Commit | Line | Data |
---|---|---|
8e2b057d | 1 | ;;; button.el --- clickable buttons |
0c26f463 | 2 | ;; |
ba318903 | 3 | ;; Copyright (C) 2001-2014 Free Software Foundation, Inc. |
0c26f463 MB |
4 | ;; |
5 | ;; Author: Miles Bader <miles@gnu.org> | |
6 | ;; Keywords: extensions | |
bd78fa1d | 7 | ;; Package: emacs |
0c26f463 MB |
8 | ;; |
9 | ;; This file is part of GNU Emacs. | |
10 | ;; | |
eb3fa2cf | 11 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
0c26f463 | 12 | ;; it under the terms of the GNU General Public License as published by |
eb3fa2cf GM |
13 | ;; the Free Software Foundation, either version 3 of the License, or |
14 | ;; (at your option) any later version. | |
15 | ||
0c26f463 MB |
16 | ;; GNU Emacs is distributed in the hope that it will be useful, |
17 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 | ;; GNU General Public License for more details. | |
eb3fa2cf | 20 | |
0c26f463 | 21 | ;; You should have received a copy of the GNU General Public License |
eb3fa2cf | 22 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
0c26f463 MB |
23 | |
24 | ;;; Commentary: | |
25 | ;; | |
26 | ;; This package defines functions for inserting and manipulating | |
27 | ;; clickable buttons in Emacs buffers, such as might be used for help | |
28 | ;; hyperlinks, etc. | |
29 | ;; | |
30 | ;; In some ways it duplicates functionality also offered by the | |
31 | ;; `widget' package, but the button package has the advantage that it | |
32 | ;; is (1) much faster, (2) much smaller, and (3) much, much, simpler | |
33 | ;; (the code, that is, not the interface). | |
34 | ;; | |
35 | ;; Buttons can either use overlays, in which case the button is | |
36 | ;; represented by the overlay itself, or text-properties, in which case | |
37 | ;; the button is represented by a marker or buffer-position pointing | |
38 | ;; somewhere in the button. In the latter case, no markers into the | |
39 | ;; buffer are retained, which is important for speed if there are are | |
4d265b4d GM |
40 | ;; extremely large numbers of buttons. Note however that if there is |
41 | ;; an existing face text-property at the site of the button, the | |
42 | ;; button face may not be visible. Using overlays avoids this. | |
0c26f463 MB |
43 | ;; |
44 | ;; Using `define-button-type' to define default properties for buttons | |
58179cce | 45 | ;; is not necessary, but it is encouraged, since doing so makes the |
0c26f463 MB |
46 | ;; resulting code clearer and more efficient. |
47 | ;; | |
48 | ||
49 | ;;; Code: | |
50 | ||
51 | \f | |
52 | ;; Globals | |
53 | ||
0e0d5683 | 54 | ;; Use color for the MS-DOS port because it doesn't support underline. |
f8ac059a GM |
55 | ;; FIXME if MS-DOS correctly answers the (supports) question, it need |
56 | ;; no longer be a special case. | |
605dd5bf | 57 | (defface button '((t :inherit link)) |
d28242e1 | 58 | "Default face used for buttons." |
21b9448f | 59 | :group 'basic-faces) |
0c26f463 | 60 | |
0c26f463 MB |
61 | (defvar button-map |
62 | (let ((map (make-sparse-keymap))) | |
2b786e07 JR |
63 | ;; The following definition needs to avoid using escape sequences that |
64 | ;; might get converted to ^M when building loaddefs.el | |
65 | (define-key map [(control ?m)] 'push-button) | |
0c26f463 | 66 | (define-key map [mouse-2] 'push-button) |
24fc9480 JB |
67 | ;; FIXME: You'd think that for keymaps coming from text-properties on the |
68 | ;; mode-line or header-line, the `mode-line' or `header-line' prefix | |
69 | ;; shouldn't be necessary! | |
70 | (define-key map [mode-line mouse-2] 'push-button) | |
71 | (define-key map [header-line mouse-2] 'push-button) | |
