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1 | ;;; button.el --- Clickable buttons |
2 | ;; | |
3 | ;; Copyright (C) 2001 Free Software Foundation, Inc. | |
4 | ;; | |
5 | ;; Author: Miles Bader <miles@gnu.org> | |
6 | ;; Keywords: extensions | |
7 | ;; | |
8 | ;; This file is part of GNU Emacs. | |
9 | ;; | |
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
12 | ;; the Free Software Foundation; either version 2, or (at your option) | |
13 | ;; any later version. | |
14 | ;; | |
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ;; | |
20 | ;; You should have received a copy of the GNU General Public License | |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
24 | ||
25 | ;;; Commentary: | |
26 | ;; | |
27 | ;; This package defines functions for inserting and manipulating | |
28 | ;; clickable buttons in Emacs buffers, such as might be used for help | |
29 | ;; hyperlinks, etc. | |
30 | ;; | |
31 | ;; In some ways it duplicates functionality also offered by the | |
32 | ;; `widget' package, but the button package has the advantage that it | |
33 | ;; is (1) much faster, (2) much smaller, and (3) much, much, simpler | |
34 | ;; (the code, that is, not the interface). | |
35 | ;; | |
36 | ;; Buttons can either use overlays, in which case the button is | |
37 | ;; represented by the overlay itself, or text-properties, in which case | |
38 | ;; the button is represented by a marker or buffer-position pointing | |
39 | ;; somewhere in the button. In the latter case, no markers into the | |
40 | ;; buffer are retained, which is important for speed if there are are | |
41 | ;; extremely large numbers of buttons. | |
42 | ;; | |
43 | ;; Using `define-button-type' to define default properties for buttons | |
44 | ;; is not necessary, but it is is encouraged, since doing so makes the | |
45 | ;; resulting code clearer and more efficient. | |
46 | ;; | |
47 | ||
48 | ;;; Code: | |
49 | ||
50 | \f | |
51 | ;; Globals | |
52 | ||
53 | (defface button '((t :underline t)) | |
54 | "Default face used for buttons.") | |
55 | ||
56 | ;;;###autoload | |
57 | (defvar button-map | |
58 | (let ((map (make-sparse-keymap))) | |
59 | (define-key map "\r" 'push-button) | |
60 | (define-key map [mouse-2] 'push-button) | |
61 | map) | |
62 | "Keymap used by buttons.") | |
63 | ||
64 | ;;;###autoload | |
65 | (defvar button-buffer-map | |
66 | (let ((map (make-sparse-keymap))) | |
67 | (define-key map [?\t] 'forward-button) | |
68 | (define-key map [backtab] 'backward-button) | |
69 | map) | |
70 | "Keymap useful for buffers containing buttons. | |
71 | Mode-specific keymaps may want to use this as their parent keymap.") | |
72 | ||
73 | ;; Default properties for buttons | |
74 | (put 'default-button 'face 'button) | |
75 | (put 'default-button 'mouse-face 'highlight) | |
76 | (put 'default-button 'keymap button-map) | |
77 | (put 'default-button 'type 'button) | |
62dc75c4 | 78 | (put 'default-button 'action 'ignore) |
0c26f463 MB |
79 | (put 'default-button 'help-echo "mouse-2, RET: Push this button") |
80 | ;; Make overlay buttons go away if their underlying text is deleted. | |
81 | (put 'default-button 'evaporate t) | |
82 | ;; Prevent insertions adjacent to the text-property buttons from | |
83 | ;; inheriting its properties. | |
84 | (put 'default-button 'rear-nonsticky t) | |
85 | ;; Text property buttons don't have a `button' property of their own, so | |
86 | ;; they inherit this. | |
87 | (put 'default-button 'button t) | |
88 | ||
530893b2 MB |
89 | ;; A `category-symbol' property for the default button type |
90 | (put 'button 'button-category-symbol 'default-button) | |
91 | ||
0c26f463 MB |
92 | \f |
93 | ;; Button types (which can be used to hold default properties for buttons) | |
94 | ||
ded42dd3 MB |
95 | ;; Because button-type properties are inherited by buttons using the |
96 | ;; special `category' property (implemented by both overlays and | |
97 | ;; text-properties), we need to store them on a symbol to which the | |
98 | ;; `category' properties can point. Instead of using the symbol that's | |
