Function: narrow-to-page

narrow-to-page is an interactive and byte-compiled function defined in page.el.gz.

Signature

(narrow-to-page &optional ARG)

Documentation

Make text outside current page invisible.

A numeric arg specifies to move forward or backward by that many pages, thus showing a page other than the one point was originally in.

View in manual

Probably introduced at or before Emacs version 19.1.

Key Bindings

Source Code

;; Defined in /usr/src/emacs/lisp/textmodes/page.el.gz
(defun narrow-to-page (&optional arg)
  "Make text outside current page invisible.
A numeric arg specifies to move forward or backward by that many pages,
thus showing a page other than the one point was originally in."
  (interactive "P")
  (setq arg (if arg (prefix-numeric-value arg) 0))
  (save-excursion
    (widen)
    (if (> arg 0)
	(forward-page arg)
      (if (< arg 0)
	  (let ((adjust 0)
		(opoint (point)))
	    ;; If we are not now at the beginning of a page,
	    ;; move back one extra time, to get to the start of this page.
	    (save-excursion
	      (beginning-of-line)
	      (or (and (looking-at page-delimiter)
		       (eq (match-end 0) opoint))
		  (setq adjust 1)))
	    (forward-page (- arg adjust)))))
    ;; Find the end of the page.
    (set-match-data nil)
    (forward-page)
    ;; If we stopped due to end of buffer, stay there.
    ;; If we stopped after a page delimiter, put end of restriction
    ;; at the beginning of that line.
    ;; Before checking the match that was found,
    ;; verify that forward-page actually set the match data.
    (if (and (match-beginning 0)
	     (save-excursion
	       (goto-char (match-beginning 0)) ; was (beginning-of-line)
	       (looking-at page-delimiter)))
	(goto-char (match-beginning 0))) ; was (beginning-of-line)
    (narrow-to-region (point)
		      (progn
			;; Find the top of the page.
			(forward-page -1)
			;; If we found beginning of buffer, stay there.
			;; If extra text follows page delimiter on same line,
			;; include it.
			;; Otherwise, show text starting with following line.
			(if (and (eolp) (not (bobp)))
			    (forward-line 1))
			(point)))))