4 @setfilename ../info/widget
5 @settitle The Emacs Widget Library
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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 @acronym{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 field 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 extends 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))
345 (widget-insert "Here is some documentation.\n\nName: ")
346 (widget-create 'editable-field
349 (widget-create 'menu-choice
352 :help-echo "Choose me, please!"
353 :notify (lambda (widget &rest ignore)
354 (message "%s is a good choice!"
355 (widget-value widget)))
356 '(item :tag "This option" :value "This")
357 '(choice-item "That option")
358 '(editable-field :menu-tag "No option" "Thus option"))
359 (widget-insert "Address: ")
360 (widget-create 'editable-field
361 "Some Place\nIn some City\nSome country.")
362 (widget-insert "\nSee also ")
364 :notify (lambda (&rest ignore)
365 (widget-value-set widget-example-repeat
370 " for more information.\n\nNumbers: count to three below\n")
371 (setq widget-example-repeat
372 (widget-create 'editable-list
373 :entry-format "%i %d %v"
374 :notify (lambda (widget &rest ignore)
375 (let ((old (widget-get widget
377 (new (length (widget-value widget))))
379 (widget-put widget ':example-length new)
380 (message "You can count to %d." new))))
381 :value '("One" "Eh, two?" "Five!")
382 '(editable-field :value "three")))
383 (widget-insert "\n\nSelect multiple:\n\n")
384 (widget-create 'checkbox t)
385 (widget-insert " This\n")
386 (widget-create 'checkbox nil)
387 (widget-insert " That\n")
388 (widget-create 'checkbox
389 :notify (lambda (&rest ignore) (message "Tickle"))
391 (widget-insert " Thus\n\nSelect one:\n\n")
392 (widget-create 'radio-button-choice
394 :notify (lambda (widget &rest ignore)
395 (message "You selected %s"
396 (widget-value widget)))
397 '(item "One") '(item "Another One.") '(item "A Final One."))
399 (widget-create 'push-button
400 :notify (lambda (&rest ignore)
401 (if (= (length (widget-value widget-example-repeat))
403 (message "Congratulation!")
404 (error "Three was the count!")))
407 (widget-create 'push-button
408 :notify (lambda (&rest ignore)
412 (use-local-map widget-keymap)
416 @node Setting Up the Buffer, Basic Types, Programming Example, Top
417 @comment node-name, next, previous, up
418 @section Setting Up the Buffer
420 Widgets are created with @code{widget-create}, which returns a
421 @dfn{widget} object. This object can be queried and manipulated by
422 other widget functions, until it is deleted with @code{widget-delete}.
423 After the widgets have been created, @code{widget-setup} must be called
426 @defun widget-create type [ keyword argument ]@dots{}
427 Create and return a widget of type @var{type}.
428 The syntax for the @var{type} argument is described in @ref{Basic Types}.
430 The keyword arguments can be used to overwrite the keyword arguments
431 that are part of @var{type}.
434 @defun widget-delete widget
435 Delete @var{widget} and remove it from the buffer.
439 Set up a buffer to support widgets.
441 This should be called after creating all the widgets and before allowing
442 the user to edit them.
446 If you want to insert text outside the widgets in the form, the
447 recommended way to do that is with @code{widget-insert}.
450 Insert the arguments, either strings or characters, at point.
451 The inserted text will be read-only.
454 There is a standard widget keymap which you might find useful.
456 @findex widget-button-press
457 @findex widget-button-click
458 @defvr Const widget-keymap
459 A keymap with the global keymap as its parent.@*
460 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
461 @code{widget-backward}, respectively. @key{RET} and @kbd{Mouse-2}
462 are bound to @code{widget-button-press} and
463 @code{widget-button-click}.@refill
466 @defvar widget-global-map
467 Keymap used by @code{widget-button-press} and @code{widget-button-click}
468 when not on a button. By default this is @code{global-map}.
471 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
472 @comment node-name, next, previous, up
475 The syntax of a type specification is given below:
478 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
482 Where, @var{name} is a widget name, @var{keyword} is the name of a
483 property, @var{argument} is the value of the property, and @var{args}
484 are interpreted in a widget specific way.
486 @cindex keyword arguments
487 The following keyword arguments that apply to all widgets:
490 @vindex value@r{ keyword}
492 The initial value for widgets of this type.
494 @vindex format@r{ keyword}
496 This string will be inserted in the buffer when you create a widget.
497 The following @samp{%} escapes are available:
502 The text inside will be marked as a button.
504 By default, the text will be shown in @code{widget-button-face}, and
505 surrounded by brackets.
507 @defopt widget-button-prefix
508 String to prefix buttons.
511 @defopt widget-button-suffix
512 String to suffix buttons.
517 The text inside will be displayed with the face specified by
521 This will be replaced with the buffer representation of the widget's
522 value. What this is depends on the widget type.
