4 @setfilename ../info/widget
5 @settitle The Emacs Widget Library
7 Copyright @copyright{} 2000 Free Software Foundation, Inc.
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23 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
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40 * Widget: (widget). Documenting the "widget" package used by the
41 Emacs Custom facility.
44 @node Top, Introduction, (dir), (dir)
45 @comment node-name, next, previous, up
46 @top The Emacs Widget Library
51 * Programming Example::
52 * Setting Up the Buffer::
56 * Defining New Widgets::
64 @node Introduction, User Interface, Top, Top
65 @comment node-name, next, previous, up
68 Most graphical user interface toolkits provide a number of standard
69 user interface controls (sometimes known as `widgets' or `gadgets').
70 Emacs doesn't really support anything like this, except for an
71 incredibly powerful text ``widget.'' On the other hand, Emacs does
72 provide the necessary primitives to implement many other widgets
73 within a text buffer. The @code{widget} package simplifies this task.
76 @cindex widgets, basic types
77 The basic widgets are:
81 Areas of text with an associated action. Intended for hypertext links
84 Like link, but intended for stand-alone buttons.
86 An editable text field. It can be either variable or fixed length.
88 Allows the user to choose one of multiple options from a menu, each
89 option is itself a widget. Only the selected option will be visible in
91 @item radio-button-choice
92 Allows the user to choose one of multiple options by activating radio
93 buttons. The options are implemented as widgets. All options will be
94 visible in the buffer.
96 A simple constant widget intended to be used in the @code{menu-choice} and
97 @code{radio-button-choice} widgets.
99 A button item only intended for use in choices. When invoked, the user
100 will be asked to select another option from the choice widget.
102 A simple @samp{on}/@samp{off} switch.
104 A checkbox (@samp{[ ]}/@samp{[X]}).
106 Create an editable list. The user can insert or delete items in the
107 list. Each list item is itself a widget.
110 Now, of what possible use can support for widgets be in a text editor?
111 I'm glad you asked. The answer is that widgets are useful for
112 implementing forms. A @dfn{form} in Emacs is a buffer where the user is
113 supposed to fill out a number of fields, each of which has a specific
114 meaning. The user is not supposed to change or delete any of the text
115 between the fields. Examples of forms in Emacs are the @file{forms}
116 package (of course), the customize buffers, the mail and news compose
117 modes, and the @sc{html} form support in the @file{w3} browser.
119 @cindex widget library, why use it
120 The advantages for a programmer of using the @code{widget} package to
125 More complex fields than just editable text are supported.
127 You can give the users immediate feedback if they enter invalid data in a
128 text field, and sometimes prevent entering invalid data.
130 You can have fixed sized fields, thus allowing multiple fields to be
133 It is simple to query or set the value of a field.
135 Editing happens in the buffer, not in the mini-buffer.
137 Packages using the library get a uniform look, making them easier for
140 As support for embedded graphics improve, the widget library will be
141 extended to use the GUI features. This means that your code using the
142 widget library will also use the new graphic features automatically.
145 In order to minimize the code that is loaded by users who does not
146 create any widgets, the code has been split in two files:
148 @cindex widget library, files
151 This will declare the user variables, define the function
152 @code{widget-define}, and autoload the function @code{widget-create}.
154 Everything else is here, there is no reason to load it explicitly, as
155 it will be autoloaded when needed.
158 @node User Interface, Programming Example, Introduction, Top
159 @comment node-name, next, previous, up
160 @section User Interface
162 A form consist of read only text for documentation and some fields,
163 where each field contains two parts, a tag and a value. The tags are
164 used to identify the fields, so the documentation can refer to the
165 @samp{foo field}, meaning the field tagged with @samp{Foo}. Here is an
169 Here is some documentation.
171 Name: @i{My Name} @strong{Choose}: This option
172 Address: @i{Some Place
176 See also @b{_other work_} for more information.
178 Numbers: count to three below
179 @b{[INS]} @b{[DEL]} @i{One}
180 @b{[INS]} @b{[DEL]} @i{Eh, two?}
181 @b{[INS]} @b{[DEL]} @i{Five!}
196 @b{[Apply Form]} @b{[Reset Form]}
199 The top level widgets in is example are tagged @samp{Name},
200 @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers},
201 @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and
202 @samp{[Reset Form]}. There are basically two things the user can do
203 within a form, namely editing the editable text fields and activating
206 @subsection Editable Text Fields
208 In the example, the value for the @samp{Name} is most likely displayed
209 in an editable text field, and so are values for each of the members of
210 the @samp{Numbers} list. All the normal Emacs editing operations are
211 available for editing these fields. The only restriction is that each
212 change you make must be contained within a single editable text field.
213 For example, capitalizing all text from the middle of one field to the
214 middle of another field is prohibited.
216 Editing text fields are created by the @code{editable-field} widget.
218 The editing text fields are highlighted with the
219 @code{widget-field-face} face, making them easy to find.
221 @deffn Face widget-field-face
222 Face used for other editing fields.
227 @cindex widget buttons
228 @cindex button widgets
229 Some portions of the buffer have an associated @dfn{action}, which can
230 be @dfn{invoked} by a standard key or mouse command. These portions
231 are called @dfn{buttons}. The default commands for activating a button
236 @deffn Command widget-button-press @var{pos} &optional @var{event}
237 Invoke the button at @var{pos}, defaulting to point.
238 If point is not located on a button, invoke the binding in
239 @code{widget-global-map} (by default the global map).
