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 @strong{Warning:} In an @code{editable-field} widget, the editable
217 field must not be adjacent to another widget---that won't work.
218 You must put some text in between. Either make this text part of
219 the @code{editable-field} widget itself, or insert it with
220 @code{widget-insert}.
222 The @code{:format} keyword is useful for generating the necessary
223 text; for instance, if you give it a value of @code{"Name: %v "},
224 the @samp{Name: } part will provide the necessary separating text
225 before the field and the trailing space will provide the
226 separating text after the field. If you don't include the
227 @code{:size} keyword, the field will extend to the end of the
228 line, and the terminating newline will provide separation after.
230 The editing text fields are highlighted with the
231 @code{widget-field-face} face, making them easy to find.
233 @deffn Face widget-field-face
234 Face used for other editing fields.
239 @cindex widget buttons
240 @cindex button widgets
241 Some portions of the buffer have an associated @dfn{action}, which can
242 be @dfn{invoked} by a standard key or mouse command. These portions
243 are called @dfn{buttons}. The default commands for activating a button
248 @deffn Command widget-button-press @var{pos} &optional @var{event}
249 Invoke the button at @var{pos}, defaulting to point.
250 If point is not located on a button, invoke the binding in
251 @code{widget-global-map} (by default the global map).
254 @kindex Mouse-2 @r{(on button widgets})
256 @deffn Command widget-button-click @var{event}
257 Invoke the button at the location of the mouse pointer. If the mouse
258 pointer is located in an editable text field, invoke the binding in
259 @code{widget-global-map} (by default the global map).
263 There are several different kind of buttons, all of which are present in
267 @cindex option field tag
268 @item The Option Field Tags
269 When you invoke one of these buttons, you will be asked to choose
270 between a number of different options. This is how you edit an option
271 field. Option fields are created by the @code{menu-choice} widget. In
272 the example, @samp{@b{Choose}} is an option field tag.
273 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons
274 Activating these will insert or delete elements from an editable list.
275 The list is created by the @code{editable-list} widget.
276 @cindex embedded buttons
277 @item Embedded Buttons
278 The @samp{@b{_other work_}} is an example of an embedded
279 button. Embedded buttons are not associated with a fields, but can serve
280 any purpose, such as implementing hypertext references. They are
281 usually created by the @code{link} widget.
282 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons
283 Activating one of these will convert it to the other. This is useful
284 for implementing multiple-choice fields. You can create it with the
285 @code{checkbox} widget.
286 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons
287 Only one radio button in a @code{radio-button-choice} widget can be
288 selected at any time. When you invoke one of the unselected radio
289 buttons, it will be selected and the previous selected radio button will
291 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons
292 These are explicit buttons made with the @code{push-button} widget. The
293 main difference from the @code{link} widget is that the buttons will be
294 displayed as GUI buttons when possible.
297 To make them easier to locate, buttons are emphasized in the buffer.
299 @deffn Face widget-button-face
300 Face used for buttons.
303 @defopt widget-mouse-face
304 Face used for highlighting a button when the mouse pointer moves across
308 @subsection Navigation
310 You can use all the normal Emacs commands to move around in a form
311 buffer, plus you will have these additional commands:
315 @deffn Command widget-forward &optional count
316 Move point @var{count} buttons or editing fields forward.
319 @deffn Command widget-backward &optional count
320 Move point @var{count} buttons or editing fields backward.
324 @node Programming Example, Setting Up the Buffer, User Interface, Top
325 @comment node-name, next, previous, up
326 @section Programming Example
328 @cindex widgets, programming example
329 @cindex example of using widgets
330 Here is the code to implement the user interface example (@pxref{User
339 (defvar widget-example-repeat)
341 (defun widget-example ()
342 "Create the widgets from the Widget manual."
344 (switch-to-buffer "*Widget Example*")
345 (kill-all-local-variables)
346 (make-local-variable 'widget-example-repeat)
347 (let ((inhibit-read-only t))
350 (widget-insert "Here is some documentation.\n\nName: ")
351 (widget-create 'editable-field
353 :format "%v " ; Text after the field!
355 (widget-create 'menu-choice
358 :help-echo "Choose me, please!"
359 :notify (lambda (widget &rest ignore)
360 (message "%s is a good choice!"
361 (widget-value widget)))
362 '(item :tag "This option" :value "This")
363 '(choice-item "That option")
364 '(editable-field :menu-tag "No option" "Thus option"))
365 (widget-insert "Address: ")
366 (widget-create 'editable-field
367 "Some Place\nIn some City\nSome country.")
368 (widget-insert "\nSee also ")
370 :notify (lambda (&rest ignore)
371 (widget-value-set widget-example-repeat
376 " for more information.\n\nNumbers: count to three below\n")
377 (setq widget-example-repeat
378 (widget-create 'editable-list
379 :entry-format "%i %d %v"
380 :notify (lambda (widget &rest ignore)
381 (let ((old (widget-get widget
383 (new (length (widget-value widget))))
385 (widget-put widget ':example-length new)
386 (message "You can count to %d." new))))
387 :value '("One" "Eh, two?" "Five!")