525 Insert the string specified by @code{:doc} here.
528 Like @samp{%d}, with the following modifications: If the documentation
529 string is more than one line, it will add a button which will toggle
530 between showing only the first line, and showing the full text.
531 Furthermore, if there is no @code{:doc} property in the widget, it will
532 instead examine the @code{:documentation-property} property. If it is a
533 lambda expression, it will be called with the widget's value as an
534 argument, and the result will be used as the documentation text.
537 Insert the string specified by @code{:tag} here, or the @code{princ}
538 representation of the value if there is no tag.
541 Insert a literal @samp{%}.
544 @vindex button-face@r{ keyword}
546 Face used to highlight text inside %[ %] in the format.
548 @vindex button-prefix@r{ keyword}
549 @vindex button-suffix@r{ keyword}
551 @itemx :button-suffix
552 Text around %[ %] in the format.
560 The string is inserted literally.
563 The value of the symbol is expanded according to this table.
566 @vindex doc@r{ keyword}
568 The string inserted by the @samp{%d} escape in the format
571 @vindex tag@r{ keyword}
573 The string inserted by the @samp{%t} escape in the format
576 @vindex tag-glyph@r{ keyword}
578 Name of image to use instead of the string specified by @code{:tag} on
579 Emacsen that supports it.
581 @vindex help-echo@r{ keyword}
583 Specifies how to display a message whenever you move to the widget with
584 either @code{widget-forward} or @code{widget-backward} or move the mouse
585 over it (using the standard @code{help-echo} mechanism). The argument
586 is either a string to display, a function of one argument, the widget,
587 which should return a string to display, or a form that evaluates to
590 @vindex indent@r{ keyword}
592 An integer indicating the absolute number of spaces to indent children
595 @vindex offset@r{ keyword}
597 An integer indicating how many extra spaces to add to the widget's
598 grandchildren compared to this widget.
600 @vindex extra-offset@r{ keyword}
602 An integer indicating how many extra spaces to add to the widget's
603 children compared to this widget.
605 @vindex notify@r{ keyword}
607 A function called each time the widget or a nested widget is changed.
608 The function is called with two or three arguments. The first argument
609 is the widget itself, the second argument is the widget that was
610 changed, and the third argument is the event leading to the change, if
613 @vindex menu-tag@r{ keyword}
615 Tag used in the menu when the widget is used as an option in a
616 @code{menu-choice} widget.
618 @vindex menu-tag-get@r{ keyword}
620 Function used for finding the tag when the widget is used as an option
621 in a @code{menu-choice} widget. By default, the tag used will be either the
622 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
623 representation of the @code{:value} property if not.
625 @vindex match@r{ keyword}
627 Should be a function called with two arguments, the widget and a value,
628 and returning non-@code{nil} if the widget can represent the specified value.
630 @vindex validate@r{ keyword}
632 A function which takes a widget as an argument, and returns @code{nil}
633 if the widget's current value is valid for the widget. Otherwise it
634 should return the widget containing the invalid data, and set that
635 widget's @code{:error} property to a string explaining the error.
637 The following predefined function can be used:
639 @defun widget-children-validate widget
640 All the @code{:children} of @var{widget} must be valid.
643 @vindex tab-order@r{ keyword}
645 Specify the order in which widgets are traversed with
646 @code{widget-forward} or @code{widget-backward}. This is only partially
651 Widgets with tabbing order @code{-1} are ignored.
654 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
655 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
656 whichever comes first.
659 When on a widget with no tabbing order specified, go to the next widget
660 in the buffer with a positive tabbing order, or @code{nil}
663 @vindex parent@r{ keyword}
665 The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
666 element of a @code{editable-list} widget).
668 @vindex sibling-args@r{ keyword}
670 This keyword is only used for members of a @code{radio-button-choice} or
671 @code{checklist}. The value should be a list of extra keyword
672 arguments, which will be used when creating the @code{radio-button} or
673 @code{checkbox} associated with this item.
677 @deffn {User Option} widget-glyph-directory
678 Directory where glyphs are found.
679 Widget will look here for a file with the same name as specified for the
680 image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
683 @deffn{User Option} widget-glyph-enable
684 If non-@code{nil}, allow glyphs to appear on displays where they are supported.
696 * radio-button-choice::
706 @node link, url-link, Basic Types, Basic Types
707 @comment node-name, next, previous, up
708 @subsection The @code{link} Widget
709 @findex link@r{ widget}
714 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
717 The @var{value}, if present, is used to initialize the @code{:value}
718 property. The value should be a string, which will be inserted in the
721 By default the link will be shown in brackets.
723 @defopt widget-link-prefix
724 String to prefix links.
727 @defopt widget-link-suffix
728 String to suffix links.
731 @node url-link, info-link, link, Basic Types
732 @comment node-name, next, previous, up
733 @subsection The @code{url-link} Widget
734 @findex url-link@r{ widget}
739 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
742 @findex browse-url-browser-function@r{, and @code{url-link} widget}
743 When this link is invoked, the @acronym{WWW} browser specified by
744 @code{browse-url-browser-function} will be called with @var{url}.
