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1 | \input texinfo.tex |
2 | ||
3 | @c $Id: widget.texi,v 1.99 1997/04/06 20:34:01 abraham Exp $ | |
4 | ||
5 | @c %**start of header | |
6 | @setfilename widget | |
7 | @settitle The Emacs Widget Library | |
8 | @iftex | |
9 | @afourpaper | |
10 | @headings double | |
11 | @end iftex | |
12 | @c %**end of header | |
13 | ||
14 | @node Top, Introduction, (dir), (dir) | |
15 | @comment node-name, next, previous, up | |
16 | @top The Emacs Widget Library | |
17 | ||
18 | Version: 1.71 | |
19 | ||
20 | @menu | |
21 | * Introduction:: | |
22 | * User Interface:: | |
23 | * Programming Example:: | |
24 | * Setting Up the Buffer:: | |
25 | * Basic Types:: | |
26 | * Sexp Types:: | |
27 | * Widget Properties:: | |
28 | * Defining New Widgets:: | |
29 | * Widget Wishlist.:: | |
30 | @end menu | |
31 | ||
32 | @node Introduction, User Interface, Top, Top | |
33 | @comment node-name, next, previous, up | |
34 | @section Introduction | |
35 | ||
36 | Most graphical user interface toolkits, such as Motif and XView, provide | |
37 | a number of standard user interface controls (sometimes known as | |
38 | `widgets' or `gadgets'). Emacs doesn't really support anything like | |
39 | this, except for an incredible powerful text ``widget''. On the other | |
40 | hand, Emacs does provide the necessary primitives to implement many | |
41 | other widgets within a text buffer. The @code{widget} package | |
42 | simplifies this task. | |
43 | ||
44 | The basic widgets are: | |
45 | ||
46 | @table @code | |
47 | @item link | |
48 | Areas of text with an associated action. Intended for hypertext links | |
49 | embedded in text. | |
50 | @item push-button | |
51 | Like link, but intended for stand-alone buttons. | |
52 | @item editable-field | |
53 | An editable text field. It can be either variable or fixed length. | |
54 | @item menu-choice | |
55 | Allows the user to choose one of multiple options from a menu, each | |
56 | option is itself a widget. Only the selected option will be visible in | |
57 | the buffer. | |
58 | @item radio-button-choice | |
59 | Allows the user to choose one of multiple options by pushing radio | |
60 | buttons. The options are implemented as widgets. All options will be | |
61 | visible in the buffer. | |
62 | @item item | |
63 | A simple constant widget intended to be used in the @code{menu-choice} and | |
64 | @code{radio-button-choice} widgets. | |
65 | @item choice-item | |
66 | An button item only intended for use in choices. When pushed, the user | |
67 | will be asked to select another option from the choice widget. | |
68 | @item toggle | |
69 | A simple @samp{on}/@samp{off} switch. | |
70 | @item checkbox | |
71 | A checkbox (@samp{[ ]}/@samp{[X]}). | |
72 | @item editable-list | |
73 | Create an editable list. The user can insert or delete items in the | |
74 | list. Each list item is itself a widget. | |
75 | @end table | |
76 | ||
77 | Now of what possible use can support for widgets be in a text editor? | |
78 | I'm glad you asked. The answer is that widgets are useful for | |
79 | implementing forms. A @dfn{form} in emacs is a buffer where the user is | |
80 | supposed to fill out a number of fields, each of which has a specific | |
81 | meaning. The user is not supposed to change or delete any of the text | |
82 | between the fields. Examples of forms in Emacs are the @file{forms} | |
83 | package (of course), the customize buffers, the mail and news compose | |
84 | modes, and the @sc{html} form support in the @file{w3} browser. | |
85 | ||
86 | The advantages for a programmer of using the @code{widget} package to | |
87 | implement forms are: | |
88 | ||
89 | @enumerate | |
90 | @item | |
91 | More complex field than just editable text are supported. | |
92 | @item | |
93 | You can give the user immediate feedback if he enters invalid data in a | |
94 | text field, and sometimes prevent entering invalid data. | |
95 | @item | |
96 | You can have fixed sized fields, thus allowing multiple field to be | |
97 | lined up in columns. | |
98 | @item | |
99 | It is simple to query or set the value of a field. | |
100 | @item | |
101 | Editing happens in buffer, not in the mini-buffer. | |
102 | @item | |
103 | Packages using the library get a uniform look, making them easier for | |
104 | the user to learn. | |
105 | @item | |
106 | As support for embedded graphics improve, the widget library will | |
107 | extended to support it. This means that your code using the widget | |
108 | library will also use the new graphic features by automatic. | |
109 | @end enumerate | |
110 | ||
111 | In order to minimize the code that is loaded by users who does not | |
112 | create any widgets, the code has been split in two files: | |
113 | ||
114 | @table @file | |
115 | @item widget.el | |
116 | This will declare the user variables, define the function | |
117 | @code{widget-define}, and autoload the function @code{widget-create}. | |
118 | @item wid-edit.el | |
119 | Everything else is here, there is no reason to load it explicitly, as | |
120 | it will be autoloaded when needed. | |
121 | @end table | |
122 | ||
123 | @node User Interface, Programming Example, Introduction, Top | |
124 | @comment node-name, next, previous, up | |
125 | @section User Interface | |
126 | ||
127 | A form consist of read only text for documentation and some fields, | |
128 | where each the fields contain two parts, as tag and a value. The tags | |
129 | are used to identify the fields, so the documentation can refer to the | |
130 | foo field, meaning the field tagged with @samp{Foo}. Here is an example | |
131 | form: | |
132 | ||
133 | @example | |
134 | Here is some documentation. | |
135 | ||
136 | Name: @i{My Name} @strong{Choose}: This option | |
137 | Address: @i{Some Place | |
138 | In some City | |
139 | Some country.} | |
140 | ||
141 | See also @b{_other work_} for more information. | |
142 | ||
143 | Numbers: count to three below | |
144 | @b{[INS]} @b{[DEL]} @i{One} | |
145 | @b{[INS]} @b{[DEL]} @i{Eh, two?} | |
146 | @b{[INS]} @b{[DEL]} @i{Five!} | |
147 | @b{[INS]} | |
148 | ||
149 | Select multiple: | |
150 | ||
151 | @b{[X]} This | |
152 | @b{[ ]} That | |
153 | @b{[X]} Thus | |
154 | ||
155 | Select one: | |
156 | ||
157 | @b{(*)} One | |
158 | @b{( )} Another One. | |
159 | @b{( )} A Final One. | |
160 | ||
161 | @b{[Apply Form]} @b{[Reset Form]} | |
162 | @end example | |
163 | ||
164 | The top level widgets in is example are tagged @samp{Name}, | |
165 | @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers}, | |
166 | @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and | |
167 | @samp{[Reset Form]}. There are basically two thing the user can do within | |
168 | a form, namely editing the editable text fields and activating the | |
169 | buttons. | |
170 | ||
171 | @subsection Editable Text Fields | |
172 | ||
173 | In the example, the value for the @samp{Name} is most likely displayed | |
174 | in an editable text field, and so are values for each of the members of | |
175 | the @samp{Numbers} list. All the normal Emacs editing operations are | |