388 '(editable-field :value "three")))
389 (widget-insert "\n\nSelect multiple:\n\n")
390 (widget-create 'checkbox t)
391 (widget-insert " This\n")
392 (widget-create 'checkbox nil)
393 (widget-insert " That\n")
394 (widget-create 'checkbox
395 :notify (lambda (&rest ignore) (message "Tickle"))
397 (widget-insert " Thus\n\nSelect one:\n\n")
398 (widget-create 'radio-button-choice
400 :notify (lambda (widget &rest ignore)
401 (message "You selected %s"
402 (widget-value widget)))
403 '(item "One") '(item "Another One.") '(item "A Final One."))
405 (widget-create 'push-button
406 :notify (lambda (&rest ignore)
407 (if (= (length (widget-value widget-example-repeat))
409 (message "Congratulation!")
410 (error "Three was the count!")))
413 (widget-create 'push-button
414 :notify (lambda (&rest ignore)
418 (use-local-map widget-keymap)
422 @node Setting Up the Buffer, Basic Types, Programming Example, Top
423 @comment node-name, next, previous, up
424 @section Setting Up the Buffer
426 Widgets are created with @code{widget-create}, which returns a
427 @dfn{widget} object. This object can be queried and manipulated by
428 other widget functions, until it is deleted with @code{widget-delete}.
429 After the widgets have been created, @code{widget-setup} must be called
432 @defun widget-create type [ keyword argument ]@dots{}
433 Create and return a widget of type @var{type}.
434 The syntax for the @var{type} argument is described in @ref{Basic Types}.
436 The keyword arguments can be used to overwrite the keyword arguments
437 that are part of @var{type}.
440 @defun widget-delete widget
441 Delete @var{widget} and remove it from the buffer.
445 Set up a buffer to support widgets.
447 This should be called after creating all the widgets and before allowing
448 the user to edit them.
452 If you want to insert text outside the widgets in the form, the
453 recommended way to do that is with @code{widget-insert}.
456 Insert the arguments, either strings or characters, at point.
457 The inserted text will be read-only.
460 There is a standard widget keymap which you might find useful.
462 @findex widget-button-press
463 @findex widget-button-click
464 @defvr Const widget-keymap
465 A keymap with the global keymap as its parent.@*
466 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
467 @code{widget-backward}, respectively. @key{RET} and @kbd{Mouse-2}
468 are bound to @code{widget-button-press} and
469 @code{widget-button-click}.@refill
472 @defvar widget-global-map
473 Keymap used by @code{widget-button-press} and @code{widget-button-click}
474 when not on a button. By default this is @code{global-map}.
477 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
478 @comment node-name, next, previous, up
481 The syntax of a type specification is given below:
484 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
488 Where, @var{name} is a widget name, @var{keyword} is the name of a
489 property, @var{argument} is the value of the property, and @var{args}
490 are interpreted in a widget specific way.
492 @cindex keyword arguments
493 The following keyword arguments that apply to all widgets:
496 @vindex value@r{ keyword}
498 The initial value for widgets of this type.
500 @vindex format@r{ keyword}
502 This string will be inserted in the buffer when you create a widget.
503 The following @samp{%} escapes are available:
508 The text inside will be marked as a button.
510 By default, the text will be shown in @code{widget-button-face}, and
511 surrounded by brackets.
513 @defopt widget-button-prefix
514 String to prefix buttons.
517 @defopt widget-button-suffix
518 String to suffix buttons.
523 The text inside will be displayed with the face specified by
527 This will be replaced with the buffer representation of the widget's
528 value. What this is depends on the widget type.
531 Insert the string specified by @code{:doc} here.
534 Like @samp{%d}, with the following modifications: If the documentation
535 string is more than one line, it will add a button which will toggle
536 between showing only the first line, and showing the full text.
537 Furthermore, if there is no @code{:doc} property in the widget, it will
538 instead examine the @code{:documentation-property} property. If it is a
539 lambda expression, it will be called with the widget's value as an
540 argument, and the result will be used as the documentation text.
543 Insert the string specified by @code{:tag} here, or the @code{princ}
544 representation of the value if there is no tag.
547 Insert a literal @samp{%}.
550 @vindex button-face@r{ keyword}
552 Face used to highlight text inside %[ %] in the format.
554 @vindex button-prefix@r{ keyword}
555 @vindex button-suffix@r{ keyword}
557 @itemx :button-suffix
558 Text around %[ %] in the format.
566 The string is inserted literally.
569 The value of the symbol is expanded according to this table.
572 @vindex doc@r{ keyword}
574 The string inserted by the @samp{%d} escape in the format
577 @vindex tag@r{ keyword}
579 The string inserted by the @samp{%t} escape in the format
582 @vindex tag-glyph@r{ keyword}
584 Name of image to use instead of the string specified by @code{:tag} on
585 Emacsen that supports it.
587 @vindex help-echo@r{ keyword}
589 Specifies how to display a message whenever you move to the widget with
590 either @code{widget-forward} or @code{widget-backward} or move the mouse
591 over it (using the standard @code{help-echo} mechanism). The argument
592 is either a string to display, a function of one argument, the widget,
593 which should return a string to display, or a form that evaluates to
596 @vindex indent@r{ keyword}
598 An integer indicating the absolute number of spaces to indent children
601 @vindex offset@r{ keyword}
603 An integer indicating how many extra spaces to add to the widget's
604 grandchildren compared to this widget.