746 @node info-link, push-button, url-link, Basic Types
747 @comment node-name, next, previous, up
748 @subsection The @code{info-link} Widget
749 @findex info-link@r{ widget}
754 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
757 When this link is invoked, the built-in Info reader is started on
760 @node push-button, editable-field, info-link, Basic Types
761 @comment node-name, next, previous, up
762 @subsection The @code{push-button} Widget
763 @findex push-button@r{ widget}
768 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
771 The @var{value}, if present, is used to initialize the @code{:value}
772 property. The value should be a string, which will be inserted in the
775 By default the tag will be shown in brackets.
777 @defopt widget-push-button-prefix
778 String to prefix push buttons.
781 @defopt widget-push-button-suffix
782 String to suffix push buttons.
785 @node editable-field, text, push-button, Basic Types
786 @comment node-name, next, previous, up
787 @subsection The @code{editable-field} Widget
788 @findex editable-field@r{ widget}
793 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
796 The @var{value}, if present, is used to initialize the @code{:value}
797 property. The value should be a string, which will be inserted in
798 field. This widget will match all string values.
800 The following extra properties are recognized:
803 @vindex size@r{ keyword}
805 The width of the editable field.@*
806 By default the field will reach to the end of the line.
808 @vindex value-face@r{ keyword}
810 Face used for highlighting the editable field. Default is
811 @code{widget-field-face}, see @ref{User Interface}.
813 @vindex secret@r{ keyword}
815 Character used to display the value. You can set this to e.g.@: @code{?*}
816 if the field contains a password or other secret information. By
817 default, this is @code{nil}, and the value is not secret.
819 @vindex valid-regexp@r{ keyword}
821 By default the @code{:validate} function will match the content of the
822 field with the value of this attribute. The default value is @code{""}
823 which matches everything.
825 @vindex keymap@r{ keyword}
826 @vindex widget-field-keymap
828 Keymap used in the editable field. The default value is
829 @code{widget-field-keymap}, which allows you to use all the normal
830 editing commands, even if the buffer's major mode suppresses some of
831 them. Pressing @key{RET} invokes the function specified by
835 @node text, menu-choice, editable-field, Basic Types
836 @comment node-name, next, previous, up
837 @subsection The @code{text} Widget
838 @findex text@r{ widget}
840 @vindex widget-text-keymap
841 This is just like @code{editable-field}, but intended for multiline text
842 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
843 does not rebind the @key{RET} key.
845 @node menu-choice, radio-button-choice, text, Basic Types
846 @comment node-name, next, previous, up
847 @subsection The @code{menu-choice} Widget
848 @findex menu-choice@r{ widget}
853 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
856 The @var{type} argument represents each possible choice. The widget's
857 value will be that of the chosen @var{type} argument. This widget will
858 match any value matching at least one of the specified @var{type}
862 @vindex void@r{ keyword}
864 Widget type used as a fallback when the value does not match any of the
865 specified @var{type} arguments.
867 @vindex case-fold@r{ keyword}
869 Set this to @code{nil} if you don't want to ignore case when prompting for a
870 choice through the minibuffer.
872 @vindex children@r{ keyword}
874 A list whose @sc{car} is the widget representing the currently chosen
877 @vindex choice@r{ keyword}
879 The current chosen type.
881 @vindex args@r{ keyword}
886 @node radio-button-choice, item, menu-choice, Basic Types
887 @comment node-name, next, previous, up
888 @subsection The @code{radio-button-choice} Widget
889 @findex radio-button-choice@r{ widget}
894 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
897 The @var{type} argument represents each possible choice. The widget's
898 value will be that of the chosen @var{type} argument. This widget will
899 match any value matching at least one of the specified @var{type}
902 The following extra properties are recognized.
905 @vindex entry-format@r{ keyword}
907 This string will be inserted for each entry in the list.
908 The following @samp{%} escapes are available:
911 Replace with the buffer representation of the @var{type} widget.
913 Replace with the radio button.
915 Insert a literal @samp{%}.
918 @vindex button-args@r{ keyword}
920 A list of keywords to pass to the radio buttons. Useful for setting
921 e.g.@: the @samp{:help-echo} for each button.
