smooth-scrolling.el

About

This package offers a minor mode which make emacs scroll smoothly. It keeps 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 minimising the frequency of 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. For example, when using the built-in variables, clicking with the mouse in the margin will immediately scroll the window to maintain the margin, so the text that you clicked on will no longer be under the mouse. This can be disorienting. In contrast, this mode will not do any scrolling until you actually move up or down a line.

Also, the built-in margin code does not interact well with small windows. If the margin is more than half the window height, you get some weird behavior, because the point is always hitting both the top and bottom margins. This package auto-adjusts the margin in each buffer to never exceed half the window height, so the top and bottom margins never overlap.

See also emacswiki's SmoothScrolling page for more information, although at the time of writing, its content probably did more to confuse than enlighten.

Installation

You have various options, including the following:

• Install the package from MELPA (see this friendly quickstart guide)
• Install via el-get
• Simply download this repository and place the elisp file somewhere on your load-path.

Usage

To interactively toggle the mode on / off:

M-x smooth-scrolling-mode

To make the mode permanent, put this in your .emacs:

(require 'smooth-scrolling)
(smooth-scrolling-mode 1)

Difference with smooth-scroll.el

This package should not be confused with the similarly-named smooth-scroll.el, which has similar goals but takes a different approach, requiring navigation keys to be bound to dedicated scroll-{up,down,left,right}-1 functions.

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 honored. 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.
• Minimize the number of autoloads in the file. Currently everything is marked as such.

Authors

Originally written by Adam Spiers, it was made into a proper ELPA package by Jeremy Bondeson, and later converted into a minor mode by Ryan C. Thompson.

Thanks also to Mark Hulme-Jones and consolers on #emacs for helping debug issues with line-wrapping in the original implementation.