4 @setfilename ../info/widget
5 @settitle The Emacs Widget Library
12 @node Top, Introduction, (dir), (dir)
13 @comment node-name, next, previous, up
14 @top The Emacs Widget Library
19 * Programming Example::
20 * Setting Up the Buffer::
24 * Defining New Widgets::
31 @node Introduction, User Interface, Top, Top
32 @comment node-name, next, previous, up
35 Most graphical user interface toolkits, such as Motif and XView, provide
36 a number of standard user interface controls (sometimes known as
37 `widgets' or `gadgets'). Emacs doesn't really support anything like
38 this, except for an incredible powerful text ``widget''. On the other
39 hand, Emacs does provide the necessary primitives to implement many
40 other widgets within a text buffer. The @code{widget} package
43 The basic widgets are:
47 Areas of text with an associated action. Intended for hypertext links
50 Like link, but intended for stand-alone buttons.
52 An editable text field. It can be either variable or fixed length.
54 Allows the user to choose one of multiple options from a menu, each
55 option is itself a widget. Only the selected option will be visible in
57 @item radio-button-choice
58 Allows the user to choose one of multiple options by activating radio
59 buttons. The options are implemented as widgets. All options will be
60 visible in the buffer.
62 A simple constant widget intended to be used in the @code{menu-choice} and
63 @code{radio-button-choice} widgets.
65 An button item only intended for use in choices. When invoked, the user
66 will be asked to select another option from the choice widget.
68 A simple @samp{on}/@samp{off} switch.
70 A checkbox (@samp{[ ]}/@samp{[X]}).
72 Create an editable list. The user can insert or delete items in the
73 list. Each list item is itself a widget.
76 Now of what possible use can support for widgets be in a text editor?
77 I'm glad you asked. The answer is that widgets are useful for
78 implementing forms. A @dfn{form} in emacs is a buffer where the user is
79 supposed to fill out a number of fields, each of which has a specific
80 meaning. The user is not supposed to change or delete any of the text
81 between the fields. Examples of forms in Emacs are the @file{forms}
82 package (of course), the customize buffers, the mail and news compose
83 modes, and the @sc{html} form support in the @file{w3} browser.
85 The advantages for a programmer of using the @code{widget} package to
90 More complex field than just editable text are supported.
92 You can give the user immediate feedback if he enters invalid data in a
93 text field, and sometimes prevent entering invalid data.
95 You can have fixed sized fields, thus allowing multiple field to be
98 It is simple to query or set the value of a field.
100 Editing happens in buffer, not in the mini-buffer.
102 Packages using the library get a uniform look, making them easier for
105 As support for embedded graphics improve, the widget library will
106 extended to support it. This means that your code using the widget
107 library will also use the new graphic features by automatic.
110 In order to minimize the code that is loaded by users who does not
111 create any widgets, the code has been split in two files:
115 This will declare the user variables, define the function
116 @code{widget-define}, and autoload the function @code{widget-create}.
118 Everything else is here, there is no reason to load it explicitly, as
119 it will be autoloaded when needed.
122 @node User Interface, Programming Example, Introduction, Top
123 @comment node-name, next, previous, up
124 @section User Interface
126 A form consist of read only text for documentation and some fields,
127 where each the fields contain two parts, as tag and a value. The tags
128 are used to identify the fields, so the documentation can refer to the
129 foo field, meaning the field tagged with @samp{Foo}. Here is an example
133 Here is some documentation.
135 Name: @i{My Name} @strong{Choose}: This option
136 Address: @i{Some Place
140 See also @b{_other work_} for more information.
142 Numbers: count to three below
143 @b{[INS]} @b{[DEL]} @i{One}
144 @b{[INS]} @b{[DEL]} @i{Eh, two?}
145 @b{[INS]} @b{[DEL]} @i{Five!}
160 @b{[Apply Form]} @b{[Reset Form]}
163 The top level widgets in is example are tagged @samp{Name},
164 @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers},
165 @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and
166 @samp{[Reset Form]}. There are basically two thing the user can do within
167 a form, namely editing the editable text fields and activating the
170 @subsection Editable Text Fields
172 In the example, the value for the @samp{Name} is most likely displayed
173 in an editable text field, and so are values for each of the members of
174 the @samp{Numbers} list. All the normal Emacs editing operations are
175 available for editing these fields. The only restriction is that each
176 change you make must be contained within a single editable text field.
177 For example, capitalizing all text from the middle of one field to the
178 middle of another field is prohibited.
180 Editing text fields are created by the @code{editable-field} widget.
182 The editing text fields are highlighted with the
183 @code{widget-field-face} face, making them easy to find.
185 @deffn Face widget-field-face
186 Face used for other editing fields.
191 Some portions of the buffer have an associated @dfn{action}, which can
192 be @dfn{invoked} by a standard key or mouse command. These portions
193 are called @dfn{buttons}. The default commands for activating a button
198 @deffn Command widget-button-press @var{pos} &optional @var{event}
199 Invoke the button at @var{pos}, defaulting to point.
200 If point is not located on a button, invoke the binding in
201 @code{widget-global-map} (by default the global map).
