Line data Source code
1 : ;;; button.el --- clickable buttons
2 : ;;
3 : ;; Copyright (C) 2001-2017 Free Software Foundation, Inc.
4 : ;;
5 : ;; Author: Miles Bader <miles@gnu.org>
6 : ;; Keywords: extensions
7 : ;; Package: emacs
8 : ;;
9 : ;; This file is part of GNU Emacs.
10 : ;;
11 : ;; GNU Emacs is free software: you can redistribute it and/or modify
12 : ;; it under the terms of the GNU General Public License as published by
13 : ;; the Free Software Foundation, either version 3 of the License, or
14 : ;; (at your option) any later version.
15 :
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.
20 :
21 : ;; You should have received a copy of the GNU General Public License
22 : ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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
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.
43 : ;;
44 : ;; Using `define-button-type' to define default properties for buttons
45 : ;; is not necessary, but it is encouraged, since doing so makes the
46 : ;; resulting code clearer and more efficient.
47 : ;;
48 :
49 : ;;; Code:
50 :
51 :
52 : ;; Globals
53 :
54 : ;; Use color for the MS-DOS port because it doesn't support underline.
55 : ;; FIXME if MS-DOS correctly answers the (supports) question, it need
56 : ;; no longer be a special case.
57 : (defface button '((t :inherit link))
58 : "Default face used for buttons."
59 : :group 'basic-faces)
60 :
61 : (defvar button-map
62 : (let ((map (make-sparse-keymap)))
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)
66 : (define-key map [mouse-2] 'push-button)
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)
72 : map)
73 : "Keymap used by buttons.")
74 :
75 : (defvar button-buffer-map
76 : (let ((map (make-sparse-keymap)))
77 : (define-key map [?\t] 'forward-button)
78 : (define-key map "\e\t" 'backward-button)
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)
89 : ;; action may be either a function to call, or a marker to go to
90 : (put 'default-button 'action 'ignore)
91 : (put 'default-button 'help-echo (purecopy "mouse-2, RET: Push this button"))
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)
97 :
98 : ;; A `category-symbol' property for the default button type
99 : (put 'button 'button-category-symbol 'default-button)
100 :
101 :
102 : ;; Button types (which can be used to hold default properties for buttons)
103 :
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 57 : (or (get type 'button-category-symbol)
117 57 : (error "Unknown button type `%s'" type)))
118 :
119 : (defun define-button-type (name &rest properties)
120 : "Define a `button type' called NAME (a symbol).
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
124 : creating the button, using the :type keyword argument).
125 :
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)."
130 57 : (let ((catsym (make-symbol (concat (symbol-name name) "-button")))
131 : (super-catsym
132 57 : (button-category-symbol
133 57 : (or (plist-get properties 'supertype)
134 57 : (plist-get properties :supertype)
135 57 : 'button))))
136 : ;; Provide a link so that it's easy to find the real symbol.
137 57 : (put name 'button-category-symbol catsym)
138 : ;; Initialize NAME's properties using the global defaults.
139 57 : (let ((default-props (symbol-plist super-catsym)))
140 617 : (while default-props
141 1120 : (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 57 : (put catsym 'type name)
145 : ;; Add the properties in PROPERTIES to the real symbol.
146 221 : (while properties
147 328 : (let ((prop (pop properties)))
148 164 : (when (eq prop :supertype)
149 164 : (setq prop 'supertype))
150 328 : (put catsym prop (pop properties))))
151 : ;; Make sure there's a `supertype' property
152 57 : (unless (get catsym 'supertype)
153 57 : (put catsym 'supertype 'button))
154 57 : name))
155 :
156 : (defun button-type-put (type prop val)
157 : "Set the button-type TYPE's PROP property to VAL."
158 0 : (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 0 : (get (button-category-symbol type) prop))
163 :
164 : (defun button-type-subtype-p (type supertype)
165 : "Return t if button-type TYPE is a subtype of SUPERTYPE."
166 0 : (or (eq type supertype)
167 0 : (and type
168 0 : (button-type-subtype-p (button-type-get type 'supertype)
169 0 : supertype))))
170 :
171 :
172 : ;; Button properties and other attributes
173 :
174 : (defun button-start (button)
175 : "Return the position at which BUTTON starts."
176 0 : (if (overlayp button)
177 0 : (overlay-start button)
178 : ;; Must be a text-property button.
179 0 : (or (previous-single-property-change (1+ button) 'button)
180 0 : (point-min))))
181 :
182 : (defun button-end (button)
183 : "Return the position at which BUTTON ends."
184 0 : (if (overlayp button)
185 0 : (overlay-end button)
186 : ;; Must be a text-property button.