242 @kindex Mouse-2 @r{(on button widgets})
244 @deffn Command widget-button-click @var{event}
245 Invoke the button at the location of the mouse pointer. If the mouse
246 pointer is located in an editable text field, invoke the binding in
247 @code{widget-global-map} (by default the global map).
251 There are several different kind of buttons, all of which are present in
255 @cindex option field tag
256 @item The Option Field Tags
257 When you invoke one of these buttons, you will be asked to choose
258 between a number of different options. This is how you edit an option
259 field. Option fields are created by the @code{menu-choice} widget. In
260 the example, @samp{@b{Choose}} is an option field tag.
261 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons
262 Activating these will insert or delete elements from an editable list.
263 The list is created by the @code{editable-list} widget.
264 @cindex embedded buttons
265 @item Embedded Buttons
266 The @samp{@b{_other work_}} is an example of an embedded
267 button. Embedded buttons are not associated with a fields, but can serve
268 any purpose, such as implementing hypertext references. They are
269 usually created by the @code{link} widget.
270 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons
271 Activating one of these will convert it to the other. This is useful
272 for implementing multiple-choice fields. You can create it with the
273 @code{checkbox} widget.
274 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons
275 Only one radio button in a @code{radio-button-choice} widget can be
276 selected at any time. When you invoke one of the unselected radio
277 buttons, it will be selected and the previous selected radio button will
279 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons
280 These are explicit buttons made with the @code{push-button} widget. The
281 main difference from the @code{link} widget is that the buttons will be
282 displayed as GUI buttons when possible.
285 To make them easier to locate, buttons are emphasized in the buffer.
287 @deffn Face widget-button-face
288 Face used for buttons.
291 @defopt widget-mouse-face
292 Face used for highlighting a button when the mouse pointer moves across
296 @subsection Navigation
298 You can use all the normal Emacs commands to move around in a form
299 buffer, plus you will have these additional commands:
303 @deffn Command widget-forward &optional count
304 Move point @var{count} buttons or editing fields forward.
307 @deffn Command widget-backward &optional count
308 Move point @var{count} buttons or editing fields backward.
312 @node Programming Example, Setting Up the Buffer, User Interface, Top
313 @comment node-name, next, previous, up
314 @section Programming Example
316 @cindex widgets, programming example
317 @cindex example of using widgets
318 Here is the code to implement the user interface example (@pxref{User
327 (defvar widget-example-repeat)
329 (defun widget-example ()
330 "Create the widgets from the Widget manual."
332 (switch-to-buffer "*Widget Example*")
333 (kill-all-local-variables)
334 (make-local-variable 'widget-example-repeat)
335 (let ((inhibit-read-only t))
337 (widget-insert "Here is some documentation.\n\nName: ")
338 (widget-create 'editable-field
341 (widget-create 'menu-choice
344 :help-echo "Choose me, please!"
345 :notify (lambda (widget &rest ignore)
346 (message "%s is a good choice!"
347 (widget-value widget)))
348 '(item :tag "This option" :value "This")
349 '(choice-item "That option")
350 '(editable-field :menu-tag "No option" "Thus option"))
351 (widget-insert "Address: ")
352 (widget-create 'editable-field
353 "Some Place\nIn some City\nSome country.")
354 (widget-insert "\nSee also ")
356 :notify (lambda (&rest ignore)
357 (widget-value-set widget-example-repeat
361 (widget-insert " for more information.\n\nNumbers: count to three below\n")
362 (setq widget-example-repeat
363 (widget-create 'editable-list
364 :entry-format "%i %d %v"
365 :notify (lambda (widget &rest ignore)
366 (let ((old (widget-get widget
368 (new (length (widget-value widget))))
370 (widget-put widget ':example-length new)
371 (message "You can count to %d." new))))
372 :value '("One" "Eh, two?" "Five!")
373 '(editable-field :value "three")))
374 (widget-insert "\n\nSelect multiple:\n\n")
375 (widget-create 'checkbox t)
376 (widget-insert " This\n")
377 (widget-create 'checkbox nil)
378 (widget-insert " That\n")
379 (widget-create 'checkbox
380 :notify (lambda (&rest ignore) (message "Tickle"))
382 (widget-insert " Thus\n\nSelect one:\n\n")
383 (widget-create 'radio-button-choice
385 :notify (lambda (widget &rest ignore)
386 (message "You selected %s"
387 (widget-value widget)))
388 '(item "One") '(item "Another One.") '(item "A Final One."))
390 (widget-create 'push-button
391 :notify (lambda (&rest ignore)
392 (if (= (length (widget-value widget-example-repeat))
394 (message "Congratulation!")
395 (error "Three was the count!")))
398 (widget-create 'push-button
399 :notify (lambda (&rest ignore)
403 (use-local-map widget-keymap)
407 @node Setting Up the Buffer, Basic Types, Programming Example, Top
408 @comment node-name, next, previous, up
409 @section Setting Up the Buffer
411 Widgets are created with @code{widget-create}, which returns a
412 @dfn{widget} object. This object can be queried and manipulated by
413 other widget functions, until it is deleted with @code{widget-delete}.
414 After the widgets have been created, @code{widget-setup} must be called
417 @defun widget-create type [ keyword argument ]@dots{}
418 Create and return a widget of type @var{type}.
419 The syntax for the @var{type} argument is described in @ref{Basic Types}.
421 The keyword arguments can be used to overwrite the keyword arguments
422 that are part of @var{type}.
425 @defun widget-delete widget
426 Delete @var{widget} and remove it from the buffer.
430 Set up a buffer to support widgets.
432 This should be called after creating all the widgets and before allowing
433 the user to edit them.