606 @vindex extra-offset@r{ keyword}
608 An integer indicating how many extra spaces to add to the widget's
609 children compared to this widget.
611 @vindex notify@r{ keyword}
613 A function called each time the widget or a nested widget is changed.
614 The function is called with two or three arguments. The first argument
615 is the widget itself, the second argument is the widget that was
616 changed, and the third argument is the event leading to the change, if
619 @vindex menu-tag@r{ keyword}
621 Tag used in the menu when the widget is used as an option in a
622 @code{menu-choice} widget.
624 @vindex menu-tag-get@r{ keyword}
626 Function used for finding the tag when the widget is used as an option
627 in a @code{menu-choice} widget. By default, the tag used will be either the
628 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
629 representation of the @code{:value} property if not.
631 @vindex match@r{ keyword}
633 Should be a function called with two arguments, the widget and a value,
634 and returning non-@code{nil} if the widget can represent the specified value.
636 @vindex validate@r{ keyword}
638 A function which takes a widget as an argument, and returns @code{nil}
639 if the widget's current value is valid for the widget. Otherwise it
640 should return the widget containing the invalid data, and set that
641 widget's @code{:error} property to a string explaining the error.
643 The following predefined function can be used:
645 @defun widget-children-validate widget
646 All the @code{:children} of @var{widget} must be valid.
649 @vindex tab-order@r{ keyword}
651 Specify the order in which widgets are traversed with
652 @code{widget-forward} or @code{widget-backward}. This is only partially
657 Widgets with tabbing order @code{-1} are ignored.
660 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
661 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
662 whichever comes first.
665 When on a widget with no tabbing order specified, go to the next widget
666 in the buffer with a positive tabbing order, or @code{nil}
669 @vindex parent@r{ keyword}
671 The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
672 element of a @code{editable-list} widget).
674 @vindex sibling-args@r{ keyword}
676 This keyword is only used for members of a @code{radio-button-choice} or
677 @code{checklist}. The value should be a list of extra keyword
678 arguments, which will be used when creating the @code{radio-button} or
679 @code{checkbox} associated with this item.
683 @deffn {User Option} widget-glyph-directory
684 Directory where glyphs are found.
685 Widget will look here for a file with the same name as specified for the
686 image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
689 @deffn{User Option} widget-glyph-enable
690 If non-@code{nil}, allow glyphs to appear on displays where they are supported.
702 * radio-button-choice::
712 @node link, url-link, Basic Types, Basic Types
713 @comment node-name, next, previous, up
714 @subsection The @code{link} Widget
715 @findex link@r{ widget}
720 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
723 The @var{value}, if present, is used to initialize the @code{:value}
724 property. The value should be a string, which will be inserted in the
727 By default the link will be shown in brackets.
729 @defopt widget-link-prefix
730 String to prefix links.
733 @defopt widget-link-suffix
734 String to suffix links.
737 @node url-link, info-link, link, Basic Types
738 @comment node-name, next, previous, up
739 @subsection The @code{url-link} Widget
740 @findex url-link@r{ widget}
745 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
748 @findex browse-url-browser-function@r{, and @code{url-link} widget}
749 When this link is invoked, the @acronym{WWW} browser specified by
750 @code{browse-url-browser-function} will be called with @var{url}.
752 @node info-link, push-button, url-link, Basic Types
753 @comment node-name, next, previous, up
754 @subsection The @code{info-link} Widget
755 @findex info-link@r{ widget}
760 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
763 When this link is invoked, the built-in Info reader is started on
766 @node push-button, editable-field, info-link, Basic Types
767 @comment node-name, next, previous, up
768 @subsection The @code{push-button} Widget
769 @findex push-button@r{ widget}
774 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
777 The @var{value}, if present, is used to initialize the @code{:value}
778 property. The value should be a string, which will be inserted in the
781 By default the tag will be shown in brackets.
783 @defopt widget-push-button-prefix
784 String to prefix push buttons.
787 @defopt widget-push-button-suffix
788 String to suffix push buttons.
791 @node editable-field, text, push-button, Basic Types
792 @comment node-name, next, previous, up
793 @subsection The @code{editable-field} Widget
794 @findex editable-field@r{ widget}
799 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
802 The @var{value}, if present, is used to initialize the @code{:value}
803 property. The value should be a string, which will be inserted in
804 field. This widget will match all string values.
806 The following extra properties are recognized:
809 @vindex size@r{ keyword}
811 The width of the editable field.@*
812 By default the field will reach to the end of the line.
814 @vindex value-face@r{ keyword}
816 Face used for highlighting the editable field. Default is
817 @code{widget-field-face}, see @ref{User Interface}.
819 @vindex secret@r{ keyword}
821 Character used to display the value. You can set this to e.g.@: @code{?*}
822 if the field contains a password or other secret information. By
823 default, this is @code{nil}, and the value is not secret.
825 @vindex valid-regexp@r{ keyword}
827 By default the @code{:validate} function will match the content of the
828 field with the value of this attribute. The default value is @code{""}
829 which matches everything.
