;;; reveal.el --- Automatically reveal hidden text at point -*- lexical-binding: t -*- ;; Copyright (C) 2000-2023 Free Software Foundation, Inc. ;; Author: Stefan Monnier ;; Keywords: outlines ;; This file is part of GNU Emacs. ;; GNU Emacs is free software: you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by ;; the Free Software Foundation, either version 3 of the License, or ;; (at your option) any later version. ;; GNU Emacs is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; You should have received a copy of the GNU General Public License ;; along with GNU Emacs. If not, see . ;;; Commentary: ;; Reveal mode is a minor mode that makes sure that text around point ;; is always visible. When point enters a region of hidden text, ;; `reveal-mode' temporarily makes it visible. ;; ;; Overlays can also use the `display' property. For them to be ;; revealed, the `reveal-toggle-invisible' property also has to be ;; present, and should be a function to toggle between having a ;; display property and not. ;; ;; This is normally used in conjunction with `outline-minor-mode', ;; `hs-minor-mode', `hide-ifdef-mode', ... ;; ;; It only works with packages that hide text using overlays. ;; Packages can provide special support for it by placing ;; a function in the `reveal-toggle-invisible' property on the symbol ;; used as the value of the `invisible' overlay property. ;; The function is called right after revealing (or re-hiding) the ;; text with two arguments: the overlay and a boolean that's non-nil ;; if we have just revealed the text. When revealing, that function ;; may re-hide some of the text. ;;; Todo: ;; - find other hysteresis features. ;; - don't hide after a scroll command ;; - delay hiding by a couple seconds (i.e. hide in the background) ;;; Code: (defgroup reveal nil "Reveal hidden text on the fly." :group 'convenience) (defcustom reveal-around-mark t "Reveal text around the mark, if active." :type 'boolean :group 'reveal) (defcustom reveal-auto-hide t "Automatically hide revealed text when leaving it. If nil, the `reveal-hide-revealed' command can be useful to hide revealed text manually." :type 'boolean :version "28.1") (defvar-local reveal-open-spots nil "List of spots in the buffer which are open. Each element has the form (WINDOW . OVERLAY).") (defvar-local reveal-last-tick nil) ;; Actual code (defun reveal-post-command () ;; Refresh the spots that might have changed. ;; `Refreshing' here means to try and re-hide the corresponding text. ;; We don't refresh everything correctly: ;; - we only refresh spots in the current window. ;; FIXME: do we actually know that (current-buffer) = (window-buffer) ? (with-local-quit (with-demoted-errors "Reveal: %s" (let ((old-ols (delq nil (mapcar (lambda (x) ;; We refresh any spot in the current window as well ;; as any spots associated with a dead window or ;; a window which does not show this buffer any more. (cond ((eq (car x) (selected-window)) (cdr x)) ((not (and (window-live-p (car x)) (eq (window-buffer (car x)) (current-buffer)))) ;; Adopt this since it's owned by a window that's ;; either not live or at least not showing this ;; buffer any more. (setcar x (selected-window)) (cdr x)))) reveal-open-spots)))) (setq old-ols (reveal-open-new-overlays old-ols)) (when reveal-auto-hide (reveal-close-old-overlays old-ols)))))) (defun reveal-open-new-overlays (old-ols) (let ((repeat t)) (while repeat (setq repeat nil) (dolist (ol (nconc (when (and reveal-around-mark mark-active) (overlays-at (mark))) (overlays-at (point)))) (setq old-ols (delq ol old-ols)) (when (overlay-start ol) ;Check it's still live. ;; We either have an invisible overlay, or a display ;; overlay. Always reveal invisible text, but only reveal ;; display properties if `reveal-toggle-invisible' is ;; present. (let* ((inv (overlay-get ol 'invisible)) (disp (and (overlay-get ol 'display) (overlay-get ol 'reveal-toggle-invisible))) (hidden (invisible-p inv)) (ellipsis (and hidden (not (eq t hidden)))) open) (when (and (or ellipsis