bug#8453: enhancement to image mode

[Christian Wittern]

Hello, I am trying to send this through the send bug report function, I hope
it works.

With the help of Drew Adams on gnu.emacs.help, I added the following to
image-mode, which allows one to visit the following or previous image, which
is useful if images are in a series, such as in pages of books. If this is
deemed useful, I would like to have this added to emacs.

(require 'image-mode)
(define-key image-mode-map "n" 'next-image)
(define-key image-mode-map "p" 'previous-image)

(defun next-image (arg)
"when visitng an image, go to the next image in the same
directory of the same type. No argument or nil will move to the
following image in ascending order, t will move to the previous
one. Thanks to Drew Adams for help with this on gnu.emacs.help"
(interactive "P")
(unless (and (buffer-file-name) (eq major-mode 'image-mode))
(error "Not visiting a file in image mode"))
(let* ((files (directory-files
(file-name-directory (buffer-file-name)) nil
(file-name-extension (buffer-file-name)) ))
(len (length files))
(this (file-name-nondirectory (buffer-file-name)))
(idx 0))
(catch 'next-image
(dolist (file files)
(when (string= this file) (throw 'next-image (1+ idx)))
(setq idx (1+ idx))))
(setq idx (+ idx (if arg -1 1)))
(when (< idx 0) (setq idx (1- len)))
(when (>= idx len) (setq idx 0))
(find-file (elt files idx))))

(defun previous-image (arg)
"when visitng an image, go to the next image in the same
directory of the same type. No argument or nil will move to the
following image in ascending order, t will move to the previous
one. Thanks to Drew Adams for help with this on gnu.emacs.help"
(interactive "P")
(next-image t))

--
Christian Wittern

[Stefan Monnier]

> With the help of Drew Adams on gnu.emacs.help, I added the following to
> image-mode, which allows one to visit the following or previous image, which
> is useful if images are in a series, such as in pages of books. If this is
> deemed useful, I would like to have this added to emacs.

This looks very handy, indeed. I'd recommend to slightly change the
code so it just looks for the first filename greater than the current
name (so it also works in the odd case where the current file is not in
the directory any more).

I'm currently traveling, so if someone else can take care of
cleaning-up and installing this code, I'd appreciate it.

Stefan

PS: this again calls for closer integration between doc-mode and image-mode.

[Chong Yidong]

Stefan Monnier <mon...@iro.umontreal.ca> writes:

>> With the help of Drew Adams on gnu.emacs.help, I added the following
>> to image-mode, which allows one to visit the following or previous
>> image, which is useful if images are in a series, such as in pages of
>> books. If this is deemed useful, I would like to have this added to
>> emacs.
>
> This looks very handy, indeed. I'd recommend to slightly change the
> code so it just looks for the first filename greater than the current
> name (so it also works in the odd case where the current file is not
> in the directory any more).

Done, with some substantial modifications.