176 | available for editing these fields. The only restriction is that each | |
177 | change you make must be contained within a single editable text field. | |
178 | For example, capitalizing all text from the middle of one field to the | |
179 | middle of another field is prohibited. | |
180 | ||
181 | Editing text fields are created by the @code{editable-field} widget. | |
182 | ||
183 | The editing text fields are highlighted with the | |
184 | @code{widget-field-face} face, making them easy to find. | |
185 | ||
186 | @deffn Face widget-field-face | |
187 | Face used for other editing fields. | |
188 | @end deffn | |
189 | ||
190 | @subsection Buttons | |
191 | ||
192 | Some portions of the buffer have an associated @dfn{action}, which can | |
193 | be @dfn{activated} by a standard key or mouse command. These portions | |
194 | are called @dfn{buttons}. The default commands for activating a button | |
195 | are: | |
196 | ||
197 | @table @kbd | |
198 | @item @key{RET} | |
199 | @deffn Command widget-button-press @var{pos} &optional @var{event} | |
200 | Activate the button at @var{pos}, defaulting to point. | |
201 | If point is not located on a button, activate the binding in | |
202 | @code{widget-global-map} (by default the global map). | |
203 | @end deffn | |
204 | ||
205 | @item mouse-2 | |
206 | @deffn Command widget-button-click @var{event} | |
207 | Activate the button at the location of the mouse pointer. If the mouse | |
208 | pointer is located in an editable text field, activate the binding in | |
209 | @code{widget-global-map} (by default the global map). | |
210 | @end deffn | |
211 | @end table | |
212 | ||
213 | There are several different kind of buttons, all of which are present in | |
214 | the example: | |
215 | ||
216 | @table @emph | |
217 | @item The Option Field Tags. | |
218 | When you activate one of these buttons, you will be asked to choose | |
219 | between a number of different options. This is how you edit an option | |
220 | field. Option fields are created by the @code{menu-choice} widget. In | |
221 | the example, @samp{@b{Choose}} is an option field tag. | |
222 | @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons. | |
223 | Activating these will insert or delete elements from a editable list. | |
224 | The list is created by the @code{editable-list} widget. | |
225 | @item Embedded Buttons. | |
226 | The @samp{@b{_other work_}} is an example of an embedded | |
227 | button. Embedded buttons are not associated with a fields, but can serve | |
228 | any purpose, such as implementing hypertext references. They are | |
229 | usually created by the @code{link} widget. | |
230 | @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons. | |
231 | Activating one of these will convert it to the other. This is useful | |
232 | for implementing multiple-choice fields. You can create it wit | |
233 | @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons. | |
234 | Only one radio button in a @code{radio-button-choice} widget can be selected at any | |
235 | time. When you push one of the unselected radio buttons, it will be | |
236 | selected and the previous selected radio button will become unselected. | |
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. | |
241 | enough. | |
242 | @end table | |
243 | ||
244 | To make them easier to locate, buttons are emphasized in the buffer. | |
245 | ||
246 | @deffn Face widget-button-face | |
247 | Face used for buttons. | |
248 | @end deffn | |
249 | ||
250 | @defopt widget-mouse-face | |
251 | Face used for buttons when the mouse pointer is above it. | |
252 | @end defopt | |
253 | ||
254 | @subsection Navigation | |
255 | ||
256 | You can use all the normal Emacs commands to move around in a form | |
257 | buffer, plus you will have these additional commands: | |
258 | ||
259 | @table @kbd | |
260 | @item @key{TAB} | |
261 | @deffn Command widget-forward &optional count | |
262 | Move point @var{count} buttons or editing fields forward. | |
263 | @end deffn | |
264 | @item @key{M-TAB} | |
265 | @deffn Command widget-backward &optional count | |
266 | Move point @var{count} buttons or editing fields backward. | |
267 | @end deffn | |
268 | @end table | |
269 | ||
270 | @node Programming Example, Setting Up the Buffer, User Interface, Top | |
271 | @comment node-name, next, previous, up | |
272 | @section Programming Example | |
273 | ||
274 | Here is the code to implement the user interface example (see @ref{User | |
275 | Interface}). | |
276 | ||
277 | @lisp | |
278 | (require 'widget) | |
279 | ||
280 | (eval-when-compile | |
281 | (require 'wid-edit)) | |
282 | ||
283 | (defvar widget-example-repeat) | |
284 | ||
285 | (defun widget-example () | |
286 | "Create the widgets from the Widget manual." | |
287 | (interactive) | |
288 | (switch-to-buffer "*Widget Example*") | |
289 | (kill-all-local-variables) | |
290 | (make-local-variable 'widget-example-repeat) | |
291 | (let ((inhibit-read-only t)) | |
292 | (erase-buffer)) | |
293 | (widget-insert "Here is some documentation.\n\nName: ") | |
294 | (widget-create 'editable-field | |
295 | :size 13 | |
296 | "My Name") | |
297 | (widget-create 'menu-choice | |
298 | :tag "Choose" | |
299 | :value "This" | |
300 | :help-echo "Choose me, please!" | |
301 | :notify (lambda (widget &rest ignore) | |
302 | (message "%s is a good choice!" | |
303 | (widget-value widget))) | |
304 | '(item :tag "This option" :value "This") | |
305 | '(choice-item "That option") | |
306 | '(editable-field :menu-tag "No option" "Thus option")) | |
307 | (widget-insert "Address: ") | |
308 | (widget-create 'editable-field | |
309 | "Some Place\nIn some City\nSome country.") | |
310 | (widget-insert "\nSee also ") | |
311 | (widget-create 'link | |
312 | :notify (lambda (&rest ignore) | |
313 | (widget-value-set widget-example-repeat | |
314 | '("En" "To" "Tre")) | |
315 | (widget-setup)) | |
316 | "other work") | |
317 | (widget-insert " for more information.\n\nNumbers: count to three below\n") | |
318 | (setq widget-example-repeat | |
319 | (widget-create 'editable-list | |
320 | :entry-format "%i %d %v" | |
321 | :notify (lambda (widget &rest ignore) | |
322 | (let ((old (widget-get widget | |
323 | ':example-length)) | |
324 | (new (length (widget-value widget)))) | |
325 | (unless (eq old new) | |
326 | (widget-put widget ':example-length new) | |
327 | (message "You can count to %d." new)))) | |
328 | :value '("One" "Eh, two?" "Five!") | |
329 | '(editable-field :value "three"))) | |
330 | (widget-insert "\n\nSelect multiple:\n\n") | |
331 | (widget-create 'checkbox t) | |
332 | (widget-insert " This\n") | |
333 | (widget-create 'checkbox nil) | |
334 | (widget-insert " That\n") | |
335 | (widget-create 'checkbox | |
336 | :notify (lambda (&rest ignore) (message "Tickle")) | |
337 | t) | |
338 | (widget-insert " Thus\n\nSelect one:\n\n") | |
339 | (widget-create 'radio-button-choice | |
340 | :value "One" | |
341 | :notify (lambda (widget &rest ignore) | |
342 | (message "You selected %s" | |
343 | (widget-value widget))) | |
344 | '(item "One") '(item "Anthor One.") '(item "A Final One.")) | |
345 | (widget-insert "\n") | |
346 | (widget-create 'push-button | |