205 @deffn Command widget-button-click @var{event}
206 Invoke the button at the location of the mouse pointer. If the mouse
207 pointer is located in an editable text field, invoke the binding in
208 @code{widget-global-map} (by default the global map).
212 There are several different kind of buttons, all of which are present in
216 @item The Option Field Tags.
217 When you invoke one of these buttons, you will be asked to choose
218 between a number of different options. This is how you edit an option
219 field. Option fields are created by the @code{menu-choice} widget. In
220 the example, @samp{@b{Choose}} is an option field tag.
221 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons.
222 Activating these will insert or delete elements from a editable list.
223 The list is created by the @code{editable-list} widget.
224 @item Embedded Buttons.
225 The @samp{@b{_other work_}} is an example of an embedded
226 button. Embedded buttons are not associated with a fields, but can serve
227 any purpose, such as implementing hypertext references. They are
228 usually created by the @code{link} widget.
229 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons.
230 Activating one of these will convert it to the other. This is useful
231 for implementing multiple-choice fields. You can create it wit
232 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons.
233 Only one radio button in a @code{radio-button-choice} widget can be
234 selected at any time. When you invoke one of the unselected radio
235 buttons, it will be selected and the previous selected radio button will
237 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons.
238 These are explicit buttons made with the @code{push-button} widget. The main
239 difference from the @code{link} widget is that the buttons are will be
240 displayed as GUI buttons when possible.
244 To make them easier to locate, buttons are emphasized in the buffer.
246 @deffn Face widget-button-face
247 Face used for buttons.
250 @defopt widget-mouse-face
251 Face used for buttons when the mouse pointer is above it.
254 @subsection Navigation
256 You can use all the normal Emacs commands to move around in a form
257 buffer, plus you will have these additional commands:
261 @deffn Command widget-forward &optional count
262 Move point @var{count} buttons or editing fields forward.
265 @deffn Command widget-backward &optional count
266 Move point @var{count} buttons or editing fields backward.
270 @node Programming Example, Setting Up the Buffer, User Interface, Top
271 @comment node-name, next, previous, up
272 @section Programming Example
274 Here is the code to implement the user interface example (see @ref{User
283 (defvar widget-example-repeat)
285 (defun widget-example ()
286 "Create the widgets from the Widget manual."
288 (kill-buffer (get-buffer-create "*Widget Example*"))
289 (switch-to-buffer (get-buffer-create "*Widget Example*"))
290 (kill-all-local-variables)
291 (make-local-variable 'widget-example-repeat)
292 (widget-insert "Here is some documentation.\n\nName: ")
293 (widget-create 'editable-field
296 (widget-create 'menu-choice
299 :help-echo "Choose me, please!"
300 :notify (lambda (widget &rest ignore)
301 (message "%s is a good choice!"
302 (widget-value widget)))
303 '(item :tag "This option" :value "This")
304 '(choice-item "That option")
305 '(editable-field :menu-tag "No option" "Thus option"))
306 (widget-insert "Address: ")
307 (widget-create 'editable-field
308 "Some Place\nIn some City\nSome country.")
309 (widget-insert "\nSee also ")
311 :notify (lambda (&rest ignore)
312 (widget-value-set widget-example-repeat
316 (widget-insert " for more information.\n\nNumbers: count to three below\n")
317 (setq widget-example-repeat
318 (widget-create 'editable-list
319 :entry-format "%i %d %v"
320 :notify (lambda (widget &rest ignore)
321 (let ((old (widget-get widget
323 (new (length (widget-value widget))))
325 (widget-put widget ':example-length new)
326 (message "You can count to %d." new))))
327 :value '("One" "Eh, two?" "Five!")
328 '(editable-field :value "three")))
329 (widget-insert "\n\nSelect multiple:\n\n")
330 (widget-create 'checkbox t)
331 (widget-insert " This\n")
332 (widget-create 'checkbox nil)
333 (widget-insert " That\n")
334 (widget-create 'checkbox
335 :notify (lambda (&rest ignore) (message "Tickle"))
337 (widget-insert " Thus\n\nSelect one:\n\n")
338 (widget-create 'radio-button-choice
340 :notify (lambda (widget &rest ignore)
341 (message "You selected %s"
342 (widget-value widget)))
343 '(item "One") '(item "Another One.") '(item "A Final One."))
345 (widget-create 'push-button
346 :notify (lambda (&rest ignore)
347 (if (= (length (widget-value widget-example-repeat))
349 (message "Congratulation!")
350 (error "Three was the count!")))
353 (widget-create 'push-button
354 :notify (lambda (&rest ignore)
358 (use-local-map widget-keymap)
362 @node Setting Up the Buffer, Basic Types, Programming Example, Top
363 @comment node-name, next, previous, up
364 @section Setting Up the Buffer
366 Widgets are created with @code{widget-create}, which returns a
367 @dfn{widget} object. This object can be queried and manipulated by
368 other widget functions, until it is deleted with @code{widget-delete}.
