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-rw-r--r--emacs3
-rw-r--r--emacs.d/lisp/smooth-scrolling.el201
-rw-r--r--emacs.elcbin11343 -> 11368 bytes
3 files changed, 204 insertions, 0 deletions
diff --git a/emacs b/emacs
index 2bf9884..6d43c4f 100644
--- a/emacs
+++ b/emacs
@@ -340,6 +340,9 @@ If this is set during find-file, flyspell mode gets enabled automaticaly.")
(scroll-bar-mode 1)
(set-scroll-bar-mode 'right))))
+;; smooth-scrolling (do not jump to the middle of the screen)
+(require 'smooth-scrolling nil 'noerror)
+
;; browse-kill-ring
(when (require 'browse-kill-ring nil 'noerror)
(progn (browse-kill-ring-default-keybindings)
diff --git a/emacs.d/lisp/smooth-scrolling.el b/emacs.d/lisp/smooth-scrolling.el
new file mode 100644
index 0000000..d3321ef
--- /dev/null
+++ b/emacs.d/lisp/smooth-scrolling.el
@@ -0,0 +1,201 @@
+;; smooth-scrolling.el
+;; $Id$
+;; Adam Spiers <emacs-ss@adamspiers.org>
+;;
+;; Make emacs scroll smoothly, keeping the point away from the top and
+;; bottom of the current buffer's window in order to keep lines of
+;; context around the point visible as much as possible, whilst
+;; avoiding sudden scroll jumps which are visually confusing.
+;;
+;; This is a nice alternative to all the native scroll-* custom
+;; variables, which unfortunately cannot provide this functionality
+;; perfectly. `scroll-margin' comes closest, but has some bugs
+;; (e.g. with handling of mouse clicks). See
+;;
+;; http://www.emacswiki.org/cgi-bin/wiki/SmoothScrolling
+;;
+;; for the gory details.
+;;
+;;;_* Installation
+;;
+;; Put somewhere on your `load-path' and include
+;;
+;; (require 'smooth-scrolling)
+;;
+;; in your .emacs initialization file.
+;;
+;;;_* Notes
+;;
+;; This only affects the behaviour of the `next-line' and
+;; `previous-line' functions, usually bound to the cursor keys and
+;; C-n/C-p, and repeated isearches (`isearch-repeat'). Other methods
+;; of moving the point will behave as normal according to the standard
+;; custom variables.
+;;
+;; Prefix arguments to `next-line' and `previous-line' are honoured.
+;; The minimum number of lines are scrolled in order to keep the
+;; point outside the margin.
+;;
+;; There is one case where moving the point in this fashion may cause
+;; a jump: if the point is placed inside one of the margins by another
+;; method (e.g. left mouse click, or M-x goto-line) and then moved in
+;; the normal way, the advice code will scroll the minimum number of
+;; lines in order to keep the point outside the margin. This jump may
+;; cause some slight confusion at first, but hopefully it is justified
+;; by the benefit of automatically ensuring `smooth-scroll-margin'
+;; lines of context are visible around the point as often as possible.
+;;
+;;;_* TODO
+;;
+;; - Maybe add option to avoid scroll jumps when point is within
+;; margin.
+;;
+;;;_* Acknowledgements
+;;
+;; Thanks to Mark Hulme-Jones and consolers on #emacs for helping
+;; debug issues with line-wrapping.
+;;
+;;;_* License
+;;
+;; Released under the GNU General Public License v2 or later, with
+;; all rights assigned to the Free Software Foundation.
+;;
+
+;;;_* Code follows
+;;;_ + disable `scroll-margin'
+(setq scroll-margin 0)
+;;;_ + defcustoms
+(defcustom smooth-scroll-margin 10
+ "Number of lines of visible margin at the top and bottom of a window.
+If the point is within these margins, then scrolling will occur
+smoothly for `previous-line' at the top of the window, and for
+`next-line' at the bottom.
+
+This is very similar in its goal to `scroll-margin'. However, it
+is implemented by activating `smooth-scroll-down' and
+`smooth-scroll-up' advise via `defadvice' for `previous-line' and
+`next-line' respectively. As a result it avoids problems
+afflicting `scroll-margin', such as a sudden jump and unexpected
+highlighting of a region when the mouse is clicked in the margin.
+
+Scrolling only occurs when the point is closer to the window
+boundary it is heading for (top or bottom) than the middle of the
+window. This is to intelligently handle the case where the
+margins cover the whole buffer (e.g. `smooth-scroll-margin' set
+to 5 and `window-height' returning 10 or less).
+
+See also `smooth-scroll-strict-margins'."