437 If you want to insert text outside the widgets in the form, the
438 recommended way to do that is with @code{widget-insert}.
441 Insert the arguments, either strings or characters, at point.
442 The inserted text will be read-only.
445 There is a standard widget keymap which you might find useful.
447 @findex widget-button-press
448 @findex widget-button-click
449 @defvr Const widget-keymap
450 A keymap with the global keymap as its parent.@*
451 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
452 @code{widget-backward}, respectively. @key{RET} and @kbd{Mouse-2}
453 are bound to @code{widget-button-press} and
454 @code{widget-button-click}.@refill
457 @defvar widget-global-map
458 Keymap used by @code{widget-button-press} and @code{widget-button-click}
459 when not on a button. By default this is @code{global-map}.
462 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
463 @comment node-name, next, previous, up
466 The syntax of a type specification is given below:
469 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
473 Where, @var{name} is a widget name, @var{keyword} is the name of a
474 property, @var{argument} is the value of the property, and @var{args}
475 are interpreted in a widget specific way.
477 @cindex keyword arguments
478 The following keyword arguments that apply to all widgets:
481 @vindex value@r{ keyword}
483 The initial value for widgets of this type.
485 @vindex format@r{ keyword}
487 This string will be inserted in the buffer when you create a widget.
488 The following @samp{%} escapes are available:
493 The text inside will be marked as a button.
495 By default, the text will be shown in @code{widget-button-face}, and
496 surrounded by brackets.
498 @defopt widget-button-prefix
499 String to prefix buttons.
502 @defopt widget-button-suffix
503 String to suffix buttons.
508 The text inside will be displayed with the face specified by
512 This will be replaced with the buffer representation of the widget's
513 value. What this is depends on the widget type.
516 Insert the string specified by @code{:doc} here.
519 Like @samp{%d}, with the following modifications: If the documentation
520 string is more than one line, it will add a button which will toggle
521 between showing only the first line, and showing the full text.
522 Furthermore, if there is no @code{:doc} property in the widget, it will
523 instead examine the @code{:documentation-property} property. If it is a
524 lambda expression, it will be called with the widget's value as an
525 argument, and the result will be used as the documentation text.
528 Insert the string specified by @code{:tag} here, or the @code{princ}
529 representation of the value if there is no tag.
532 Insert a literal @samp{%}.
535 @vindex button-face@r{ keyword}
537 Face used to highlight text inside %[ %] in the format.
539 @vindex button-prefix@r{ keyword}
540 @vindex button-suffix@r{ keyword}
542 @itemx :button-suffix
543 Text around %[ %] in the format.
551 The string is inserted literally.
554 The value of the symbol is expanded according to this table.
557 @vindex doc@r{ keyword}
559 The string inserted by the @samp{%d} escape in the format
562 @vindex tag@r{ keyword}
564 The string inserted by the @samp{%t} escape in the format
567 @vindex tag-glyph@r{ keyword}
569 Name of image to use instead of the string specified by @code{:tag} on
570 Emacsen that supports it.
572 @vindex help-echo@r{ keyword}
574 Specifies how to display a message whenever you move to the widget with
575 either @code{widget-forward} or @code{widget-backward} or move the mouse
576 over it (using the standard @code{help-echo} mechanism). The argument
577 is either a string to display or a function of one argument, the widget,
578 which should return a string to display.
580 @vindex indent@r{ keyword}
582 An integer indicating the absolute number of spaces to indent children
585 @vindex offset@r{ keyword}
587 An integer indicating how many extra spaces to add to the widget's
588 grandchildren compared to this widget.
590 @vindex extra-offset@r{ keyword}
592 An integer indicating how many extra spaces to add to the widget's
593 children compared to this widget.
595 @vindex notify@r{ keyword}
597 A function called each time the widget or a nested widget is changed.
598 The function is called with two or three arguments. The first argument
599 is the widget itself, the second argument is the widget that was
600 changed, and the third argument is the event leading to the change, if
603 @vindex menu-tag@r{ keyword}
605 Tag used in the menu when the widget is used as an option in a
606 @code{menu-choice} widget.
608 @vindex menu-tag-get@r{ keyword}
610 Function used for finding the tag when the widget is used as an option
611 in a @code{menu-choice} widget. By default, the tag used will be either the
612 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
613 representation of the @code{:value} property if not.
615 @vindex match@r{ keyword}
617 Should be a function called with two arguments, the widget and a value,
618 and returning non-nil if the widget can represent the specified value.
620 @vindex validate@r{ keyword}
622 A function which takes a widget as an argument, and returns @code{nil}
623 if the widget's current value is valid for the widget. Otherwise it
624 should return the widget containing the invalid data, and set that
625 widget's @code{:error} property to a string explaining the error.
627 The following predefined function can be used:
629 @defun widget-children-validate widget
630 All the @code{:children} of @var{widget} must be valid.
633 @vindex tab-order@r{ keyword}
635 Specify the order in which widgets are traversed with
636 @code{widget-forward} or @code{widget-backward}. This is only partially
641 Widgets with tabbing order @code{-1} are ignored.
644 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
645 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
646 whichever comes first.
649 When on a widget with no tabbing order specified, go to the next widget
650 in the buffer with a positive tabbing order, or @code{nil}
653 @vindex parent@r{ keyword}
655 The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
656 element of a @code{editable-list} widget).
658 @vindex sibling-args@r{ keyword}
660 This keyword is only used for members of a @code{radio-button-choice} or
661 @code{checklist}. The value should be a list of extra keyword
662 arguments, which will be used when creating the @code{radio-button} or
663 @code{checkbox} associated with this item.