347 | :notify (lambda (&rest ignore) | |
348 | (if (= (length (widget-value widget-example-repeat)) | |
349 | 3) | |
350 | (message "Congratulation!") | |
351 | (error "Three was the count!"))) | |
352 | "Apply Form") | |
353 | (widget-insert " ") | |
354 | (widget-create 'push-button | |
355 | :notify (lambda (&rest ignore) | |
356 | (widget-example)) | |
357 | "Reset Form") | |
358 | (widget-insert "\n") | |
359 | (use-local-map widget-keymap) | |
360 | (widget-setup)) | |
361 | @end lisp | |
362 | ||
363 | @node Setting Up the Buffer, Basic Types, Programming Example, Top | |
364 | @comment node-name, next, previous, up | |
365 | @section Setting Up the Buffer | |
366 | ||
367 | Widgets are created with @code{widget-create}, which returns a | |
368 | @dfn{widget} object. This object can be queried and manipulated by | |
369 | other widget functions, until it is deleted with @code{widget-delete}. | |
370 | After the widgets have been created, @code{widget-setup} must be called | |
371 | to enable them. | |
372 | ||
373 | @defun widget-create type [ keyword argument ]@dots{} | |
374 | Create and return a widget of type @var{type}. | |
375 | The syntax for the @var{type} argument is described in @ref{Basic Types}. | |
376 | ||
377 | The keyword arguments can be used to overwrite the keyword arguments | |
378 | that are part of @var{type}. | |
379 | @end defun | |
380 | ||
381 | @defun widget-delete widget | |
382 | Delete @var{widget} and remove it from the buffer. | |
383 | @end defun | |
384 | ||
385 | @defun widget-setup | |
386 | Setup a buffer to support widgets. | |
387 | ||
388 | This should be called after creating all the widgets and before allowing | |
389 | the user to edit them. | |
390 | @refill | |
391 | @end defun | |
392 | ||
393 | If you want to insert text outside the widgets in the form, the | |
394 | recommended way to do that is with @code{widget-insert}. | |
395 | ||
396 | @defun widget-insert | |
397 | Insert the arguments, either strings or characters, at point. | |
398 | The inserted text will be read only. | |
399 | @end defun | |
400 | ||
401 | There is a standard widget keymap which you might find useful. | |
402 | ||
403 | @defvr Const widget-keymap | |
404 | A keymap with the global keymap as its parent.@* | |
405 | @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and | |
406 | @code{widget-backward}, respectively. @kbd{@key{RET}} and @kbd{mouse-2} | |
407 | are bound to @code{widget-button-press} and | |
408 | @code{widget-button-}.@refill | |
409 | @end defvr | |
410 | ||
411 | @defvar widget-global-map | |
412 | Keymap used by @code{widget-button-press} and @code{widget-button-click} | |
413 | when not on a button. By default this is @code{global-map}. | |
414 | @end defvar | |
415 | ||
416 | @node Basic Types, Sexp Types, Setting Up the Buffer, Top | |
417 | @comment node-name, next, previous, up | |
418 | @section Basic Types | |
419 | ||
420 | The syntax of a type specification is given below: | |
421 | ||
422 | @example | |
423 | NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS) | |
424 | | NAME | |
425 | @end example | |
426 | ||
427 | Where, @var{name} is a widget name, @var{keyword} is the name of a | |
428 | property, @var{argument} is the value of the property, and @var{args} | |
429 | are interpreted in a widget specific way. | |
430 | ||
431 | There following keyword arguments that apply to all widgets: | |
432 | ||
433 | @table @code | |
434 | @item :value | |
435 | The initial value for widgets of this type. | |
436 | ||
437 | @item :format | |
438 | This string will be inserted in the buffer when you create a widget. | |
439 | The following @samp{%} escapes are available: | |
440 | ||
441 | @table @samp | |
442 | @item %[ | |
443 | @itemx %] | |
444 | The text inside will be marked as a button. | |
445 | ||
446 | @item %@{ | |
447 | @itemx %@} | |
448 | The text inside will be displayed with the face specified by | |
449 | @code{:sample-face}. | |
450 | ||
451 | @item %v | |
452 | This will be replaces with the buffer representation of the widgets | |
453 | value. What this is depends on the widget type. | |
454 | ||
455 | @item %d | |
456 | Insert the string specified by @code{:doc} here. | |
457 | ||
458 | @item %h | |
459 | Like @samp{%d}, with the following modifications: If the documentation | |
460 | string is more than one line, it will add a button which will toggle | |
461 | between showing only the first line, and showing the full text. | |
462 | Furthermore, if there is no @code{:doc} property in the widget, it will | |
463 | instead examine the @code{:documentation-property} property. If it is a | |
464 | lambda expression, it will be called with the widget's value as an | |
465 | argument, and the result will be used as the documentation text. | |
466 | ||
467 | @item %t | |
468 | Insert the string specified by @code{:tag} here, or the @code{princ} | |
469 | representation of the value if there is no tag. | |
470 | ||
471 | @item %% | |
472 | Insert a literal @samp{%}. | |
473 | @end table | |
474 | ||
475 | @item :button-face | |
476 | Face used to highlight text inside %[ %] in the format. | |
477 | ||
478 | @item :doc | |
479 | The string inserted by the @samp{%d} escape in the format | |
480 | string. | |
481 | ||
482 | @item :tag | |
483 | The string inserted by the @samp{%t} escape in the format | |
484 | string. | |
485 | ||
486 | @item :tag-glyph | |
487 | Name of image to use instead of the string specified by `:tag' on | |
488 | Emacsen that supports it. | |
489 | ||
490 | @item :help-echo | |
491 | Message displayed whenever you move to the widget with either | |
492 | @code{widget-forward} or @code{widget-backward}. | |
493 | ||
494 | @item :indent | |
495 | An integer indicating the absolute number of spaces to indent children | |
496 | of this widget. | |
497 | ||
498 | @item :offset | |
499 | An integer indicating how many extra spaces to add to the widget's | |
500 | grandchildren compared to this widget. | |
501 | ||
502 | @item :extra-offset | |
503 | An integer indicating how many extra spaces to add to the widget's | |
504 | children compared to this widget. | |
505 | ||
506 | @item :notify | |
507 | A function called each time the widget or a nested widget is changed. | |
508 | The function is called with two or three arguments. The first argument | |
509 | is the widget itself, the second argument is the widget that was | |
510 | changed, and the third argument is the event leading to the change, if | |
511 | any. | |
512 | ||
513 | @item :menu-tag | |
514 | Tag used in the menu when the widget is used as an option in a | |
515 | @code{menu-choice} widget. | |
516 | ||
517 | @item :menu-tag-get | |
518 | Function used for finding the tag when the widget is used as an option | |
519 | in a @code{menu-choice} widget. By default, the tag used will be either the | |
520 | @code{:menu-tag} or @code{:tag} property if present, or the @code{princ} | |
521 | representation of the @code{:value} property if not. | |
522 | ||
523 | @item :match | |
524 | Should be a function called with two arguments, the widget and a value, | |