+ :type 'integer
+ :group 'windows)
+
+(defcustom smooth-scroll-strict-margins t
+ "If true, the advice code supporting `smooth-scroll-margin'
+will use `count-screen-lines' to determine the number of
+*visible* lines between the point and the window top/bottom,
+rather than `count-lines' which obtains the number of actual
+newlines. This is because there might be extra newlines hidden
+by a mode such as folding-mode, outline-mode, org-mode etc., or
+fewer due to very long lines being displayed wrapped when
+`truncate-lines' is nil.
+
+However, using `count-screen-lines' can supposedly cause
+performance issues in buffers with extremely long lines. Setting
+`cache-long-line-scans' may be able to address this;
+alternatively you can set this variable to nil so that the advice
+code uses `count-lines', and put up with the fact that sometimes
+the point will be allowed to stray into the margin."
+ :type 'boolean
+ :group 'windows)
+;;;_ + helper functions
+(defun smooth-scroll-lines-from-window-top ()
+ "Work out, using the function indicated by
+`smooth-scroll-strict-margins', what the current screen line is,
+relative to the top of the window. Counting starts with 1 referring
+to the top line in the window."
+ (interactive)
+ (cond ((= (window-start) (point))
+ ;; In this case, count-screen-lines would return 0, so we override.
+ 1)
+ (smooth-scroll-strict-margins
+ (count-screen-lines (window-start) (point) 'count-final-newline))
+ (t
+ (count-lines (window-start) (point)))))
+
+(defun smooth-scroll-lines-from-window-bottom ()
+ "Work out, using the function indicated by
+`smooth-scroll-strict-margins', how many screen lines there are
+between the point and the bottom of the window. Counting starts
+with 1 referring to the bottom line in the window."
+ (interactive)
+ (if smooth-scroll-strict-margins
+ (count-screen-lines (point) (window-end))
+ (count-lines (point) (window-end))))
+;;;_ + after advice
+
+(defun smooth-scroll-down ()
+ "Scroll down smoothly if cursor is within `smooth-scroll-margin'
+lines of the top of the window."
+ (and
+ ;; Only scroll down if there is buffer above the start of the window.
+ (> (line-number-at-pos (window-start)) 1)
+ (let ((lines-from-window-top
+ (smooth-scroll-lines-from-window-top)))
+ (and
+ ;; Only scroll down if we're within the top margin
+ (<= lines-from-window-top smooth-scroll-margin)
+ ;; Only scroll down if we're in the top half of the window
+ (<= lines-from-window-top
+ ;; N.B. `window-height' includes modeline, so if it returned 21,
+ ;; that would mean exactly 10 lines in the top half and 10 in
+ ;; the bottom. 22 (or any even number) means there's one in the
+ ;; middle. In both cases the following expression will
+ ;; yield 10:
+ (/ (1- (window-height)) 2))
+ (save-excursion
+ (scroll-down
+ (1+ (- smooth-scroll-margin lines-from-window-top))))))))
+
+(defun smooth-scroll-up ()
+ "Scroll up smoothly if cursor is within `smooth-scroll-margin'
+lines of the bottom of the window."
+ (and
+ ;; Only scroll up if there is buffer below the end of the window.
+ (< (window-end) (buffer-end 1))
+ (let ((lines-from-window-bottom
+ (smooth-scroll-lines-from-window-bottom)))
+ (and
+ ;; Only scroll up if we're within the bottom margin
+ (<= lines-from-window-bottom smooth-scroll-margin)
+ ;; Only scroll up if we're in the bottom half of the window.
+ (<= lines-from-window-bottom
+ ;; See above notes on `window-height'.
+ (/ (1- (window-height)) 2))
+ (save-excursion
+ (scroll-up
+ (1+ (- smooth-scroll-margin lines-from-window-bottom))))))))
+
+(defadvice previous-line (after smooth-scroll-down
+ (&optional arg try-vscroll)
+ activate)
+ (smooth-scroll-down))
+(defadvice next-line (after smooth-scroll-up
+ (&optional arg try-vscroll)
+ activate)
+ (smooth-scroll-up))
+
+(defadvice isearch-repeat (after isearch-smooth-scroll
+ (direction)
+ activate)
+ (if (eq direction 'forward)
+ (smooth-scroll-up)
+ (smooth-scroll-down)))
+
+;;;_ + provide
+(provide 'smooth-scrolling)
+
+;;;_* Local emacs variables
+
+;;Local variables:
+;;allout-layout: (0 : -1 0)
+;;mode: allout
+;;End:
diff --git a/emacs.elc b/emacs.elc
index 45c4007..cef909a 100644
--- a/emacs.elc
+++ b/emacs.elc
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