831 @vindex keymap@r{ keyword}
832 @vindex widget-field-keymap
834 Keymap used in the editable field. The default value is
835 @code{widget-field-keymap}, which allows you to use all the normal
836 editing commands, even if the buffer's major mode suppresses some of
837 them. Pressing @key{RET} invokes the function specified by
841 @node text, menu-choice, editable-field, Basic Types
842 @comment node-name, next, previous, up
843 @subsection The @code{text} Widget
844 @findex text@r{ widget}
846 @vindex widget-text-keymap
847 This is just like @code{editable-field}, but intended for multiline text
848 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
849 does not rebind the @key{RET} key.
851 @node menu-choice, radio-button-choice, text, Basic Types
852 @comment node-name, next, previous, up
853 @subsection The @code{menu-choice} Widget
854 @findex menu-choice@r{ widget}
859 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
862 The @var{type} argument represents each possible choice. The widget's
863 value will be that of the chosen @var{type} argument. This widget will
864 match any value matching at least one of the specified @var{type}
868 @vindex void@r{ keyword}
870 Widget type used as a fallback when the value does not match any of the
871 specified @var{type} arguments.
873 @vindex case-fold@r{ keyword}
875 Set this to @code{nil} if you don't want to ignore case when prompting for a
876 choice through the minibuffer.
878 @vindex children@r{ keyword}
880 A list whose @sc{car} is the widget representing the currently chosen
883 @vindex choice@r{ keyword}
885 The current chosen type.
887 @vindex args@r{ keyword}
892 @node radio-button-choice, item, menu-choice, Basic Types
893 @comment node-name, next, previous, up
894 @subsection The @code{radio-button-choice} Widget
895 @findex radio-button-choice@r{ widget}
900 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
903 The @var{type} argument represents each possible choice. The widget's
904 value will be that of the chosen @var{type} argument. This widget will
905 match any value matching at least one of the specified @var{type}
908 The following extra properties are recognized.
911 @vindex entry-format@r{ keyword}
913 This string will be inserted for each entry in the list.
914 The following @samp{%} escapes are available:
917 Replace with the buffer representation of the @var{type} widget.
919 Replace with the radio button.
921 Insert a literal @samp{%}.
924 @vindex button-args@r{ keyword}
926 A list of keywords to pass to the radio buttons. Useful for setting
927 e.g.@: the @samp{:help-echo} for each button.
929 @vindex buttons@r{ keyword}
931 The widgets representing the radio buttons.
933 @vindex children@r{ keyword}
935 The widgets representing each type.
937 @vindex choice@r{ keyword}
939 The current chosen type
941 @vindex args@r{ keyword}
946 You can add extra radio button items to a @code{radio-button-choice}
947 widget after it has been created with the function
948 @code{widget-radio-add-item}.
950 @defun widget-radio-add-item widget type
951 Add to @code{radio-button-choice} widget @var{widget} a new radio button
952 item of type @var{type}.
955 Please note that such items added after the @code{radio-button-choice}
956 widget has been created will @strong{not} be properly destructed when
957 you call @code{widget-delete}.
959 @node item, choice-item, radio-button-choice, Basic Types
960 @comment node-name, next, previous, up
961 @subsection The @code{item} Widget
962 @findex item@r{ widget}
967 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
970 The @var{value}, if present, is used to initialize the @code{:value}
971 property. The value should be a string, which will be inserted in the
972 buffer. This widget will only match the specified value.
974 @node choice-item, toggle, item, Basic Types
975 @comment node-name, next, previous, up
976 @subsection The @code{choice-item} Widget
977 @findex choice-item@r{ widget}
982 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
985 The @var{value}, if present, is used to initialize the @code{:value}
986 property. The value should be a string, which will be inserted in the
987 buffer as a button. Activating the button of a @code{choice-item} is
988 equivalent to activating the parent widget. This widget will only match
991 @node toggle, checkbox, choice-item, Basic Types
992 @comment node-name, next, previous, up
993 @subsection The @code{toggle} Widget
994 @findex toggle@r{ widget}
999 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
1002 The widget has two possible states, @samp{on} and @samp{off}, which
1003 correspond to a @code{t} or @code{nil} value, respectively.
1005 The following extra properties are recognized:
1009 A string representing the @samp{on} state. By default the string
1012 A string representing the @samp{off} state. By default the string
1014 @vindex on-glyph@r{ keyword}
1016 Name of a glyph to be used instead of the @samp{:on} text string, on
1017 emacsen that supports this.
1018 @vindex off-glyph@r{ keyword}
1020 Name of a glyph to be used instead of the @samp{:off} text string, on
1021 emacsen that supports this.
1024 @node checkbox, checklist, toggle, Basic Types
1025 @comment node-name, next, previous, up
1026 @subsection The @code{checkbox} Widget
1027 @findex checkbox@r{ widget}
1029 This widget has two possible states, @samp{selected} and
1030 @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
1035 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
1038 @node checklist, editable-list, checkbox, Basic Types
1039 @comment node-name, next, previous, up
1040 @subsection The @code{checklist} Widget
1041 @findex checklist@r{ widget}
1046 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
1049 The @var{type} arguments represent each checklist item. The widget's
1050 value will be a list containing the values of all checked @var{type}
1051 arguments. The checklist widget will match a list whose elements all
1052 match at least one of the specified @var{type} arguments.