187 0 : (or (next-single-property-change button 'button)
188 0 : (point-max))))
189 :
190 : (defun button-get (button prop)
191 : "Get the property of button BUTTON named PROP."
192 0 : (cond ((overlayp button)
193 0 : (overlay-get button prop))
194 0 : ((button--area-button-p button)
195 0 : (get-text-property (cdr button)
196 0 : prop (button--area-button-string button)))
197 0 : ((markerp button)
198 0 : (get-text-property button prop (marker-buffer button)))
199 : (t ; Must be a text-property button.
200 0 : (get-text-property button prop))))
201 :
202 : (defun button-put (button prop val)
203 : "Set BUTTON's PROP property to VAL."
204 : ;; Treat some properties specially.
205 0 : (cond ((memq prop '(type :type))
206 : ;; We translate a `type' property a `category' property, since
207 : ;; that's what's actually used by overlays/text-properties for
208 : ;; inheriting properties.
209 0 : (setq prop 'category)
210 0 : (setq val (button-category-symbol val)))
211 0 : ((eq prop 'category)
212 : ;; Disallow updating the `category' property directly.
213 0 : (error "Button `category' property may not be set directly")))
214 : ;; Add the property.
215 0 : (cond ((overlayp button)
216 0 : (overlay-put button prop val))
217 0 : ((button--area-button-p button)
218 0 : (setq button (button--area-button-string button))
219 0 : (put-text-property 0 (length button) prop val button))
220 : (t ; Must be a text-property button.
221 0 : (put-text-property
222 0 : (or (previous-single-property-change (1+ button) 'button)
223 0 : (point-min))
224 0 : (or (next-single-property-change button 'button)
225 0 : (point-max))
226 0 : prop val))))
227 :
228 : (defun button-activate (button &optional use-mouse-action)
229 : "Call BUTTON's `action' property.
230 : If USE-MOUSE-ACTION is non-nil, invoke the button's `mouse-action'
231 : property instead of `action'; if the button has no `mouse-action',
232 : the value of `action' is used instead.
233 :
234 : The action can either be a marker or a function. If it's a
235 : marker then goto it. Otherwise it it is a function then it is
236 : called with BUTTON as only argument. BUTTON is either an
237 : overlay, a buffer position, or (for buttons in the mode-line or
238 : header-line) a string."
239 0 : (let ((action (or (and use-mouse-action (button-get button 'mouse-action))
240 0 : (button-get button 'action))))
241 0 : (if (markerp action)
242 0 : (save-selected-window
243 0 : (select-window (display-buffer (marker-buffer action)))
244 0 : (goto-char action)
245 0 : (recenter 0))
246 0 : (funcall action button))))
247 :
248 : (defun button-label (button)
249 : "Return BUTTON's text label."
250 0 : (if (button--area-button-p button)
251 0 : (substring-no-properties (button--area-button-string button))
252 0 : (buffer-substring-no-properties (button-start button)
253 0 : (button-end button))))
254 :
255 : (defsubst button-type (button)
256 : "Return BUTTON's button-type."
257 0 : (button-get button 'type))
258 :
259 : (defun button-has-type-p (button type)
260 : "Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes."
261 0 : (button-type-subtype-p (button-get button 'type) type))
262 :
263 : (defun button--area-button-p (b)
264 : "Return non-nil if BUTTON is an area button.
265 : Such area buttons are used for buttons in the mode-line and header-line."
266 0 : (stringp (car-safe b)))
267 :
268 : (defalias 'button--area-button-string #'car
269 : "Return area button BUTTON's button-string.")
270 :
271 : ;; Creating overlay buttons
272 :
273 : (defun make-button (beg end &rest properties)
274 : "Make a button from BEG to END in the current buffer.
275 : The remaining arguments form a sequence of PROPERTY VALUE pairs,
276 : specifying properties to add to the button.
277 : In addition, the keyword argument :type may be used to specify a
278 : button-type from which to inherit other properties; see
279 : `define-button-type'.
280 :
281 : Also see `make-text-button', `insert-button'."
282 0 : (let ((overlay (make-overlay beg end nil t nil)))
283 0 : (while properties
284 0 : (button-put overlay (pop properties) (pop properties)))
285 : ;; Put a pointer to the button in the overlay, so it's easy to get
286 : ;; when we don't actually have a reference to the overlay.
287 0 : (overlay-put overlay 'button overlay)
288 : ;; If the user didn't specify a type, use the default.
289 0 : (unless (overlay-get overlay 'category)
290 0 : (overlay-put overlay 'category 'default-button))
291 : ;; OVERLAY is the button, so return it
292 0 : overlay))
293 :
294 : (defun insert-button (label &rest properties)
295 : "Insert a button with the label LABEL.
296 : The remaining arguments form a sequence of PROPERTY VALUE pairs,
297 : specifying properties to add to the button.