667 @deffn {User Option} widget-glyph-directory
668 Directory where glyphs are found.
669 Widget will look here for a file with the same name as specified for the
670 image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
673 @deffn{User Option} widget-glyph-enable
674 If non-nil, allow glyphs to appear on displays where they are supported.
686 * radio-button-choice::
696 @node link, url-link, Basic Types, Basic Types
697 @comment node-name, next, previous, up
698 @subsection The @code{link} Widget
699 @findex link@r{ widget}
704 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
707 The @var{value}, if present, is used to initialize the @code{:value}
708 property. The value should be a string, which will be inserted in the
711 By default the link will be shown in brackets.
713 @defopt widget-link-prefix
714 String to prefix links.
717 @defopt widget-link-suffix
718 String to suffix links.
721 @node url-link, info-link, link, Basic Types
722 @comment node-name, next, previous, up
723 @subsection The @code{url-link} Widget
724 @findex url-link@r{ widget}
729 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
732 @findex browse-url-browser-function@r{, and @code{url-link} widget}
733 When this link is invoked, the @sc{www} browser specified by
734 @code{browse-url-browser-function} will be called with @var{url}.
736 @node info-link, push-button, url-link, Basic Types
737 @comment node-name, next, previous, up
738 @subsection The @code{info-link} Widget
739 @findex info-link@r{ widget}
744 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
747 When this link is invoked, the built-in Info reader is started on
750 @node push-button, editable-field, info-link, Basic Types
751 @comment node-name, next, previous, up
752 @subsection The @code{push-button} Widget
753 @findex push-button@r{ widget}
758 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
761 The @var{value}, if present, is used to initialize the @code{:value}
762 property. The value should be a string, which will be inserted in the
765 By default the tag will be shown in brackets.
767 @defopt widget-push-button-prefix
768 String to prefix push buttons.
771 @defopt widget-push-button-suffix
772 String to suffix push buttons.
775 @node editable-field, text, push-button, Basic Types
776 @comment node-name, next, previous, up
777 @subsection The @code{editable-field} Widget
778 @findex editable-field@r{ widget}
783 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
786 The @var{value}, if present, is used to initialize the @code{:value}
787 property. The value should be a string, which will be inserted in
788 field. This widget will match all string values.
790 The following extra properties are recognized:
793 @vindex size@r{ keyword}
795 The width of the editable field.@*
796 By default the field will reach to the end of the line.
798 @vindex value-face@r{ keyword}
800 Face used for highlighting the editable field. Default is
801 @code{widget-field-face}, see @ref{User Interface}.
803 @vindex secret@r{ keyword}
805 Character used to display the value. You can set this to e.g.@: @code{?*}
806 if the field contains a password or other secret information. By
807 default, this is nil, and the value is not secret.
809 @vindex valid-regexp@r{ keyword}
811 By default the @code{:validate} function will match the content of the
812 field with the value of this attribute. The default value is @code{""}
813 which matches everything.
815 @vindex keymap@r{ keyword}
816 @vindex widget-field-keymap
818 Keymap used in the editable field. The default value is
819 @code{widget-field-keymap}, which allows you to use all the normal
820 editing commands, even if the buffer's major mode suppresses some of
821 them. Pressing @key{RET} invokes the function specified by
825 @node text, menu-choice, editable-field, Basic Types
826 @comment node-name, next, previous, up
827 @subsection The @code{text} Widget
828 @findex text@r{ widget}
830 @vindex widget-text-keymap
831 This is just like @code{editable-field}, but intended for multiline text
832 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
833 does not rebind the @key{RET} key.
835 @node menu-choice, radio-button-choice, text, Basic Types
836 @comment node-name, next, previous, up
837 @subsection The @code{menu-choice} Widget
838 @findex menu-choice@r{ widget}
843 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
846 The @var{type} argument represents each possible choice. The widget's
847 value will be that of the chosen @var{type} argument. This widget will
848 match any value matching at least one of the specified @var{type}
852 @vindex void@r{ keyword}
854 Widget type used as a fallback when the value does not match any of the
855 specified @var{type} arguments.
857 @vindex case-fold@r{ keyword}
859 Set this to nil if you don't want to ignore case when prompting for a
860 choice through the minibuffer.
862 @vindex children@r{ keyword}
864 A list whose @code{car} is the widget representing the currently chosen
867 @vindex choice@r{ keyword}
869 The current chosen type.
871 @vindex args@r{ keyword}
876 @node radio-button-choice, item, menu-choice, Basic Types
877 @comment node-name, next, previous, up
878 @subsection The @code{radio-button-choice} Widget
879 @findex radio-button-choice@r{ widget}
884 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
887 The @var{type} argument represents each possible choice. The widget's
888 value will be that of the chosen @var{type} argument. This widget will
889 match any value matching at least one of the specified @var{type}
892 The following extra properties are recognized.
895 @vindex entry-format@r{ keyword}
897 This string will be inserted for each entry in the list.
898 The following @samp{%} escapes are available:
901 Replace with the buffer representation of the @var{type} widget.
903 Replace with the radio button.
905 Insert a literal @samp{%}.
908 @vindex button-args@r{ keyword}
910 A list of keywords to pass to the radio buttons. Useful for setting
911 e.g.@: the @samp{:help-echo} for each button.
913 @vindex buttons@r{ keyword}
915 The widgets representing the radio buttons.
917 @vindex children@r{ keyword}
919 The widgets representing each type.
921 @vindex choice@r{ keyword}
923 The current chosen type
925 @vindex args@r{ keyword}
930 You can add extra radio button items to a @code{radio-button-choice}
931 widget after it has been created with the function
932 @code{widget-radio-add-item}.