369 After the widgets have been created, @code{widget-setup} must be called
372 @defun widget-create type [ keyword argument ]@dots{}
373 Create and return a widget of type @var{type}.
374 The syntax for the @var{type} argument is described in @ref{Basic Types}.
376 The keyword arguments can be used to overwrite the keyword arguments
377 that are part of @var{type}.
380 @defun widget-delete widget
381 Delete @var{widget} and remove it from the buffer.
385 Setup a buffer to support widgets.
387 This should be called after creating all the widgets and before allowing
388 the user to edit them.
392 If you want to insert text outside the widgets in the form, the
393 recommended way to do that is with @code{widget-insert}.
396 Insert the arguments, either strings or characters, at point.
397 The inserted text will be read only.
400 There is a standard widget keymap which you might find useful.
402 @defvr Const widget-keymap
403 A keymap with the global keymap as its parent.@*
404 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
405 @code{widget-backward}, respectively. @kbd{@key{RET}} and @kbd{mouse-2}
406 are bound to @code{widget-button-press} and
407 @code{widget-button-}.@refill
410 @defvar widget-global-map
411 Keymap used by @code{widget-button-press} and @code{widget-button-click}
412 when not on a button. By default this is @code{global-map}.
415 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
416 @comment node-name, next, previous, up
419 The syntax of a type specification is given below:
422 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
426 Where, @var{name} is a widget name, @var{keyword} is the name of a
427 property, @var{argument} is the value of the property, and @var{args}
428 are interpreted in a widget specific way.
430 There following keyword arguments that apply to all widgets:
434 The initial value for widgets of this type.
437 This string will be inserted in the buffer when you create a widget.
438 The following @samp{%} escapes are available:
443 The text inside will be marked as a button.
445 By default, the text will be shown in @code{widget-button-face}, and
446 surrounded by brackets.
448 @defopt widget-button-prefix
449 String to prefix buttons.
452 @defopt widget-button-suffix
453 String to suffix buttons.
458 The text inside will be displayed with the face specified by
462 This will be replaces with the buffer representation of the widgets
463 value. What this is depends on the widget type.
466 Insert the string specified by @code{:doc} here.
469 Like @samp{%d}, with the following modifications: If the documentation
470 string is more than one line, it will add a button which will toggle
471 between showing only the first line, and showing the full text.
472 Furthermore, if there is no @code{:doc} property in the widget, it will
473 instead examine the @code{:documentation-property} property. If it is a
474 lambda expression, it will be called with the widget's value as an
475 argument, and the result will be used as the documentation text.
478 Insert the string specified by @code{:tag} here, or the @code{princ}
479 representation of the value if there is no tag.
482 Insert a literal @samp{%}.
486 Face used to highlight text inside %[ %] in the format.
489 @itemx :button-suffix
491 Text around %[ %] in the format.
499 The string is inserted literally.
502 The value of the symbol is expanded according to this table.
506 The string inserted by the @samp{%d} escape in the format
510 The string inserted by the @samp{%t} escape in the format
514 Name of image to use instead of the string specified by `:tag' on
515 Emacsen that supports it.
518 Message displayed whenever you move to the widget with either
519 @code{widget-forward} or @code{widget-backward}.
522 An integer indicating the absolute number of spaces to indent children
526 An integer indicating how many extra spaces to add to the widget's
527 grandchildren compared to this widget.
530 An integer indicating how many extra spaces to add to the widget's
531 children compared to this widget.
534 A function called each time the widget or a nested widget is changed.
535 The function is called with two or three arguments. The first argument
536 is the widget itself, the second argument is the widget that was
537 changed, and the third argument is the event leading to the change, if
541 Tag used in the menu when the widget is used as an option in a
542 @code{menu-choice} widget.
545 Function used for finding the tag when the widget is used as an option
546 in a @code{menu-choice} widget. By default, the tag used will be either the
547 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
548 representation of the @code{:value} property if not.
551 Should be a function called with two arguments, the widget and a value,
552 and returning non-nil if the widget can represent the specified value.
555 A function which takes a widget as an argument, and return nil if the
556 widgets current value is valid for the widget. Otherwise, it should
557 return the widget containing the invalid data, and set that widgets
558 @code{:error} property to a string explaining the error.
560 The following predefined function can be used:
562 @defun widget-children-validate widget
563 All the @code{:children} of @var{widget} must be valid.
567 Specify the order in which widgets are traversed with
568 @code{widget-forward} or @code{widget-backward}. This is only partially
573 Widgets with tabbing order @code{-1} are ignored.
576 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
577 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
578 whichever comes first.
581 When on a widget with no tabbing order specified, go to the next widget
582 in the buffer with a positive tabbing order, or @code{nil}
586 The parent of a nested widget (e.g. a @code{menu-choice} item or an
587 element of a @code{editable-list} widget).
