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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) | |
78 | (put 'default-button 'action 'button-nop) | |
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 | ||
89 | ;; This is the default button action. | |
90 | (defun button-nop (button) | |
91 | "Do nothing to BUTTON." | |
92 | nil) | |
93 | ||
94 | \f | |
95 | ;; Button types (which can be used to hold default properties for buttons) | |
96 | ||
97 | ;;;###autoload | |
98 | (defun define-button-type (name &rest properties) | |
99 | "Define a `button type' called NAME. | |
100 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
101 | specifying properties to use as defaults for buttons with this type | |
102 | \(a button's type may be set by giving it a `type' property when | |
103 | creating the button)." | |
104 | ;; We use a different symbol than NAME (with `-button' appended, and | |
105 | ;; uninterned) to store the properties. This is to avoid name | |
106 | ;; clashes, since many very general properties may be include in | |
107 | ;; PROPERTIES. | |
108 | (let ((catsym (make-symbol (concat (symbol-name name) "-button")))) | |
109 | ;; Provide a link so that it's easy to find the real symbol. | |
110 | (put name 'button-category-symbol catsym) | |
111 | ;; Initialize NAME's properties using the global defaults. | |
112 | (let ((default-props (symbol-plist 'default-button))) | |
113 | (while default-props | |
114 | (put catsym (pop default-props) (pop default-props)))) | |
115 | ;; Add NAME as the `type' property, which will then be returned as | |
116 | ;; the type property of individual buttons. | |
117 | (put catsym 'type name) | |
118 | ;; Add the properties in PROPERTIES to the real symbol. | |
119 | (while properties | |
120 | (put catsym (pop properties) (pop properties))) | |
121 | name)) | |
122 | ||
123 | ;; [this is an internal function] | |
124 | (defsubst button-category-symbol (type) | |
125 | "Return the symbol used by button-type TYPE to store properties. | |
126 | Buttons inherit them by setting their `category' property to that symbol." | |
127 | (or (get type 'button-category-symbol) | |
128 | (error "Unknown button type `%s'" type))) | |
129 | ||
130 | (defun button-type-put (type prop val) | |
131 | "Set the button-type TYPE's PROP property to VAL." | |
132 | (put (button-category-symbol type) prop val)) | |
133 | ||
134 | (defun button-type-get (type prop) | |
135 | "Get the property of button-type TYPE named PROP." | |
136 | (get (button-category-symbol type) prop)) | |
137 | ||
138 | \f | |
139 | ;; Button properties and other attributes | |
140 | ||
141 | (defun button-start (button) | |
142 | "Return the position at which BUTTON starts." | |
143 | (if (overlayp button) | |
144 | (overlay-start button) | |
145 | ;; Must be a text-property button. | |
146 | (or (previous-single-property-change (1+ button) 'button) | |
147 | (point-min)))) | |
148 | ||
149 | (defun button-end (button) | |
150 | "Return the position at which BUTTON ends." | |
151 | (if (overlayp button) | |
152 | (overlay-end button) | |
153 | ;; Must be a text-property button. | |
154 | (or (next-single-property-change button 'button) | |
155 | (point-max)))) | |
156 | ||
157 | (defun button-get (button prop) | |
158 | "Get the property of button BUTTON named PROP." | |
159 | (if (overlayp button) | |
160 | (overlay-get button prop) | |
161 | ;; Must be a text-property button. | |
162 | (get-text-property button prop))) | |
163 | ||
164 | (defun button-put (button prop val) | |
165 | "Set BUTTON's PROP property to VAL." | |
166 | ;; Treat some properties specially. | |
167 | (cond ((eq prop 'type) | |
168 | ;; We translate a `type' property a `category' property, since | |
169 | ;; that's what's actually used by overlays/text-properties for | |
170 | ;; inheriting properties. | |
171 | (setq prop 'category) | |
172 | (setq val (button-category-symbol val))) | |
173 | ((eq prop 'category) | |
174 | ;; Disallow updating the `category' property directly. | |
