1 ;;; button.el --- clickable buttons
3 ;; Copyright (C) 2001, 2002, 2003, 2004, 2005,
4 ;; 2006, 2007 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 2, or (at your option)
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; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24 ;; Boston, MA 02110-1301, USA.
28 ;; This package defines functions for inserting and manipulating
29 ;; clickable buttons in Emacs buffers, such as might be used for help
32 ;; In some ways it duplicates functionality also offered by the
33 ;; `widget' package, but the button package has the advantage that it
34 ;; is (1) much faster, (2) much smaller, and (3) much, much, simpler
35 ;; (the code, that is, not the interface).
37 ;; Buttons can either use overlays, in which case the button is
38 ;; represented by the overlay itself, or text-properties, in which case
39 ;; the button is represented by a marker or buffer-position pointing
40 ;; somewhere in the button. In the latter case, no markers into the
41 ;; buffer are retained, which is important for speed if there are are
42 ;; extremely large numbers of buttons.
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 (defface button
'((((type pc
) (class color
))
56 (:foreground
"lightblue"))
58 "Default face used for buttons."
63 (let ((map (make-sparse-keymap)))
64 (define-key map
"\r" 'push-button
)
65 (define-key map
[mouse-2
] 'push-button
)
67 "Keymap used by buttons.")
70 (defvar button-buffer-map
71 (let ((map (make-sparse-keymap)))
72 (define-key map
[?
\t] 'forward-button
)
73 (define-key map
"\e\t" 'backward-button
)
74 (define-key map
[backtab] 'backward-button)
76 "Keymap useful for buffers containing buttons.
77 Mode-specific keymaps may want to use this as their parent keymap.")
79 ;; Default properties for buttons
80 (put 'default-button 'face 'button)
81 (put 'default-button 'mouse-face 'highlight)
82 (put 'default-button 'keymap button-map)
83 (put 'default-button 'type 'button)
84 ;; action may be either a function to call, or a marker to go to
85 (put 'default-button 'action 'ignore)
86 (put 'default-button 'help-echo "mouse-2, RET: Push this button")
87 ;; Make overlay buttons go away if their underlying text is deleted.
88 (put 'default-button 'evaporate t)
89 ;; Prevent insertions adjacent to the text-property buttons from
90 ;; inheriting its properties.
91 (put 'default-button 'rear-nonsticky t)
93 ;; A `category-symbol' property for the default button type
94 (put 'button 'button-category-symbol 'default-button)
97 ;; Button types (which can be used to hold default properties for buttons)
99 ;; Because button-type properties are inherited by buttons using the
100 ;; special `category' property (implemented by both overlays and
101 ;; text-properties), we need to store them on a symbol to which the
102 ;; `category' properties can point. Instead of using the symbol that's
103 ;; the name of each button-type, however, we use a separate symbol (with
104 ;; `-button' appended, and uninterned) to store the properties. This is
105 ;; to avoid name clashes.
107 ;; [this is an internal function]
108 (defsubst button-category-symbol (type)
109 "Return the symbol used by button-type TYPE to store properties.
110 Buttons inherit them by setting their `category' property to that symbol."
111 (or (get type 'button-category-symbol)
112 (error "Unknown button type `%s'" type)))
115 (defun define-button-type (name &rest properties)
116 "Define a `button type' called NAME.
117 The remaining arguments form a sequence of PROPERTY VALUE pairs,
118 specifying properties to use as defaults for buttons with this type
119 \(a button's type may be set by giving it a `type' property when
120 creating the button, using the :type keyword argument).
122 In addition, the keyword argument :supertype may be used to specify a
123 button-type from which NAME inherits its default property values
124 \(however, the inheritance happens only when NAME is defined; subsequent
125 changes to a supertype are not reflected in its subtypes)."
126 (let ((catsym (make-symbol (concat (symbol-name name) "-button")))
128 (button-category-symbol
129 (or (plist-get properties 'supertype)
130 (plist-get properties :supertype)
132 ;; Provide a link so that it's easy to find the real symbol.
133 (put name 'button-category-symbol catsym)
134 ;; Initialize NAME's properties using the global defaults.
135 (let ((default-props (symbol-plist super-catsym)))
137 (put catsym (pop default-props) (pop default-props))))
138 ;; Add NAME as the `type' property, which will then be returned as
139 ;; the type property of individual buttons.
140 (put catsym 'type name)
141 ;; Add the properties in PROPERTIES to the real symbol.
143 (let ((prop (pop properties)))
144 (when (eq prop :supertype)
145 (setq prop 'supertype))
146 (put catsym prop (pop properties))))
147 ;; Make sure there's a `supertype' property
148 (unless (get catsym 'supertype)
149 (put catsym 'supertype 'button))
152 (defun button-type-put (type prop val)
153 "Set the button-type TYPE's PROP property to VAL."