0c26f463 MB |
72 | map) |
73 | "Keymap used by buttons.") | |
74 | ||
0c26f463 MB |
75 | (defvar button-buffer-map |
76 | (let ((map (make-sparse-keymap))) | |
77 | (define-key map [?\t] 'forward-button) | |
272199ae | 78 | (define-key map "\e\t" 'backward-button) |
0c26f463 MB |
79 | (define-key map [backtab] 'backward-button) |
80 | map) | |
81 | "Keymap useful for buffers containing buttons. | |
82 | Mode-specific keymaps may want to use this as their parent keymap.") | |
83 | ||
84 | ;; Default properties for buttons | |
85 | (put 'default-button 'face 'button) | |
86 | (put 'default-button 'mouse-face 'highlight) | |
87 | (put 'default-button 'keymap button-map) | |
88 | (put 'default-button 'type 'button) | |
bea55b5b | 89 | ;; action may be either a function to call, or a marker to go to |
62dc75c4 | 90 | (put 'default-button 'action 'ignore) |
1e8780b1 | 91 | (put 'default-button 'help-echo (purecopy "mouse-2, RET: Push this button")) |
0c26f463 MB |
92 | ;; Make overlay buttons go away if their underlying text is deleted. |
93 | (put 'default-button 'evaporate t) | |
94 | ;; Prevent insertions adjacent to the text-property buttons from | |
95 | ;; inheriting its properties. | |
96 | (put 'default-button 'rear-nonsticky t) | |
0c26f463 | 97 | |
530893b2 MB |
98 | ;; A `category-symbol' property for the default button type |
99 | (put 'button 'button-category-symbol 'default-button) | |
100 | ||
0c26f463 MB |
101 | \f |
102 | ;; Button types (which can be used to hold default properties for buttons) | |
103 | ||
ded42dd3 MB |
104 | ;; Because button-type properties are inherited by buttons using the |
105 | ;; special `category' property (implemented by both overlays and | |
106 | ;; text-properties), we need to store them on a symbol to which the | |
107 | ;; `category' properties can point. Instead of using the symbol that's | |
108 | ;; the name of each button-type, however, we use a separate symbol (with | |
109 | ;; `-button' appended, and uninterned) to store the properties. This is | |
110 | ;; to avoid name clashes. | |
111 | ||
112 | ;; [this is an internal function] | |
113 | (defsubst button-category-symbol (type) | |
114 | "Return the symbol used by button-type TYPE to store properties. | |
115 | Buttons inherit them by setting their `category' property to that symbol." | |
116 | (or (get type 'button-category-symbol) | |
117 | (error "Unknown button type `%s'" type))) | |
118 | ||
0c26f463 | 119 | (defun define-button-type (name &rest properties) |
b9712b1c | 120 | "Define a `button type' called NAME (a symbol). |
0c26f463 MB |
121 | The remaining arguments form a sequence of PROPERTY VALUE pairs, |
122 | specifying properties to use as defaults for buttons with this type | |
123 | \(a button's type may be set by giving it a `type' property when | |
ecdbe16a | 124 | creating the button, using the :type keyword argument). |
ded42dd3 | 125 | |
ecdbe16a MB |
126 | In addition, the keyword argument :supertype may be used to specify a |
127 | button-type from which NAME inherits its default property values | |
128 | \(however, the inheritance happens only when NAME is defined; subsequent | |
129 | changes to a supertype are not reflected in its subtypes)." | |
588c722f MB |
130 | (let ((catsym (make-symbol (concat (symbol-name name) "-button"))) |
131 | (super-catsym | |
132 | (button-category-symbol | |
530893b2 | 133 | (or (plist-get properties 'supertype) |
588c722f MB |
134 | (plist-get properties :supertype) |
135 | 'button)))) | |
0c26f463 MB |
136 | ;; Provide a link so that it's easy to find the real symbol. |
137 | (put name 'button-category-symbol catsym) | |
