;; This file: http://user.it.uu.se/~embe8573/conf/emacs-init/scroll.el

(require 'cl-macs)

;; civilized scrolling - one line at a time
(setq scroll-conservatively 10000)
(setq auto-window-vscroll nil)

;; scroll the current window
(defun scroll-up-1 ()
  (interactive)
  (scroll-down 1) )
(defun scroll-down-1 ()
  (interactive)
  (scroll-up 1) )

;; automatic scrolling
(defun start-automatic-scroll-down ()
  (interactive)
  (let ((win))
    (cl-loop do
             (progn (setq win (window-end))
                    (scroll-down-1)
                    (sleep-for 1) ; put speed here in seconds
                    (redisplay) )
     until (= win (window-end)) )))
;; (start-automatic-scroll-down)
;;                             ^ test here

;; scroll up/down the other window
(defun scroll-up-other-window ()
  (interactive)
  (scroll-other-window-down 1) )
(defun scroll-down-other-window ()
  (interactive)
  (scroll-other-window 1) )

;; scroll one chunk (pane) of text
(defun get-window-lines ()
  (let*((edges  (window-inside-edges))
        (top    (nth 1 edges))
        (bottom (nth 3 edges))
        (lines  (- bottom top)) )
    (if (member major-mode '(Buffer-menu-mode package-menu-mode w3m-mode))
        (1- lines)
      lines) ))

(defun scroll-up-pane ()
  (interactive)
  (scroll-down (get-window-lines) ))
(defun scroll-down-pane ()
  (interactive)
  (scroll-up (get-window-lines)) )

;; scroll horizontally
(put 'scroll-left  'disabled nil)
(put 'scroll-right 'disabled nil)
(setq hscroll-margin 1)
(setq hscroll-step   1)

(defun scroll-left-1 ()
  (interactive)
  (scroll-right 1 0) ) ; yes, "the opposite" here
(defun scroll-right-1 ()
  (interactive)
  (scroll-left 1 0) )  ; ditto
(defun scroll-left-home ()
  (interactive)
  (while (> (scroll-left-1) 0)) )

;; functions to assign certain keys those functions in many modes
(defun set-pane-scroll-keys (map)
  "Set MAP keys for vertical scrolling in panes."
  (define-key map "I" #'scroll-up-pane)
  (define-key map "K" #'scroll-down-pane) )

(defun set-scroll-keys (map &optional horizontally)
  "Set MAP keys for scrolling, vertically and optionally HORIZONTALLY.
Also invoke `set-pane-scroll-keys'."
  (when horizontally
    (define-key map "j" #'scroll-left-1)
    (define-key map "l" #'scroll-right-1) )
  (define-key map "i"    #'scroll-up-1)
  (define-key map "k"    #'scroll-down-1)
  (set-pane-scroll-keys map) )

(defun set-vertical-keys (map)
  "Set MAP keys for moving point vertically."
  (define-key map "i" #'previous-line)
  (define-key map "k" #'next-line) )

(provide 'scroll)