590 This keyword is only used for members of a @code{radio-button-choice} or
591 @code{checklist}. The value should be a list of extra keyword
592 arguments, which will be used when creating the @code{radio-button} or
593 @code{checkbox} associated with this item.
597 @deffn {User Option} widget-glyph-directory
598 Directory where glyphs are found.
599 Widget will look here for a file with the same name as specified for the
600 image, with either a @samp{.xpm} (if supported) or @samp{.xbm} extension.
603 @deffn{User Option} widget-glyph-enable
604 If non-nil, allow glyphs to appear on displays where they are supported.
616 * radio-button-choice::
626 @node link, url-link, Basic Types, Basic Types
627 @comment node-name, next, previous, up
628 @subsection The @code{link} Widget
633 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
636 The @var{value}, if present, is used to initialize the @code{:value}
637 property. The value should be a string, which will be inserted in the
640 By default the link will be shown in brackets.
642 @defopt widget-link-prefix
643 String to prefix links.
646 @defopt widget-link-suffix
647 String to suffix links.
650 @node url-link, info-link, link, Basic Types
651 @comment node-name, next, previous, up
652 @subsection The @code{url-link} Widget
657 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
660 When this link is invoked, the @sc{www} browser specified by
661 @code{browse-url-browser-function} will be called with @var{url}.
663 @node info-link, push-button, url-link, Basic Types
664 @comment node-name, next, previous, up
665 @subsection The @code{info-link} Widget
670 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
673 When this link is invoked, the build-in info browser is started on
676 @node push-button, editable-field, info-link, Basic Types
677 @comment node-name, next, previous, up
678 @subsection The @code{push-button} Widget
683 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
686 The @var{value}, if present, is used to initialize the @code{:value}
687 property. The value should be a string, which will be inserted in the
690 By default the tag will be shown in brackets.
692 @defopt widget-push-button-prefix
693 String to prefix push buttons.
696 @defopt widget-push-button-suffix
697 String to suffix push buttons.
700 @node editable-field, text, push-button, Basic Types
701 @comment node-name, next, previous, up
702 @subsection The @code{editable-field} Widget
707 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
710 The @var{value}, if present, is used to initialize the @code{:value}
711 property. The value should be a string, which will be inserted in
712 field. This widget will match all string values.
714 The following extra properties are recognized.
718 The width of the editable field.@*
719 By default the field will reach to the end of the line.
722 Face used for highlighting the editable field. Default is
723 @code{widget-field-face}.
726 Character used to display the value. You can set this to e.g. @code{?*}
727 if the field contains a password or other secret information. By
728 default, the value is not secret.
731 By default the @code{:validate} function will match the content of the
732 field with the value of this attribute. The default value is @code{""}
733 which matches everything.
736 Keymap used in the editable field. The default value is
737 @code{widget-field-keymap}, which allows you to use all the normal
738 editing commands, even if the buffers major mode suppress some of them.
739 Pressing return invokes the function specified by @code{:action}.
742 @node text, menu-choice, editable-field, Basic Types
743 @comment node-name, next, previous, up
744 @subsection The @code{text} Widget
746 This is just like @code{editable-field}, but intended for multiline text
747 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
748 does not rebind the return key.
750 @node menu-choice, radio-button-choice, text, Basic Types
751 @comment node-name, next, previous, up
752 @subsection The @code{menu-choice} Widget
757 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
760 The @var{type} arguments represents each possible choice. The widgets
761 value of will be the value of the chosen @var{type} argument. This
762 widget will match any value that matches at least one of the specified
763 @var{type} arguments.
767 Widget type used as a fallback when the value does not match any of the
768 specified @var{type} arguments.
771 Set this to nil if you don't want to ignore case when prompting for a
772 choice through the minibuffer.
775 A list whose car is the widget representing the currently chosen type in
779 The current chosen type
785 @node radio-button-choice, item, menu-choice, Basic Types
786 @comment node-name, next, previous, up
787 @subsection The @code{radio-button-choice} Widget
792 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
795 The @var{type} arguments represents each possible choice. The widgets
796 value of will be the value of the chosen @var{type} argument. This
797 widget will match any value that matches at least one of the specified
798 @var{type} arguments.
800 The following extra properties are recognized.
804 This string will be inserted for each entry in the list.
805 The following @samp{%} escapes are available:
808 Replaced with the buffer representation of the @var{type} widget.
810 Replace with the radio button.
812 Insert a literal @samp{%}.
816 A list of keywords to pass to the radio buttons. Useful for setting
817 e.g. the @samp{:help-echo} for each button.
820 The widgets representing the radio buttons.
823 The widgets representing each type.
826 The current chosen type
832 You can add extra radio button items to a @code{radio-button-choice}
833 widget after it has been created with the function
834 @code{widget-radio-add-item}.
836 @defun widget-radio-add-item widget type
837 Add to @code{radio-button-choice} widget @var{widget} a new radio button item of type
841 Please note that such items added after the @code{radio-button-choice}
842 widget has been created will @strong{not} be properly destructed when
843 you call @code{widget-delete}.