525 | and returning non-nil if the widget can represent the specified value. | |
526 | ||
527 | @item :validate | |
528 | A function which takes a widget as an argument, and return nil if the | |
529 | widgets current value is valid for the widget. Otherwise, it should | |
530 | return the widget containing the invalid data, and set that widgets | |
531 | @code{:error} property to a string explaining the error. | |
532 | ||
533 | @item :tab-order | |
534 | Specify the order in which widgets are traversed with | |
535 | @code{widget-forward} or @code{widget-backward}. This is only partially | |
536 | implemented. | |
537 | ||
538 | @enumerate a | |
539 | @item | |
540 | Widgets with tabbing order @code{-1} are ignored. | |
541 | ||
542 | @item | |
543 | (Unimplemented) When on a widget with tabbing order @var{n}, go to the | |
544 | next widget in the buffer with tabbing order @var{n+1} or @code{nil}, | |
545 | whichever comes first. | |
546 | ||
547 | @item | |
548 | When on a widget with no tabbing order specified, go to the next widget | |
549 | in the buffer with a positive tabbing order, or @code{nil} | |
550 | @end enumerate | |
551 | ||
552 | @item :parent | |
553 | The parent of a nested widget (e.g. a @code{menu-choice} item or an | |
554 | element of a @code{editable-list} widget). | |
555 | ||
556 | @item :sibling-args | |
557 | This keyword is only used for members of a @code{radio-button-choice} or | |
558 | @code{checklist}. The value should be a list of extra keyword | |
559 | arguments, which will be used when creating the @code{radio-button} or | |
560 | @code{checkbox} associated with this item. | |
561 | ||
562 | @end table | |
563 | ||
564 | @deffn {User Option} widget-glyph-directory | |
565 | Directory where glyphs are found. | |
566 | Widget will look here for a file with the same name as specified for the | |
567 | image, with either a @samp{.xpm} (if supported) or @samp{.xbm} extension. | |
568 | @end deffn | |
569 | ||
570 | @deffn{User Option} widget-glyph-enable | |
571 | If non-nil, allow glyphs to appear on displayes where they are supported. | |
572 | @end deffn | |
573 | ||
574 | ||
575 | @menu | |
576 | * link:: | |
577 | * url-link:: | |
578 | * info-link:: | |
579 | * push-button:: | |
580 | * editable-field:: | |
581 | * text:: | |
582 | * menu-choice:: | |
583 | * radio-button-choice:: | |
584 | * item:: | |
585 | * choice-item:: | |
586 | * toggle:: | |
587 | * checkbox:: | |
588 | * checklist:: | |
589 | * editable-list:: | |
590 | @end menu | |
591 | ||
592 | @node link, url-link, Basic Types, Basic Types | |
593 | @comment node-name, next, previous, up | |
594 | @subsection The @code{link} Widget | |
595 | ||
596 | Syntax: | |
597 | ||
598 | @example | |
599 | TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ]) | |
600 | @end example | |
601 | ||
602 | The @var{value}, if present, is used to initialize the @code{:value} | |
603 | property. The value should be a string, which will be inserted in the | |
604 | buffer. | |
605 | ||
606 | @node url-link, info-link, link, Basic Types | |
607 | @comment node-name, next, previous, up | |
608 | @subsection The @code{url-link} Widget | |
609 | ||
610 | Syntax: | |
611 | ||
612 | @example | |
613 | TYPE ::= (url-link [KEYWORD ARGUMENT]... URL) | |
614 | @end example | |
615 | ||
616 | When this link is activated, the @sc{www} browser specified by | |
617 | @code{browse-url-browser-function} will be called with @var{url}. | |
618 | ||
619 | @node info-link, push-button, url-link, Basic Types | |
620 | @comment node-name, next, previous, up | |
621 | @subsection The @code{info-link} Widget | |
622 | ||
623 | Syntax: | |
624 | ||
625 | @example | |
626 | TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS) | |
627 | @end example | |
628 | ||
629 | When this link is activated, the build-in info browser is started on | |
630 | @var{address}. | |
631 | ||
632 | @node push-button, editable-field, info-link, Basic Types | |
633 | @comment node-name, next, previous, up | |
634 | @subsection The @code{push-button} Widget | |
635 | ||
636 | Syntax: | |
637 | ||
638 | @example | |
639 | TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ]) | |
640 | @end example | |
641 | ||
642 | The @var{value}, if present, is used to initialize the @code{:value} | |
643 | property. The value should be a string, which will be inserted in the | |
644 | buffer. | |
645 | ||
646 | @node editable-field, text, push-button, Basic Types | |
647 | @comment node-name, next, previous, up | |
648 | @subsection The @code{editable-field} Widget | |
649 | ||
650 | Syntax: | |
651 | ||
652 | @example | |
653 | TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ]) | |
654 | @end example | |
655 | ||
656 | The @var{value}, if present, is used to initialize the @code{:value} | |
657 | property. The value should be a string, which will be inserted in | |
658 | field. This widget will match all string values. | |
659 | ||
660 | The following extra properties are recognized. | |
661 | ||
662 | @table @code | |
663 | @item :size | |
664 | The width of the editable field.@* | |
665 | By default the field will reach to the end of the line. | |
666 | ||
667 | @item :value-face | |
668 | Face used for highlighting the editable field. Default is | |
669 | @code{widget-field-face}. | |
670 | ||
671 | @item :secret | |
672 | Character used to display the value. You can set this to e.g. @code{?*} | |
673 | if the field contains a password or other secret information. By | |
674 | default, the value is not secret. | |
675 | ||
676 | @item :valid-regexp | |
677 | By default the @code{:validate} function will match the content of the | |
678 | field with the value of this attribute. The default value is @code{""} | |
679 | which matches everything. | |
680 | ||
681 | @item :keymap | |
682 | Keymap used in the editable field. The default value is | |
683 | @code{widget-field-keymap}, which allows you to use all the normal | |
684 | editing commands, even if the buffers major mode supress some of them. | |
685 | Pressing return activates the function specified by @code{:activate}. | |
686 | ||
687 | @item :hide-front-space | |
688 | @itemx :hide-rear-space | |
689 | In order to keep track of the editable field, emacs places an invisible | |
690 | space character in front of the field, and for fixed sized fields also | |
691 | in the rear end of the field. For fields that extent to the end of the | |
692 | line, the terminating linefeed serves that purpose instead. | |
693 | ||
694 | Emacs will try to make the spaces intangible when it is safe to do so. | |
695 | Intangible means that the cursor motion commands will skip over the | |
696 | character as if it didn't exist. This is safe to do when the text | |
697 | preceding or following the widget cannot possible change during the | |
698 | lifetime of the @code{editable-field} widget. The preferred way to tell | |
699 | Emacs this, is to add text to the @code{:format} property around the | |
700 | value. For example @code{:format "Tag: %v "}. | |
701 | ||
702 | You can overwrite the internal safety check by setting the | |
703 | @code{:hide-front-space} or @code{:hide-rear-space} properties to | |