175 | (error "Button `category' property may not be set directly"))) | |
176 | ;; Add the property. | |
177 | (if (overlayp button) | |
178 | (overlay-put button prop val) | |
179 | ;; Must be a text-property button. | |
180 | (put-text-property | |
181 | (or (previous-single-property-change (1+ button) 'button) | |
182 | (point-min)) | |
183 | (or (next-single-property-change button 'button) | |
184 | (point-max)) | |
185 | prop val))) | |
186 | ||
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187 | (defsubst button-activate (button use-mouse-action) |
188 | "Call BUTTON's action property. | |
189 | If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action | |
190 | instead of its normal action; if the button has no mouse-action, | |
191 | the normal action is used instead." | |
192 | (funcall (or (and use-mouse-action (button-get button 'mouse-action)) | |
193 | (button-get button 'action)) | |
194 | button)) | |
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195 | |
196 | (defun button-label (button) | |
197 | "Return BUTTON's text label." | |
198 | (buffer-substring-no-properties (button-start button) (button-end button))) | |
199 | ||
200 | \f | |
201 | ;; Creating overlay buttons | |
202 | ||
203 | ;;;###autoload | |
204 | (defun make-button (beg end &rest properties) | |
205 | "Make a button from BEG to END in the current buffer. | |
206 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
207 | specifying properties to add to the button. In particular, the `type' | |
208 | property may be used to specify a button-type from which to inherit | |
209 | other properties; see `define-button-type'. | |
210 | ||
211 | Also see `make-text-button', `insert-button'." | |
212 | (let ((overlay (make-overlay beg end nil t nil))) | |
213 | (while properties | |
214 | (button-put overlay (pop properties) (pop properties))) | |
215 | ;; Put a pointer to the button in the overlay, so it's easy to get | |
216 | ;; when we don't actually have a reference to the overlay. | |
217 | (overlay-put overlay 'button overlay) | |
218 | ;; If the user didn't specify a type, use the default. | |
219 | (unless (overlay-get overlay 'category) | |
220 | (overlay-put overlay 'category 'default-button)) | |
221 | ;; OVERLAY is the button, so return it | |
222 | overlay)) | |
223 | ||
224 | ;;;###autoload | |
225 | (defun insert-button (label &rest properties) | |
226 | "Insert a button with the label LABEL. | |
227 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
228 | specifying properties to add to the button. In particular, the `type' | |
229 | property may be used to specify a button-type from which to inherit | |
230 | other properties; see `define-button-type'. | |
231 | ||
232 | Also see `insert-text-button', `make-button'." | |
233 | (apply #'make-button | |
234 | (prog1 (point) (insert label)) | |
235 | (point) | |
236 | properties)) | |
237 | ||
238 | \f | |
239 | ;; Creating text-property buttons | |
240 | ||
241 | ;;;###autoload | |
242 | (defun make-text-button (beg end &rest properties) | |
243 | "Make a button from BEG to END in the current buffer. | |
244 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
245 | specifying properties to add to the button. In particular, the `type' | |
246 | property may be used to specify a button-type from which to inherit | |
247 | other properties; see `define-button-type'. | |
248 | ||
249 | This function is like `make-button', except that the button is actually | |
250 | part of the text instead of being a property of the buffer. Creating | |
251 | large numbers of buttons can also be somewhat faster using | |
252 | `make-text-button'. | |
253 | ||
254 | Also see `insert-text-button'." | |
255 | (let (prop val) | |
256 | (while properties | |
257 | (setq prop (pop properties)) | |
258 | (setq val (pop properties)) | |
259 | ;; Note that all the following code is basically equivalent to | |
260 | ;; `button-put', but we can do it much more efficiently since we | |