845 @node item, choice-item, radio-button-choice, Basic Types
846 @comment node-name, next, previous, up
847 @subsection The @code{item} Widget
852 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
855 The @var{value}, if present, is used to initialize the @code{:value}
856 property. The value should be a string, which will be inserted in the
857 buffer. This widget will only match the specified value.
859 @node choice-item, toggle, item, Basic Types
860 @comment node-name, next, previous, up
861 @subsection The @code{choice-item} Widget
866 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
869 The @var{value}, if present, is used to initialize the @code{:value}
870 property. The value should be a string, which will be inserted in the
871 buffer as a button. Activating the button of a @code{choice-item} is
872 equivalent to activating the parent widget. This widget will only match
875 @node toggle, checkbox, choice-item, Basic Types
876 @comment node-name, next, previous, up
877 @subsection The @code{toggle} Widget
882 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
885 The widget has two possible states, `on' and `off', which corresponds to
886 a @code{t} or @code{nil} value.
888 The following extra properties are recognized.
892 String representing the `on' state. By default the string @samp{on}.
894 String representing the `off' state. By default the string @samp{off}.
896 Name of a glyph to be used instead of the `:on' text string, on emacsen
899 Name of a glyph to be used instead of the `:off' text string, on emacsen
903 @node checkbox, checklist, toggle, Basic Types
904 @comment node-name, next, previous, up
905 @subsection The @code{checkbox} Widget
907 The widget has two possible states, `selected' and `unselected', which
908 corresponds to a @code{t} or @code{nil} value.
913 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
916 @node checklist, editable-list, checkbox, Basic Types
917 @comment node-name, next, previous, up
918 @subsection The @code{checklist} Widget
923 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
926 The @var{type} arguments represents each checklist item. The widgets
927 value of will be a list containing the value of each ticked @var{type}
928 argument. The checklist widget will match a list whose elements all
929 matches at least one of the specified @var{type} arguments.
931 The following extra properties are recognized.
935 This string will be inserted for each entry in the list.
936 The following @samp{%} escapes are available:
939 Replaced with the buffer representation of the @var{type} widget.
941 Replace with the checkbox.
943 Insert a literal @samp{%}.
947 Usually, a checklist will only match if the items are in the exact
948 sequence given in the specification. By setting @code{:greedy} to
949 non-nil, it will allow the items to come in any sequence. However, if
950 you extract the value they will be in the sequence given in the
951 checklist. I.e. the original sequence is forgotten.
954 A list of keywords to pass to the checkboxes. Useful for setting
955 e.g. the @samp{:help-echo} for each checkbox.
958 The widgets representing the checkboxes.
961 The widgets representing each type.
967 @node editable-list, group, checklist, Basic Types
968 @comment node-name, next, previous, up
969 @subsection The @code{editable-list} Widget
974 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
977 The value is a list, where each member represents one widget of type
980 The following extra properties are recognized.
984 This string will be inserted for each entry in the list.
985 The following @samp{%} escapes are available:
988 This will be replaced with the buffer representation of the @var{type}
991 Insert the @b{[INS]} button.
993 Insert the @b{[DEL]} button.
995 Insert a literal @samp{%}.
998 @item :insert-button-args
999 A list of keyword arguments to pass to the insert buttons.
1001 @item :delete-button-args
1002 A list of keyword arguments to pass to the delete buttons.
1004 @item :append-button-args
1005 A list of keyword arguments to pass to the trailing insert button.
1009 The widgets representing the insert and delete buttons.
1012 The widgets representing the elements of the list.
1015 List whose car is the type of the list elements.
1019 @node group, , editable-list, Basic Types
1020 @comment node-name, next, previous, up
1021 @subsection The @code{group} Widget
1023 This widget simply group other widget together.
1028 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1031 The value is a list, with one member for each @var{type}.
1033 @node Sexp Types, Widget Properties, Basic Types, Top
1037 A number of widgets for editing s-expressions (lisp types) are also
1038 available. These basically fall in the following categories.
1047 @node constants, generic, Sexp Types, Sexp Types
1048 @comment node-name, next, previous, up
1049 @subsection The Constant Widgets.
1051 The @code{const} widget can contain any lisp expression, but the user is
1052 prohibited from editing edit it, which is mainly useful as a component
1053 of one of the composite widgets.
1055 The syntax for the @code{const} widget is
1058 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1061 The @var{value}, if present, is used to initialize the @code{:value}
1062 property and can be any s-expression.
1065 This will display any valid s-expression in an immutable part of the
1069 There are two variations of the @code{const} widget, namely
1070 @code{variable-item} and @code{function-item}. These should contain a
1071 symbol with a variable or function binding. The major difference from
1072 the @code{const} widget is that they will allow the user to see the
1073 variable or function documentation for the symbol.