154 (put (button-category-symbol type) prop val))
156 (defun button-type-get (type prop)
157 "Get the property of button-type TYPE named PROP."
158 (get (button-category-symbol type) prop))
160 (defun button-type-subtype-p (type supertype)
161 "Return t if button-type TYPE is a subtype of SUPERTYPE."
162 (or (eq type supertype)
164 (button-type-subtype-p (button-type-get type 'supertype)
168 ;; Button properties and other attributes
170 (defun button-start (button)
171 "Return the position at which BUTTON starts."
172 (if (overlayp button)
173 (overlay-start button)
174 ;; Must be a text-property button.
175 (or (previous-single-property-change (1+ button) 'button)
178 (defun button-end (button)
179 "Return the position at which BUTTON ends."
180 (if (overlayp button)
182 ;; Must be a text-property button.
183 (or (next-single-property-change button 'button)
186 (defun button-get (button prop)
187 "Get the property of button BUTTON named PROP."
188 (if (overlayp button)
189 (overlay-get button prop)
190 ;; Must be a text-property button.
191 (get-text-property button prop)))
193 (defun button-put (button prop val)
194 "Set BUTTON's PROP property to VAL."
195 ;; Treat some properties specially.
196 (cond ((memq prop '(type :type))
197 ;; We translate a `type' property a `category' property, since
198 ;; that's what's actually used by overlays/text-properties for
199 ;; inheriting properties.
200 (setq prop 'category)
201 (setq val (button-category-symbol val)))
203 ;; Disallow updating the `category' property directly.
204 (error "Button `category' property may not be set directly")))
206 (if (overlayp button)
207 (overlay-put button prop val)
208 ;; Must be a text-property button.
210 (or (previous-single-property-change (1+ button) 'button)
212 (or (next-single-property-change button 'button)
216 (defsubst button-activate (button &optional use-mouse-action)
217 "Call BUTTON's action property.
218 If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
219 instead of its normal action; if the button has no mouse-action,
220 the normal action is used instead."
221 (let ((action (or (and use-mouse-action (button-get button 'mouse-action))
222 (button-get button 'action))))
224 (save-selected-window
225 (select-window (display-buffer (marker-buffer action)))
228 (funcall action button))))
230 (defun button-label (button)
231 "Return BUTTON's text label."
232 (buffer-substring-no-properties (button-start button) (button-end button)))
234 (defsubst button-type (button)
235 "Return BUTTON's button-type."
236 (button-get button 'type))
238 (defun button-has-type-p (button type)
239 "Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes."
240 (button-type-subtype-p (button-get button 'type) type))
243 ;; Creating overlay buttons
246 (defun make-button (beg end &rest properties)
247 "Make a button from BEG to END in the current buffer.
248 The remaining arguments form a sequence of PROPERTY VALUE pairs,
249 specifying properties to add to the button.
250 In addition, the keyword argument :type may be used to specify a
251 button-type from which to inherit other properties; see
252 `define-button-type'.
254 Also see `make-text-button', `insert-button'."
255 (let ((overlay (make-overlay beg end nil t nil)))
257 (button-put overlay (pop properties) (pop properties)))
258 ;; Put a pointer to the button in the overlay, so it's easy to get
259 ;; when we don't actually have a reference to the overlay.
260 (overlay-put overlay 'button overlay)
261 ;; If the user didn't specify a type, use the default.
262 (unless (overlay-get overlay 'category)
263 (overlay-put overlay 'category 'default-button))
264 ;; 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
286 (defun make-text-button (beg end &rest properties)
287 "Make a button from BEG to END in the current buffer.
288 The remaining arguments form a sequence of PROPERTY VALUE pairs,
289 specifying properties to add to the button.
290 In addition, the keyword argument :type may be used to specify a
291 button-type from which to inherit other properties; see
292 `define-button-type'.
294 This function is like `make-button', except that the button is actually
295 part of the text instead of being a property of the buffer. Creating
296 large numbers of buttons can also be somewhat faster using
299 Also see `insert-text-button'."
301 (or (plist-member properties 'type)
302 (plist-member properties :type))))
303 ;; Disallow setting the `category' property directly.
304 (when (plist-get properties 'category)
305 (error "Button `category' property may not be set directly"))
306 (if (null type-entry)
307 ;; The user didn't specify a `type' property, use the default.
308 (setq properties (cons 'category (cons 'default-button properties)))
309 ;; The user did specify a `type' property. Translate it into a
310 ;; `category' property, which is what's actually used by
311 ;; text-properties for inheritance.
312 (setcar type-entry 'category)
313 (setcar (cdr type-entry)
314 (button-category-symbol (car (cdr type-entry))))))
315 ;; Now add all the text properties at once
316 (add-text-properties beg end
317 ;; Each button should have a non-eq `button'
318 ;; property so that next-single-property-change can
319 ;; detect boundaries reliably.
320 (cons 'button (cons (list t) properties)))
321 ;; Return something that can be used to get at the button.