298 : In addition, the keyword argument :type may be used to specify a
299 : button-type from which to inherit other properties; see
300 : `define-button-type'.
301 :
302 : Also see `insert-text-button', `make-button'."
303 0 : (apply #'make-button
304 0 : (prog1 (point) (insert label))
305 0 : (point)
306 0 : properties))
307 :
308 :
309 : ;; Creating text-property buttons
310 :
311 : (defun make-text-button (beg end &rest properties)
312 : "Make a button from BEG to END in the current buffer.
313 : The remaining arguments form a sequence of PROPERTY VALUE pairs,
314 : specifying properties to add to the button.
315 : In addition, the keyword argument :type may be used to specify a
316 : button-type from which to inherit other properties; see
317 : `define-button-type'.
318 :
319 : This function is like `make-button', except that the button is actually
320 : part of the text instead of being a property of the buffer. That is,
321 : this function uses text properties, the other uses overlays.
322 : Creating large numbers of buttons can also be somewhat faster
323 : using `make-text-button'. Note, however, that if there is an existing
324 : face property at the site of the button, the button face may not be visible.
325 : You may want to use `make-button' in that case.
326 :
327 : BEG can also be a string, in which case it is made into a button.
328 :
329 : Also see `insert-text-button'."
330 0 : (let ((object nil)
331 : (type-entry
332 0 : (or (plist-member properties 'type)
333 0 : (plist-member properties :type))))
334 0 : (when (stringp beg)
335 0 : (setq object beg beg 0 end (length object)))
336 : ;; Disallow setting the `category' property directly.
337 0 : (when (plist-get properties 'category)
338 0 : (error "Button `category' property may not be set directly"))
339 0 : (if (null type-entry)
340 : ;; The user didn't specify a `type' property, use the default.
341 0 : (setq properties (cons 'category (cons 'default-button properties)))
342 : ;; The user did specify a `type' property. Translate it into a
343 : ;; `category' property, which is what's actually used by
344 : ;; text-properties for inheritance.
345 0 : (setcar type-entry 'category)
346 0 : (setcar (cdr type-entry)
347 0 : (button-category-symbol (car (cdr type-entry)))))
348 : ;; Now add all the text properties at once
349 0 : (add-text-properties beg end
350 : ;; Each button should have a non-eq `button'
351 : ;; property so that next-single-property-change can
352 : ;; detect boundaries reliably.
353 0 : (cons 'button (cons (list t) properties))
354 0 : object)
355 : ;; Return something that can be used to get at the button.
356 0 : (or object beg)))
357 :
358 : (defun insert-text-button (label &rest properties)
359 : "Insert a button with the label LABEL.
360 : The remaining arguments form a sequence of PROPERTY VALUE pairs,
361 : specifying properties to add to the button.
362 : In addition, the keyword argument :type may be used to specify a
363 : button-type from which to inherit other properties; see
364 : `define-button-type'.
365 :
366 : This function is like `insert-button', except that the button is
367 : actually part of the text instead of being a property of the buffer.
368 : Creating large numbers of buttons can also be somewhat faster using
369 : `insert-text-button'.
370 :
371 : Also see `make-text-button'."
372 0 : (apply #'make-text-button
373 0 : (prog1 (point) (insert label))
374 0 : (point)
375 0 : properties))
376 :
377 :
378 : ;; Finding buttons in a buffer
379 :
380 : (defun button-at (pos)
381 : "Return the button at position POS in the current buffer, or nil.
382 : If the button at POS is a text property button, the return value
383 : is a marker pointing to POS."
384 0 : (let ((button (get-char-property pos 'button)))
385 0 : (if (or (overlayp button) (null button))
386 0 : button
387 : ;; Must be a text-property button; return a marker pointing to it.
388 0 : (copy-marker pos t))))
389 :
390 : (defun next-button (pos &optional count-current)
391 : "Return the next button after position POS in the current buffer.
392 : If COUNT-CURRENT is non-nil, count any button at POS in the search,
393 : instead of starting at the next button."
394 0 : (unless count-current
395 : ;; Search for the next button boundary.
396 0 : (setq pos (next-single-char-property-change pos 'button)))
397 0 : (and (< pos (point-max))
398 0 : (or (button-at pos)
399 : ;; We must have originally been on a button, and are now in
400 : ;; the inter-button space. Recurse to find a button.
401 0 : (next-button pos))))
402 :
403 : (defun previous-button (pos &optional count-current)
404 : "Return the previous button before position POS in the current buffer.
405 : If COUNT-CURRENT is non-nil, count any button at POS in the search,
406 : instead of starting at the next button."