923 @vindex buttons@r{ keyword}
925 The widgets representing the radio buttons.
927 @vindex children@r{ keyword}
929 The widgets representing each type.
931 @vindex choice@r{ keyword}
933 The current chosen type
935 @vindex args@r{ keyword}
940 You can add extra radio button items to a @code{radio-button-choice}
941 widget after it has been created with the function
942 @code{widget-radio-add-item}.
944 @defun widget-radio-add-item widget type
945 Add to @code{radio-button-choice} widget @var{widget} a new radio button
946 item of type @var{type}.
949 Please note that such items added after the @code{radio-button-choice}
950 widget has been created will @strong{not} be properly destructed when
951 you call @code{widget-delete}.
953 @node item, choice-item, radio-button-choice, Basic Types
954 @comment node-name, next, previous, up
955 @subsection The @code{item} Widget
956 @findex item@r{ widget}
961 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
964 The @var{value}, if present, is used to initialize the @code{:value}
965 property. The value should be a string, which will be inserted in the
966 buffer. This widget will only match the specified value.
968 @node choice-item, toggle, item, Basic Types
969 @comment node-name, next, previous, up
970 @subsection The @code{choice-item} Widget
971 @findex choice-item@r{ widget}
976 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
979 The @var{value}, if present, is used to initialize the @code{:value}
980 property. The value should be a string, which will be inserted in the
981 buffer as a button. Activating the button of a @code{choice-item} is
982 equivalent to activating the parent widget. This widget will only match
985 @node toggle, checkbox, choice-item, Basic Types
986 @comment node-name, next, previous, up
987 @subsection The @code{toggle} Widget
988 @findex toggle@r{ widget}
993 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
996 The widget has two possible states, @samp{on} and @samp{off}, which
997 correspond to a @code{t} or @code{nil} value, respectively.
999 The following extra properties are recognized:
1003 A string representing the @samp{on} state. By default the string
1006 A string representing the @samp{off} state. By default the string
1008 @vindex on-glyph@r{ keyword}
1010 Name of a glyph to be used instead of the @samp{:on} text string, on
1011 emacsen that supports this.
1012 @vindex off-glyph@r{ keyword}
1014 Name of a glyph to be used instead of the @samp{:off} text string, on
1015 emacsen that supports this.
1018 @node checkbox, checklist, toggle, Basic Types
1019 @comment node-name, next, previous, up
1020 @subsection The @code{checkbox} Widget
1021 @findex checkbox@r{ widget}
1023 This widget has two possible states, @samp{selected} and
1024 @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
1029 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
1032 @node checklist, editable-list, checkbox, Basic Types
1033 @comment node-name, next, previous, up
1034 @subsection The @code{checklist} Widget
1035 @findex checklist@r{ widget}
1040 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
1043 The @var{type} arguments represent each checklist item. The widget's
1044 value will be a list containing the values of all checked @var{type}
1045 arguments. The checklist widget will match a list whose elements all
1046 match at least one of the specified @var{type} arguments.
1048 The following extra properties are recognized:
1051 @vindex entry-format@r{ keyword}
1053 This string will be inserted for each entry in the list.
1054 The following @samp{%} escapes are available:
1057 Replaced with the buffer representation of the @var{type} widget.
1059 Replace with the checkbox.
1061 Insert a literal @samp{%}.
1064 @vindex greedy@r{ keyword}
1066 Usually a checklist will only match if the items are in the exact
1067 sequence given in the specification. By setting @code{:greedy} to
1068 non-@code{nil}, it will allow the items to come in any sequence.
1069 However, if you extract the value they will be in the sequence given
1070 in the checklist, i.e.@: the original sequence is forgotten.
1072 @vindex button-args@r{ keyword}
1074 A list of keywords to pass to the checkboxes. Useful for setting
1075 e.g.@: the @samp{:help-echo} for each checkbox.