934 @defun widget-radio-add-item widget type
935 Add to @code{radio-button-choice} widget @var{widget} a new radio button
936 item of type @var{type}.
939 Please note that such items added after the @code{radio-button-choice}
940 widget has been created will @strong{not} be properly destructed when
941 you call @code{widget-delete}.
943 @node item, choice-item, radio-button-choice, Basic Types
944 @comment node-name, next, previous, up
945 @subsection The @code{item} Widget
946 @findex item@r{ widget}
951 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
954 The @var{value}, if present, is used to initialize the @code{:value}
955 property. The value should be a string, which will be inserted in the
956 buffer. This widget will only match the specified value.
958 @node choice-item, toggle, item, Basic Types
959 @comment node-name, next, previous, up
960 @subsection The @code{choice-item} Widget
961 @findex choice-item@r{ widget}
966 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
969 The @var{value}, if present, is used to initialize the @code{:value}
970 property. The value should be a string, which will be inserted in the
971 buffer as a button. Activating the button of a @code{choice-item} is
972 equivalent to activating the parent widget. This widget will only match
975 @node toggle, checkbox, choice-item, Basic Types
976 @comment node-name, next, previous, up
977 @subsection The @code{toggle} Widget
978 @findex toggle@r{ widget}
983 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
986 The widget has two possible states, @samp{on} and @samp{off}, which
987 correspond to a @code{t} or @code{nil} value, respectively.
989 The following extra properties are recognized:
993 A string representing the @samp{on} state. By default the string
996 A string representing the @samp{off} state. By default the string
998 @vindex on-glyph@r{ keyword}
1000 Name of a glyph to be used instead of the @samp{:on} text string, on
1001 emacsen that supports this.
1002 @vindex off-glyph@r{ keyword}
1004 Name of a glyph to be used instead of the @samp{:off} text string, on
1005 emacsen that supports this.
1008 @node checkbox, checklist, toggle, Basic Types
1009 @comment node-name, next, previous, up
1010 @subsection The @code{checkbox} Widget
1011 @findex checkbox@r{ widget}
1013 This widget has two possible states, @samp{selected} and
1014 @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
1019 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
1022 @node checklist, editable-list, checkbox, Basic Types
1023 @comment node-name, next, previous, up
1024 @subsection The @code{checklist} Widget
1025 @findex checklist@r{ widget}
1030 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
1033 The @var{type} arguments represent each checklist item. The widget's
1034 value will be a list containing the values of all checked @var{type}
1035 arguments. The checklist widget will match a list whose elements all
1036 match at least one of the specified @var{type} arguments.
1038 The following extra properties are recognized:
1041 @vindex entry-format@r{ keyword}
1043 This string will be inserted for each entry in the list.
1044 The following @samp{%} escapes are available:
1047 Replaced with the buffer representation of the @var{type} widget.
1049 Replace with the checkbox.
1051 Insert a literal @samp{%}.
1054 @vindex greedy@r{ keyword}
1056 Usually a checklist will only match if the items are in the exact
1057 sequence given in the specification. By setting @code{:greedy} to
1058 non-nil, it will allow the items to come in any sequence. However, if
1059 you extract the value they will be in the sequence given in the
1060 checklist, i.e.@: the original sequence is forgotten.
1062 @vindex button-args@r{ keyword}
1064 A list of keywords to pass to the checkboxes. Useful for setting
1065 e.g.@: the @samp{:help-echo} for each checkbox.
1067 @vindex buttons@r{ keyword}
1069 The widgets representing the checkboxes.
1071 @vindex children@r{ keyword}
1073 The widgets representing each type.
1075 @vindex args@r{ keyword}
1080 @node editable-list, group, checklist, Basic Types
1081 @comment node-name, next, previous, up
1082 @subsection The @code{editable-list} Widget
1083 @findex editable-list@r{ widget}
1088 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
1091 The value is a list, where each member represents one widget of type
1094 The following extra properties are recognized:
1097 @vindex entry-format@r{ keyword}
1099 This string will be inserted for each entry in the list.
1100 The following @samp{%} escapes are available:
1103 This will be replaced with the buffer representation of the @var{type}
1106 Insert the @b{[INS]} button.
1108 Insert the @b{[DEL]} button.
1110 Insert a literal @samp{%}.
1113 @vindex insert-button-args@r{ keyword}
1114 @item :insert-button-args
1115 A list of keyword arguments to pass to the insert buttons.
1117 @vindex delete-button-args@r{ keyword}
1118 @item :delete-button-args
1119 A list of keyword arguments to pass to the delete buttons.
1121 @vindex append-button-args@r{ keyword}
1122 @item :append-button-args
1123 A list of keyword arguments to pass to the trailing insert button.
1125 @vindex buttons@r{ keyword}
1127 The widgets representing the insert and delete buttons.
1129 @vindex children@r{ keyword}
1131 The widgets representing the elements of the list.
1133 @vindex args@r{ keyword}
1135 List whose @code{car} is the type of the list elements.
1138 @node group, , editable-list, Basic Types
1139 @comment node-name, next, previous, up
1140 @subsection The @code{group} Widget
1141 @findex group@r{ widget}
1143 This widget simply group other widgets together.
1148 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1151 The value is a list, with one member for each @var{type}.
1153 @node Sexp Types, Widget Properties, Basic Types, Top
1158 A number of widgets for editing @dfn{s-expressions} (lisp types), sexp
1159 for short, are also available. These basically fall in several
1160 categories described in this section.