1054 The following extra properties are recognized:
1057 @vindex entry-format@r{ keyword}
1059 This string will be inserted for each entry in the list.
1060 The following @samp{%} escapes are available:
1063 Replaced with the buffer representation of the @var{type} widget.
1065 Replace with the checkbox.
1067 Insert a literal @samp{%}.
1070 @vindex greedy@r{ keyword}
1072 Usually a checklist will only match if the items are in the exact
1073 sequence given in the specification. By setting @code{:greedy} to
1074 non-@code{nil}, it will allow the items to come in any sequence.
1075 However, if you extract the value they will be in the sequence given
1076 in the checklist, i.e.@: the original sequence is forgotten.
1078 @vindex button-args@r{ keyword}
1080 A list of keywords to pass to the checkboxes. Useful for setting
1081 e.g.@: the @samp{:help-echo} for each checkbox.
1083 @vindex buttons@r{ keyword}
1085 The widgets representing the checkboxes.
1087 @vindex children@r{ keyword}
1089 The widgets representing each type.
1091 @vindex args@r{ keyword}
1096 @node editable-list, group, checklist, Basic Types
1097 @comment node-name, next, previous, up
1098 @subsection The @code{editable-list} Widget
1099 @findex editable-list@r{ widget}
1104 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
1107 The value is a list, where each member represents one widget of type
1110 The following extra properties are recognized:
1113 @vindex entry-format@r{ keyword}
1115 This string will be inserted for each entry in the list.
1116 The following @samp{%} escapes are available:
1119 This will be replaced with the buffer representation of the @var{type}
1122 Insert the @b{[INS]} button.
1124 Insert the @b{[DEL]} button.
1126 Insert a literal @samp{%}.
1129 @vindex insert-button-args@r{ keyword}
1130 @item :insert-button-args
1131 A list of keyword arguments to pass to the insert buttons.
1133 @vindex delete-button-args@r{ keyword}
1134 @item :delete-button-args
1135 A list of keyword arguments to pass to the delete buttons.
1137 @vindex append-button-args@r{ keyword}
1138 @item :append-button-args
1139 A list of keyword arguments to pass to the trailing insert button.
1141 @vindex buttons@r{ keyword}
1143 The widgets representing the insert and delete buttons.
1145 @vindex children@r{ keyword}
1147 The widgets representing the elements of the list.
1149 @vindex args@r{ keyword}
1151 List whose @sc{car} is the type of the list elements.
1154 @node group, , editable-list, Basic Types
1155 @comment node-name, next, previous, up
1156 @subsection The @code{group} Widget
1157 @findex group@r{ widget}
1159 This widget simply group other widgets together.
1164 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1167 The value is a list, with one member for each @var{type}.
1169 @node Sexp Types, Widget Properties, Basic Types, Top
1174 A number of widgets for editing @dfn{s-expressions} (Lisp types), sexp
1175 for short, are also available. These basically fall in several
1176 categories described in this section.
1185 @node constants, generic, Sexp Types, Sexp Types
1186 @comment node-name, next, previous, up
1187 @subsection The Constant Widgets
1188 @cindex constant widgets
1190 The @code{const} widget can contain any Lisp expression, but the user is
1191 prohibited from editing it, which is mainly useful as a component of one
1192 of the composite widgets.
1194 The syntax for the @code{const} widget is:
1197 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1200 The @var{value}, if present, is used to initialize the @code{:value}
1201 property and can be any s-expression.
1204 This will display any valid s-expression in an immutable part of the
1208 There are two variations of the @code{const} widget, namely
1209 @code{variable-item} and @code{function-item}. These should contain a
1210 symbol with a variable or function binding. The major difference from
1211 the @code{const} widget is that they will allow the user to see the
1212 variable or function documentation for the symbol.
1214 @deffn Widget variable-item
1215 An immutable symbol that is bound as a variable.
1218 @deffn Widget function-item
1219 An immutable symbol that is bound as a function.
1222 @node generic, atoms, constants, Sexp Types
1223 @comment node-name, next, previous, up
1224 @subsection Generic Sexp Widget
1225 @cindex generic sexp widget
1227 The @code{sexp} widget can contain any Lisp expression, and allows the
1228 user to edit it inline in the buffer.
1230 The syntax for the @code{sexp} widget is:
1233 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1237 This will allow you to edit any valid s-expression in an editable buffer
1240 The @code{sexp} widget takes the same keyword arguments as the
1241 @code{editable-field} widget. @xref{editable-field}.
1244 @node atoms, composite, generic, Sexp Types
1245 @comment node-name, next, previous, up
1246 @subsection Atomic Sexp Widgets
1247 @cindex atomic sexp widget
1249 The atoms are s-expressions that do not consist of other s-expressions.
1250 For example, a string, a file name, or a symbol are atoms, while a list
1251 is a composite type. You can edit the value of an atom with the
1254 The syntax for all the atoms are:
1257 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1260 The @var{value}, if present, is used to initialize the @code{:value}
1261 property and must be an expression of the same type as the widget.
1262 That is, the string widget can only be initialized with a string.
1264 All the atom widgets take the same keyword arguments as the
1265 @code{editable-field} widget. @xref{editable-field}.