407 0 : (let ((button (button-at pos)))
408 0 : (if button
409 0 : (if count-current
410 0 : button
411 : ;; We started out on a button, so move to its start and look
412 : ;; for the previous button boundary.
413 0 : (setq pos (previous-single-char-property-change
414 0 : (button-start button) 'button))
415 0 : (let ((new-button (button-at pos)))
416 0 : (if new-button
417 : ;; We are in a button again; this can happen if there
418 : ;; are adjacent buttons (or at bob).
419 0 : (unless (= pos (button-start button)) new-button)
420 : ;; We are now in the space between buttons.
421 0 : (previous-button pos))))
422 : ;; We started out in the space between buttons.
423 0 : (setq pos (previous-single-char-property-change pos 'button))
424 0 : (or (button-at pos)
425 0 : (and (> pos (point-min))
426 0 : (button-at (1- pos)))))))
427 :
428 :
429 : ;; User commands
430 :
431 : (defun push-button (&optional pos use-mouse-action)
432 : "Perform the action specified by a button at location POS.
433 : POS may be either a buffer position or a mouse-event. If
434 : USE-MOUSE-ACTION is non-nil, invoke the button's `mouse-action'
435 : property instead of its `action' property; if the button has no
436 : `mouse-action', the value of `action' is used instead.
437 :
438 : The action in both cases may be either a function to call or a
439 : marker to display and is invoked using `button-activate' (which
440 : see).
441 :
442 : POS defaults to point, except when `push-button' is invoked
443 : interactively as the result of a mouse-event, in which case, the
444 : mouse event is used.
445 : If there's no button at POS, do nothing and return nil, otherwise
446 : return t."
447 : (interactive
448 0 : (list (if (integerp last-command-event) (point) last-command-event)))
449 0 : (if (and (not (integerp pos)) (eventp pos))
450 : ;; POS is a mouse event; switch to the proper window/buffer
451 0 : (let ((posn (event-start pos)))
452 0 : (with-current-buffer (window-buffer (posn-window posn))
453 0 : (if (posn-string posn)
454 : ;; mode-line, header-line, or display string event.
455 0 : (button-activate (posn-string posn) t)
456 0 : (push-button (posn-point posn) t))))
457 : ;; POS is just normal position
458 0 : (let ((button (button-at (or pos (point)))))
459 0 : (when button
460 0 : (button-activate button use-mouse-action)
461 0 : t))))
462 :
463 : (defun forward-button (n &optional wrap display-message)
464 : "Move to the Nth next button, or Nth previous button if N is negative.
465 : If N is 0, move to the start of any button at point.
466 : If WRAP is non-nil, moving past either end of the buffer continues from the
467 : other end.
468 : If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
469 : Any button with a non-nil `skip' property is skipped over.
470 : Returns the button found."
471 : (interactive "p\nd\nd")
472 0 : (let (button)
473 0 : (if (zerop n)
474 : ;; Move to start of current button
475 0 : (if (setq button (button-at (point)))
476 0 : (goto-char (button-start button)))
477 : ;; Move to Nth next button
478 0 : (let ((iterator (if (> n 0) #'next-button #'previous-button))
479 0 : (wrap-start (if (> n 0) (point-min) (point-max)))
480 : opoint fail)
481 0 : (setq n (abs n))
482 0 : (setq button t) ; just to start the loop
483 0 : (while (and (null fail) (> n 0) button)
484 0 : (setq button (funcall iterator (point)))
485 0 : (when (and (not button) wrap)
486 0 : (setq button (funcall iterator wrap-start t)))
487 0 : (when button
488 0 : (goto-char (button-start button))
489 : ;; Avoid looping forever (e.g., if all the buttons have
490 : ;; the `skip' property).
491 0 : (cond ((null opoint)
492 0 : (setq opoint (point)))
493 0 : ((= opoint (point))
494 0 : (setq fail t)))
495 0 : (unless (button-get button 'skip)
496 0 : (setq n (1- n)))))))
497 0 : (if (null button)
498 0 : (user-error (if wrap "No buttons!" "No more buttons"))
499 0 : (let ((msg (and display-message (button-get button 'help-echo))))
500 0 : (when msg
501 0 : (message "%s" msg)))
502 0 : button)))
503 :
504 : (defun backward-button (n &optional wrap display-message)
505 : "Move to the Nth previous button, or Nth next button if N is negative.
506 : If N is 0, move to the start of any button at point.
507 : If WRAP is non-nil, moving past either end of the buffer continues from the
508 : other end.
509 : If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
510 : Any button with a non-nil `skip' property is skipped over.
511 : Returns the button found."
512 : (interactive "p\nd\nd")
513 0 : (forward-button (- n) wrap display-message))
514 :
515 :
516 : (provide 'button)
517 :
518 : ;;; button.el ends here
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