1169 @node constants, generic, Sexp Types, Sexp Types
1170 @comment node-name, next, previous, up
1171 @subsection The Constant Widgets
1172 @cindex constant widgets
1174 The @code{const} widget can contain any lisp expression, but the user is
1175 prohibited from editing it, which is mainly useful as a component of one
1176 of the composite widgets.
1178 The syntax for the @code{const} widget is:
1181 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1184 The @var{value}, if present, is used to initialize the @code{:value}
1185 property and can be any s-expression.
1188 This will display any valid s-expression in an immutable part of the
1192 There are two variations of the @code{const} widget, namely
1193 @code{variable-item} and @code{function-item}. These should contain a
1194 symbol with a variable or function binding. The major difference from
1195 the @code{const} widget is that they will allow the user to see the
1196 variable or function documentation for the symbol.
1198 @deffn Widget variable-item
1199 An immutable symbol that is bound as a variable.
1202 @deffn Widget function-item
1203 An immutable symbol that is bound as a function.
1206 @node generic, atoms, constants, Sexp Types
1207 @comment node-name, next, previous, up
1208 @subsection Generic Sexp Widget
1209 @cindex generic sexp widget
1211 The @code{sexp} widget can contain any lisp expression, and allows the
1212 user to edit it inline in the buffer.
1214 The syntax for the @code{sexp} widget is:
1217 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1221 This will allow you to edit any valid s-expression in an editable buffer
1224 The @code{sexp} widget takes the same keyword arguments as the
1225 @code{editable-field} widget. @xref{editable-field}.
1228 @node atoms, composite, generic, Sexp Types
1229 @comment node-name, next, previous, up
1230 @subsection Atomic Sexp Widgets
1231 @cindex atomic sexp widget
1233 The atoms are s-expressions that do not consist of other s-expressions.
1234 For example, a string, a file name, or a symbol are atoms, while a list
1235 is a composite type. You can edit the value of an atom with the
1238 The syntax for all the atoms are:
1241 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1244 The @var{value}, if present, is used to initialize the @code{:value}
1245 property and must be an expression of the same type as the widget.
1246 That is, the string widget can only be initialized with a string.
1248 All the atom widgets take the same keyword arguments as the
1249 @code{editable-field} widget. @xref{editable-field}.
1251 @deffn Widget string
1252 Allows you to edit a string in an editable field.
1255 @deffn Widget regexp
1256 Allows you to edit a regular expression in an editable field.
1259 @deffn Widget character
1260 Allows you to enter a character in an editable field.
1264 Allows you to edit a file name in an editable field. If you invoke
1265 the tag button, you can edit the file name in the mini-buffer with
1270 @vindex must-match@r{ keyword}
1272 If this is set to non-nil, only existing file names will be allowed in
1277 @deffn Widget directory
1278 Allows you to edit a directory name in an editable field.
1279 Similar to the @code{file} widget.
1282 @deffn Widget symbol
1283 Allows you to edit a lisp symbol in an editable field.
1286 @deffn Widget function
1287 Allows you to edit a lambda expression, or a function name with completion.
1290 @deffn Widget variable
1291 Allows you to edit a variable name, with completion.
1294 @deffn Widget integer
1295 Allows you to edit an integer in an editable field.
1298 @deffn Widget number
1299 Allows you to edit a number in an editable field.
1302 @deffn Widget boolean
1303 Allows you to edit a boolean. In lisp this means a variable which is
1304 either nil meaning false, or non-nil meaning true.
1308 @node composite, , atoms, Sexp Types
1309 @comment node-name, next, previous, up
1310 @subsection Composite Sexp Widgets
1311 @cindex composite sexp widgets
1313 The syntax for the composite widget is:
1316 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1320 where each @var{component} must be a widget type. Each component widget
1321 will be displayed in the buffer, and will be editable by the user.
1324 The value of a @code{cons} widget is a cons-cell where the @code{car} is
1325 the value of the first component and the @code{cdr} is the value of the
1326 second component. There must be exactly two components.
1330 The value of a @code{list} widget is a list containing the value of
1331 each of its component.
1334 @deffn Widget vector
1335 The value of a @code{vector} widget is a vector containing the value of
1336 each of its component.
1339 The above suffice for specifying fixed size lists and vectors. To get
1340 variable length lists and vectors, you can use a @code{choice},
1341 @code{set}, or @code{repeat} widgets together with the @code{:inline}
1342 keywords. If any component of a composite widget has the @code{:inline}
1343 keyword set, its value must be a list which will then be spliced into
1344 the composite. For example, to specify a list whose first element must
1345 be a file name, and whose remaining arguments should either by the
1346 symbol @code{t} or two files, you can use the following widget
1353 :value ("foo" "bar")
1357 The value of a widget of this type will either have the form
1358 @code{(file t)} or @code{(file string string)}.
1360 This concept of inline is probably hard to understand. It was certainly
1361 hard to implement, so instead of confusing you more by trying to explain
1362 it here, I'll just suggest you meditate over it for a while.
1364 @deffn Widget choice
1365 Allows you to edit a sexp which may have one of a fixed set of types.
1366 It is currently implemented with the @code{choice-menu} basic widget,
1367 and has a similar syntax.
1371 Allows you to specify a type which must be a list whose elements all
1372 belong to given set. The elements of the list are not significant.
1373 This is implemented on top of the @code{checklist} basic widget, and has
1377 @deffn Widget repeat
1378 Allows you to specify a variable length list whose members are all of
1379 the same type. Implemented on top of the @code{editable-list} basic
1380 widget, and has a similar syntax.