99 | ;; the name of each button-type, however, we use a separate symbol (with | |
100 | ;; `-button' appended, and uninterned) to store the properties. This is | |
101 | ;; to avoid name clashes. | |
102 | ||
103 | ;; [this is an internal function] | |
104 | (defsubst button-category-symbol (type) | |
105 | "Return the symbol used by button-type TYPE to store properties. | |
106 | Buttons inherit them by setting their `category' property to that symbol." | |
107 | (or (get type 'button-category-symbol) | |
108 | (error "Unknown button type `%s'" type))) | |
109 | ||
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110 | ;;;###autoload |
111 | (defun define-button-type (name &rest properties) | |
112 | "Define a `button type' called NAME. | |
113 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
114 | specifying properties to use as defaults for buttons with this type | |
115 | \(a button's type may be set by giving it a `type' property when | |
ded42dd3 MB |
116 | creating the button). |
117 | ||
118 | The property `supertype' may be used to specify a button-type from which | |
119 | NAME inherits its default property values \(however, the inheritance | |
120 | happens only when NAME is defined; subsequent changes to a supertype are | |
121 | not reflected in its subtypes)." | |
122 | (let* ((catsym (make-symbol (concat (symbol-name name) "-button"))) | |
530893b2 MB |
123 | (supertype |
124 | (or (plist-get properties 'supertype) | |
125 | (plist-get properties :supertype))) | |
ded42dd3 MB |
126 | (super-catsym |
127 | (if supertype (button-category-symbol supertype) 'default-button))) | |
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128 | ;; Provide a link so that it's easy to find the real symbol. |
129 | (put name 'button-category-symbol catsym) | |
130 | ;; Initialize NAME's properties using the global defaults. | |
ded42dd3 | 131 | (let ((default-props (symbol-plist super-catsym))) |
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132 | (while default-props |
133 | (put catsym (pop default-props) (pop default-props)))) | |
134 | ;; Add NAME as the `type' property, which will then be returned as | |
135 | ;; the type property of individual buttons. | |
136 | (put catsym 'type name) | |
137 | ;; Add the properties in PROPERTIES to the real symbol. | |
138 | (while properties | |
530893b2 MB |
139 | (let ((prop (pop properties))) |
140 | (when (eq prop :supertype) | |
141 | (setq prop 'supertype)) | |
142 | (put catsym prop (pop properties)))) | |
0c26f463 MB |
143 | name)) |
144 | ||
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145 | (defun button-type-put (type prop val) |
146 | "Set the button-type TYPE's PROP property to VAL." | |
147 | (put (button-category-symbol type) prop val)) | |
148 | ||
149 | (defun button-type-get (type prop) | |
150 | "Get the property of button-type TYPE named PROP." | |
151 | (get (button-category-symbol type) prop)) | |
152 | ||
ded42dd3 MB |
153 | (defun button-type-subtype-p (type supertype) |
154 | "Return t if button-type TYPE is a subtype of SUPERTYPE." | |
155 | (or (eq type supertype) | |
156 | (and type | |
157 | (button-type-subtype-p (button-type-get type 'supertype) | |
158 | supertype)))) | |
159 | ||
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160 | \f |
161 | ;; Button properties and other attributes | |
162 | ||
163 | (defun button-start (button) | |
164 | "Return the position at which BUTTON starts." | |
165 | (if (overlayp button) | |
166 | (overlay-start button) | |
167 | ;; Must be a text-property button. | |
168 | (or (previous-single-property-change (1+ button) 'button) | |
169 | (point-min)))) | |
170 | ||
171 | (defun button-end (button) | |
172 | "Return the position at which BUTTON ends." | |
173 | (if (overlayp button) | |
174 | (overlay-end button) | |
175 | ;; Must be a text-property button. | |
176 | (or (next-single-property-change button 'button) | |
177 | (point-max)))) | |
178 | ||
179 | (defun button-get (button prop) | |
180 | "Get the property of button BUTTON named PROP." | |
