1 ;;; button.el --- clickable buttons
3 ;; Copyright (C) 2001-2014 Free Software Foundation, Inc.
5 ;; Author: Miles Bader <miles@gnu.org>
6 ;; Keywords: extensions
9 ;; This file is part of XEmacs.
11 ;; XEmacs 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.
16 ;; XEmacs 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.
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/>.
26 ;; This package defines functions for inserting and manipulating
27 ;; clickable buttons in Emacs buffers, such as might be used for help
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).
35 ;; Buttons can either use extents, in which case the button is
36 ;; represented by the extent 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 extents avoids this.
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.
54 (defface button '((t (:underline t)))
55 "Default face used for buttons."
59 (let ((map (make-sparse-keymap 'button-map)))
60 ;; The following definition needs to avoid using escape sequences that
61 ;; might get converted to ^M when building loaddefs.el
62 (define-key map [(control ?m)] 'push-button)
63 (define-key map [button2] 'push-button)
65 "Keymap used by buttons.")
67 (defvar button-buffer-map
68 (let ((map (make-sparse-keymap 'button-buffer-map)))
69 (define-key map [?\t] 'forward-button)
70 (define-key map "\e\t" 'backward-button)
71 (define-key map [backtab] 'backward-button)
73 "Keymap useful for buffers containing buttons.
74 Mode-specific keymaps may want to use this as their parent keymap.")
76 ;; Default properties for buttons
77 (put 'default-button 'face 'button)
78 (put 'default-button 'mouse-face 'highlight)
79 (put 'default-button 'keymap button-map)
80 (put 'default-button 'type 'button)
81 ;; action may be either a function to call, or a marker to go to
82 (put 'default-button 'action 'ignore)
83 (put 'default-button 'help-echo "mouse-2, RET: Push this button")
84 ;; Make extent buttons go away if their underlying text is deleted.
85 (put 'default-button 'detachable t)
86 ;; Prevent insertions adjacent to the text-property buttons from
87 ;; inheriting its properties.
88 (put 'default-button 'rear-nonsticky t)
90 ;; A `category-symbol' property for the default button type
91 (put 'button 'button-category-symbol 'default-button)
94 ;; Button types (which can be used to hold default properties for buttons)
96 ;; Because button-type properties are inherited by buttons using the
97 ;; special `category' property (implemented by both extents and
98 ;; text-properties), we need to store them on a symbol to which the
99 ;; `category' properties can point. Instead of using the symbol that's
100 ;; the name of each button-type, however, we use a separate symbol (with
101 ;; `-button' appended, and uninterned) to store the properties. This is
102 ;; to avoid name clashes.
104 ;; [this is an internal function]
105 (defsubst button-category-symbol (type)
106 "Return the symbol used by button-type TYPE to store properties.
107 Buttons inherit them by setting their `category' property to that symbol."
108 (or (get type 'button-category-symbol)
109 (error "Unknown button type `%s'" type)))
112 (defun define-button-type (name &rest properties)
113 "Define a `button type' called NAME (a symbol).
114 The remaining arguments form a sequence of PROPERTY VALUE pairs,
115 specifying properties to use as defaults for buttons with this type
116 \(a button's type may be set by giving it a `type' property when
117 creating the button, using the :type keyword argument).
119 In addition, the keyword argument :supertype may be used to specify a
120 button-type from which NAME inherits its default property values
121 \(however, the inheritance happens only when NAME is defined; subsequent
122 changes to a supertype are not reflected in its subtypes)."
123 (let ((catsym (make-symbol (concat (symbol-name name) "-button")))
125 (button-category-symbol
126 (or (plist-get properties 'supertype)
127 (plist-get properties :supertype)
129 ;; Provide a link so that it's easy to find the real symbol.
130 (put name 'button-category-symbol catsym)
131 ;; Initialize NAME's properties using the global defaults.
132 (let ((default-props (symbol-plist super-catsym)))
134 (put catsym (pop default-props) (pop default-props))))
135 ;; Add NAME as the `type' property, which will then be returned as
136 ;; the type property of individual buttons.
137 (put catsym 'type name)
138 ;; Add the properties in PROPERTIES to the real symbol.
140 (let ((prop (pop properties)))
141 (when (eq prop :supertype)
142 (setq prop 'supertype))
143 (put catsym prop (pop properties))))
144 ;; Make sure there's a `supertype' property
145 (unless (get catsym 'supertype)
146 (put catsym 'supertype 'button))
149 (defun button-type-put (type prop val)
150 "Set the button-type TYPE's PROP property to VAL."
151 (put (button-category-symbol type) prop val))
153 (defun button-type-get (type prop)
154 "Get the property of button-type TYPE named PROP."
155 (get (button-category-symbol type) prop))
157 (defun button-type-subtype-p (type supertype)
158 "Return t if button-type TYPE is a subtype of SUPERTYPE."
