1 ;;; button.el --- clickable buttons
3 ;; Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
4 ;; 2010, 2011, 2012 Free Software Foundation, Inc.
6 ;; Author: Miles Bader <miles@gnu.org>
7 ;; Keywords: extensions
9 ;; This file is part of GNU Emacs.
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.
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.
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 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.
44 ;; Using `define-button-type' to define default properties for buttons
45 ;; is not necessary, but it is is encouraged, since doing so makes the
46 ;; resulting code clearer and more efficient.
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
'((((type pc
) (class color
))
58 (:foreground
"lightblue"))
59 (((supports :underline t
)) :underline t
)
60 (t (:foreground
"lightblue")))
61 "Default face used for buttons."
65 (let ((map (make-sparse-keymap)))
66 ;; The following definition needs to avoid using escape sequences that
67 ;; might get converted to ^M when building loaddefs.el
68 (define-key map
[(control ?m
)] 'push-button
)
69 (define-key map
[mouse-2
] 'push-button
)
71 "Keymap used by buttons.")
73 (defvar button-buffer-map
74 (let ((map (make-sparse-keymap)))
75 (define-key map
[?
\t] 'forward-button
)
76 (define-key map
"\e\t" 'backward-button
)
77 (define-key map
[backtab] 'backward-button)
79 "Keymap useful for buffers containing buttons.
80 Mode-specific keymaps may want to use this as their parent keymap.")
82 ;; Default properties for buttons
83 (put 'default-button 'face 'button)
84 (put 'default-button 'mouse-face 'highlight)
85 (put 'default-button 'keymap button-map)
86 (put 'default-button 'type 'button)
87 ;; action may be either a function to call, or a marker to go to
88 (put 'default-button 'action 'ignore)
89 (put 'default-button 'help-echo (purecopy "mouse-2, RET: Push this button"))
90 ;; Make overlay buttons go away if their underlying text is deleted.
91 (put 'default-button 'evaporate t)
92 ;; Prevent insertions adjacent to the text-property buttons from
93 ;; inheriting its properties.
94 (put 'default-button 'rear-nonsticky t)
96 ;; A `category-symbol' property for the default button type
97 (put 'button 'button-category-symbol 'default-button)
100 ;; Button types (which can be used to hold default properties for buttons)
102 ;; Because button-type properties are inherited by buttons using the
103 ;; special `category' property (implemented by both overlays and
104 ;; text-properties), we need to store them on a symbol to which the
105 ;; `category' properties can point. Instead of using the symbol that's
106 ;; the name of each button-type, however, we use a separate symbol (with
107 ;; `-button' appended, and uninterned) to store the properties. This is
108 ;; to avoid name clashes.
110 ;; [this is an internal function]
111 (defsubst button-category-symbol (type)
112 "Return the symbol used by button-type TYPE to store properties.
113 Buttons inherit them by setting their `category' property to that symbol."
114 (or (get type 'button-category-symbol)
115 (error "Unknown button type `%s'" type)))
117 (defun define-button-type (name &rest properties)
118 "Define a `button type' called NAME (a symbol).
119 The remaining arguments form a sequence of PROPERTY VALUE pairs,
120 specifying properties to use as defaults for buttons with this type
121 \(a button's type may be set by giving it a `type' property when
122 creating the button, using the :type keyword argument).
124 In addition, the keyword argument :supertype may be used to specify a
125 button-type from which NAME inherits its default property values
126 \(however, the inheritance happens only when NAME is defined; subsequent
127 changes to a supertype are not reflected in its subtypes)."
128 (let ((catsym (make-symbol (concat (symbol-name name) "-button")))
130 (button-category-symbol
131 (or (plist-get properties 'supertype)
132 (plist-get properties :supertype)
134 ;; Provide a link so that it's easy to find the real symbol.
135 (put name 'button-category-symbol catsym)
136 ;; Initialize NAME's properties using the global defaults.
137 (let ((default-props (symbol-plist super-catsym)))
139 (put catsym (pop default-props) (pop default-props))))
140 ;; Add NAME as the `type' property, which will then be returned as
141 ;; the type property of individual buttons.
142 (put catsym 'type name)
143 ;; Add the properties in PROPERTIES to the real symbol.
145 (let ((prop (pop properties)))
146 (when (eq prop :supertype)
147 (setq prop 'supertype))
148 (put catsym prop (pop properties))))
149 ;; Make sure there's a `supertype' property
150 (unless (get catsym 'supertype)
151 (put catsym 'supertype 'button))
154 (defun button-type-put (type prop val)
155 "Set the button-type TYPE's PROP property to VAL."
156 (put (button-category-symbol type) prop val))
158 (defun button-type-get (type prop)
159 "Get the property of button-type TYPE named PROP."
160 (get (button-category-symbol type) prop))
162 (defun button-type-subtype-p (type supertype)
163 "Return t if button-type TYPE is a subtype of SUPERTYPE."
164 (or (eq type supertype)
166 (button-type-subtype-p (button-type-get type 'supertype)
170 ;; Button properties and other attributes
172 (defun button-start (button)
173 "Return the position at which BUTTON starts."