181 | (if (overlayp button) | |
182 | (overlay-get button prop) | |
183 | ;; Must be a text-property button. | |
184 | (get-text-property button prop))) | |
185 | ||
186 | (defun button-put (button prop val) | |
187 | "Set BUTTON's PROP property to VAL." | |
188 | ;; Treat some properties specially. | |
530893b2 | 189 | (cond ((memq prop '(type :type)) |
0c26f463 MB |
190 | ;; We translate a `type' property a `category' property, since |
191 | ;; that's what's actually used by overlays/text-properties for | |
192 | ;; inheriting properties. | |
193 | (setq prop 'category) | |
194 | (setq val (button-category-symbol val))) | |
195 | ((eq prop 'category) | |
196 | ;; Disallow updating the `category' property directly. | |
197 | (error "Button `category' property may not be set directly"))) | |
198 | ;; Add the property. | |
199 | (if (overlayp button) | |
200 | (overlay-put button prop val) | |
201 | ;; Must be a text-property button. | |
202 | (put-text-property | |
203 | (or (previous-single-property-change (1+ button) 'button) | |
204 | (point-min)) | |
205 | (or (next-single-property-change button 'button) | |
206 | (point-max)) | |
207 | prop val))) | |
208 | ||
1e00f720 | 209 | (defsubst button-activate (button &optional use-mouse-action) |
d6bc0bdc MB |
210 | "Call BUTTON's action property. |
211 | If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action | |
212 | instead of its normal action; if the button has no mouse-action, | |
213 | the normal action is used instead." | |
214 | (funcall (or (and use-mouse-action (button-get button 'mouse-action)) | |
215 | (button-get button 'action)) | |
216 | button)) | |
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217 | |
218 | (defun button-label (button) | |
219 | "Return BUTTON's text label." | |
220 | (buffer-substring-no-properties (button-start button) (button-end button))) | |
221 | ||
530893b2 MB |
222 | (defsubst button-type (button) |
223 | (button-get button 'type)) | |
224 | ||
ded42dd3 MB |
225 | (defun button-has-type-p (button type) |
226 | "Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes." | |
227 | (button-type-subtype-p (button-get button 'type) type)) | |
228 | ||
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229 | \f |
230 | ;; Creating overlay buttons | |
231 | ||
232 | ;;;###autoload | |
233 | (defun make-button (beg end &rest properties) | |
234 | "Make a button from BEG to END in the current buffer. | |
235 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
236 | specifying properties to add to the button. In particular, the `type' | |
237 | property may be used to specify a button-type from which to inherit | |
238 | other properties; see `define-button-type'. | |
239 | ||
240 | Also see `make-text-button', `insert-button'." | |
241 | (let ((overlay (make-overlay beg end nil t nil))) | |
242 | (while properties | |
243 | (button-put overlay (pop properties) (pop properties))) | |
244 | ;; Put a pointer to the button in the overlay, so it's easy to get | |
245 | ;; when we don't actually have a reference to the overlay. | |
246 | (overlay-put overlay 'button overlay) | |
247 | ;; If the user didn't specify a type, use the default. | |
248 | (unless (overlay-get overlay 'category) | |
249 | (overlay-put overlay 'category 'default-button)) | |
250 | ;; OVERLAY is the button, so return it | |
251 | overlay)) | |
252 | ||
253 | ;;;###autoload | |
254 | (defun insert-button (label &rest properties) | |
255 | "Insert a button with the label LABEL. | |
256 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
257 | specifying properties to add to the button. In particular, the `type' | |
258 | property may be used to specify a button-type from which to inherit | |
259 | other properties; see `define-button-type'. | |
260 | ||
261 | Also see `insert-text-button', `make-button'." | |
262 | (apply #'make-button | |
263 | (prog1 (point) (insert label)) | |
264 | (point) | |
265 | properties)) | |
266 | ||
267 | \f | |
268 | ;; Creating text-property buttons | |
269 | ||
270 | ;;;###autoload | |