1267 @deffn Widget string
1268 Allows you to edit a string in an editable field.
1271 @deffn Widget regexp
1272 Allows you to edit a regular expression in an editable field.
1275 @deffn Widget character
1276 Allows you to enter a character in an editable field.
1280 Allows you to edit a file name in an editable field. If you invoke
1281 the tag button, you can edit the file name in the mini-buffer with
1286 @vindex must-match@r{ keyword}
1288 If this is set to non-@code{nil}, only existing file names will be
1289 allowed in the minibuffer.
1293 @deffn Widget directory
1294 Allows you to edit a directory name in an editable field.
1295 Similar to the @code{file} widget.
1298 @deffn Widget symbol
1299 Allows you to edit a Lisp symbol in an editable field.
1302 @deffn Widget function
1303 Allows you to edit a lambda expression, or a function name with completion.
1306 @deffn Widget variable
1307 Allows you to edit a variable name, with completion.
1310 @deffn Widget integer
1311 Allows you to edit an integer in an editable field.
1314 @deffn Widget number
1315 Allows you to edit a number in an editable field.
1318 @deffn Widget boolean
1319 Allows you to edit a boolean. In Lisp this means a variable which is
1320 either @code{nil} meaning false, or non-@code{nil} meaning true.
1324 @node composite, , atoms, Sexp Types
1325 @comment node-name, next, previous, up
1326 @subsection Composite Sexp Widgets
1327 @cindex composite sexp widgets
1329 The syntax for the composite widget is:
1332 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1336 where each @var{component} must be a widget type. Each component widget
1337 will be displayed in the buffer, and will be editable by the user.
1340 The value of a @code{cons} widget is a cons-cell where the @sc{car} is
1341 the value of the first component and the @sc{cdr} is the value of the
1342 second component. There must be exactly two components.
1346 The value of a @code{list} widget is a list containing the value of
1347 each of its component.
1350 @deffn Widget vector
1351 The value of a @code{vector} widget is a vector containing the value of
1352 each of its component.
1355 The above suffice for specifying fixed size lists and vectors. To get
1356 variable length lists and vectors, you can use a @code{choice},
1357 @code{set}, or @code{repeat} widgets together with the @code{:inline}
1358 keywords. If any component of a composite widget has the @code{:inline}
1359 keyword set, its value must be a list which will then be spliced into
1360 the composite. For example, to specify a list whose first element must
1361 be a file name, and whose remaining arguments should either by the
1362 symbol @code{t} or two files, you can use the following widget
1369 :value ("foo" "bar")
1373 The value of a widget of this type will either have the form
1374 @code{(file t)} or @code{(file string string)}.
1376 This concept of inline is probably hard to understand. It was certainly
1377 hard to implement, so instead of confusing you more by trying to explain
1378 it here, I'll just suggest you meditate over it for a while.
1380 @deffn Widget choice
1381 Allows you to edit a sexp which may have one of a fixed set of types.
1382 It is currently implemented with the @code{choice-menu} basic widget,
1383 and has a similar syntax.
1387 Allows you to specify a type which must be a list whose elements all
1388 belong to given set. The elements of the list are not significant.
1389 This is implemented on top of the @code{checklist} basic widget, and has
1393 @deffn Widget repeat
1394 Allows you to specify a variable length list whose members are all of
1395 the same type. Implemented on top of the @code{editable-list} basic
1396 widget, and has a similar syntax.
1399 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1400 @comment node-name, next, previous, up
1402 @cindex properties of widgets
1403 @cindex widget properties
1405 You can examine or set the value of a widget by using the widget object
1406 that was returned by @code{widget-create}.
1408 @defun widget-value widget
1409 Return the current value contained in @var{widget}.
1410 It is an error to call this function on an uninitialized widget.
1413 @defun widget-value-set widget value
1414 Set the value contained in @var{widget} to @var{value}.
1415 It is an error to call this function with an invalid @var{value}.
1418 @strong{Important:} You @emph{must} call @code{widget-setup} after
1419 modifying the value of a widget before the user is allowed to edit the
1420 widget again. It is enough to call @code{widget-setup} once if you
1421 modify multiple widgets. This is currently only necessary if the widget
1422 contains an editing field, but may be necessary for other widgets in the
1425 If your application needs to associate some information with the widget
1426 objects, for example a reference to the item being edited, it can be
1427 done with @code{widget-put} and @code{widget-get}. The property names
1428 must begin with a @samp{:}.
1430 @defun widget-put widget property value
1431 In @var{widget} set @var{property} to @var{value}.
1432 @var{property} should be a symbol, while @var{value} can be anything.
1435 @defun widget-get widget property
1436 In @var{widget} return the value for @var{property}.
1437 @var{property} should be a symbol, the value is what was last set by
1438 @code{widget-put} for @var{property}.
1441 @defun widget-member widget property
1442 Non-@code{nil} if @var{widget} has a value (even @code{nil}) for
1443 property @var{property}.
1446 Occasionally it can be useful to know which kind of widget you have,
1447 i.e.@: the name of the widget type you gave when the widget was created.