704 | non-nil. This is not recommended. For example, @emph{all} text that | |
705 | belongs to a widget (i.e. is created from its @code{:format} string) will | |
706 | change whenever the widget changes its value. | |
707 | ||
708 | @end table | |
709 | ||
710 | @node text, menu-choice, editable-field, Basic Types | |
711 | @comment node-name, next, previous, up | |
712 | @subsection The @code{text} Widget | |
713 | ||
714 | This is just like @code{editable-field}, but intended for multiline text | |
715 | fields. The default @code{:keymap} is @code{widget-text-keymap}, which | |
716 | does not rebind the return key. | |
717 | ||
718 | @node menu-choice, radio-button-choice, text, Basic Types | |
719 | @comment node-name, next, previous, up | |
720 | @subsection The @code{menu-choice} Widget | |
721 | ||
722 | Syntax: | |
723 | ||
724 | @example | |
725 | TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... ) | |
726 | @end example | |
727 | ||
728 | The @var{type} arguments represents each possible choice. The widgets | |
729 | value of will be the value of the chosen @var{type} argument. This | |
730 | widget will match any value that matches at least one of the specified | |
731 | @var{type} arguments. | |
732 | ||
733 | @table @code | |
734 | @item :void | |
735 | Widget type used as a fallback when the value does not match any of the | |
736 | specified @var{type} arguments. | |
737 | ||
738 | @item :case-fold | |
739 | Set this to nil if you don't want to ignore case when prompting for a | |
740 | choice through the minibuffer. | |
741 | ||
742 | @item :children | |
743 | A list whose car is the widget representing the currently chosen type in | |
744 | the buffer. | |
745 | ||
746 | @item :choice | |
747 | The current chosen type | |
748 | ||
749 | @item :args | |
750 | The list of types. | |
751 | @end table | |
752 | ||
753 | @node radio-button-choice, item, menu-choice, Basic Types | |
754 | @comment node-name, next, previous, up | |
755 | @subsection The @code{radio-button-choice} Widget | |
756 | ||
757 | Syntax: | |
758 | ||
759 | @example | |
760 | TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... ) | |
761 | @end example | |
762 | ||
763 | The @var{type} arguments represents each possible choice. The widgets | |
764 | value of will be the value of the chosen @var{type} argument. This | |
765 | widget will match any value that matches at least one of the specified | |
766 | @var{type} arguments. | |
767 | ||
768 | The following extra properties are recognized. | |
769 | ||
770 | @table @code | |
771 | @item :entry-format | |
772 | This string will be inserted for each entry in the list. | |
773 | The following @samp{%} escapes are available: | |
774 | @table @samp | |
775 | @item %v | |
776 | Replaced with the buffer representation of the @var{type} widget. | |
777 | @item %b | |
778 | Replace with the radio button. | |
779 | @item %% | |
780 | Insert a literal @samp{%}. | |
781 | @end table | |
782 | ||
783 | @item button-args | |
784 | A list of keywords to pass to the radio buttons. Useful for setting | |
785 | e.g. the @samp{:help-echo} for each button. | |
786 | ||
787 | @item :buttons | |
788 | The widgets representing the radio buttons. | |
789 | ||
790 | @item :children | |
791 | The widgets representing each type. | |
792 | ||
793 | @item :choice | |
794 | The current chosen type | |
795 | ||
796 | @item :args | |
797 | The list of types. | |
798 | @end table | |
799 | ||
800 | You can add extra radio button items to a @code{radio-button-choice} | |
801 | widget after it has been created with the function | |
802 | @code{widget-radio-add-item}. | |
803 | ||
804 | @defun widget-radio-add-item widget type | |
805 | Add to @code{radio-button-choice} widget @var{widget} a new radio button item of type | |
806 | @var{type}. | |
807 | @end defun | |
808 | ||
809 | Please note that such items added after the @code{radio-button-choice} | |
810 | widget has been created will @strong{not} be properly destructed when | |
811 | you call @code{widget-delete}. | |
812 | ||
813 | @node item, choice-item, radio-button-choice, Basic Types | |
814 | @comment node-name, next, previous, up | |
815 | @subsection The @code{item} Widget | |
816 | ||
817 | Syntax: | |
818 | ||
819 | @example | |
820 | ITEM ::= (item [KEYWORD ARGUMENT]... VALUE) | |
821 | @end example | |
822 | ||
823 | The @var{value}, if present, is used to initialize the @code{:value} | |
824 | property. The value should be a string, which will be inserted in the | |
825 | buffer. This widget will only match the specified value. | |
826 | ||
827 | @node choice-item, toggle, item, Basic Types | |
828 | @comment node-name, next, previous, up | |
829 | @subsection The @code{choice-item} Widget | |
830 | ||
831 | Syntax: | |
832 | ||
833 | @example | |
834 | ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE) | |
835 | @end example | |
836 | ||
837 | The @var{value}, if present, is used to initialize the @code{:value} | |
838 | property. The value should be a string, which will be inserted in the | |
839 | buffer as a button. Activating the button of a @code{choice-item} is | |
840 | equivalent to activating the parent widget. This widget will only match | |
841 | the specified value. | |
842 | ||
843 | @node toggle, checkbox, choice-item, Basic Types | |
844 | @comment node-name, next, previous, up | |
845 | @subsection The @code{toggle} Widget | |
846 | ||
847 | Syntax: | |
848 | ||
849 | @example | |
850 | TYPE ::= (toggle [KEYWORD ARGUMENT]...) | |
851 | @end example | |
852 | ||
853 | The widget has two possible states, `on' and `off', which corresponds to | |
854 | a @code{t} or @code{nil} value. | |
855 | ||
856 | The following extra properties are recognized. | |
857 | ||
858 | @table @code | |
859 | @item :on | |
860 | String representing the `on' state. By default the string @samp{on}. | |
861 | @item :off | |
862 | String representing the `off' state. By default the string @samp{off}. | |
863 | @item :on-glyph | |
864 | Name of a glyph to be used instead of the `:on' text string, on emacsen | |
865 | that supports it. | |
866 | @item :off-glyph | |
867 | Name of a glyph to be used instead of the `:off' text string, on emacsen | |
868 | that supports it. | |
869 | @end table | |
870 | ||
871 | @node checkbox, checklist, toggle, Basic Types | |
872 | @comment node-name, next, previous, up | |
873 | @subsection The @code{checkbox} Widget | |
874 | ||
875 | The widget has two possible states, `selected' and `unselected', which | |
876 | corresponds to a @code{t} or @code{nil} value. | |
877 | ||
878 | Syntax: | |
879 | ||
880 | @example | |
881 | TYPE ::= (checkbox [KEYWORD ARGUMENT]...) | |
882 | @end example | |
883 | ||
884 | @node checklist, editable-list, checkbox, Basic Types | |
885 | @comment node-name, next, previous, up | |
886 | @subsection The @code{checklist} Widget | |
887 | ||
888 | Syntax: | |
889 | ||
890 | @example | |
891 | TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... ) | |
892 | @end example | |
893 | ||
894 | The @var{type} arguments represents each checklist item. The widgets | |
895 | value of will be a list containing the value of each ticked @var{type} | |