1075 @deffn Widget variable-item
1076 An immutable symbol that is bound as a variable.
1079 @deffn Widget function-item
1080 An immutable symbol that is bound as a function.
1083 @node generic, atoms, constants, Sexp Types
1084 @comment node-name, next, previous, up
1085 @subsection Generic Sexp Widget.
1087 The @code{sexp} widget can contain any lisp expression, and allows the
1088 user to edit it inline in the buffer.
1090 The syntax for the @code{sexp} widget is
1093 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1097 This will allow you to edit any valid s-expression in an editable buffer
1100 The @code{sexp} widget takes the same keyword arguments as the
1101 @code{editable-field} widget.
1104 @node atoms, composite, generic, Sexp Types
1105 @comment node-name, next, previous, up
1106 @subsection Atomic Sexp Widgets.
1108 The atoms are s-expressions that does not consist of other
1109 s-expressions. A string is an atom, while a list is a composite type.
1110 You can edit the value of an atom with the following widgets.
1112 The syntax for all the atoms are
1115 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1118 The @var{value}, if present, is used to initialize the @code{:value}
1119 property and must be an expression of the same type as the widget.
1120 I.e. the string widget can only be initialized with a string.
1122 All the atom widgets take the same keyword arguments as the
1123 @code{editable-field} widget.
1125 @deffn Widget string
1126 Allows you to edit a string in an editable field.
1129 @deffn Widget regexp
1130 Allows you to edit a regular expression in an editable field.
1133 @deffn Widget character
1134 Allows you to enter a character in an editable field.
1138 Allows you to edit a file name in an editable field. If you invoke
1139 the tag button, you can edit the file name in the mini-buffer with
1145 If this is set to non-nil, only existing file names will be allowed in
1150 @deffn Widget directory
1151 Allows you to edit a directory name in an editable field.
1152 Similar to the @code{file} widget.
1155 @deffn Widget symbol
1156 Allows you to edit a lisp symbol in an editable field.
1159 @deffn Widget function
1160 Allows you to edit a lambda expression, or a function name with completion.
1163 @deffn Widget variable
1164 Allows you to edit a variable name, with completion.
1167 @deffn Widget integer
1168 Allows you to edit an integer in an editable field.
1171 @deffn Widget number
1172 Allows you to edit a number in an editable field.
1175 @deffn Widget boolean
1176 Allows you to edit a boolean. In lisp this means a variable which is
1177 either nil meaning false, or non-nil meaning true.
1181 @node composite, , atoms, Sexp Types
1182 @comment node-name, next, previous, up
1183 @subsection Composite Sexp Widgets.
1185 The syntax for the composite are
1188 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1191 Where each @var{component} must be a widget type. Each component widget
1192 will be displayed in the buffer, and be editable to the user.
1195 The value of a @code{cons} widget is a cons-cell where the car is the
1196 value of the first component and the cdr is the value of the second
1197 component. There must be exactly two components.
1201 The value of a @code{list} widget is a list containing the value of
1202 each of its component.
1205 @deffn Widget vector
1206 The value of a @code{vector} widget is a vector containing the value of
1207 each of its component.
1210 The above suffice for specifying fixed size lists and vectors. To get
1211 variable length lists and vectors, you can use a @code{choice},
1212 @code{set} or @code{repeat} widgets together with the @code{:inline}
1213 keywords. If any component of a composite widget has the @code{:inline}
1214 keyword set, its value must be a list which will then be spliced into
1215 the composite. For example, to specify a list whose first element must
1216 be a file name, and whose remaining arguments should either by the
1217 symbol @code{t} or two files, you can use the following widget
1224 :value ("foo" "bar")
1228 The value of a widget of this type will either have the form
1229 @samp{(file t)} or @code{(file string string)}.
1231 This concept of inline is probably hard to understand. It was certainly
1232 hard to implement so instead of confuse you more by trying to explain it
1233 here, I'll just suggest you meditate over it for a while.
1235 @deffn Widget choice
1236 Allows you to edit a sexp which may have one of fixed set of types. It
1237 is currently implemented with the @code{choice-menu} basic widget, and
1238 has a similar syntax.
1242 Allows you to specify a type which must be a list whose elements all
1243 belong to given set. The elements of the list is not significant. This
1244 is implemented on top of the @code{checklist} basic widget, and has a
1248 @deffn Widget repeat
1249 Allows you to specify a variable length list whose members are all of
1250 the same type. Implemented on top of the `editable-list' basic widget,
1251 and has a similar syntax.
1254 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1255 @comment node-name, next, previous, up
1258 You can examine or set the value of a widget by using the widget object
1259 that was returned by @code{widget-create}.