271 | (defun make-text-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, | |
274 | specifying properties to add to the button. In particular, the `type' | |
275 | property may be used to specify a button-type from which to inherit | |
276 | other properties; see `define-button-type'. | |
277 | ||
278 | This function is like `make-button', except that the button is actually | |
279 | part of the text instead of being a property of the buffer. Creating | |
280 | large numbers of buttons can also be somewhat faster using | |
281 | `make-text-button'. | |
282 | ||
283 | Also see `insert-text-button'." | |
284 | (let (prop val) | |
285 | (while properties | |
286 | (setq prop (pop properties)) | |
287 | (setq val (pop properties)) | |
288 | ;; Note that all the following code is basically equivalent to | |
289 | ;; `button-put', but we can do it much more efficiently since we | |
290 | ;; already have BEG and END. | |
530893b2 | 291 | (cond ((memq prop '(type :type)) |
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292 | ;; We translate a `type' property into a `category' |
293 | ;; property, since that's what's actually used by | |
294 | ;; text-properties for inheritance. | |
295 | (setq prop 'category) | |
296 | (setq val (button-category-symbol val))) | |
297 | ((eq prop 'category) | |
298 | ;; Disallow setting the `category' property directly. | |
299 | (error "Button `category' property may not be set directly"))) | |
300 | ;; Add the property. | |
301 | (put-text-property beg end prop val))) | |
302 | ;; Return something that can be used to get at the button. | |
303 | beg) | |
304 | ||
305 | ;;;###autoload | |
306 | (defun insert-text-button (label &rest properties) | |
307 | "Insert a button with the label LABEL. | |
308 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
309 | specifying properties to add to the button. In particular, the `type' | |
310 | property may be used to specify a button-type from which to inherit | |
311 | other properties; see `define-button-type'. | |
312 | ||
313 | This function is like `insert-button', except that the button is | |
314 | actually part of the text instead of being a property of the buffer. | |
315 | Creating large numbers of buttons can also be somewhat faster using | |
316 | `insert-text-button'. | |
317 | ||
318 | Also see `make-text-button'." | |
319 | (apply #'make-text-button | |
320 | (prog1 (point) (insert label)) | |
321 | (point) | |
322 | properties)) | |
323 | ||
324 | \f | |
325 | ;; Finding buttons in a buffer | |
326 | ||
327 | (defun button-at (pos) | |
328 | "Return the button at position POS in the current buffer, or nil." | |
329 | (let ((button (get-char-property pos 'button))) | |
330 | (if (or (overlayp button) (null button)) | |
331 | button | |
332 | ;; Must be a text-property button; return a marker pointing to it. | |
333 | (copy-marker pos t)))) | |
334 | ||
fee34a28 MB |
335 | (defun next-button (pos &optional count-current) |
336 | "Return the next button after position POS in the current buffer. | |
0c26f463 | 337 | If COUNT-CURRENT is non-nil, count any button at POS in the search, |
fee34a28 | 338 | instead of starting at the next button." |
0c26f463 MB |
339 | (unless count-current |
340 | ;; Search for the next button boundary. | |
341 | (setq pos (next-single-char-property-change pos 'button))) | |
fee34a28 MB |
342 | (and (< pos (point-max)) |
343 | (or (button-at pos) | |
0c26f463 MB |
344 | ;; We must have originally been on a button, and are now in |
345 | ;; the inter-button space. Recurse to find a button. | |
fee34a28 | 346 | (next-button pos)))) |
0c26f463 | 347 | |
fee34a28 | 348 | (defun previous-button (pos &optional count-current) |
0c26f463 | 349 | "Return the Nth button before position POS in the current buffer. |
0c26f463 | 350 | If COUNT-CURRENT is non-nil, count any button at POS in the search, |
fee34a28 MB |
351 | instead of starting at the next button." |
352 | (unless count-current | |
353 | (setq pos (previous-single-char-property-change pos 'button))) | |
354 | (and (> pos (point-min)) | |