1449 @defun widget-type widget
1450 Return the name of @var{widget}, a symbol.
1453 @cindex active widget
1454 @cindex inactive widget
1455 @cindex activate a widget
1456 @cindex deactivate a widget
1457 Widgets can be in two states: active, which means they are modifiable by
1458 the user, or inactive, which means they cannot be modified by the user.
1459 You can query or set the state with the following code:
1462 ;; Examine if @var{widget} is active or not.
1463 (if (widget-apply @var{widget} :active)
1464 (message "Widget is active.")
1465 (message "Widget is inactive.")
1467 ;; Make @var{widget} inactive.
1468 (widget-apply @var{widget} :deactivate)
1470 ;; Make @var{widget} active.
1471 (widget-apply @var{widget} :activate)
1474 A widget is inactive if it, or any of its ancestors (found by
1475 following the @code{:parent} link), have been deactivated. To make sure
1476 a widget is really active, you must therefore activate both it and
1481 (widget-apply widget :activate)
1482 (setq widget (widget-get widget :parent)))
1485 You can check if a widget has been made inactive by examining the value
1486 of the @code{:inactive} keyword. If this is non-@code{nil}, the widget itself
1487 has been deactivated. This is different from using the @code{:active}
1488 keyword, in that the latter tells you if the widget @strong{or} any of
1489 its ancestors have been deactivated. Do not attempt to set the
1490 @code{:inactive} keyword directly. Use the @code{:activate}
1491 @code{:deactivate} keywords instead.
1494 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1495 @comment node-name, next, previous, up
1496 @section Defining New Widgets
1498 @cindex defining new widgets
1500 You can define specialized widgets with @code{define-widget}. It allows
1501 you to create a shorthand for more complex widgets, including specifying
1502 component widgets and new default values for the keyword
1505 @defun define-widget name class doc &rest args
1506 Define a new widget type named @var{name} from @code{class}.
1508 @var{name} and class should both be symbols, @code{class} should be one
1509 of the existing widget types.
1511 The third argument @var{doc} is a documentation string for the widget.
1513 After the new widget has been defined, the following two calls will
1514 create identical widgets:
1519 (widget-create @var{name})
1524 (apply widget-create @var{class} @var{args})
1530 Using @code{define-widget} just stores the definition of the widget type
1531 in the @code{widget-type} property of @var{name}, which is what
1532 @code{widget-create} uses.
1534 If you only want to specify defaults for keywords with no complex
1535 conversions, you can use @code{identity} as your conversion function.
1537 The following additional keyword arguments are useful when defining new
1540 @vindex convert-widget@r{ keyword}
1541 @item :convert-widget
1542 Function to convert a widget type before creating a widget of that
1543 type. It takes a widget type as an argument, and returns the converted
1544 widget type. When a widget is created, this function is called for the
1545 widget type and all the widget's parent types, most derived first.
1547 The following predefined functions can be used here:
1549 @defun widget-types-convert-widget widget
1550 Convert @code{:args} as widget types in @var{widget}.
1553 @defun widget-value-convert-widget widget
1554 Initialize @code{:value} from @code{:args} in @var{widget}.
1557 @vindex copy@r{ keyword}
1559 Function to deep copy a widget type. It takes a shallow copy of the
1560 widget type as an argument (made by @code{copy-sequence}), and returns a
1561 deep copy. The purpose of this is to avoid having different instances
1562 of combined widgets share nested attributes.
1564 The following predefined functions can be used here:
1566 @defun widget-types-copy widget
1567 Copy @code{:args} as widget types in @var{widget}.
1570 @vindex value-to-internal@r{ keyword}
1571 @item :value-to-internal
1572 Function to convert the value to the internal format. The function
1573 takes two arguments, a widget and an external value, and returns the
1574 internal value. The function is called on the present @code{:value}
1575 when the widget is created, and on any value set later with
1576 @code{widget-value-set}.
1578 @vindex value-to-external@r{ keyword}
1579 @item :value-to-external
1580 Function to convert the value to the external format. The function
1581 takes two arguments, a widget and an internal value, and returns the
1582 external value. The function is called on the present @code{:value}
1583 when the widget is created, and on any value set later with
1584 @code{widget-value-set}.
1586 @vindex create@r{ keyword}
1588 Function to create a widget from scratch. The function takes one
1589 argument, a widget type, and creates a widget of that type, inserts it
1590 in the buffer, and returns a widget object.
1592 @vindex delete@r{ keyword}
1594 Function to delete a widget. The function takes one argument, a widget,
1595 and should remove all traces of the widget from the buffer.
1597 The default value is:
1599 @defun widget-default-delete widget
1600 Remove @var{widget} from the buffer.
1601 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1604 In most cases you should not change this value, but instead use
1605 @code{:value-delete} to make any additional cleanup.
1607 @vindex value-create@r{ keyword}
1609 Function to expand the @samp{%v} escape in the format string. It will
1610 be called with the widget as its argument and should insert a
1611 representation of the widget's value in the buffer.
1613 Nested widgets should be listed in @code{:children} or @code{:buttons}
1614 to make sure they are automatically deleted.
1616 @vindex value-delete@r{ keyword}
1618 Should remove the representation of the widget's value from the buffer.
1619 It will be called with the widget as its argument. It doesn't have to
1620 remove the text, but it should release markers and delete nested widgets
1621 if these are not listed in @code{:children} or @code{:buttons}.
