Re: image-load-path/load-path function

[Bill Wohler <wohler@newt.com>]

Rainer,

I copied your *-image-load-path function, changed gmm to mh, made a
couple of changes (listed below), and updated our software to use scoped
copies of image-load-path/load-path.

- Delete mh-image-directory variable per previous email.

- Remove periods from (error) strings per Emacs conventions. See Info
  node `(elisp)Programming Tips'.

- Remove quotes around %s. There isn't an explicit Emacs convention
  about this, but it's used in less than 10% of the cases so I made it
  an MH-E convention.

- Add comment before a bit that took me a minute to grok.

I think we're ready to move it to image.el. Let me know if you think I
should proceed.

I think the name image-load-path would be fine: If you ask for the
variable image-load-path, you get the image load path, if you ask for
the function image-load-path, you get the image load path. Seems
consistent. What do you think?


(defun mh-image-load-path (library image &optional path)
  "Return a suitable search path for images of LIBRARY.

Images for LIBRARY are searched for in \"../../etc/images\" and
\"../etc/images\" relative to the files in \"lisp/LIBRARY\", in
`image-load-path', or in `load-path'.

This function returns value of `load-path' augmented with the
path to IMAGE.  If PATH is given, it is used instead of
`load-path'."
  (unless library (error "No library specified"))
  (unless image   (error "No image specified"))
  (let ((mh-image-directory))
    (cond
     ;; Try relative setting.
     ((let (mh-library-name d1ei d2ei)
        ;; First, find library in the load-path.
        (setq mh-library-name (locate-library library))
        (if (not mh-library-name)
            (error "Cannot find library %s in load-path" library))
        ;; And then set mh-image-directory relative to that.
        (setq
         ;; Go down 2 levels.
         d2ei (expand-file-name
               (concat (file-name-directory mh-library-name)
                       "../../etc/images"))
         ;; Go down 1 level.
         d1ei (expand-file-name
               (concat (file-name-directory mh-library-name)
                       "../etc/images")))
        (setq mh-image-directory
              ;; Set it to nil if image is not found.
              (cond ((file-exists-p (expand-file-name image d2ei)) d2ei)
                    ((file-exists-p (expand-file-name image d1ei)) d1ei)))))
     ;; Check for images in image-load-path or load-path.
     ((let ((img image)
            (dir (or
                  ;; Images in image-load-path.
                  (mh-image-search-load-path image)
                  ;; Images in load-path.
                  (locate-library image)))
            parent)
        ;; Since the image might be in a nested directory
        ;; (for example, mail/attach.pbm), adjust `mh-image-directory'
        ;; accordingly.
        (and dir
             (setq dir (file-name-directory dir))
             (progn
               (while (setq parent (file-name-directory img))
                 (setq img (directory-file-name parent)
                       dir (expand-file-name "../" dir)))
               (setq mh-image-directory dir))))))
    ;;
    (unless (file-exists-p mh-image-directory)
      (error "Directory %s in mh-image-directory does not exist"
	     mh-image-directory))
    (unless (file-exists-p (expand-file-name image mh-image-directory))
      (error "Directory %s in mh-image-directory does not contain image %s"
             mh-image-directory image))
    ;; Return augmented `image-load-path' or `load-path'.
    (cond ((and path (symbolp path))
           (nconc (list mh-image-directory)
                  (delete mh-image-directory
                          (if (boundp path)
                              (copy-sequence (symbol-value path))
                            nil))))
          (t
           (nconc (list mh-image-directory)
                  (delete mh-image-directory
                          (copy-sequence load-path)))))))
-- 
Bill Wohler <wohler@newt.com>  http://www.newt.com/wohler/  GnuPG ID:610BD9AD
Maintainer of comp.mail.mh FAQ and MH-E. Vote Libertarian!
If you're passed on the right, you're in the wrong lane.


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