896 | argument. The checklist widget will match a list whose elements all | |
897 | matches at least one of the specified @var{type} arguments. | |
898 | ||
899 | The following extra properties are recognized. | |
900 | ||
901 | @table @code | |
902 | @item :entry-format | |
903 | This string will be inserted for each entry in the list. | |
904 | The following @samp{%} escapes are available: | |
905 | @table @samp | |
906 | @item %v | |
907 | Replaced with the buffer representation of the @var{type} widget. | |
908 | @item %b | |
909 | Replace with the checkbox. | |
910 | @item %% | |
911 | Insert a literal @samp{%}. | |
912 | @end table | |
913 | ||
914 | @item button-args | |
915 | A list of keywords to pass to the checkboxes. Useful for setting | |
916 | e.g. the @samp{:help-echo} for each checkbox. | |
917 | ||
918 | @item :buttons | |
919 | The widgets representing the checkboxes. | |
920 | ||
921 | @item :children | |
922 | The widgets representing each type. | |
923 | ||
924 | @item :args | |
925 | The list of types. | |
926 | @end table | |
927 | ||
928 | @node editable-list, , checklist, Basic Types | |
929 | @comment node-name, next, previous, up | |
930 | @subsection The @code{editable-list} Widget | |
931 | ||
932 | Syntax: | |
933 | ||
934 | @example | |
935 | TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE) | |
936 | @end example | |
937 | ||
938 | The value is a list, where each member represent one widget of type | |
939 | @var{type}. | |
940 | ||
941 | The following extra properties are recognized. | |
942 | ||
943 | @table @code | |
944 | @item :entry-format | |
945 | This string will be inserted for each entry in the list. | |
946 | The following @samp{%} escapes are available: | |
947 | @table @samp | |
948 | @item %v | |
949 | This will be replaced with the buffer representation of the @var{type} | |
950 | widget. | |
951 | @item %i | |
952 | Insert the @b{[INS]} button. | |
953 | @item %d | |
954 | Insert the @b{[DEL]} button. | |
955 | @item %% | |
956 | Insert a literal @samp{%}. | |
957 | @end table | |
958 | ||
959 | @item :insert-button-args | |
960 | A list of keyword arguments to pass to the insert buttons. | |
961 | ||
962 | @item :delete-button-args | |
963 | A list of keyword arguments to pass to the delete buttons. | |
964 | ||
965 | @item :append-button-args | |
966 | A list of keyword arguments to pass to the trailing insert button. | |
967 | ||
968 | ||
969 | @item :buttons | |
970 | The widgets representing the insert and delete buttons. | |
971 | ||
972 | @item :children | |
973 | The widgets representing the elements of the list. | |
974 | ||
975 | @item :args | |
976 | List whose car is the type of the list elements. | |
977 | ||
978 | @end table | |
979 | ||
980 | @node Sexp Types, Widget Properties, Basic Types, Top | |
981 | @comment | |
982 | @section Sexp Types | |
983 | ||
984 | A number of widgets for editing s-expressions (lisp types) are also | |
985 | available. These basically fall in three categories: @dfn{atoms}, | |
986 | @dfn{composite types}, and @dfn{generic}. | |
987 | ||
988 | @menu | |
989 | * generic:: | |
990 | * atoms:: | |
991 | * composite:: | |
992 | @end menu | |
993 | ||
994 | @node generic, atoms, Sexp Types, Sexp Types | |
995 | @comment node-name, next, previous, up | |
996 | @subsection The Generic Widget. | |
997 | ||
998 | The @code{const} and @code{sexp} widgets can contain any lisp | |
999 | expression. In the case of the @code{const} widget the user is | |
1000 | prohibited from editing edit it, which is mainly useful as a component | |
1001 | of one of the composite widgets. | |
1002 | ||
1003 | The syntax for the generic widgets is | |
1004 | ||
1005 | @example | |
1006 | TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ]) | |
1007 | @end example | |
1008 | ||
1009 | The @var{value}, if present, is used to initialize the @code{:value} | |
1010 | property and can be any s-expression. | |
1011 | ||
1012 | @deffn Widget const | |
1013 | This will display any valid s-expression in an immutable part of the | |
1014 | buffer. | |
1015 | @end deffn | |
1016 | ||
1017 | @deffn Widget sexp | |
1018 | This will allow you to edit any valid s-expression in an editable buffer | |
1019 | field. | |
1020 | ||
1021 | The @code{sexp} widget takes the same keyword arguments as the | |
1022 | @code{editable-field} widget. | |
1023 | @end deffn | |
1024 | ||
1025 | @node atoms, composite, generic, Sexp Types | |
1026 | @comment node-name, next, previous, up | |
1027 | @subsection Atomic Sexp Widgets. | |
1028 | ||
1029 | The atoms are s-expressions that does not consist of other | |
1030 | s-expressions. A string is an atom, while a list is a composite type. | |
1031 | You can edit the value of an atom with the following widgets. | |
1032 | ||
1033 | The syntax for all the atoms are | |
1034 | ||
1035 | @example | |
1036 | TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ]) | |
1037 | @end example | |
1038 | ||
1039 | The @var{value}, if present, is used to initialize the @code{:value} | |
1040 | property and must be an expression of the same type as the widget. | |
1041 | I.e. the string widget can only be initialized with a string. | |
1042 | ||
1043 | All the atom widgets take the same keyword arguments as the @code{editable-field} | |
1044 | widget. | |
1045 | ||
1046 | @deffn Widget string | |
1047 | Allows you to edit a string in an editable field. | |
1048 | @end deffn | |
1049 | ||
1050 | @deffn Widget file | |
1051 | Allows you to edit a file name in an editable field. You you activate | |
1052 | the tag button, you can edit the file name in the mini-buffer with | |
1053 | completion. | |
1054 | ||
1055 | Keywords: | |
1056 | @table @code | |
1057 | @item :must-match | |
1058 | If this is set to non-nil, only existing file names will be allowed in | |
1059 | the minibuffer. | |
1060 | @end table | |
1061 | @end deffn | |
1062 | ||
1063 | @deffn Widget directory | |
1064 | Allows you to edit a directory name in an editable field. | |
1065 | Similar to the @code{file} widget. | |
1066 | @end deffn | |
1067 | ||
1068 | @deffn Widget symbol | |
1069 | Allows you to edit a lisp symbol in an editable field. | |
1070 | @end deffn | |
1071 | ||
1072 | @deffn Widget integer | |
1073 | Allows you to edit an integer in an editable field. | |
1074 | @end deffn | |
1075 | ||
1076 | @deffn Widget number | |
1077 | Allows you to edit a number in an editable field. | |
1078 | @end deffn | |
1079 | ||
1080 | @deffn Widget boolean | |
1081 | Allows you to edit a boolean. In lisp this means a variable which is | |
1082 | either nil meaning false, or non-nil meaning true. | |
1083 | @end deffn | |
1084 | ||
1085 | ||
1086 | @node composite, , atoms, Sexp Types | |
1087 | @comment node-name, next, previous, up | |
1088 | @subsection Composite Sexp Widgets. | |
1089 | ||
1090 | The syntax for the composite are | |
1091 | ||
1092 | @example | |
1093 | TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...) | |
1094 | @end example | |
1095 | ||
1096 | Where each @var{component} must be a widget type. Each component widget | |
1097 | will be displayed in the buffer, and be editable to the user. | |