1623 @vindex value-get@r{ keyword}
1625 Function to extract the value of a widget, as it is displayed in the
1628 The following predefined function can be used here:
1630 @defun widget-value-value-get widget
1631 Return the @code{:value} property of @var{widget}.
1634 @vindex format-handler@r{ keyword}
1635 @item :format-handler
1636 Function to handle unknown @samp{%} escapes in the format string. It
1637 will be called with the widget and the character that follows the
1638 @samp{%} as arguments. You can set this to allow your widget to handle
1639 non-standard escapes.
1641 @findex widget-default-format-handler
1642 You should end up calling @code{widget-default-format-handler} to handle
1643 unknown escape sequences, which will handle the @samp{%h} and any future
1644 escape sequences, as well as give an error for unknown escapes.
1646 @vindex action@r{ keyword}
1648 Function to handle user initiated events. By default, @code{:notify}
1651 The following predefined function can be used here:
1653 @defun widget-parent-action widget &optional event
1654 Tell @code{:parent} of @var{widget} to handle the @code{:action}.
1655 Optional @var{event} is the event that triggered the action.
1658 @vindex prompt-value@r{ keyword}
1660 Function to prompt for a value in the minibuffer. The function should
1661 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1662 @var{unbound} and should return a value for widget entered by the user.
1663 @var{prompt} is the prompt to use. @var{value} is the default value to
1664 use, unless @var{unbound} is non-@code{nil}, in which case there is no default
1665 value. The function should read the value using the method most natural
1666 for this widget, and does not have to check that it matches.
1669 If you want to define a new widget from scratch, use the @code{default}
1672 @deffn Widget default
1673 Widget used as a base for other widgets.
1675 It provides most of the functionality that is referred to as ``by
1676 default'' in this text.
1679 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1680 @comment node-name, next, previous, up
1681 @section Widget Browser
1682 @cindex widget browser
1684 There is a separate package to browse widgets. This is intended to help
1685 programmers who want to examine the content of a widget. The browser
1686 shows the value of each keyword, but uses links for certain keywords
1687 such as @samp{:parent}, which avoids printing cyclic structures.
1689 @deffn Command widget-browse @var{widget}
1690 Create a widget browser for @var{widget}.
1691 When called interactively, prompt for @var{widget}.
1694 @deffn Command widget-browse-other-window @var{widget}
1695 Create a widget browser for @var{widget} and show it in another window.
1696 When called interactively, prompt for @var{widget}.
1699 @deffn Command widget-browse-at @var{pos}
1700 Create a widget browser for the widget at @var{pos}.
1701 When called interactively, use the position of point.
1704 @node Widget Minor Mode, Utilities, Widget Browser, Top
1705 @comment node-name, next, previous, up
1706 @section Widget Minor Mode
1707 @cindex widget minor mode
1709 There is a minor mode for manipulating widgets in major modes that
1710 don't provide any support for widgets themselves. This is mostly
1711 intended to be useful for programmers doing experiments.
1713 @deffn Command widget-minor-mode
1714 Toggle minor mode for traversing widgets.
1715 With arg, turn widget mode on if and only if arg is positive.
1718 @defvar widget-minor-mode-keymap
1719 Keymap used in @code{widget-minor-mode}.
1722 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1723 @comment node-name, next, previous, up
1725 @cindex utility functions for widgets
1727 @defun widget-prompt-value widget prompt [ value unbound ]
1728 Prompt for a value matching @var{widget}, using @var{prompt}.
1729 The current value is assumed to be @var{value}, unless @var{unbound} is
1730 non-@code{nil}.@refill
1733 @defun widget-get-sibling widget
1734 Get the item which @var{widget} is assumed to toggle.
1735 This is only meaningful for radio buttons or checkboxes in a list.
1738 @node Widget Wishlist, Index, Utilities, Top
1739 @comment node-name, next, previous, up
1745 It should be possible to add or remove items from a list with @kbd{C-k}
1746 and @kbd{C-o} (suggested by @sc{rms}).
1749 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1750 dash (@samp{-}). The dash should be a button that, when invoked, asks
1751 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1752 the ugly buttons, the dash is my idea).
1755 The @code{menu-choice} tag should be prettier, something like the abbreviated
1759 Finish @code{:tab-order}.
1762 Make indentation work with glyphs and proportional fonts.
1765 Add commands to show overview of object and class hierarchies to the
1769 Find a way to disable mouse highlight for inactive widgets.
1772 Find a way to make glyphs look inactive.
1775 Add @code{property-list} widget.
1778 Add @code{association-list} widget.
1781 Add @code{key-binding} widget.
1784 Add @code{widget} widget for editing widget specifications.
1787 Find clean way to implement variable length list.
1788 See @code{TeX-printer-list} for an explanation.
1791 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1794 Add a @code{mailto} widget.
1797 @node Index, , Widget Wishlist, Top
1798 @comment node-name, next, previous, up
1801 This is an alphabetical listing of all concepts, functions, commands,
1802 variables, and widgets described in this manual.
1805 @setchapternewpage odd
1810 arch-tag: 2b427731-4c61-4e72-85de-5ccec9c623f0