1077 @vindex buttons@r{ keyword}
1079 The widgets representing the checkboxes.
1081 @vindex children@r{ keyword}
1083 The widgets representing each type.
1085 @vindex args@r{ keyword}
1090 @node editable-list, group, checklist, Basic Types
1091 @comment node-name, next, previous, up
1092 @subsection The @code{editable-list} Widget
1093 @findex editable-list@r{ widget}
1098 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
1101 The value is a list, where each member represents one widget of type
1104 The following extra properties are recognized:
1107 @vindex entry-format@r{ keyword}
1109 This string will be inserted for each entry in the list.
1110 The following @samp{%} escapes are available:
1113 This will be replaced with the buffer representation of the @var{type}
1116 Insert the @b{[INS]} button.
1118 Insert the @b{[DEL]} button.
1120 Insert a literal @samp{%}.
1123 @vindex insert-button-args@r{ keyword}
1124 @item :insert-button-args
1125 A list of keyword arguments to pass to the insert buttons.
1127 @vindex delete-button-args@r{ keyword}
1128 @item :delete-button-args
1129 A list of keyword arguments to pass to the delete buttons.
1131 @vindex append-button-args@r{ keyword}
1132 @item :append-button-args
1133 A list of keyword arguments to pass to the trailing insert button.
1135 @vindex buttons@r{ keyword}
1137 The widgets representing the insert and delete buttons.
1139 @vindex children@r{ keyword}
1141 The widgets representing the elements of the list.
1143 @vindex args@r{ keyword}
1145 List whose @sc{car} is the type of the list elements.
1148 @node group, , editable-list, Basic Types
1149 @comment node-name, next, previous, up
1150 @subsection The @code{group} Widget
1151 @findex group@r{ widget}
1153 This widget simply group other widgets together.
1158 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1161 The value is a list, with one member for each @var{type}.
1163 @node Sexp Types, Widget Properties, Basic Types, Top
1168 A number of widgets for editing @dfn{s-expressions} (Lisp types), sexp
1169 for short, are also available. These basically fall in several
1170 categories described in this section.
1179 @node constants, generic, Sexp Types, Sexp Types
1180 @comment node-name, next, previous, up
1181 @subsection The Constant Widgets
1182 @cindex constant widgets
1184 The @code{const} widget can contain any Lisp expression, but the user is
1185 prohibited from editing it, which is mainly useful as a component of one
1186 of the composite widgets.
1188 The syntax for the @code{const} widget is:
1191 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1194 The @var{value}, if present, is used to initialize the @code{:value}
1195 property and can be any s-expression.
1198 This will display any valid s-expression in an immutable part of the
1202 There are two variations of the @code{const} widget, namely
1203 @code{variable-item} and @code{function-item}. These should contain a
1204 symbol with a variable or function binding. The major difference from
1205 the @code{const} widget is that they will allow the user to see the
1206 variable or function documentation for the symbol.
1208 @deffn Widget variable-item
1209 An immutable symbol that is bound as a variable.
1212 @deffn Widget function-item
1213 An immutable symbol that is bound as a function.
1216 @node generic, atoms, constants, Sexp Types
1217 @comment node-name, next, previous, up
1218 @subsection Generic Sexp Widget
1219 @cindex generic sexp widget
1221 The @code{sexp} widget can contain any Lisp expression, and allows the
1222 user to edit it inline in the buffer.
1224 The syntax for the @code{sexp} widget is:
1227 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1231 This will allow you to edit any valid s-expression in an editable buffer
1234 The @code{sexp} widget takes the same keyword arguments as the
1235 @code{editable-field} widget. @xref{editable-field}.
1238 @node atoms, composite, generic, Sexp Types
1239 @comment node-name, next, previous, up
1240 @subsection Atomic Sexp Widgets
1241 @cindex atomic sexp widget
1243 The atoms are s-expressions that do not consist of other s-expressions.
1244 For example, a string, a file name, or a symbol are atoms, while a list
1245 is a composite type. You can edit the value of an atom with the
1248 The syntax for all the atoms are:
1251 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1254 The @var{value}, if present, is used to initialize the @code{:value}
1255 property and must be an expression of the same type as the widget.
1256 That is, the string widget can only be initialized with a string.
1258 All the atom widgets take the same keyword arguments as the
1259 @code{editable-field} widget. @xref{editable-field}.
1261 @deffn Widget string
1262 Allows you to edit a string in an editable field.
1265 @deffn Widget regexp
1266 Allows you to edit a regular expression in an editable field.
1269 @deffn Widget character
1270 Allows you to enter a character in an editable field.
1274 Allows you to edit a file name in an editable field. If you invoke
1275 the tag button, you can edit the file name in the mini-buffer with
1280 @vindex must-match@r{ keyword}
1282 If this is set to non-@code{nil}, only existing file names will be
1283 allowed in the minibuffer.
1287 @deffn Widget directory
1288 Allows you to edit a directory name in an editable field.
1289 Similar to the @code{file} widget.
1292 @deffn Widget symbol
1293 Allows you to edit a Lisp symbol in an editable field.
1296 @deffn Widget function
1297 Allows you to edit a lambda expression, or a function name with completion.
1300 @deffn Widget variable
1301 Allows you to edit a variable name, with completion.
1304 @deffn Widget integer
1305 Allows you to edit an integer in an editable field.
1308 @deffn Widget number
1309 Allows you to edit a number in an editable field.
1312 @deffn Widget boolean
1313 Allows you to edit a boolean. In Lisp this means a variable which is
1314 either @code{nil} meaning false, or non-@code{nil} meaning true.