355 | (or (button-at (1- pos)) | |
356 | ;; We must have originally been on a button, and are now in | |
357 | ;; the inter-button space. Recurse to find a button. | |
358 | (previous-button pos)))) | |
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359 | |
360 | \f | |
361 | ;; User commands | |
362 | ||
d6bc0bdc | 363 | (defun push-button (&optional pos use-mouse-action) |
0c26f463 MB |
364 | "Perform the action specified by a button at location POS. |
365 | POS may be either a buffer position or a mouse-event. | |
d6bc0bdc MB |
366 | If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action |
367 | instead of its normal action; if the button has no mouse-action, | |
368 | the normal action is used instead. | |
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369 | POS defaults to point, except when `push-button' is invoked |
370 | interactively as the result of a mouse-event, in which case, the | |
371 | mouse event is used. | |
372 | If there's no button at POS, do nothing and return nil, otherwise | |
373 | return t." | |
374 | (interactive | |
375 | (list (if (integerp last-command-event) (point) last-command-event))) | |
376 | (if (and (not (integerp pos)) (eventp pos)) | |
377 | ;; POS is a mouse event; switch to the proper window/buffer | |
378 | (let ((posn (event-start pos))) | |
379 | (with-current-buffer (window-buffer (posn-window posn)) | |
d6bc0bdc | 380 | (push-button (posn-point posn) t))) |
0c26f463 MB |
381 | ;; POS is just normal position |
382 | (let ((button (button-at (or pos (point))))) | |
383 | (if (not button) | |
384 | nil | |
d6bc0bdc | 385 | (button-activate button use-mouse-action) |
0c26f463 MB |
386 | t)))) |
387 | ||
388 | (defun forward-button (n &optional wrap display-message) | |
389 | "Move to the Nth next button, or Nth previous button if N is negative. | |
fee34a28 | 390 | If N is 0, move to the start of any button at point. |
0c26f463 MB |
391 | If WRAP is non-nil, moving past either end of the buffer continues from the |
392 | other end. | |
393 | If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed. | |
fee34a28 | 394 | Any button with a non-nil `skip' property is skipped over. |
0c26f463 MB |
395 | Returns the button found." |
396 | (interactive "p\nd\nd") | |
fee34a28 MB |
397 | (let (button) |
398 | (if (zerop n) | |
399 | ;; Move to start of current button | |
400 | (if (setq button (button-at (point))) | |
401 | (goto-char (button-start button))) | |
402 | ;; Move to Nth next button | |
403 | (let ((iterator (if (> n 0) #'next-button #'previous-button)) | |
404 | (wrap-start (if (> n 0) (point-min) (point-max)))) | |
405 | (setq n (abs n)) | |
406 | (setq button t) ; just to start the loop | |
407 | (while (and (> n 0) button) | |
408 | (setq button (funcall iterator (point))) | |
409 | (when (and (not button) wrap) | |
410 | (setq button (funcall iterator wrap-start t))) | |
411 | (when button | |
412 | (goto-char (button-start button)) | |
413 | (unless (button-get button 'skip) | |
414 | (setq n (1- n))))))) | |
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415 | (if (null button) |
416 | (error (if wrap "No buttons!" "No more buttons")) | |
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417 | (let ((msg (and display-message (button-get button 'help-echo)))) |
418 | (when msg | |
419 | (message "%s" msg))) | |
420 | button))) | |
421 | ||
422 | (defun backward-button (n &optional wrap display-message) | |
423 | "Move to the Nth previous button, or Nth next button if N is negative. | |
fee34a28 | 424 | If N is 0, move to the start of any button at point. |
0c26f463 MB |
425 | If WRAP is non-nil, moving past either end of the buffer continues from the |
426 | other end. | |
427 | If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed. | |
fee34a28 | 428 | Any button with a non-nil `skip' property is skipped over. |
0c26f463 MB |
429 | Returns the button found." |
430 | (interactive "p\nd\nd") | |
431 | (forward-button (- n) wrap display-message)) | |
432 | ||
433 | ||
434 | (provide 'button) | |
435 | ||
436 | ;;; button.el ends here |