1098 | ||
1099 | @deffn Widget cons | |
1100 | The value of a @code{cons} widget is a cons-cell where the car is the | |
1101 | value of the first component and the cdr is the value of the second | |
1102 | component. There must be exactly two components. | |
1103 | @end deffn | |
1104 | ||
1105 | @deffn Widget lisp | |
1106 | The value of a @code{lisp} widget is a list containing the value of | |
1107 | each of its component. | |
1108 | @end deffn | |
1109 | ||
1110 | @deffn Widget vector | |
1111 | The value of a @code{vector} widget is a vector containing the value of | |
1112 | each of its component. | |
1113 | @end deffn | |
1114 | ||
1115 | The above suffice for specifying fixed size lists and vectors. To get | |
1116 | variable length lists and vectors, you can use a @code{choice}, | |
1117 | @code{set} or @code{repeat} widgets together with the @code{:inline} | |
1118 | keywords. If any component of a composite widget has the @code{:inline} | |
1119 | keyword set, its value must be a list which will then be spliced into | |
1120 | the composite. For example, to specify a list whose first element must | |
1121 | be a file name, and whose remaining arguments should either by the | |
1122 | symbol @code{t} or two files, you can use the following widget | |
1123 | specification: | |
1124 | ||
1125 | @example | |
1126 | (list file | |
1127 | (choice (const t) | |
1128 | (list :inline t | |
1129 | :value ("foo" "bar") | |
1130 | string string))) | |
1131 | @end example | |
1132 | ||
1133 | The value of a widget of this type will either have the form | |
1134 | @samp{(file t)} or @code{(file string string)}. | |
1135 | ||
1136 | This concept of inline is probably hard to understand. It was certainly | |
1137 | hard to implement so instead of confuse you more by trying to explain it | |
1138 | here, I'll just suggest you meditate over it for a while. | |
1139 | ||
1140 | @deffn Widget choice | |
1141 | Allows you to edit a sexp which may have one of fixed set of types. It | |
1142 | is currently implemented with the @code{choice-menu} basic widget, and | |
1143 | has a similar syntax. | |
1144 | @end deffn | |
1145 | ||
1146 | @deffn Widget set | |
1147 | Allows you to specify a type which must be a list whose elements all | |
1148 | belong to given set. The elements of the list is not significant. This | |
1149 | is implemented on top of the @code{checklist} basic widget, and has a | |
1150 | similar syntax. | |
1151 | @end deffn | |
1152 | ||
1153 | @deffn Widget repeat | |
1154 | Allows you to specify a variable length list whose members are all of | |
1155 | the same type. Implemented on top of the `editable-list' basic widget, | |
1156 | and has a similar syntax. | |
1157 | @end deffn | |
1158 | ||
1159 | @node Widget Properties, Defining New Widgets, Sexp Types, Top | |
1160 | @comment node-name, next, previous, up | |
1161 | @section Properties | |
1162 | ||
1163 | You can examine or set the value of a widget by using the widget object | |
1164 | that was returned by @code{widget-create}. | |
1165 | ||
1166 | @defun widget-value widget | |
1167 | Return the current value contained in @var{widget}. | |
1168 | It is an error to call this function on an uninitialized widget. | |
1169 | @end defun | |
1170 | ||
1171 | @defun widget-value-set widget value | |
1172 | Set the value contained in @var{widget} to @var{value}. | |
1173 | It is an error to call this function with an invalid @var{value}. | |
1174 | @end defun | |
1175 | ||
1176 | @strong{Important:} You @emph{must} call @code{widget-setup} after | |
1177 | modifying the value of a widget before the user is allowed to edit the | |
1178 | widget again. It is enough to call @code{widget-setup} once if you | |
1179 | modify multiple widgets. This is currently only necessary if the widget | |
1180 | contains an editing field, but may be necessary for other widgets in the | |
1181 | future. | |
1182 | ||
1183 | If your application needs to associate some information with the widget | |
1184 | objects, for example a reference to the item being edited, it can be | |
1185 | done with @code{widget-put} and @code{widget-get}. The property names | |
1186 | must begin with a @samp{:}. | |
1187 | ||
1188 | @defun widget-put widget property value | |
1189 | In @var{widget} set @var{property} to @var{value}. | |
1190 | @var{property} should be a symbol, while @var{value} can be anything. | |
1191 | @end defun | |
1192 | ||
1193 | @defun widget-get widget property | |
1194 | In @var{widget} return the value for @var{property}. | |
1195 | @var{property} should be a symbol, the value is what was last set by | |
1196 | @code{widget-put} for @var{property}. | |
1197 | @end defun | |
1198 | ||
1199 | @defun widget-member widget property | |
1200 | Non-nil if @var{widget} has a value (even nil) for property @var{property}. | |
1201 | @end defun | |
1202 | ||
1203 | Occasionally it can be useful to know which kind of widget you have, | |
1204 | i.e. the name of the widget type you gave when the widget was created. | |
1205 | ||
1206 | @defun widget-type widget | |
1207 | Return the name of @var{widget}, a symbol. | |
1208 | @end defun | |
1209 | ||
1210 | Widgets can be in two states: active, which means they are modifiable by | |
1211 | the user, or inactive, which means they cannot be modified by the user. | |
1212 | You can query or set the state with the following code: | |
1213 | ||
1214 | @lisp | |
1215 | ;; Examine if @var{widget} is active or not. | |
1216 | (if (widget-apply @var{widget} :active) | |
1217 | (message "Widget is active.") | |
1218 | (message "Widget is inactive.") | |
1219 | ||
1220 | ;; Make @var{widget} inactive. | |
1221 | (widget-apply @var{widget} :deactivate) | |
1222 | ||
1223 | ;; Make @var{widget} active. | |
1224 | (widget-apply @var{widget} :activate) | |
1225 | @end lisp | |
1226 | ||
1227 | A widget is inactive if itself, or any of its ancestors (found by | |
1228 | following the @code{:parent} link) have been deactivated. To make sure | |
1229 | a widget is really active, you must therefore activate both itself, and | |
1230 | all its ancestors. | |
1231 | ||
1232 | @lisp | |
1233 | (while widget | |
1234 | (widget-apply widget :activate) | |
1235 | (setq widget (widget-get widget :parent))) | |
1236 | @end lisp | |
1237 | ||
1238 | You can check if a widget has been made inactive by examining the value | |
1239 | of @code{:inactive} keyword. If this is non-nil, the widget itself has | |
1240 | been deactivated. This is different from using the @code{:active} | |
1241 | keyword, in that the later tell you if the widget @strong{or} any of its | |
1242 | ancestors have been deactivated. Do not attempt to set the | |
1243 | @code{:inactive} keyword directly. Use the @code{:activate} | |
1244 | @code{:deactivated} keywords instead. | |
1245 | ||
1246 | ||
1247 | @node Defining New Widgets, Widget Wishlist., Widget Properties, Top | |
1248 | @comment node-name, next, previous, up | |
1249 | @section Defining New Widgets | |
1250 | ||
1251 | You can define specialized widgets with @code{define-widget}. It allows | |
