-format-handler
1627 You should end up calling @code{widget-default-format-handler} to handle
1628 unknown escape sequences, which will handle the @samp{%h} and any future
1629 escape sequences, as well as give an error for unknown escapes.
1631 @vindex action@r{ keyword}
1633 Function to handle user initiated events. By default, @code{:notify}
1636 The following predefined function can be used here:
1638 @defun widget-parent-action widget &optional event
1639 Tell @code{:parent} of @var{widget} to handle the @code{:action}.
1640 Optional @var{event} is the event that triggered the action.
1643 @vindex prompt-value@r{ keyword}
1645 Function to prompt for a value in the minibuffer. The function should
1646 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1647 @var{unbound} and should return a value for widget entered by the user.
1648 @var{prompt} is the prompt to use. @var{value} is the default value to
1649 use, unless @var{unbound} is non-nil, in which case there is no default
1650 value. The function should read the value using the method most natural
1651 for this widget, and does not have to check that it matches.
1654 If you want to define a new widget from scratch, use the @code{default}
1657 @deffn Widget default
1658 Widget used as a base for other widgets.
1660 It provides most of the functionality that is referred to as ``by
1661 default'' in this text.
1664 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1665 @comment node-name, next, previous, up
1666 @section Widget Browser
1667 @cindex widget browser
1669 There is a separate package to browse widgets. This is intended to help
1670 programmers who want to examine the content of a widget. The browser
1671 shows the value of each keyword, but uses links for certain keywords
1672 such as @samp{:parent}, which avoids printing cyclic structures.
1674 @deffn Command widget-browse @var{widget}
1675 Create a widget browser for @var{widget}.
1676 When called interactively, prompt for @var{widget}.
1679 @deffn Command widget-browse-other-window @var{widget}
1680 Create a widget browser for @var{widget} and show it in another window.
1681 When called interactively, prompt for @var{widget}.
1684 @deffn Command widget-browse-at @var{pos}
1685 Create a widget browser for the widget at @var{pos}.
1686 When called interactively, use the position of point.
1689 @node Widget Minor Mode, Utilities, Widget Browser, Top
1690 @comment node-name, next, previous, up
1691 @section Widget Minor Mode
1692 @cindex widget minor mode
1694 There is a minor mode for manipulating widgets in major modes that
1695 don't provide any support for widgets themselves. This is mostly
1696 intended to be useful for programmers doing experiments.
1698 @deffn Command widget-minor-mode
1699 Toggle minor mode for traversing widgets.
1700 With arg, turn widget mode on if and only if arg is positive.
1703 @defvar widget-minor-mode-keymap
1704 Keymap used in @code{widget-minor-mode}.
1707 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1708 @comment node-name, next, previous, up
1710 @cindex utility functions for widgets
1712 @defun widget-prompt-value widget prompt [ value unbound ]
1713 Prompt for a value matching @var{widget}, using @var{prompt}.
1714 The current value is assumed to be @var{value}, unless @var{unbound} is
1718 @defun widget-get-sibling widget
1719 Get the item which @var{widget} is assumed to toggle.
1720 This is only meaningful for radio buttons or checkboxes in a list.
1723 @node Widget Wishlist, Index, Utilities, Top
1724 @comment node-name, next, previous, up
1730 It should be possible to add or remove items from a list with @kbd{C-k}
1731 and @kbd{C-o} (suggested by @sc{rms}).
1734 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1735 dash (@samp{-}). The dash should be a button that, when invoked, asks
1736 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1737 the ugly buttons, the dash is my idea).
1740 The @code{menu-choice} tag should be prettier, something like the abbreviated
1744 Finish @code{:tab-order}.
1747 Make indentation work with glyphs and proportional fonts.
1750 Add commands to show overview of object and class hierarchies to the
1754 Find a way to disable mouse highlight for inactive widgets.
1757 Find a way to make glyphs look inactive.
1760 Add @code{property-list} widget.
1763 Add @code{association-list} widget.
1766 Add @code{key-binding} widget.
1769 Add @code{widget} widget for editing widget specifications.
1772 Find clean way to implement variable length list.
1773 See @code{TeX-printer-list} for an explanation.
1776 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1779 Add a @code{mailto} widget.
1782 @node Index, , Widget Wishlist, Top
1783 @comment node-name, next, previous, up
1786 This is an alphabetical listing of all concepts, functions, commands,
1787 variables, and widgets described in this manual.
1790 @setchapternewpage odd
1795 arch-tag: 2b427731-4c61-4e72-85de-5ccec9c623f0