138 | ;; Initialize NAME's properties using the global defaults. | |
ded42dd3 | 139 | (let ((default-props (symbol-plist super-catsym))) |
0c26f463 MB |
140 | (while default-props |
141 | (put catsym (pop default-props) (pop default-props)))) | |
142 | ;; Add NAME as the `type' property, which will then be returned as | |
143 | ;; the type property of individual buttons. | |
144 | (put catsym 'type name) | |
145 | ;; Add the properties in PROPERTIES to the real symbol. | |
146 | (while properties | |
530893b2 MB |
147 | (let ((prop (pop properties))) |
148 | (when (eq prop :supertype) | |
149 | (setq prop 'supertype)) | |
150 | (put catsym prop (pop properties)))) | |
588c722f MB |
151 | ;; Make sure there's a `supertype' property |
152 | (unless (get catsym 'supertype) | |
153 | (put catsym 'supertype 'button)) | |
0c26f463 MB |
154 | name)) |
155 | ||
0c26f463 MB |
156 | (defun button-type-put (type prop val) |
157 | "Set the button-type TYPE's PROP property to VAL." | |
158 | (put (button-category-symbol type) prop val)) | |
159 | ||
160 | (defun button-type-get (type prop) | |
161 | "Get the property of button-type TYPE named PROP." | |
162 | (get (button-category-symbol type) prop)) | |
163 | ||
ded42dd3 MB |
164 | (defun button-type-subtype-p (type supertype) |
165 | "Return t if button-type TYPE is a subtype of SUPERTYPE." | |
166 | (or (eq type supertype) | |
167 | (and type | |
168 | (button-type-subtype-p (button-type-get type 'supertype) | |
169 | supertype)))) | |
170 | ||
0c26f463 MB |
171 | \f |
172 | ;; Button properties and other attributes | |
173 | ||
174 | (defun button-start (button) | |
175 | "Return the position at which BUTTON starts." | |
176 | (if (overlayp button) | |
177 | (overlay-start button) | |
178 | ;; Must be a text-property button. | |
179 | (or (previous-single-property-change (1+ button) 'button) | |
180 | (point-min)))) | |
181 | ||
182 | (defun button-end (button) | |
183 | "Return the position at which BUTTON ends." | |
184 | (if (overlayp button) | |
185 | (overlay-end button) | |
186 | ;; Must be a text-property button. | |
187 | (or (next-single-property-change button 'button) | |
188 | (point-max)))) | |
189 | ||
190 | (defun button-get (button prop) | |
191 | "Get the property of button BUTTON named PROP." | |
24fc9480 JB |
192 | (cond ((overlayp button) |
193 | (overlay-get button prop)) | |
194 | ((button--area-button-p button) | |
4b0df848 SM |
195 | (get-text-property (cdr button) |
196 | prop (button--area-button-string button))) | |
24fc9480 JB |
197 | (t ; Must be a text-property button. |
198 | (get-text-property button prop)))) | |
0c26f463 MB |
199 | |
200 | (defun button-put (button prop val) | |
201 | "Set BUTTON's PROP property to VAL." | |
202 | ;; Treat some properties specially. | |
530893b2 | 203 | (cond ((memq prop '(type :type)) |
0c26f463 MB |
204 | ;; We translate a `type' property a `category' property, since |
205 | ;; that's what's actually used by overlays/text-properties for | |
206 | ;; inheriting properties. | |
207 | (setq prop 'category) | |
208 | (setq val (button-category-symbol val))) | |
209 | ((eq prop 'category) | |
210 | ;; Disallow updating the `category' property directly. | |
211 | (error "Button `category' property may not be set directly"))) | |
212 | ;; Add the property. | |
24fc9480 JB |
213 | (cond ((overlayp button) |
214 | (overlay-put button prop val)) | |
215 | ((button--area-button-p button) | |
216 | (setq button (button--area-button-string button)) | |
217 | (put-text-property 0 (length button) prop val button)) | |
218 | (t ; Must be a text-property button. | |