1261 @defun widget-value widget
1262 Return the current value contained in @var{widget}.
1263 It is an error to call this function on an uninitialized widget.
1266 @defun widget-value-set widget value
1267 Set the value contained in @var{widget} to @var{value}.
1268 It is an error to call this function with an invalid @var{value}.
1271 @strong{Important:} You @emph{must} call @code{widget-setup} after
1272 modifying the value of a widget before the user is allowed to edit the
1273 widget again. It is enough to call @code{widget-setup} once if you
1274 modify multiple widgets. This is currently only necessary if the widget
1275 contains an editing field, but may be necessary for other widgets in the
1278 If your application needs to associate some information with the widget
1279 objects, for example a reference to the item being edited, it can be
1280 done with @code{widget-put} and @code{widget-get}. The property names
1281 must begin with a @samp{:}.
1283 @defun widget-put widget property value
1284 In @var{widget} set @var{property} to @var{value}.
1285 @var{property} should be a symbol, while @var{value} can be anything.
1288 @defun widget-get widget property
1289 In @var{widget} return the value for @var{property}.
1290 @var{property} should be a symbol, the value is what was last set by
1291 @code{widget-put} for @var{property}.
1294 @defun widget-member widget property
1295 Non-nil if @var{widget} has a value (even nil) for property @var{property}.
1298 Occasionally it can be useful to know which kind of widget you have,
1299 i.e. the name of the widget type you gave when the widget was created.
1301 @defun widget-type widget
1302 Return the name of @var{widget}, a symbol.
1305 Widgets can be in two states: active, which means they are modifiable by
1306 the user, or inactive, which means they cannot be modified by the user.
1307 You can query or set the state with the following code:
1310 ;; Examine if @var{widget} is active or not.
1311 (if (widget-apply @var{widget} :active)
1312 (message "Widget is active.")
1313 (message "Widget is inactive.")
1315 ;; Make @var{widget} inactive.
1316 (widget-apply @var{widget} :deactivate)
1318 ;; Make @var{widget} active.
1319 (widget-apply @var{widget} :activate)
1322 A widget is inactive if itself, or any of its ancestors (found by
1323 following the @code{:parent} link) have been deactivated. To make sure
1324 a widget is really active, you must therefore activate both itself, and
1329 (widget-apply widget :activate)
1330 (setq widget (widget-get widget :parent)))
1333 You can check if a widget has been made inactive by examining the value
1334 of @code{:inactive} keyword. If this is non-nil, the widget itself has
1335 been deactivated. This is different from using the @code{:active}
1336 keyword, in that the later tell you if the widget @strong{or} any of its
1337 ancestors have been deactivated. Do not attempt to set the
1338 @code{:inactive} keyword directly. Use the @code{:activate}
1339 @code{:deactivated} keywords instead.
1342 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1343 @comment node-name, next, previous, up
1344 @section Defining New Widgets
1346 You can define specialized widgets with @code{define-widget}. It allows
1347 you to create a shorthand for more complex widgets, including specifying
1348 component widgets and default new default values for the keyword
1351 @defun widget-define name class doc &rest args
1352 Define a new widget type named @var{name} from @code{class}.
1354 @var{name} and class should both be symbols, @code{class} should be one
1355 of the existing widget types.
1357 The third argument @var{DOC} is a documentation string for the widget.
1359 After the new widget has been defined, the following two calls will
1360 create identical widgets:
1365 (widget-create @var{name})
1370 (apply widget-create @var{class} @var{args})
1376 Using @code{widget-define} does just store the definition of the widget
1377 type in the @code{widget-type} property of @var{name}, which is what
1378 @code{widget-create} uses.
1380 If you just want to specify defaults for keywords with no complex
1381 conversions, you can use @code{identity} as your conversion function.
1383 The following additional keyword arguments are useful when defining new
1386 @item :convert-widget
1387 Function to convert a widget type before creating a widget of that
1388 type. It takes a widget type as an argument, and returns the converted
1389 widget type. When a widget is created, this function is called for the
1390 widget type and all the widgets parent types, most derived first.
1392 The following predefined functions can be used here:
1394 @defun widget-types-convert-widget widget
1395 Convert @code{:args} as widget types in @var{widget}.
1398 @defun widget-value-convert-widget widget
1399 Initialize @code{:value} from @code{:args} in @var{widget}.
1402 @item :value-to-internal
1403 Function to convert the value to the internal format. The function
1404 takes two arguments, a widget and an external value, and returns the
1405 internal value. The function is called on the present @code{:value}
1406 when the widget is created, and on any value set later with
1407 @code{widget-value-set}.
1409 @item :value-to-external
1410 Function to convert the value to the external format. The function
1411 takes two arguments, a widget and an internal value, and returns the
1412 internal value. The function is called on the present @code{:value}
1413 when the widget is created, and on any value set later with
1414 @code{widget-value-set}.
1417 Function to create a widget from scratch. The function takes one
1418 argument, a widget type, and create a widget of that type, insert it in
1419 the buffer, and return a widget object.
1422 Function to delete a widget. The function takes one argument, a widget,
1423 and should remove all traces of the widget from the buffer.
1426 Function to expand the @samp{%v} escape in the format string. It will
1427 be called with the widget as its argument. Should
1428 insert a representation of the widgets value in the buffer.
