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|
;;; pdf-history.el --- A simple stack-based history in PDF buffers. -*- lexical-binding: t -*-
;; Copyright (C) 2013, 2014 Andreas Politz
;; Author: Andreas Politz <politza@fh-trier.de>
;; Keywords: files, multimedia
;; This program 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.
;; This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
(require 'pdf-view)
(require 'pdf-util)
;;; Code:
(defgroup pdf-history nil
"A simple stack-based history."
:group 'pdf-tools)
(defvar-local pdf-history-stack nil
"The stack of history items.")
(defvar-local pdf-history-index nil
"The current index into the `pdf-history-stack'.")
(defvar pdf-history-minor-mode-map
(let ((kmap (make-sparse-keymap)))
(define-key kmap (kbd "B") 'pdf-history-backward)
(define-key kmap (kbd "N") 'pdf-history-forward)
kmap)
"Keymap used in `pdf-history-minor-mode'.")
;;;###autoload
(define-minor-mode pdf-history-minor-mode
"Keep a history of previously visited pages.
This is a simple stack-based history. Turning the page or
following a link pushes the left-behind page on the stack, which
may be naviagted with the following keys.
\\{pdf-history-minor-mode-map}"
nil nil nil
(pdf-util-assert-pdf-buffer)
(pdf-history-clear)
(cond
(pdf-history-minor-mode
(pdf-history-push)
(add-hook 'pdf-view-after-change-page-hook
'pdf-history-before-change-page-hook nil t))
(t
(remove-hook 'pdf-view-after-change-page-hook
'pdf-history-before-change-page-hook t))))
(defun pdf-history-before-change-page-hook ()
"Push a history item, before leaving this page."
(when (and pdf-history-minor-mode
(not (bound-and-true-p pdf-isearch-active-mode))
(pdf-view-current-page))
(pdf-history-push)))
(defun pdf-history-push ()
"Push the current page on the stack.
This function does nothing, if current stack item already
represents the current page."
(interactive)
(let ((item (pdf-history-create-item)))
(unless (and pdf-history-stack
(equal (nth pdf-history-index
pdf-history-stack) item))
(setq pdf-history-stack
(last pdf-history-stack
(- (length pdf-history-stack)
pdf-history-index))
pdf-history-index 0)
(push item pdf-history-stack))))
(defun pdf-history-clear ()
"Remove all history items."
(interactive)
(setq pdf-history-stack nil
pdf-history-index 0)
(pdf-history-push))
(defun pdf-history-create-item ()
"Create a history item representing the current page."
(list
(pdf-view-current-page)))
(defun pdf-history-beginning-of-history-p ()
"Return t, if at the beginning of the history."
(= pdf-history-index 0))
(defun pdf-history-end-of-history-p ()
"Return t, if at the end of the history."
(= pdf-history-index
(1- (length pdf-history-stack))))
(defun pdf-history-backward (n)
"Go N-times backward in the history."
(interactive "p")
(cond
((and (> n 0)
(pdf-history-end-of-history-p))
(error "End of history"))
((and (< n 0)
(pdf-history-beginning-of-history-p))
(error "Beginning of history"))
((/= n 0)
(let ((i (min (max 0 (+ pdf-history-index n))
(1- (length pdf-history-stack)))))
(prog1
(- (+ pdf-history-index n) i)
(pdf-history-goto i))))
(t 0)))
(defun pdf-history-forward (n)
"Go N-times forward in the history."
(interactive "p")
(pdf-history-backward (- n)))
(defun pdf-history-goto (n)
"Go to item N in the history."
(interactive "p")
(when (null pdf-history-stack)
(error "The history is empty"))
(cond
((>= n (length pdf-history-stack))
(error "End of history"))
((< n 0)
(error "Beginning of history"))
(t
(setq pdf-history-index n)
(pdf-view-goto-page
(car (nth n pdf-history-stack))))))
(defun pdf-history-debug ()
"Visualize the history in the header-line."
(interactive)
(setq header-line-format
'(:eval
(let ((pages (mapcar 'car pdf-history-stack))
(index pdf-history-index)
header)
(dotimes (i (length pages))
(push (propertize
(format "%s" (nth i pages))
'face
(and (= i index) 'match))
header))
(concat
"(" (format "%d" index) ") "
(mapconcat 'identity (nreverse header) " | "))))))
(provide 'pdf-history)
;;; pdf-history.el ends here
|
