This library provides minor mode volatile-highlights-mode, which brings visual feedback to some operations by highlighting portions relating to the operations.

All of highlights made by this library will be removed when any new operation is executed.

To install this library, save the file "volatile-highlights.el" to a directory in your load-path (you can view the current load-path using C-h v load-path <RET> within Emacs), then add following lines to your .emacs start up file:

(require 'volatile-highlights)
(volatile-highlights-mode t)

To toggle volatile highlighting, type:

M-x volatile-highlights-mode <RET>

While this minor mode is on, a string `VHl' will be displayed on the modeline.

Currently, operations listed below will be highlighted While the minor mode `volatile-highlights-mode' is on:

• undo: Volatile highlights will be put on the text inserted by undo.

• yank and yank-pop: Volatile highlights will be put on the text inserted by yank' or yank-pop.

• kill-region, kill-line, any other killing function: Volatile highlights will be put at the positions where the killed text used to be.

• delete-region: Same as kill-region, but not as reliable since delete-region is an inline function.

• find-tag: Volatile highlights will be put on the tag name which was found by find-tag.

• occur-mode-goto-occurrence and occur-mode-display-occurrence: Volatile highlights will be put on the occurrence which is selected by occur-mode-goto-occurrence or occur-mode-display-occurrence.

• Non incremental search operations: Volatile highlights will be put on the the text found by commands listed below:

  nonincremental-search-forward
  nonincremental-search-backward
  nonincremental-re-search-forward
  nonincremental-re-search-backward
  nonincremental-repeat-search-forward
  nonincremental-repeat-search-backward
  

Highlighting support for each operations can be turned on/off individually via customization. Also check out the customization group by:

M-x customize-group RET volatile-highlights RET

The following user options are provided to help you get the look you want:

First, you can change the color for volatile highlighting by editing the face:

• vhl/default-face: Face used for volatile highlights.

  When you edit the face, make sure the background color does not overlap with the default background color, otherwise the highlights will not be visible.

Next, choose whether you want to highlight the zero width ranges as well:

• Vhl/highlight-zero-width-ranges: If t, highlight the positions of zero-width ranges.

  For example, if a deletion is highlighted, then the position where the deleted text used to be would be highlighted.

  Default value is nil.

And then, choose whether you want to use visual effect 'pulsing' or not:

• vhl/use-pulsing-visual-effect-p: Whether to use visual effect 'pulsing' for volatile highlighting. Pulsing involves a bright highlight that slowly shifts to the background color.

  When the value is nil, Volatile highlighting will remain visible until next command occurs.

  If vhl/use-pulsing-visual-effect-p is non-nil, but the return value of the function vhl/pulse/available-p is nil, then this user option is ignored.

  Default value is nil.

You can also fine-tune the pulsing animation with the user options below.

• vhl/pulse-iterations: Number of iterations of a pulse animation for volatile highlights.

  Default value is 10.

• vhl/pulse-start-delay: Delay before pulse animation begins in seconds.

  Default value is 0.1.

• vhl/pulse-iteration-delay: Delay between iterations of the pulse animation in seconds.

  Default value is 0.03.

;;-----------------------------------------------------------------------------
;; Supporting vip-mode.
;;-----------------------------------------------------------------------------
(vhl/define-extension 'vip 'vip-yank)
(vhl/install-extension 'vip)

;;-----------------------------------------------------------------------------
;; Supporting evil-mode.
;;-----------------------------------------------------------------------------
(vhl/define-extension 'evil 'evil-paste-after 'evil-paste-before
                      'evil-paste-pop 'evil-move)
(vhl/install-extension 'evil)

;;-----------------------------------------------------------------------------
;; Supporting undo-tree.
;;-----------------------------------------------------------------------------
(vhl/define-extension 'undo-tree 'undo-tree-yank 'undo-tree-move)
(vhl/install-extension 'undo-tree)