1431 Should remove the representation of the widgets value from the buffer.
1432 It will be called with the widget as its argument. It doesn't have to
1433 remove the text, but it should release markers and delete nested widgets
1434 if such has been used.
1436 The following predefined function can be used here:
1438 @defun widget-children-value-delete widget
1439 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1443 Function to extract the value of a widget, as it is displayed in the
1446 The following predefined function can be used here:
1448 @defun widget-value-value-get widget
1449 Return the @code{:value} property of @var{widget}.
1452 @item :format-handler
1453 Function to handle unknown @samp{%} escapes in the format string. It
1454 will be called with the widget and the escape character as arguments.
1455 You can set this to allow your widget to handle non-standard escapes.
1457 You should end up calling @code{widget-default-format-handler} to handle
1458 unknown escape sequences, which will handle the @samp{%h} and any future
1459 escape sequences, as well as give an error for unknown escapes.
1462 Function to handle user initiated events. By default, @code{:notify}
1465 The following predefined function can be used here:
1467 @defun widget-parent-action widget &optional event
1468 Tell @code{:parent} of @var{widget} to handle the @code{:action}.@*
1469 Optional @var{event} is the event that triggered the action.
1473 Function to prompt for a value in the minibuffer. The function should
1474 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1475 @var{unbound} and should return a value for widget entered by the user.
1476 @var{prompt} is the prompt to use. @var{value} is the default value to
1477 use, unless @var{unbound} is non-nil in which case there are no default
1478 value. The function should read the value using the method most natural
1479 for this widget, and does not have to check that it matches.
1482 If you want to define a new widget from scratch, use the @code{default}
1485 @deffn Widget default
1486 Widget used as a base for other widgets.
1488 It provides most of the functionality that is referred to as ``by
1489 default'' in this text.
1492 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1493 @comment node-name, next, previous, up
1494 @section Widget Browser
1496 There is a separate package to browse widgets. This is intended to help
1497 programmers who want to examine the content of a widget. The browser
1498 shows the value of each keyword, but uses links for certain keywords
1499 such as `:parent', which avoids printing cyclic structures.
1501 @deffn Command widget-browse WIDGET
1502 Create a widget browser for WIDGET.
1503 When called interactively, prompt for WIDGET.
1506 @deffn Command widget-browse-other-window WIDGET
1507 Create a widget browser for WIDGET and show it in another window.
1508 When called interactively, prompt for WIDGET.
1511 @deffn Command widget-browse-at POS
1512 Create a widget browser for the widget at POS.
1513 When called interactively, use the position of point.
1516 @node Widget Minor Mode, Utilities, Widget Browser, Top
1517 @comment node-name, next, previous, up
1518 @section Widget Minor Mode
1520 There is a minor mode for manipulating widgets in major modes that
1521 doesn't provide any support for widgets themselves. This is mostly
1522 intended to be useful for programmers doing experiments.
1524 @deffn Command widget-minor-mode
1525 Toggle minor mode for traversing widgets.
1526 With arg, turn widget mode on if and only if arg is positive.
1529 @defvar widget-minor-mode-keymap
1530 Keymap used in @code{widget-minor-mode}.
1533 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1534 @comment node-name, next, previous, up
1537 @defun widget-prompt-value widget prompt [ value unbound ]
1538 Prompt for a value matching @var{widget}, using @var{prompt}.@*
1539 The current value is assumed to be @var{value}, unless @var{unbound} is
1543 @defun widget-get-sibling widget
1544 Get the item @var{widget} is assumed to toggle.@*
1545 This is only meaningful for radio buttons or checkboxes in a list.
1548 @node Widget Wishlist, , Utilities, Top
1549 @comment node-name, next, previous, up
1554 It should be possible to add or remove items from a list with @kbd{C-k}
1555 and @kbd{C-o} (suggested by @sc{rms}).
1558 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1559 dash (@samp{-}). The dash should be a button that, when invoked, ask
1560 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1561 the ugly buttons, the dash is my idea).
1564 The @code{menu-choice} tag should be prettier, something like the abbreviated
1568 Finish @code{:tab-order}.
1571 Make indentation work with glyphs and proportional fonts.
1574 Add commands to show overview of object and class hierarchies to the
1578 Find a way to disable mouse highlight for inactive widgets.
1581 Find a way to make glyphs look inactive.
1584 Add @code{property-list} widget.
1587 Add @code{association-list} widget.
1590 Add @code{key-binding} widget.
1593 Add @code{widget} widget for editing widget specifications.
1596 Find clean way to implement variable length list.
1597 See @code{TeX-printer-list} for an explanation.
1600 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1606 @kbd{C-e e} in a fixed size field should go to the end of the text in
1607 the field, not the end of the field itself.
1610 Use and overlay instead of markers to delimit the widget. Create
1611 accessors for the end points.
1614 Clicking on documentation links should call @code{describe-function} or
1615 @code{widget-browse-other-window} and friends directly, instead of going
1616 through @code{apropos}. If more than one function is valid for the
1617 symbol, it should pop up a menu.