159 (or (eq type supertype)
161 (button-type-subtype-p (button-type-get type 'supertype)
165 ;; Button properties and other attributes
167 (defun button-start (button)
168 "Return the position at which BUTTON starts."
170 (extent-start-position button)
171 ;; Must be a text-property button.
172 (or (previous-single-property-change (1+ button) 'button)
175 (defun button-end (button)
176 "Return the position at which BUTTON ends."
178 (extent-end-position button)
179 ;; Must be a text-property button.
180 (or (next-single-property-change button 'button)
183 (defun button-get (button prop)
184 "Get the property of button BUTTON named PROP."
185 (cond ((extentp button)
186 (or (extent-property button prop)
187 (let ((category (extent-property button 'category)))
189 (get category prop)))))
190 ((button--area-button-p button)
191 (get-text-property (cdr button)
192 prop (button--area-button-string button)))
193 (t ; Must be a text-property button.
194 (get-text-property button prop))))
196 (defun button-put (button prop val)
197 "Set BUTTON's PROP property to VAL."
198 ;; Treat some properties specially.
199 (cond ((memq prop '(type :type))
200 ;; We translate a `type' property a `category' property, since
201 ;; that's what's actually used by extents/text-properties for
202 ;; inheriting properties.
203 (setq prop 'category)
204 (setq val (button-category-symbol val)))
206 ;; Disallow updating the `category' property directly.
207 (error "Button `category' property may not be set directly")))
209 (cond ((extentp button)
210 (set-extent-property button prop val))
211 ((button--area-button-p button)
212 (setq button (button--area-button-string button))
213 (put-text-property 0 (length button) prop val button))
214 (t ; Must be a text-property button.
216 (or (previous-single-property-change (1+ button) 'button)
218 (or (next-single-property-change button 'button)
223 (defun button-activate (button &optional use-mouse-action)
224 "Call BUTTON's action property.
225 If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
226 instead of its normal action; if the button has no mouse-action,
227 the normal action is used instead.
229 The action can either be a marker or a function. If it's a
230 marker then goto it. Otherwise if it is a function then it is
231 called with BUTTON as only argument. BUTTON is either an
232 extent, a buffer position, or (for buttons in the mode-line or
233 header-line) a string."
234 (let ((action (or (and use-mouse-action (button-get button 'mouse-action))
235 (button-get button 'action))))
237 (save-selected-window
238 (select-window (display-buffer (marker-buffer action)))
241 (funcall action button))))
243 (defun button-label (button)
244 "Return BUTTON's text label."
245 (if (button--area-button-p button)
246 (substring-no-properties (button--area-button-string button))
247 (buffer-substring-no-properties (button-start button)
248 (button-end button))))
250 (defsubst button-type (button)
251 "Return BUTTON's button-type."
252 (button-get button 'type))
254 (defun button-has-type-p (button type)
255 "Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes."
256 (button-type-subtype-p (button-get button 'type) type))
258 (defun button--area-button-p (b)
259 "Return non-nil if BUTTON is an area button.
260 Such area buttons are used for buttons in the mode-line and header-line."
261 (stringp (car-safe b)))
263 (defalias 'button--area-button-string #'car)
265 ;; Creating extent buttons
268 (defun make-button (beg end &rest properties)
269 "Make a button from BEG to END in the current buffer.
270 The remaining arguments form a sequence of PROPERTY VALUE pairs,
271 specifying properties to add to the button.
272 In addition, the keyword argument :type may be used to specify a
273 button-type from which to inherit other properties; see
274 `define-button-type'.
276 Also see `make-text-button', `insert-button'."
278 (setq beg (prog1 end (setq end beg))))
279 (let ((extent (make-extent beg end)))
280 (set-extent-property extent 'start-open t)
282 (button-put extent (pop properties) (pop properties)))
283 ;; Put a pointer to the button in the extent, so it's easy to get
284 ;; when we don't actually have a reference to the extent.
285 (set-extent-property extent 'button extent)
286 ;; If the user didn't specify a type, use the default.
287 (unless (extent-property extent 'category)
288 (set-extent-property extent 'category 'default-button))
289 ;; EXTENT is the button, so return it
293 (defun insert-button (label &rest properties)
294 "Insert a button with the label LABEL.
295 The remaining arguments form a sequence of PROPERTY VALUE pairs,
296 specifying properties to add to the button.
297 In addition, the keyword argument :type may be used to specify a
298 button-type from which to inherit other properties; see
299 `define-button-type'.
301 Also see `insert-text-button', `make-button'."
303 (prog1 (point) (insert label))
308 ;; Creating text-property buttons
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'.
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 extents.
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.
327 BEG can also be a string, in which case it is made into a button.
329 Also see `insert-text-button'."
332 (or (plist-member properties 'type)
333 (plist-member properties :type))))
335 (setq object beg beg 0 end (length object)))
336 ;; Disallow setting the `category' property directly.
337 (when (plist-get properties 'category)
338 (error "Button `category' property may not be set directly"))
339 (if (null type-entry)
340 ;; The user didn't specify a `type' property, use the default.