1383 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1384 @comment node-name, next, previous, up
1386 @cindex properties of widgets
1387 @cindex widget properties
1389 You can examine or set the value of a widget by using the widget object
1390 that was returned by @code{widget-create}.
1392 @defun widget-value widget
1393 Return the current value contained in @var{widget}.
1394 It is an error to call this function on an uninitialized widget.
1397 @defun widget-value-set widget value
1398 Set the value contained in @var{widget} to @var{value}.
1399 It is an error to call this function with an invalid @var{value}.
1402 @strong{Important:} You @emph{must} call @code{widget-setup} after
1403 modifying the value of a widget before the user is allowed to edit the
1404 widget again. It is enough to call @code{widget-setup} once if you
1405 modify multiple widgets. This is currently only necessary if the widget
1406 contains an editing field, but may be necessary for other widgets in the
1409 If your application needs to associate some information with the widget
1410 objects, for example a reference to the item being edited, it can be
1411 done with @code{widget-put} and @code{widget-get}. The property names
1412 must begin with a @samp{:}.
1414 @defun widget-put widget property value
1415 In @var{widget} set @var{property} to @var{value}.
1416 @var{property} should be a symbol, while @var{value} can be anything.
1419 @defun widget-get widget property
1420 In @var{widget} return the value for @var{property}.
1421 @var{property} should be a symbol, the value is what was last set by
1422 @code{widget-put} for @var{property}.
1425 @defun widget-member widget property
1426 Non-nil if @var{widget} has a value (even nil) for property @var{property}.
1429 Occasionally it can be useful to know which kind of widget you have,
1430 i.e.@: the name of the widget type you gave when the widget was created.
1432 @defun widget-type widget
1433 Return the name of @var{widget}, a symbol.
1436 @cindex active widget
1437 @cindex inactive widget
1438 @cindex activate a widget
1439 @cindex deactivate a widget
1440 Widgets can be in two states: active, which means they are modifiable by
1441 the user, or inactive, which means they cannot be modified by the user.
1442 You can query or set the state with the following code:
1445 ;; Examine if @var{widget} is active or not.
1446 (if (widget-apply @var{widget} :active)
1447 (message "Widget is active.")
1448 (message "Widget is inactive.")
1450 ;; Make @var{widget} inactive.
1451 (widget-apply @var{widget} :deactivate)
1453 ;; Make @var{widget} active.
1454 (widget-apply @var{widget} :activate)
1457 A widget is inactive if it, or any of its ancestors (found by
1458 following the @code{:parent} link), have been deactivated. To make sure
1459 a widget is really active, you must therefore activate both it and
1464 (widget-apply widget :activate)
1465 (setq widget (widget-get widget :parent)))
1468 You can check if a widget has been made inactive by examining the value
1469 of the @code{:inactive} keyword. If this is non-nil, the widget itself
1470 has been deactivated. This is different from using the @code{:active}
1471 keyword, in that the latter tells you if the widget @strong{or} any of
1472 its ancestors have been deactivated. Do not attempt to set the
1473 @code{:inactive} keyword directly. Use the @code{:activate}
1474 @code{:deactivate} keywords instead.
1477 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1478 @comment node-name, next, previous, up
1479 @section Defining New Widgets
1481 @cindex defining new widgets
1483 You can define specialized widgets with @code{widget-define}. It allows
1484 you to create a shorthand for more complex widgets, including specifying
1485 component widgets and new default values for the keyword
1488 @defun widget-define name class doc &rest args
1489 Define a new widget type named @var{name} from @code{class}.
1491 @var{name} and class should both be symbols, @code{class} should be one
1492 of the existing widget types.
1494 The third argument @var{DOC} is a documentation string for the widget.
1496 After the new widget has been defined, the following two calls will
1497 create identical widgets:
1502 (widget-create @var{name})
1507 (apply widget-create @var{class} @var{args})
1513 Using @code{widget-define} just stores the definition of the widget type
1514 in the @code{widget-type} property of @var{name}, which is what
1515 @code{widget-create} uses.
1517 If you only want to specify defaults for keywords with no complex
1518 conversions, you can use @code{identity} as your conversion function.
1520 The following additional keyword arguments are useful when defining new
1523 @vindex convert-widget@r{ keyword}
1524 @item :convert-widget
1525 Function to convert a widget type before creating a widget of that
1526 type. It takes a widget type as an argument, and returns the converted
1527 widget type. When a widget is created, this function is called for the
1528 widget type and all the widget's parent types, most derived first.
1530 The following predefined functions can be used here:
1532 @defun widget-types-convert-widget widget
1533 Convert @code{:args} as widget types in @var{widget}.
1536 @defun widget-value-convert-widget widget
1537 Initialize @code{:value} from @code{:args} in @var{widget}.
1540 @vindex value-to-internal@r{ keyword}
1541 @item :value-to-internal
1542 Function to convert the value to the internal format. The function
1543 takes two arguments, a widget and an external value, and returns the
1544 internal value. The function is called on the present @code{:value}
1545 when the widget is created, and on any value set later with
1546 @code{widget-value-set}.
1548 @vindex value-to-external@r{ keyword}
1549 @item :value-to-external
1550 Function to convert the value to the external format. The function
1551 takes two arguments, a widget and an internal value, and returns the
1552 external value. The function is called on the present @code{:value}
1553 when the widget is created, and on any value set later with
1554 @code{widget-value-set}.
1556 @vindex create@r{ keyword}
1558 Function to create a widget from scratch. The function takes one
1559 argument, a widget type, and creates a widget of that type, inserts it
1560 in the buffer, and returns a widget object.