1318 @node composite, , atoms, Sexp Types
1319 @comment node-name, next, previous, up
1320 @subsection Composite Sexp Widgets
1321 @cindex composite sexp widgets
1323 The syntax for the composite widget is:
1326 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1330 where each @var{component} must be a widget type. Each component widget
1331 will be displayed in the buffer, and will be editable by the user.
1334 The value of a @code{cons} widget is a cons-cell where the @sc{car} is
1335 the value of the first component and the @sc{cdr} is the value of the
1336 second component. There must be exactly two components.
1340 The value of a @code{list} widget is a list containing the value of
1341 each of its component.
1344 @deffn Widget vector
1345 The value of a @code{vector} widget is a vector containing the value of
1346 each of its component.
1349 The above suffice for specifying fixed size lists and vectors. To get
1350 variable length lists and vectors, you can use a @code{choice},
1351 @code{set}, or @code{repeat} widgets together with the @code{:inline}
1352 keywords. If any component of a composite widget has the @code{:inline}
1353 keyword set, its value must be a list which will then be spliced into
1354 the composite. For example, to specify a list whose first element must
1355 be a file name, and whose remaining arguments should either by the
1356 symbol @code{t} or two files, you can use the following widget
1363 :value ("foo" "bar")
1367 The value of a widget of this type will either have the form
1368 @code{(file t)} or @code{(file string string)}.
1370 This concept of inline is probably hard to understand. It was certainly
1371 hard to implement, so instead of confusing you more by trying to explain
1372 it here, I'll just suggest you meditate over it for a while.
1374 @deffn Widget choice
1375 Allows you to edit a sexp which may have one of a fixed set of types.
1376 It is currently implemented with the @code{choice-menu} basic widget,
1377 and has a similar syntax.
1381 Allows you to specify a type which must be a list whose elements all
1382 belong to given set. The elements of the list are not significant.
1383 This is implemented on top of the @code{checklist} basic widget, and has
1387 @deffn Widget repeat
1388 Allows you to specify a variable length list whose members are all of
1389 the same type. Implemented on top of the @code{editable-list} basic
1390 widget, and has a similar syntax.
1393 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1394 @comment node-name, next, previous, up
1396 @cindex properties of widgets
1397 @cindex widget properties
1399 You can examine or set the value of a widget by using the widget object
1400 that was returned by @code{widget-create}.
1402 @defun widget-value widget
1403 Return the current value contained in @var{widget}.
1404 It is an error to call this function on an uninitialized widget.
1407 @defun widget-value-set widget value
1408 Set the value contained in @var{widget} to @var{value}.
1409 It is an error to call this function with an invalid @var{value}.
1412 @strong{Important:} You @emph{must} call @code{widget-setup} after
1413 modifying the value of a widget before the user is allowed to edit the
1414 widget again. It is enough to call @code{widget-setup} once if you
1415 modify multiple widgets. This is currently only necessary if the widget
1416 contains an editing field, but may be necessary for other widgets in the
1419 If your application needs to associate some information with the widget
1420 objects, for example a reference to the item being edited, it can be
1421 done with @code{widget-put} and @code{widget-get}. The property names
1422 must begin with a @samp{:}.
1424 @defun widget-put widget property value
1425 In @var{widget} set @var{property} to @var{value}.
1426 @var{property} should be a symbol, while @var{value} can be anything.
1429 @defun widget-get widget property
1430 In @var{widget} return the value for @var{property}.
1431 @var{property} should be a symbol, the value is what was last set by
1432 @code{widget-put} for @var{property}.
1435 @defun widget-member widget property
1436 Non-@code{nil} if @var{widget} has a value (even @code{nil}) for
1437 property @var{property}.
1440 Occasionally it can be useful to know which kind of widget you have,
1441 i.e.@: the name of the widget type you gave when the widget was created.
1443 @defun widget-type widget
1444 Return the name of @var{widget}, a symbol.
1447 @cindex active widget
1448 @cindex inactive widget
1449 @cindex activate a widget
1450 @cindex deactivate a widget
1451 Widgets can be in two states: active, which means they are modifiable by
1452 the user, or inactive, which means they cannot be modified by the user.
1453 You can query or set the state with the following code:
1456 ;; Examine if @var{widget} is active or not.
1457 (if (widget-apply @var{widget} :active)
1458 (message "Widget is active.")
1459 (message "Widget is inactive.")
1461 ;; Make @var{widget} inactive.
1462 (widget-apply @var{widget} :deactivate)
1464 ;; Make @var{widget} active.