325 (defun insert-text-button (label &rest properties)
326 "Insert a button with the label LABEL.
327 The remaining arguments form a sequence of PROPERTY VALUE pairs,
328 specifying properties to add to the button.
329 In addition, the keyword argument :type may be used to specify a
330 button-type from which to inherit other properties; see
331 `define-button-type'.
333 This function is like `insert-button', except that the button is
334 actually part of the text instead of being a property of the buffer.
335 Creating large numbers of buttons can also be somewhat faster using
336 `insert-text-button'.
338 Also see `make-text-button'."
339 (apply #'make-text-button
340 (prog1 (point) (insert label))
345 ;; Finding buttons in a buffer
347 (defun button-at (pos)
348 "Return the button at position POS in the current buffer, or nil."
349 (let ((button (get-char-property pos 'button)))
350 (if (or (overlayp button) (null button))
352 ;; Must be a text-property button; return a marker pointing to it.
353 (copy-marker pos t))))
355 (defun next-button (pos &optional count-current)
356 "Return the next button after position POS in the current buffer.
357 If COUNT-CURRENT is non-nil, count any button at POS in the search,
358 instead of starting at the next button."
359 (unless count-current
360 ;; Search for the next button boundary.
361 (setq pos (next-single-char-property-change pos 'button)))
362 (and (< pos (point-max))
364 ;; We must have originally been on a button, and are now in
365 ;; the inter-button space. Recurse to find a button.
368 (defun previous-button (pos &optional count-current)
369 "Return the previous button before position POS in the current buffer.
370 If COUNT-CURRENT is non-nil, count any button at POS in the search,
371 instead of starting at the next button."
372 (let ((button (button-at pos)))
376 ;; We started out on a button, so move to its start and look
377 ;; for the previous button boundary.
378 (setq pos (previous-single-char-property-change
379 (button-start button) 'button))
380 (let ((new-button (button-at pos)))
382 ;; We are in a button again; this can happen if there
383 ;; are adjacent buttons (or at bob).
384 (unless (= pos (button-start button)) new-button)
385 ;; We are now in the space between buttons.
386 (previous-button pos))))
387 ;; We started out in the space between buttons.
388 (setq pos (previous-single-char-property-change pos 'button))
390 (and (> pos (point-min))
391 (button-at (1- pos)))))))
396 (defun push-button (&optional pos use-mouse-action)
397 "Perform the action specified by a button at location POS.
398 POS may be either a buffer position or a mouse-event. If
399 USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
400 instead of its normal action; if the button has no mouse-action,
401 the normal action is used instead. The action may be either a
402 function to call or a marker to display.
403 POS defaults to point, except when `push-button' is invoked
404 interactively as the result of a mouse-event, in which case, the
406 If there's no button at POS, do nothing and return nil, otherwise
409 (list (if (integerp last-command-event) (point) last-command-event)))
410 (if (and (not (integerp pos)) (eventp pos))
411 ;; POS is a mouse event; switch to the proper window/buffer
412 (let ((posn (event-start pos)))
413 (with-current-buffer (window-buffer (posn-window posn))
414 (push-button (posn-point posn) t)))
415 ;; POS is just normal position
416 (let ((button (button-at (or pos (point)))))
419 (button-activate button use-mouse-action)
422 (defun forward-button (n &optional wrap display-message)
423 "Move to the Nth next button, or Nth previous button if N is negative.
424 If N is 0, move to the start of any button at point.
425 If WRAP is non-nil, moving past either end of the buffer continues from the
427 If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
428 Any button with a non-nil `skip' property is skipped over.
429 Returns the button found."
430 (interactive "p\nd\nd")
433 ;; Move to start of current button
434 (if (setq button (button-at (point)))
435 (goto-char (button-start button)))
436 ;; Move to Nth next button
437 (let ((iterator (if (> n 0) #'next-button #'previous-button))
438 (wrap-start (if (> n 0) (point-min) (point-max))))
440 (setq button t) ; just to start the loop
441 (while (and (> n 0) button)
442 (setq button (funcall iterator (point)))
443 (when (and (not button) wrap)
444 (setq button (funcall iterator wrap-start t)))
446 (goto-char (button-start button))
447 (unless (button-get button 'skip)
450 (error (if wrap "No buttons!" "No more buttons"))
451 (let ((msg (and display-message (button-get button 'help-echo))))
456 (defun backward-button (n &optional wrap display-message)
457 "Move to the Nth previous button, or Nth next button if N is negative.
458 If N is 0, move to the start of any button at point.
459 If WRAP is non-nil, moving past either end of the buffer continues from the
461 If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
462 Any button with a non-nil `skip' property is skipped over.
463 Returns the button found."
464 (interactive "p\nd\nd")
465 (forward-button (- n) wrap display-message))
470 ;;; arch-tag: 5f2c7627-413b-4097-b282-630f89d9c5e9
471 ;;; button.el ends here