1562 @vindex delete@r{ keyword}
1564 Function to delete a widget. The function takes one argument, a widget,
1565 and should remove all traces of the widget from the buffer.
1567 @vindex value-create@r{ keyword}
1569 Function to expand the @samp{%v} escape in the format string. It will
1570 be called with the widget as its argument and should insert a
1571 representation of the widget's value in the buffer.
1573 @vindex value-delete@r{ keyword}
1575 Should remove the representation of the widget's value from the buffer.
1576 It will be called with the widget as its argument. It doesn't have to
1577 remove the text, but it should release markers and delete nested widgets
1578 if such have been used.
1580 The following predefined function can be used here:
1582 @defun widget-children-value-delete widget
1583 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1586 @vindex value-get@r{ keyword}
1588 Function to extract the value of a widget, as it is displayed in the
1591 The following predefined function can be used here:
1593 @defun widget-value-value-get widget
1594 Return the @code{:value} property of @var{widget}.
1597 @vindex format-handler@r{ keyword}
1598 @item :format-handler
1599 Function to handle unknown @samp{%} escapes in the format string. It
1600 will be called with the widget and the character that follows the
1601 @samp{%} as arguments. You can set this to allow your widget to handle
1602 non-standard escapes.
1604 @findex widget-default-format-handler
1605 You should end up calling @code{widget-default-format-handler} to handle
1606 unknown escape sequences, which will handle the @samp{%h} and any future
1607 escape sequences, as well as give an error for unknown escapes.
1609 @vindex action@r{ keyword}
1611 Function to handle user initiated events. By default, @code{:notify}
1614 The following predefined function can be used here:
1616 @defun widget-parent-action widget &optional event
1617 Tell @code{:parent} of @var{widget} to handle the @code{:action}.
1618 Optional @var{event} is the event that triggered the action.
1621 @vindex prompt-value@r{ keyword}
1623 Function to prompt for a value in the minibuffer. The function should
1624 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1625 @var{unbound} and should return a value for widget entered by the user.
1626 @var{prompt} is the prompt to use. @var{value} is the default value to
1627 use, unless @var{unbound} is non-nil, in which case there is no default
1628 value. The function should read the value using the method most natural
1629 for this widget, and does not have to check that it matches.
1632 If you want to define a new widget from scratch, use the @code{default}
1635 @deffn Widget default
1636 Widget used as a base for other widgets.
1638 It provides most of the functionality that is referred to as ``by
1639 default'' in this text.
1642 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1643 @comment node-name, next, previous, up
1644 @section Widget Browser
1645 @cindex widget browser
1647 There is a separate package to browse widgets. This is intended to help
1648 programmers who want to examine the content of a widget. The browser
1649 shows the value of each keyword, but uses links for certain keywords
1650 such as @samp{:parent}, which avoids printing cyclic structures.
1652 @deffn Command widget-browse WIDGET
1653 Create a widget browser for WIDGET.
1654 When called interactively, prompt for WIDGET.
1657 @deffn Command widget-browse-other-window WIDGET
1658 Create a widget browser for WIDGET and show it in another window.
1659 When called interactively, prompt for WIDGET.
1662 @deffn Command widget-browse-at POS
1663 Create a widget browser for the widget at POS.
1664 When called interactively, use the position of point.
1667 @node Widget Minor Mode, Utilities, Widget Browser, Top
1668 @comment node-name, next, previous, up
1669 @section Widget Minor Mode
1670 @cindex widget minor mode
1672 There is a minor mode for manipulating widgets in major modes that
1673 don't provide any support for widgets themselves. This is mostly
1674 intended to be useful for programmers doing experiments.
1676 @deffn Command widget-minor-mode
1677 Toggle minor mode for traversing widgets.
1678 With arg, turn widget mode on if and only if arg is positive.
1681 @defvar widget-minor-mode-keymap
1682 Keymap used in @code{widget-minor-mode}.
1685 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1686 @comment node-name, next, previous, up
1688 @cindex utility functions for widgets
1690 @defun widget-prompt-value widget prompt [ value unbound ]
1691 Prompt for a value matching @var{widget}, using @var{prompt}.
1692 The current value is assumed to be @var{value}, unless @var{unbound} is
1696 @defun widget-get-sibling widget
1697 Get the item which @var{widget} is assumed to toggle.
1698 This is only meaningful for radio buttons or checkboxes in a list.
1701 @node Widget Wishlist, Index, Utilities, Top
1702 @comment node-name, next, previous, up
1708 It should be possible to add or remove items from a list with @kbd{C-k}
1709 and @kbd{C-o} (suggested by @sc{rms}).
1712 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1713 dash (@samp{-}). The dash should be a button that, when invoked, asks
1714 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1715 the ugly buttons, the dash is my idea).
1718 The @code{menu-choice} tag should be prettier, something like the abbreviated
1722 Finish @code{:tab-order}.
1725 Make indentation work with glyphs and proportional fonts.
1728 Add commands to show overview of object and class hierarchies to the
1732 Find a way to disable mouse highlight for inactive widgets.
1735 Find a way to make glyphs look inactive.
1738 Add @code{property-list} widget.
1741 Add @code{association-list} widget.
1744 Add @code{key-binding} widget.
1747 Add @code{widget} widget for editing widget specifications.
1750 Find clean way to implement variable length list.
1751 See @code{TeX-printer-list} for an explanation.
1754 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1757 Add a @code{mailto} widget.
1760 @node Index, , Widget Wishlist, Top
1761 @comment node-name, next, previous, up
1764 This is an alphabetical listing of all concepts, functions, commands,
1765 variables, and widgets described in this manual.
1768 @setchapternewpage odd