341 (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 (setcar type-entry 'category)
346 (setcar (cdr type-entry)
347 (button-category-symbol (car (cdr type-entry)))))
348 ;; Now add all the text properties at once
349 (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 (cons 'button (cons (list t) properties))
355 ;; Return something that can be used to get at the button.
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'.
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'.
371 Also see `make-text-button'."
372 (apply #'make-text-button
373 (prog1 (point) (insert label))
378 ;; Finding buttons in a buffer
381 (defun button-at (pos)
382 "Return the button at position POS in the current buffer, or nil.
383 If the button at POS is a text property button, the return value
384 is a marker pointing to POS."
385 (let ((button (get-char-property pos 'button)))
386 (if (or (extentp button) (null button))
388 ;; Must be a text-property button; return a marker pointing to it.
389 (copy-marker pos t))))
392 (defun next-button (pos &optional count-current)
393 "Return the next button after position POS in the current buffer.
394 If COUNT-CURRENT is non-nil, count any button at POS in the search,
395 instead of starting at the next button."
396 (unless count-current
397 ;; Search for the next button boundary.
398 (setq pos (next-single-char-property-change pos 'button)))
399 (and (< pos (point-max))
401 ;; We must have originally been on a button, and are now in
402 ;; the inter-button space. Recurse to find a button.
406 (defun previous-button (pos &optional count-current)
407 "Return the previous button before position POS in the current buffer.
408 If COUNT-CURRENT is non-nil, count any button at POS in the search,
409 instead of starting at the next button."
410 (let ((button (button-at pos)))
414 ;; We started out on a button, so move to its start and look
415 ;; for the previous button boundary.
416 (setq pos (previous-single-char-property-change
417 (button-start button) 'button))
418 (let ((new-button (button-at pos)))
420 ;; We are in a button again; this can happen if there
421 ;; are adjacent buttons (or at bob).
422 (unless (= pos (button-start button)) new-button)
423 ;; We are now in the space between buttons.
424 (previous-button pos))))
425 ;; We started out in the space between buttons.
426 (setq pos (previous-single-char-property-change pos 'button))
428 (and (> pos (point-min))
429 (button-at (1- pos)))))))
435 (defun push-button (&optional pos use-mouse-action)
436 "Perform the action specified by a button at location POS.
437 POS may be either a buffer position or a mouse-event. If
438 USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
439 instead of its normal action; if the button has no mouse-action,
440 the normal action is used instead. The action may be either a
441 function to call or a marker to display and is invoked using
442 `button-activate' (which see).
444 POS defaults to point, except when `push-button' is invoked
445 interactively as the result of a mouse-event, in which case, the
447 If there's no button at POS, do nothing and return nil, otherwise
450 (list (if (mouse-event-p last-command-event) last-command-event (point))))
451 (if (and (not (integerp pos)) (eventp pos))
452 ;; POS is a mouse event; switch to the proper window/buffer
453 (with-current-buffer (event-buffer pos)
454 (if (event-over-text-area-p pos)
455 (push-button (event-point pos) t)
456 (button-activate (event-point pos) t)))
457 ;; POS is just normal position
458 (let ((button (button-at (or pos (point)))))
460 (button-activate button use-mouse-action)
464 (defun forward-button (n &optional wrap display-message)
465 "Move to the Nth next button, or Nth previous button if N is negative.
466 If N is 0, move to the start of any button at point.
467 If WRAP is non-nil, moving past either end of the buffer continues from the
469 If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
470 Any button with a non-nil `skip' property is skipped over.
471 Returns the button found."
472 (interactive "p\nd\nd")
475 ;; Move to start of current button
476 (if (setq button (button-at (point)))
477 (goto-char (button-start button)))
478 ;; Move to Nth next button
479 (let ((iterator (if (> n 0) #'next-button #'previous-button))
480 (wrap-start (if (> n 0) (point-min) (point-max)))
483 (setq button t) ; just to start the loop
484 (while (and (null fail) (> n 0) button)
485 (setq button (funcall iterator (point)))
486 (when (and (not button) wrap)
487 (setq button (funcall iterator wrap-start t)))
489 (goto-char (button-start button))
490 ;; Avoid looping forever (e.g., if all the buttons have
491 ;; the `skip' property).
493 (setq opoint (point)))
496 (unless (button-get button 'skip)
499 (error (if wrap "No buttons!" "No more buttons"))
500 (let ((msg (and display-message (button-get button 'help-echo))))
506 (defun backward-button (n &optional wrap display-message)
507 "Move to the Nth previous button, or Nth next button if N is negative.
508 If N is 0, move to the start of any button at point.
509 If WRAP is non-nil, moving past either end of the buffer continues from the
511 If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
512 Any button with a non-nil `skip' property is skipped over.
513 Returns the button found."
514 (interactive "p\nd\nd")
515 (forward-button (- n) wrap display-message))
520 ;;; button.el ends here