219 | (put-text-property | |
220 | (or (previous-single-property-change (1+ button) 'button) | |
221 | (point-min)) | |
222 | (or (next-single-property-change button 'button) | |
223 | (point-max)) | |
224 | prop val)))) | |
225 | ||
226 | (defun button-activate (button &optional use-mouse-action) | |
d6bc0bdc MB |
227 | "Call BUTTON's action property. |
228 | If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action | |
229 | instead of its normal action; if the button has no mouse-action, | |
24fc9480 JB |
230 | the normal action is used instead. |
231 | ||
232 | The action can either be a marker or a function. If it's a | |
233 | marker then goto it. Otherwise it it is a function then it is | |
234 | called with BUTTON as only argument. BUTTON is either an | |
235 | overlay, a buffer position, or (for buttons in the mode-line or | |
236 | header-line) a string." | |
bea55b5b DP |
237 | (let ((action (or (and use-mouse-action (button-get button 'mouse-action)) |
238 | (button-get button 'action)))) | |
239 | (if (markerp action) | |
240 | (save-selected-window | |
241 | (select-window (display-buffer (marker-buffer action))) | |
242 | (goto-char action) | |
243 | (recenter 0)) | |
244 | (funcall action button)))) | |
0c26f463 MB |
245 | |
246 | (defun button-label (button) | |
247 | "Return BUTTON's text label." | |
24fc9480 JB |
248 | (if (button--area-button-p button) |
249 | (substring-no-properties (button--area-button-string button)) | |
250 | (buffer-substring-no-properties (button-start button) | |
251 | (button-end button)))) | |
0c26f463 | 252 | |
530893b2 | 253 | (defsubst button-type (button) |
ecdbe16a | 254 | "Return BUTTON's button-type." |
530893b2 MB |
255 | (button-get button 'type)) |
256 | ||
ded42dd3 MB |
257 | (defun button-has-type-p (button type) |
258 | "Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes." | |
259 | (button-type-subtype-p (button-get button 'type) type)) | |
260 | ||
4c74b1e4 | 261 | (defun button--area-button-p (b) |
24fc9480 | 262 | "Return non-nil if BUTTON is an area button. |
4c74b1e4 GM |
263 | Such area buttons are used for buttons in the mode-line and header-line." |
264 | (stringp (car-safe b))) | |
24fc9480 | 265 | |
4b0df848 | 266 | (defalias 'button--area-button-string #'car |
24fc9480 | 267 | "Return area button BUTTON's button-string.") |
0c26f463 MB |
268 | \f |
269 | ;; Creating overlay buttons | |
270 | ||
0c26f463 MB |
271 | (defun make-button (beg end &rest properties) |
272 | "Make a button from BEG to END in the current buffer. | |
273 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
ecdbe16a MB |
274 | specifying properties to add to the button. |
275 | In addition, the keyword argument :type may be used to specify a | |
276 | button-type from which to inherit other properties; see | |
277 | `define-button-type'. | |
0c26f463 MB |
278 | |
279 | Also see `make-text-button', `insert-button'." | |
280 | (let ((overlay (make-overlay beg end nil t nil))) | |
281 | (while properties | |
282 | (button-put overlay (pop properties) (pop properties))) | |
283 | ;; Put a pointer to the button in the overlay, so it's easy to get | |
284 | ;; when we don't actually have a reference to the overlay. | |
285 | (overlay-put overlay 'button overlay) | |
286 | ;; If the user didn't specify a type, use the default. | |
287 | (unless (overlay-get overlay 'category) | |
288 | (overlay-put overlay 'category 'default-button)) | |
289 | ;; OVERLAY is the button, so return it | |
290 | overlay)) | |
291 | ||
0c26f463 MB |
292 | (defun insert-button (label &rest properties) |
293 | "Insert a button with the label LABEL. | |