1465 (widget-apply @var{widget} :activate)
1468 A widget is inactive if it, or any of its ancestors (found by
1469 following the @code{:parent} link), have been deactivated. To make sure
1470 a widget is really active, you must therefore activate both it and
1475 (widget-apply widget :activate)
1476 (setq widget (widget-get widget :parent)))
1479 You can check if a widget has been made inactive by examining the value
1480 of the @code{:inactive} keyword. If this is non-@code{nil}, the widget itself
1481 has been deactivated. This is different from using the @code{:active}
1482 keyword, in that the latter tells you if the widget @strong{or} any of
1483 its ancestors have been deactivated. Do not attempt to set the
1484 @code{:inactive} keyword directly. Use the @code{:activate}
1485 @code{:deactivate} keywords instead.
1488 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1489 @comment node-name, next, previous, up
1490 @section Defining New Widgets
1492 @cindex defining new widgets
1494 You can define specialized widgets with @code{define-widget}. It allows
1495 you to create a shorthand for more complex widgets, including specifying
1496 component widgets and new default values for the keyword
1499 @defun define-widget name class doc &rest args
1500 Define a new widget type named @var{name} from @code{class}.
1502 @var{name} and class should both be symbols, @code{class} should be one
1503 of the existing widget types.
1505 The third argument @var{doc} is a documentation string for the widget.
1507 After the new widget has been defined, the following two calls will
1508 create identical widgets:
1513 (widget-create @var{name})
1518 (apply widget-create @var{class} @var{args})
1524 Using @code{define-widget} just stores the definition of the widget type
1525 in the @code{widget-type} property of @var{name}, which is what
1526 @code{widget-create} uses.
1528 If you only want to specify defaults for keywords with no complex
1529 conversions, you can use @code{identity} as your conversion function.
1531 The following additional keyword arguments are useful when defining new
1534 @vindex convert-widget@r{ keyword}
1535 @item :convert-widget
1536 Function to convert a widget type before creating a widget of that
1537 type. It takes a widget type as an argument, and returns the converted
1538 widget type. When a widget is created, this function is called for the
1539 widget type and all the widget's parent types, most derived first.
1541 The following predefined functions can be used here:
1543 @defun widget-types-convert-widget widget
1544 Convert @code{:args} as widget types in @var{widget}.
1547 @defun widget-value-convert-widget widget
1548 Initialize @code{:value} from @code{:args} in @var{widget}.
1551 @vindex copy@r{ keyword}
1553 Function to deep copy a widget type. It takes a shallow copy of the
1554 widget type as an argument (made by @code{copy-sequence}), and returns a
1555 deep copy. The purpose of this is to avoid having different instances
1556 of combined widgets share nested attributes.
1558 The following predefined functions can be used here:
1560 @defun widget-types-copy widget
1561 Copy @code{:args} as widget types in @var{widget}.
1564 @vindex value-to-internal@r{ keyword}
1565 @item :value-to-internal
1566 Function to convert the value to the internal format. The function
1567 takes two arguments, a widget and an external value, and returns the
1568 internal value. The function is called on the present @code{:value}
1569 when the widget is created, and on any value set later with
1570 @code{widget-value-set}.
1572 @vindex value-to-external@r{ keyword}
1573 @item :value-to-external
1574 Function to convert the value to the external format. The function
1575 takes two arguments, a widget and an internal value, and returns the
1576 external value. The function is called on the present @code{:value}
1577 when the widget is created, and on any value set later with
1578 @code{widget-value-set}.
1580 @vindex create@r{ keyword}
1582 Function to create a widget from scratch. The function takes one
1583 argument, a widget type, and creates a widget of that type, inserts it
1584 in the buffer, and returns a widget object.
1586 @vindex delete@r{ keyword}
1588 Function to delete a widget. The function takes one argument, a widget,
1589 and should remove all traces of the widget from the buffer.
1591 The default value is:
1593 @defun widget-default-delete widget
1594 Remove @var{widget} from the buffer.
1595 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1598 In most cases you should not change this value, but instead use
1599 @code{:value-delete} to make any additional cleanup.
1601 @vindex value-create@r{ keyword}
1603 Function to expand the @samp{%v} escape in the format string. It will
1604 be called with the widget as its argument and should insert a
1605 representation of the widget's value in the buffer.
1607 Nested widgets should be listed in @code{:children} or @code{:buttons}
1608 to make sure they are automatically deleted.
1610 @vindex value-delete@r{ keyword}
1612 Should remove the representation of the widget's value from the buffer.
1613 It will be called with the widget as its argument. It doesn't have to
1614 remove the text, but it should release markers and delete nested widgets
1615 if these are not listed in @code{:children} or @code{:buttons}.
1617 @vindex value-get@r{ keyword}
1619 Function to extract the value of a widget, as it is displayed in the
1622 The following predefined function can be used here:
1624 @defun widget-value-value-get widget
1625 Return the @code{:value} property of @var{widget}.
1628 @vindex format-handler@r{ keyword}
1629 @item :format-handler
1630 Function to handle unknown @samp{%} escapes in the format string. It
1631 will be called with the widget and the character that follows the
1632 @samp{%} as arguments. You can set this to allow your widget to handle
1633 non-standard escapes.
