Re: faq.texi

[Juri Linkov]

>> Are you saying you wish it would highlight the matching text that it
>> finds each time?
>
> Something like that; given that it already has support for an overlay to
> indicate where it skipped over non-matching text, I'm imagining an
> extension of that functionality where it would (1) highlight matching text
> too (in a different color), and (2) not immediately delete the overlays
> (currently the overlay appears to be strictly temporary).
>
> I'm not sure the best way to delete the overlays though, if they were made
> longer-lasting.

I believe the patch below is a good way to do this.  When the value of
`compare-windows-highlight' is `persistent', it requires calling
`compare-windows-dehighlight' (which can be bound to a separate key)
to delete all overlays.

Index: lisp/compare-w.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/compare-w.el,v
retrieving revision 1.33
diff -c -r1.33 compare-w.el
*** lisp/compare-w.el   6 Feb 2006 14:33:32 -0000       1.33
--- lisp/compare-w.el   17 Feb 2006 21:54:57 -0000
***************
*** 117,124 ****
    :version "22.1")
  
  (defcustom compare-windows-highlight t
!   "*Non-nil means compare-windows highlights the differences."
!   :type 'boolean
    :group 'compare-w
    :version "22.1")
  
--- 117,130 ----
    :version "22.1")
  
  (defcustom compare-windows-highlight t
!   "*Non-nil means compare-windows highlights the differences.
! The value t removes highlighting immediately after invoking a command
! other than `compare-windows'.
! The value `persistent' leaves all highlighted differences.  You can clear
! out all highlighting later with the command `compare-windows-dehighlight'."
!   :type '(choice (const :tag "No highlighting" nil)
!                (const :tag "Persistent highlighting" persistent)
!                (other :tag "Highlight until next command" t))
    :group 'compare-w
    :version "22.1")
  
***************
*** 130,135 ****
--- 136,143 ----
  
  (defvar compare-windows-overlay1 nil)
  (defvar compare-windows-overlay2 nil)
+ (defvar compare-windows-overlays1 nil)
+ (defvar compare-windows-overlays2 nil)
  (defvar compare-windows-sync-point nil)
  
  ;;;###autoload
***************
*** 351,363 ****
        (overlay-put compare-windows-overlay2 'face 'compare-windows)
        (overlay-put compare-windows-overlay2 'priority 1000))
      (overlay-put compare-windows-overlay2 'window w2)
!     ;; Remove highlighting before next command is executed
!     (add-hook 'pre-command-hook 'compare-windows-dehighlight)))
  
  (defun compare-windows-dehighlight ()
    "Remove highlighting created by `compare-windows-highlight'."
    (interactive)
    (remove-hook 'pre-command-hook 'compare-windows-dehighlight)
    (and compare-windows-overlay1 (delete-overlay compare-windows-overlay1))
    (and compare-windows-overlay2 (delete-overlay compare-windows-overlay2)))
  
--- 381,402 ----
        (overlay-put compare-windows-overlay2 'face 'compare-windows)
        (overlay-put compare-windows-overlay2 'priority 1000))
      (overlay-put compare-windows-overlay2 'window w2)
!     (if (not (eq compare-windows-highlight 'persistent))
!       ;; Remove highlighting before next command is executed
!       (add-hook 'pre-command-hook 'compare-windows-dehighlight)
!       (when compare-windows-overlay1
!       (push (copy-overlay compare-windows-overlay1) compare-windows-overlays1)
!       (delete-overlay compare-windows-overlay1))
!       (when compare-windows-overlay2
!       (push (copy-overlay compare-windows-overlay2) compare-windows-overlays2)
!       (delete-overlay compare-windows-overlay2)))))
  
  (defun compare-windows-dehighlight ()
    "Remove highlighting created by `compare-windows-highlight'."
    (interactive)
    (remove-hook 'pre-command-hook 'compare-windows-dehighlight)
+   (mapc 'delete-overlay compare-windows-overlays1)
+   (mapc 'delete-overlay compare-windows-overlays2)
    (and compare-windows-overlay1 (delete-overlay compare-windows-overlay1))
    (and compare-windows-overlay2 (delete-overlay compare-windows-overlay2)))

-- 
Juri Linkov
http://www.jurta.org/emacs/