294 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
ecdbe16a MB |
295 | specifying properties to add to the button. |
296 | In addition, the keyword argument :type may be used to specify a | |
297 | button-type from which to inherit other properties; see | |
298 | `define-button-type'. | |
0c26f463 MB |
299 | |
300 | Also see `insert-text-button', `make-button'." | |
301 | (apply #'make-button | |
302 | (prog1 (point) (insert label)) | |
303 | (point) | |
304 | properties)) | |
305 | ||
306 | \f | |
307 | ;; Creating text-property buttons | |
308 | ||
0c26f463 MB |
309 | (defun make-text-button (beg end &rest properties) |
310 | "Make a button from BEG to END in the current buffer. | |
311 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
ecdbe16a MB |
312 | specifying properties to add to the button. |
313 | In addition, the keyword argument :type may be used to specify a | |
314 | button-type from which to inherit other properties; see | |
315 | `define-button-type'. | |
0c26f463 MB |
316 | |
317 | This function is like `make-button', except that the button is actually | |
4d265b4d GM |
318 | part of the text instead of being a property of the buffer. That is, |
319 | this function uses text properties, the other uses overlays. | |
320 | Creating large numbers of buttons can also be somewhat faster | |
321 | using `make-text-button'. Note, however, that if there is an existing | |
322 | face property at the site of the button, the button face may not be visible. | |
323 | You may want to use `make-button' in that case. | |
0c26f463 | 324 | |
12b139e9 SM |
325 | BEG can also be a string, in which case it is made into a button. |
326 | ||
0c26f463 | 327 | Also see `insert-text-button'." |
12b139e9 SM |
328 | (let ((object nil) |
329 | (type-entry | |
aad1926a MB |
330 | (or (plist-member properties 'type) |
331 | (plist-member properties :type)))) | |
12b139e9 SM |
332 | (when (stringp beg) |
333 | (setq object beg beg 0 end (length object))) | |
aad1926a MB |
334 | ;; Disallow setting the `category' property directly. |
335 | (when (plist-get properties 'category) | |
336 | (error "Button `category' property may not be set directly")) | |
337 | (if (null type-entry) | |
338 | ;; The user didn't specify a `type' property, use the default. | |
339 | (setq properties (cons 'category (cons 'default-button properties))) | |
340 | ;; The user did specify a `type' property. Translate it into a | |
341 | ;; `category' property, which is what's actually used by | |
342 | ;; text-properties for inheritance. | |
343 | (setcar type-entry 'category) | |
344 | (setcar (cdr type-entry) | |
12b139e9 SM |
345 | (button-category-symbol (car (cdr type-entry))))) |
346 | ;; Now add all the text properties at once | |
347 | (add-text-properties beg end | |
348 | ;; Each button should have a non-eq `button' | |
349 | ;; property so that next-single-property-change can | |
350 | ;; detect boundaries reliably. | |
351 | (cons 'button (cons (list t) properties)) | |
352 | object) | |
353 | ;; Return something that can be used to get at the button. | |
24fc9480 | 354 | (or object beg))) |
0c26f463 | 355 | |
0c26f463 MB |
356 | (defun insert-text-button (label &rest properties) |
357 | "Insert a button with the label LABEL. | |
358 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
ecdbe16a MB |
359 | specifying properties to add to the button. |
360 | In addition, the keyword argument :type may be used to specify a | |
361 | button-type from which to inherit other properties; see | |
362 | `define-button-type'. | |
0c26f463 MB |
363 | |
364 | This function is like `insert-button', except that the button is | |