174 (if (overlayp button)
175 (overlay-start button)
176 ;; Must be a text-property button.
177 (or (previous-single-property-change (1+ button) 'button)
180 (defun button-end (button)
181 "Return the position at which BUTTON ends."
182 (if (overlayp button)
184 ;; Must be a text-property button.
185 (or (next-single-property-change button 'button)
188 (defun button-get (button prop)
189 "Get the property of button BUTTON named PROP."
190 (if (overlayp button)
191 (overlay-get button prop)
192 ;; Must be a text-property button.
193 (get-text-property button prop)))
195 (defun button-put (button prop val)
196 "Set BUTTON's PROP property to VAL."
197 ;; Treat some properties specially.
198 (cond ((memq prop '(type :type))
199 ;; We translate a `type' property a `category' property, since
200 ;; that's what's actually used by overlays/text-properties for
201 ;; inheriting properties.
202 (setq prop 'category)
203 (setq val (button-category-symbol val)))
205 ;; Disallow updating the `category' property directly.
206 (error "Button `category' property may not be set directly")))
208 (if (overlayp button)
209 (overlay-put button prop val)
210 ;; Must be a text-property button.
212 (or (previous-single-property-change (1+ button) 'button)
214 (or (next-single-property-change button 'button)
218 (defsubst button-activate (button &optional use-mouse-action)
219 "Call BUTTON's action property.
220 If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
221 instead of its normal action; if the button has no mouse-action,
222 the normal action is used instead."
223 (let ((action (or (and use-mouse-action (button-get button 'mouse-action))
224 (button-get button 'action))))
226 (save-selected-window
227 (select-window (display-buffer (marker-buffer action)))
230 (funcall action button))))
232 (defun button-label (button)
233 "Return BUTTON's text label."
234 (buffer-substring-no-properties (button-start button) (button-end button)))
236 (defsubst button-type (button)
237 "Return BUTTON's button-type."
238 (button-get button 'type))
240 (defun button-has-type-p (button type)
241 "Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes."
242 (button-type-subtype-p (button-get button 'type) type))
245 ;; Creating overlay buttons
247 (defun make-button (beg end &rest properties)
248 "Make a button from BEG to END in the current buffer.
249 The remaining arguments form a sequence of PROPERTY VALUE pairs,
250 specifying properties to add to the button.
251 In addition, the keyword argument :type may be used to specify a
252 button-type from which to inherit other properties; see
253 `define-button-type'.
255 Also see `make-text-button', `insert-button'."
256 (let ((overlay (make-overlay beg end nil t nil)))
258 (button-put overlay (pop properties) (pop properties)))
259 ;; Put a pointer to the button in the overlay, so it's easy to get
260 ;; when we don't actually have a reference to the overlay.
261 (overlay-put overlay 'button overlay)
262 ;; If the user didn't specify a type, use the default.
263 (unless (overlay-get overlay 'category)
264 (overlay-put overlay 'category 'default-button))
265 ;; OVERLAY is the button, so return it
268 (defun insert-button (label &rest properties)
269 "Insert a button with the label LABEL.
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 `insert-text-button', `make-button'."
278 (prog1 (point) (insert label))
283 ;; Creating text-property buttons
285 (defun make-text-button (beg end &rest properties)
286 "Make a button from BEG to END in the current buffer.
287 The remaining arguments form a sequence of PROPERTY VALUE pairs,
288 specifying properties to add to the button.
289 In addition, the keyword argument :type may be used to specify a
290 button-type from which to inherit other properties; see
291 `define-button-type'.
293 This function is like `make-button', except that the button is actually
294 part of the text instead of being a property of the buffer. That is,
295 this function uses text properties, the other uses overlays.
296 Creating large numbers of buttons can also be somewhat faster
297 using `make-text-button'. Note, however, that if there is an existing
298 face property at the site of the button, the button face may not be visible.
299 You may want to use `make-button' in that case.
301 BEG can also be a string, in which case it is made into a button.
303 Also see `insert-text-button'."
306 (or (plist-member properties 'type)
307 (plist-member properties :type))))
309 (setq object beg beg 0 end (length object)))
310 ;; Disallow setting the `category' property directly.
311 (when (plist-get properties 'category)
312 (error "Button `category' property may not be set directly"))
313 (if (null type-entry)
314 ;; The user didn't specify a `type' property, use the default.
315 (setq properties (cons 'category (cons 'default-button properties)))
316 ;; The user did specify a `type' property. Translate it into a
317 ;; `category' property, which is what's actually used by
318 ;; text-properties for inheritance.
319 (setcar type-entry 'category)
320 (setcar (cdr type-entry)
321 (button-category-symbol (car (cdr type-entry)))))
322 ;; Now add all the text properties at once
323 (add-text-properties beg end
324 ;; Each button should have a non-eq `button'
325 ;; property so that next-single-property-change can
326 ;; detect boundaries reliably.