1635 @findex widget-default-format-handler
1636 You should end up calling @code{widget-default-format-handler} to handle
1637 unknown escape sequences, which will handle the @samp{%h} and any future
1638 escape sequences, as well as give an error for unknown escapes.
1640 @vindex action@r{ keyword}
1642 Function to handle user initiated events. By default, @code{:notify}
1645 The following predefined function can be used here:
1647 @defun widget-parent-action widget &optional event
1648 Tell @code{:parent} of @var{widget} to handle the @code{:action}.
1649 Optional @var{event} is the event that triggered the action.
1652 @vindex prompt-value@r{ keyword}
1654 Function to prompt for a value in the minibuffer. The function should
1655 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1656 @var{unbound} and should return a value for widget entered by the user.
1657 @var{prompt} is the prompt to use. @var{value} is the default value to
1658 use, unless @var{unbound} is non-@code{nil}, in which case there is no default
1659 value. The function should read the value using the method most natural
1660 for this widget, and does not have to check that it matches.
1663 If you want to define a new widget from scratch, use the @code{default}
1666 @deffn Widget default
1667 Widget used as a base for other widgets.
1669 It provides most of the functionality that is referred to as ``by
1670 default'' in this text.
1673 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1674 @comment node-name, next, previous, up
1675 @section Widget Browser
1676 @cindex widget browser
1678 There is a separate package to browse widgets. This is intended to help
1679 programmers who want to examine the content of a widget. The browser
1680 shows the value of each keyword, but uses links for certain keywords
1681 such as @samp{:parent}, which avoids printing cyclic structures.
1683 @deffn Command widget-browse @var{widget}
1684 Create a widget browser for @var{widget}.
1685 When called interactively, prompt for @var{widget}.
1688 @deffn Command widget-browse-other-window @var{widget}
1689 Create a widget browser for @var{widget} and show it in another window.
1690 When called interactively, prompt for @var{widget}.
1693 @deffn Command widget-browse-at @var{pos}
1694 Create a widget browser for the widget at @var{pos}.
1695 When called interactively, use the position of point.
1698 @node Widget Minor Mode, Utilities, Widget Browser, Top
1699 @comment node-name, next, previous, up
1700 @section Widget Minor Mode
1701 @cindex widget minor mode
1703 There is a minor mode for manipulating widgets in major modes that
1704 don't provide any support for widgets themselves. This is mostly
1705 intended to be useful for programmers doing experiments.
1707 @deffn Command widget-minor-mode
1708 Toggle minor mode for traversing widgets.
1709 With arg, turn widget mode on if and only if arg is positive.
1712 @defvar widget-minor-mode-keymap
1713 Keymap used in @code{widget-minor-mode}.
1716 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1717 @comment node-name, next, previous, up
1719 @cindex utility functions for widgets
1721 @defun widget-prompt-value widget prompt [ value unbound ]
1722 Prompt for a value matching @var{widget}, using @var{prompt}.
1723 The current value is assumed to be @var{value}, unless @var{unbound} is
1724 non-@code{nil}.@refill
1727 @defun widget-get-sibling widget
1728 Get the item which @var{widget} is assumed to toggle.
1729 This is only meaningful for radio buttons or checkboxes in a list.
1732 @node Widget Wishlist, Index, Utilities, Top
1733 @comment node-name, next, previous, up
1739 It should be possible to add or remove items from a list with @kbd{C-k}
1740 and @kbd{C-o} (suggested by @sc{rms}).
1743 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1744 dash (@samp{-}). The dash should be a button that, when invoked, asks
1745 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1746 the ugly buttons, the dash is my idea).
1749 The @code{menu-choice} tag should be prettier, something like the abbreviated
1753 Finish @code{:tab-order}.
1756 Make indentation work with glyphs and proportional fonts.
1759 Add commands to show overview of object and class hierarchies to the
1763 Find a way to disable mouse highlight for inactive widgets.
1766 Find a way to make glyphs look inactive.
1769 Add @code{property-list} widget.
1772 Add @code{association-list} widget.
1775 Add @code{key-binding} widget.
1778 Add @code{widget} widget for editing widget specifications.
1781 Find clean way to implement variable length list.
1782 See @code{TeX-printer-list} for an explanation.
1785 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1788 Add a @code{mailto} widget.
1791 @node Index, , Widget Wishlist, Top
1792 @comment node-name, next, previous, up
1795 This is an alphabetical listing of all concepts, functions, commands,
1796 variables, and widgets described in this manual.
1799 @setchapternewpage odd
1804 arch-tag: 2b427731-4c61-4e72-85de-5ccec9c623f0