365 | actually part of the text instead of being a property of the buffer. | |
366 | Creating large numbers of buttons can also be somewhat faster using | |
367 | `insert-text-button'. | |
368 | ||
369 | Also see `make-text-button'." | |
370 | (apply #'make-text-button | |
371 | (prog1 (point) (insert label)) | |
372 | (point) | |
373 | properties)) | |
374 | ||
375 | \f | |
376 | ;; Finding buttons in a buffer | |
377 | ||
378 | (defun button-at (pos) | |
9a69676a CY |
379 | "Return the button at position POS in the current buffer, or nil. |
380 | If the button at POS is a text property button, the return value | |
381 | is a marker pointing to POS." | |
0c26f463 MB |
382 | (let ((button (get-char-property pos 'button))) |
383 | (if (or (overlayp button) (null button)) | |
384 | button | |
385 | ;; Must be a text-property button; return a marker pointing to it. | |
386 | (copy-marker pos t)))) | |
387 | ||
fee34a28 MB |
388 | (defun next-button (pos &optional count-current) |
389 | "Return the next button after position POS in the current buffer. | |
0c26f463 | 390 | If COUNT-CURRENT is non-nil, count any button at POS in the search, |
fee34a28 | 391 | instead of starting at the next button." |
0c26f463 MB |
392 | (unless count-current |
393 | ;; Search for the next button boundary. | |
394 | (setq pos (next-single-char-property-change pos 'button))) | |
fee34a28 MB |
395 | (and (< pos (point-max)) |
396 | (or (button-at pos) | |
0c26f463 MB |
397 | ;; We must have originally been on a button, and are now in |
398 | ;; the inter-button space. Recurse to find a button. | |
fee34a28 | 399 | (next-button pos)))) |
0c26f463 | 400 | |
fee34a28 | 401 | (defun previous-button (pos &optional count-current) |
1106c41b | 402 | "Return the previous button before position POS in the current buffer. |
0c26f463 | 403 | If COUNT-CURRENT is non-nil, count any button at POS in the search, |
fee34a28 | 404 | instead of starting at the next button." |
1106c41b CY |
405 | (let ((button (button-at pos))) |
406 | (if button | |
407 | (if count-current | |
408 | button | |
409 | ;; We started out on a button, so move to its start and look | |
410 | ;; for the previous button boundary. | |
411 | (setq pos (previous-single-char-property-change | |
412 | (button-start button) 'button)) | |
413 | (let ((new-button (button-at pos))) | |
414 | (if new-button | |
415 | ;; We are in a button again; this can happen if there | |
416 | ;; are adjacent buttons (or at bob). | |
6d0a6f30 | 417 | (unless (= pos (button-start button)) new-button) |
1106c41b CY |
418 | ;; We are now in the space between buttons. |
419 | (previous-button pos)))) | |
420 | ;; We started out in the space between buttons. | |
421 | (setq pos (previous-single-char-property-change pos 'button)) | |
422 | (or (button-at pos) | |
423 | (and (> pos (point-min)) | |
424 | (button-at (1- pos))))))) | |
0c26f463 MB |
425 | |
426 | \f | |
427 | ;; User commands | |
428 | ||
d6bc0bdc | 429 | (defun push-button (&optional pos use-mouse-action) |
0c26f463 | 430 | "Perform the action specified by a button at location POS. |
bea55b5b DP |
431 | POS may be either a buffer position or a mouse-event. If |
432 | USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action | |
d6bc0bdc | 433 | instead of its normal action; if the button has no mouse-action, |
bea55b5b | 434 | the normal action is used instead. The action may be either a |
24fc9480 JB |
435 | function to call or a marker to display and is invoked using |
436 | `button-activate' (which see). | |
437 | ||
0c26f463 MB |
438 | POS defaults to point, except when `push-button' is invoked |