1252 | you to create a shorthand for more complex widgets, including specifying | |
1253 | component widgets and default new default values for the keyword | |
1254 | arguments. | |
1255 | ||
1256 | @defun widget-define name class doc &rest args | |
1257 | Define a new widget type named @var{name} from @code{class}. | |
1258 | ||
1259 | @var{name} and class should both be symbols, @code{class} should be one | |
1260 | of the existing widget types. | |
1261 | ||
1262 | The third argument @var{DOC} is a documentation string for the widget. | |
1263 | ||
1264 | After the new widget has been defined, the following two calls will | |
1265 | create identical widgets: | |
1266 | ||
1267 | @itemize @bullet | |
1268 | @item | |
1269 | @lisp | |
1270 | (widget-create @var{name}) | |
1271 | @end lisp | |
1272 | ||
1273 | @item | |
1274 | @lisp | |
1275 | (apply widget-create @var{class} @var{args}) | |
1276 | @end lisp | |
1277 | @end itemize | |
1278 | ||
1279 | @end defun | |
1280 | ||
1281 | Using @code{widget-define} does just store the definition of the widget | |
1282 | type in the @code{widget-type} property of @var{name}, which is what | |
1283 | @code{widget-create} uses. | |
1284 | ||
1285 | If you just want to specify defaults for keywords with no complex | |
1286 | conversions, you can use @code{identity} as your conversion function. | |
1287 | ||
1288 | The following additional keyword arguments are useful when defining new | |
1289 | widgets: | |
1290 | @table @code | |
1291 | @item :convert-widget | |
1292 | Function to convert a widget type before creating a widget of that | |
1293 | type. It takes a widget type as an argument, and returns the converted | |
1294 | widget type. When a widget is created, this function is called for the | |
1295 | widget type and all the widgets parent types, most derived first. | |
1296 | ||
1297 | @item :value-to-internal | |
1298 | Function to convert the value to the internal format. The function | |
1299 | takes two arguments, a widget and an external value, and returns the | |
1300 | internal value. The function is called on the present @code{:value} | |
1301 | when the widget is created, and on any value set later with | |
1302 | @code{widget-value-set}. | |
1303 | ||
1304 | @item :value-to-external | |
1305 | Function to convert the value to the external format. The function | |
1306 | takes two arguments, a widget and an internal value, and returns the | |
1307 | internal value. The function is called on the present @code{:value} | |
1308 | when the widget is created, and on any value set later with | |
1309 | @code{widget-value-set}. | |
1310 | ||
1311 | @item :create | |
1312 | Function to create a widget from scratch. The function takes one | |
1313 | argument, a widget type, and create a widget of that type, insert it in | |
1314 | the buffer, and return a widget object. | |
1315 | ||
1316 | @item :delete | |
1317 | Function to delete a widget. The function takes one argument, a widget, | |
1318 | and should remove all traces of the widget from the buffer. | |
1319 | ||
1320 | @item :value-create | |
1321 | Function to expand the @samp{%v} escape in the format string. It will | |
1322 | be called with the widget as its argument. Should | |
1323 | insert a representation of the widgets value in the buffer. | |
1324 | ||
1325 | @item :value-delete | |
1326 | Should remove the representation of the widgets value from the buffer. | |
1327 | It will be called with the widget as its argument. It doesn't have to | |
1328 | remove the text, but it should release markers and delete nested widgets | |
1329 | if such has been used. | |
1330 | ||
1331 | @item :format-handler | |
1332 | Function to handle unknown @samp{%} escapes in the format string. It | |
1333 | will be called with the widget and the escape character as arguments. | |
1334 | You can set this to allow your widget to handle non-standard escapes. | |
1335 | ||
1336 | You should end up calling @code{widget-default-format-handler} to handle | |
1337 | unknown escape sequences, which will handle the @samp{%h} and any future | |
1338 | escape sequences, as well as give an error for unknown escapes. | |
1339 | @end table | |
1340 | ||
1341 | If you want to define a new widget from scratch, use the @code{default} | |
1342 | widget as its base. | |
1343 | ||
1344 | @deffn Widget default [ keyword argument ] | |
1345 | Widget used as a base for other widgets. | |
1346 | ||
1347 | It provides most of the functionality that is referred to as ``by | |
1348 | default'' in this text. | |
1349 | @end deffn | |
1350 | ||
1351 | @node Widget Wishlist., , Defining New Widgets, Top | |
1352 | @comment node-name, next, previous, up | |
1353 | @section Wishlist. | |
1354 | ||
1355 | @itemize @bullet | |
1356 | @item | |
1357 | It should be possible to add or remove items from a list with @kbd{C-k} | |
1358 | and @kbd{C-o} (suggested by @sc{rms}). | |
1359 | ||
1360 | @item | |
1361 | The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single | |
1362 | dash (@samp{-}). The dash should be a button that, when activated, ask | |
1363 | whether you want to add or delete an item (@sc{rms} wanted to git rid of | |
1364 | the ugly buttons, the dash is my idea). | |
1365 | ||
1366 | @item | |
1367 | Widgets such as @code{file} and @code{symbol} should prompt with completion. | |
1368 | ||
1369 | @item | |
1370 | The @code{menu-choice} tag should be prettier, something like the abbreviated | |
1371 | menus in Open Look. | |
1372 | ||
1373 | @item | |
1374 | The functions used in many widgets, like | |
1375 | @code{widget-item-convert-widget}, should not have names that are | |
1376 | specific to the first widget where I happended to use them. | |
1377 | ||
1378 | @item | |
1379 | Flag to make @code{widget-move} skip a specified button. | |
1380 | ||
1381 | @item | |
1382 | Document `helper' functions for defining new widgets. | |
1383 | ||
1384 | @item | |
1385 | Activate the item this is below the mouse when the button is | |
1386 | released, not the item this is below the mouse when the button is | |
1387 | pressed. Dired and grep gets this right. Give feedback if possible. | |
1388 | ||
1389 | @item | |
1390 | Use @samp{@@deffn Widget} to document widgets. | |
1391 | ||
1392 | @item | |
1393 | Document global keywords in one place. | |
1394 | ||
1395 | Document keywords particular to a specific widget in the widget | |
1396 | definition. | |
1397 | ||
1398 | Document the `default' widget first. | |
1399 | ||
1400 | Split, when needed, keywords into those useful for normal | |
1401 | customization, those primarily useful when deriving, and those who | |
1402 | represent runtime information. | |
1403 | ||
1404 | @item | |
1405 | Figure out terminology and @sc{api} for the class/type/object/super | |
1406 | stuff. | |
1407 | ||
1408 | Perhaps the correct model is delegation? | |
1409 | ||
1410 | @item | |
1411 | Document @code{widget-browse}. | |
1412 | ||
1413 | @item | |
1414 | Make indentation work with glyphs and propertional fonts. | |
1415 | ||
1416 | @item | |
1417 | Add object and class hierarchies to the browser. | |
1418 | ||
1419 | @end itemize | |
1420 | ||
1421 | @contents | |
1422 | @bye |