;;; button.el --- clickable buttons
;;
-;; Copyright (C) 2001, 2002, 2003, 2004, 2005,
-;; 2006, 2007, 2008 Free Software Foundation, Inc.
+;; Copyright (C) 2001-2013 Free Software Foundation, Inc.
;;
;; Author: Miles Bader <miles@gnu.org>
;; Keywords: extensions
+;; Package: emacs
;;
;; This file is part of GNU Emacs.
;;
;; the button is represented by a marker or buffer-position pointing
;; somewhere in the button. In the latter case, no markers into the
;; buffer are retained, which is important for speed if there are are
-;; extremely large numbers of buttons.
+;; extremely large numbers of buttons. Note however that if there is
+;; an existing face text-property at the site of the button, the
+;; button face may not be visible. Using overlays avoids this.
;;
;; Using `define-button-type' to define default properties for buttons
-;; is not necessary, but it is is encouraged, since doing so makes the
+;; is not necessary, but it is encouraged, since doing so makes the
;; resulting code clearer and more efficient.
;;
;; Use color for the MS-DOS port because it doesn't support underline.
;; FIXME if MS-DOS correctly answers the (supports) question, it need
;; no longer be a special case.
-(defface button '((((type pc) (class color))
- (:foreground "lightblue"))
- (((supports :underline t)) :underline t)
- (t (:foreground "lightblue")))
+(defface button '((t :inherit link))
"Default face used for buttons."
:group 'basic-faces)
(put 'default-button 'type 'button)
;; action may be either a function to call, or a marker to go to
(put 'default-button 'action 'ignore)
-(put 'default-button 'help-echo "mouse-2, RET: Push this button")
+(put 'default-button 'help-echo (purecopy "mouse-2, RET: Push this button"))
;; Make overlay buttons go away if their underlying text is deleted.
(put 'default-button 'evaporate t)
;; Prevent insertions adjacent to the text-property buttons from
`define-button-type'.
This function is like `make-button', except that the button is actually
-part of the text instead of being a property of the buffer. Creating
-large numbers of buttons can also be somewhat faster using
-`make-text-button'.
+part of the text instead of being a property of the buffer. That is,
+this function uses text properties, the other uses overlays.
+Creating large numbers of buttons can also be somewhat faster
+using `make-text-button'. Note, however, that if there is an existing
+face property at the site of the button, the button face may not be visible.
+You may want to use `make-button' in that case.
BEG can also be a string, in which case it is made into a button.
;; Finding buttons in a buffer
(defun button-at (pos)
- "Return the button at position POS in the current buffer, or nil."
+ "Return the button at position POS in the current buffer, or nil.
+If the button at POS is a text property button, the return value
+is a marker pointing to POS."
(let ((button (get-char-property pos 'button)))
(if (or (overlayp button) (null button))
button
(goto-char (button-start button)))
;; Move to Nth next button
(let ((iterator (if (> n 0) #'next-button #'previous-button))
- (wrap-start (if (> n 0) (point-min) (point-max))))
+ (wrap-start (if (> n 0) (point-min) (point-max)))
+ opoint fail)
(setq n (abs n))
(setq button t) ; just to start the loop
- (while (and (> n 0) button)
+ (while (and (null fail) (> n 0) button)
(setq button (funcall iterator (point)))
(when (and (not button) wrap)
(setq button (funcall iterator wrap-start t)))
(when button
(goto-char (button-start button))
+ ;; Avoid looping forever (e.g., if all the buttons have
+ ;; the `skip' property).
+ (cond ((null opoint)
+ (setq opoint (point)))
+ ((= opoint (point))
+ (setq fail t)))
(unless (button-get button 'skip)
(setq n (1- n)))))))
(if (null button)
(provide 'button)
-;; arch-tag: 5f2c7627-413b-4097-b282-630f89d9c5e9
;;; button.el ends here