439 | interactively as the result of a mouse-event, in which case, the | |
440 | mouse event is used. | |
441 | If there's no button at POS, do nothing and return nil, otherwise | |
442 | return t." | |
443 | (interactive | |
444 | (list (if (integerp last-command-event) (point) last-command-event))) | |
445 | (if (and (not (integerp pos)) (eventp pos)) | |
446 | ;; POS is a mouse event; switch to the proper window/buffer | |
447 | (let ((posn (event-start pos))) | |
448 | (with-current-buffer (window-buffer (posn-window posn)) | |
4b0df848 SM |
449 | (if (posn-string posn) |
450 | ;; mode-line, header-line, or display string event. | |
451 | (button-activate (posn-string posn) t) | |
24fc9480 | 452 | (push-button (posn-point posn)) t))) |
0c26f463 MB |
453 | ;; POS is just normal position |
454 | (let ((button (button-at (or pos (point))))) | |
24fc9480 | 455 | (when button |
d6bc0bdc | 456 | (button-activate button use-mouse-action) |
0c26f463 MB |
457 | t)))) |
458 | ||
459 | (defun forward-button (n &optional wrap display-message) | |
460 | "Move to the Nth next button, or Nth previous button if N is negative. | |
fee34a28 | 461 | If N is 0, move to the start of any button at point. |
0c26f463 MB |
462 | If WRAP is non-nil, moving past either end of the buffer continues from the |
463 | other end. | |
464 | If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed. | |
fee34a28 | 465 | Any button with a non-nil `skip' property is skipped over. |
0c26f463 MB |
466 | Returns the button found." |
467 | (interactive "p\nd\nd") | |
fee34a28 MB |
468 | (let (button) |
469 | (if (zerop n) | |
470 | ;; Move to start of current button | |
471 | (if (setq button (button-at (point))) | |
472 | (goto-char (button-start button))) | |
473 | ;; Move to Nth next button | |
474 | (let ((iterator (if (> n 0) #'next-button #'previous-button)) | |
f46a3642 CY |
475 | (wrap-start (if (> n 0) (point-min) (point-max))) |
476 | opoint fail) | |
fee34a28 MB |
477 | (setq n (abs n)) |
478 | (setq button t) ; just to start the loop | |
f46a3642 | 479 | (while (and (null fail) (> n 0) button) |
fee34a28 MB |
480 | (setq button (funcall iterator (point))) |
481 | (when (and (not button) wrap) | |
482 | (setq button (funcall iterator wrap-start t))) | |
483 | (when button | |
484 | (goto-char (button-start button)) | |
f46a3642 CY |
485 | ;; Avoid looping forever (e.g., if all the buttons have |
486 | ;; the `skip' property). | |
487 | (cond ((null opoint) | |
488 | (setq opoint (point))) | |
489 | ((= opoint (point)) | |
490 | (setq fail t))) | |
fee34a28 MB |
491 | (unless (button-get button 'skip) |
492 | (setq n (1- n))))))) | |
0c26f463 MB |
493 | (if (null button) |
494 | (error (if wrap "No buttons!" "No more buttons")) | |
0c26f463 MB |
495 | (let ((msg (and display-message (button-get button 'help-echo)))) |
496 | (when msg | |
497 | (message "%s" msg))) | |
498 | button))) | |
499 | ||
500 | (defun backward-button (n &optional wrap display-message) | |
501 | "Move to the Nth previous button, or Nth next button if N is negative. | |
fee34a28 | 502 | If N is 0, move to the start of any button at point. |
0c26f463 MB |
503 | If WRAP is non-nil, moving past either end of the buffer continues from the |
504 | other end. | |
505 | If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed. | |
fee34a28 | 506 | Any button with a non-nil `skip' property is skipped over. |
0c26f463 MB |
507 | Returns the button found." |
508 | (interactive "p\nd\nd") | |
509 | (forward-button (- n) wrap display-message)) | |
510 | ||
511 | ||
512 | (provide 'button) | |
513 | ||
514 | ;;; button.el ends here |