disp) (or (setq open (or (overlay-get ol 'reveal-toggle-invisible) (and (symbolp inv) (get inv 'reveal-toggle-invisible)) (overlay-get ol 'isearch-open-invisible-temporary))) (overlay-get ol 'isearch-open-invisible) (and (consp buffer-invisibility-spec) (cdr (assq inv buffer-invisibility-spec))))) (when inv (overlay-put ol 'reveal-invisible inv)) (push (cons (selected-window) ol) reveal-open-spots) (if (null open) (overlay-put ol 'invisible nil) ;; Use the provided opening function and repeat (since the ;; opening function might have hidden a subpart around point ;; or moved/killed some of the overlays). (setq repeat t) (condition-case err (funcall open ol nil) (error (message "!!Reveal-show (funcall %s %s nil): %s !!" open ol err) ;; Let's default to a meaningful behavior to avoid ;; getting stuck in an infinite loop. (setq repeat nil) (overlay-put ol 'invisible nil)))))))))) old-ols) (defun reveal-close-old-overlays (old-ols) (if (or track-mouse ;Don't close in the middle of a click. (not (eq reveal-last-tick (setq reveal-last-tick (buffer-modified-tick))))) ;; The buffer was modified since last command: let's refrain from ;; closing any overlay because it tends to behave poorly when ;; inserting text at the end of an overlay (basically the overlay ;; should be rear-advance when it's open, but things like ;; outline-minor-mode make it non-rear-advance because it's ;; a better choice when it's closed). nil ;; The last command was only a point motion or some such ;; non-buffer-modifying command. Let's close whatever can be closed. (dolist (ol old-ols) (if (and (overlay-start ol) ;Check it's still live. (>= (point) (save-excursion (goto-char (overlay-start ol)) (line-beginning-position 1))) (<= (point) (save-excursion (goto-char (overlay-end ol)) (line-beginning-position 2))) ;; If the application has moved the overlay to some other ;; buffer, we'd better reset the buffer to its ;; original state. (eq (current-buffer) (overlay-buffer ol))) ;; Still near the overlay: keep it open. nil ;; Really close it. (let* ((inv (overlay-get ol 'reveal-invisible)) (open (or (overlay-get ol 'reveal-toggle-invisible) (get inv 'reveal-toggle-invisible) (overlay-get ol 'isearch-open-invisible-temporary)))) (if (and (overlay-start ol) ;Check it's still live. open) (condition-case err (funcall open ol t) (error (message "!!Reveal-hide (funcall %s %s t): %s !!" open ol err))) (overlay-put ol 'invisible inv)) ;; Remove the overlay from the list of open spots. (overlay-put ol 'reveal-invisible nil) (setq reveal-open-spots (delq (rassoc ol reveal-open-spots) reveal-open-spots))))))) (defun reveal-hide-revealed () "Hide all revealed text. If there is revealed text under point, this command does not hide that text." (interactive) (let ((reveal-auto-hide t)) (reveal-post-command))) (defvar-keymap reveal-mode-map ;; Override the default move-beginning-of-line and move-end-of-line ;; which skips valuable invisible text. " " #'beginning-of-line " " #'end-of-line) ;;;###autoload (define-minor-mode reveal-mode "Toggle uncloaking of invisible text near point (Reveal mode). Reveal mode is a buffer-local minor mode. When enabled, it reveals invisible text around point. Also see the `reveal-auto-hide' variable." :group 'reveal :lighter (global-reveal-mode nil " Reveal") :keymap reveal-mode-map (if reveal-mode (progn (setq-local search-invisible t) (add-hook 'post-command-hook 'reveal-post-command nil t)) (kill-local-variable 'search-invisible) (remove-hook 'post-command-hook 'reveal-post-command t))) ;;;###autoload (define-minor-mode global-reveal-mode "Toggle Reveal mode in all buffers (Global Reveal mode). Reveal mode renders invisible text around point visible again." :global t :group 'reveal (setq-default reveal-mode global-reveal-mode) (if global-reveal-mode (progn (setq search-invisible t) (add-hook 'post-command-hook 'reveal-post-command)) (setq search-invisible 'open) ;FIXME (remove-hook 'post-command-hook 'reveal-post-command))) (provide 'reveal) ;;; reveal.el ends here