261 | ;; already have BEG and END. | |
262 | (cond ((eq prop 'type) | |
263 | ;; We translate a `type' property into a `category' | |
264 | ;; property, since that's what's actually used by | |
265 | ;; text-properties for inheritance. | |
266 | (setq prop 'category) | |
267 | (setq val (button-category-symbol val))) | |
268 | ((eq prop 'category) | |
269 | ;; Disallow setting the `category' property directly. | |
270 | (error "Button `category' property may not be set directly"))) | |
271 | ;; Add the property. | |
272 | (put-text-property beg end prop val))) | |
273 | ;; Return something that can be used to get at the button. | |
274 | beg) | |
275 | ||
276 | ;;;###autoload | |
277 | (defun insert-text-button (label &rest properties) | |
278 | "Insert a button with the label LABEL. | |
279 | The remaining arguments form a sequence of PROPERTY VALUE pairs, | |
280 | specifying properties to add to the button. In particular, the `type' | |
281 | property may be used to specify a button-type from which to inherit | |
282 | other properties; see `define-button-type'. | |
283 | ||
284 | This function is like `insert-button', except that the button is | |
285 | actually part of the text instead of being a property of the buffer. | |
286 | Creating large numbers of buttons can also be somewhat faster using | |
287 | `insert-text-button'. | |
288 | ||
289 | Also see `make-text-button'." | |
290 | (apply #'make-text-button | |
291 | (prog1 (point) (insert label)) | |
292 | (point) | |
293 | properties)) | |
294 | ||
295 | \f | |
296 | ;; Finding buttons in a buffer | |
297 | ||
298 | (defun button-at (pos) | |
299 | "Return the button at position POS in the current buffer, or nil." | |
300 | (let ((button (get-char-property pos 'button))) | |
301 | (if (or (overlayp button) (null button)) | |
302 | button | |
303 | ;; Must be a text-property button; return a marker pointing to it. | |
304 | (copy-marker pos t)))) | |
305 | ||
306 | (defun next-button (pos &optional n wrap count-current) | |
307 | "Return the Nth button after position POS in the current buffer. | |
308 | If N is negative, return the Nth button before POS. | |
309 | If no Nth button is found, return nil. | |
310 | If WRAP is non-nil, the search wraps around at the end of the buffer. | |
311 | If COUNT-CURRENT is non-nil, count any button at POS in the search, | |
312 | instead of starting at the next button." | |
313 | (when (null n) | |
314 | (setq n 1)) | |
315 | (if (< n 0) | |
316 | ;; reverse direction | |
317 | (previous-button pos (- n) wrap) | |
318 | (unless count-current | |
319 | ;; Search for the next button boundary. | |
320 | (setq pos (next-single-char-property-change pos 'button))) | |
321 | (let ((button (button-at pos))) | |
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322 | (cond ((and button (button-get button 'skip)) |
323 | ;; Found a button, but the button declines to be found; recurse. | |
324 | (next-button (button-start button) n wrap)) | |
325 | ((and button (>= n 2)) | |
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326 | ;; Found a button, but we want a different one; recurse. |
327 | (next-button (button-start button) (1- n) wrap)) | |
328 | (button | |
329 | ;; This is the button we want. | |
330 | button) | |
331 | ((= pos (point-max)) | |
332 | ;; Failed to find a button going forwards, either wrap or | |
333 | ;; return failure. | |
334 | (and wrap (next-button (point-min) n nil t))) | |
335 | (t | |
336 | ;; We must have originally been on a button, and are now in | |
337 | ;; the inter-button space. Recurse to find a button. | |
338 | (next-button pos n wrap)))))) | |
339 | ||
340 | (defun previous-button (pos &optional n wrap count-current) | |
341 | "Return the Nth button before position POS in the current buffer. | |
342 | If N is negative, return the Nth button after POS. | |
343 | If no Nth button is found, return nil. | |
344 | If WRAP is non-nil, the search wraps around at the beginning of the buffer. | |