327 (cons 'button (cons (list t) properties))
329 ;; Return something that can be used to get at the button.
332 (defun insert-text-button (label &rest properties)
333 "Insert a button with the label LABEL.
334 The remaining arguments form a sequence of PROPERTY VALUE pairs,
335 specifying properties to add to the button.
336 In addition, the keyword argument :type may be used to specify a
337 button-type from which to inherit other properties; see
338 `define-button-type'.
340 This function is like `insert-button', except that the button is
341 actually part of the text instead of being a property of the buffer.
342 Creating large numbers of buttons can also be somewhat faster using
343 `insert-text-button'.
345 Also see `make-text-button'."
346 (apply #'make-text-button
347 (prog1 (point) (insert label))
352 ;; Finding buttons in a buffer
354 (defun button-at (pos)
355 "Return the button at position POS in the current buffer, or nil."
356 (let ((button (get-char-property pos 'button)))
357 (if (or (overlayp button) (null button))
359 ;; Must be a text-property button; return a marker pointing to it.
360 (copy-marker pos t))))
362 (defun next-button (pos &optional count-current)
363 "Return the next button after position POS in the current buffer.
364 If COUNT-CURRENT is non-nil, count any button at POS in the search,
365 instead of starting at the next button."
366 (unless count-current
367 ;; Search for the next button boundary.
368 (setq pos (next-single-char-property-change pos 'button)))
369 (and (< pos (point-max))
371 ;; We must have originally been on a button, and are now in
372 ;; the inter-button space. Recurse to find a button.
375 (defun previous-button (pos &optional count-current)
376 "Return the previous button before position POS in the current buffer.
377 If COUNT-CURRENT is non-nil, count any button at POS in the search,
378 instead of starting at the next button."
379 (let ((button (button-at pos)))
383 ;; We started out on a button, so move to its start and look
384 ;; for the previous button boundary.
385 (setq pos (previous-single-char-property-change
386 (button-start button) 'button))
387 (let ((new-button (button-at pos)))
389 ;; We are in a button again; this can happen if there
390 ;; are adjacent buttons (or at bob).
391 (unless (= pos (button-start button)) new-button)
392 ;; We are now in the space between buttons.
393 (previous-button pos))))
394 ;; We started out in the space between buttons.
395 (setq pos (previous-single-char-property-change pos 'button))
397 (and (> pos (point-min))
398 (button-at (1- pos)))))))
403 (defun push-button (&optional pos use-mouse-action)
404 "Perform the action specified by a button at location POS.
405 POS may be either a buffer position or a mouse-event. If
406 USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
407 instead of its normal action; if the button has no mouse-action,
408 the normal action is used instead. The action may be either a
409 function to call or a marker to display.
410 POS defaults to point, except when `push-button' is invoked
411 interactively as the result of a mouse-event, in which case, the
413 If there's no button at POS, do nothing and return nil, otherwise
416 (list (if (integerp last-command-event) (point) last-command-event)))
417 (if (and (not (integerp pos)) (eventp pos))
418 ;; POS is a mouse event; switch to the proper window/buffer
419 (let ((posn (event-start pos)))
420 (with-current-buffer (window-buffer (posn-window posn))
421 (push-button (posn-point posn) t)))
422 ;; POS is just normal position
423 (let ((button (button-at (or pos (point)))))
426 (button-activate button use-mouse-action)
429 (defun forward-button (n &optional wrap display-message)
430 "Move to the Nth next button, or Nth previous button if N is negative.
431 If N is 0, move to the start of any button at point.
432 If WRAP is non-nil, moving past either end of the buffer continues from the
434 If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
435 Any button with a non-nil `skip' property is skipped over.
436 Returns the button found."
437 (interactive "p\nd\nd")
440 ;; Move to start of current button
441 (if (setq button (button-at (point)))
442 (goto-char (button-start button)))
443 ;; Move to Nth next button
444 (let ((iterator (if (> n 0) #'next-button #'previous-button))
445 (wrap-start (if (> n 0) (point-min) (point-max)))
448 (setq button t) ; just to start the loop
449 (while (and (null fail) (> n 0) button)
450 (setq button (funcall iterator (point)))
451 (when (and (not button) wrap)
452 (setq button (funcall iterator wrap-start t)))
454 (goto-char (button-start button))
455 ;; Avoid looping forever (e.g., if all the buttons have
456 ;; the `skip' property).
458 (setq opoint (point)))
461 (unless (button-get button 'skip)
464 (error (if wrap "No buttons!" "No more buttons"))
465 (let ((msg (and display-message (button-get button 'help-echo))))
470 (defun backward-button (n &optional wrap display-message)
471 "Move to the Nth previous button, or Nth next button if N is negative.
472 If N is 0, move to the start of any button at point.
473 If WRAP is non-nil, moving past either end of the buffer continues from the
475 If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
476 Any button with a non-nil `skip' property is skipped over.
477 Returns the button found."
478 (interactive "p\nd\nd")
479 (forward-button (- n) wrap display-message))
484 ;;; button.el ends here