345 | If COUNT-CURRENT is non-nil, count any button at POS in the search, | |
346 | instead of starting at the next button." | |
347 | (when (null n) | |
348 | (setq n 1)) | |
349 | (if (< n 0) | |
350 | ;; reverse direction | |
351 | (next-button pos (- n) wrap) | |
352 | (unless count-current | |
353 | (setq pos (previous-single-char-property-change pos 'button))) | |
354 | (let ((button (and (> pos (point-min)) (button-at (1- pos))))) | |
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355 | (cond ((and button (button-get button 'skip)) |
356 | ;; Found a button, but the button declines to be found; recurse. | |
357 | (previous-button (button-start button) n wrap)) | |
358 | ((and button (>= n 2)) | |
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359 | ;; Found a button, but we want a different one; recurse. |
360 | (previous-button (button-start button) (1- n) wrap)) | |
361 | (button | |
362 | ;; This is the button we want. | |
363 | button) | |
364 | ((= pos (point-min)) | |
365 | ;; Failed to find a button going backwards, either wrap | |
366 | ;; or return failure. | |
367 | (and wrap (previous-button (point-max) n nil t))) | |
368 | (t | |
369 | ;; We must have originally been on a button, and are now in | |
370 | ;; the inter-button space. Recurse to find a button. | |
371 | (previous-button pos (max n 1) wrap)))))) | |
372 | ||
373 | \f | |
374 | ;; User commands | |
375 | ||
d6bc0bdc | 376 | (defun push-button (&optional pos use-mouse-action) |
0c26f463 MB |
377 | "Perform the action specified by a button at location POS. |
378 | POS may be either a buffer position or a mouse-event. | |
d6bc0bdc MB |
379 | If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action |
380 | instead of its normal action; if the button has no mouse-action, | |
381 | the normal action is used instead. | |
0c26f463 MB |
382 | POS defaults to point, except when `push-button' is invoked |
383 | interactively as the result of a mouse-event, in which case, the | |
384 | mouse event is used. | |
385 | If there's no button at POS, do nothing and return nil, otherwise | |
386 | return t." | |
387 | (interactive | |
388 | (list (if (integerp last-command-event) (point) last-command-event))) | |
389 | (if (and (not (integerp pos)) (eventp pos)) | |
390 | ;; POS is a mouse event; switch to the proper window/buffer | |
391 | (let ((posn (event-start pos))) | |
392 | (with-current-buffer (window-buffer (posn-window posn)) | |
d6bc0bdc | 393 | (push-button (posn-point posn) t))) |
0c26f463 MB |
394 | ;; POS is just normal position |
395 | (let ((button (button-at (or pos (point))))) | |
396 | (if (not button) | |
397 | nil | |
d6bc0bdc | 398 | (button-activate button use-mouse-action) |
0c26f463 MB |
399 | t)))) |
400 | ||
401 | (defun forward-button (n &optional wrap display-message) | |
402 | "Move to the Nth next button, or Nth previous button if N is negative. | |
403 | If WRAP is non-nil, moving past either end of the buffer continues from the | |
404 | other end. | |
405 | If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed. | |
406 | Returns the button found." | |
407 | (interactive "p\nd\nd") | |
408 | (let ((button (next-button (point) n wrap))) | |
409 | (if (null button) | |
410 | (error (if wrap "No buttons!" "No more buttons")) | |
411 | (goto-char (button-start button)) | |
412 | (let ((msg (and display-message (button-get button 'help-echo)))) | |
413 | (when msg | |
414 | (message "%s" msg))) | |
415 | button))) | |
416 | ||
417 | (defun backward-button (n &optional wrap display-message) | |
418 | "Move to the Nth previous button, or Nth next button if N is negative. | |
419 | If WRAP is non-nil, moving past either end of the buffer continues from the | |
420 | other end. | |
421 | If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed. | |
422 | Returns the button found." | |
423 | (interactive "p\nd\nd") | |
424 | (forward-button (- n) wrap display-message)) | |
425 | ||
426 | ||
427 | (provide 'button) | |
428 | ||
429 | ;;; button.el ends here |