Function: image-load-path-for-library

image-load-path-for-library is a byte-compiled function defined in image.el.gz.

Signature

(image-load-path-for-library LIBRARY IMAGE &optional PATH NO-ERROR)

Documentation

Return a suitable search path for images used by LIBRARY.

It searches for IMAGE in image-load-path (excluding
"`data-directory'/images") and load-path, followed by a path
suitable for LIBRARY, which includes "../../etc/images" and
"../etc/images" relative to the library file itself, and then
in "`data-directory'/images".

Then this function returns a list of directories which contains first the directory in which IMAGE was found, followed by the value of load-path. If PATH is given, it is used instead of load-path.

If NO-ERROR is non-nil and a suitable path can't be found, don't signal an error. Instead, return a list of directories as before, except that nil appears in place of the image directory.

Here is an example that uses a common idiom to provide compatibility with versions of Emacs that lack the variable image-load-path:

    ;; Shush compiler.
    (defvar image-load-path)

    (let* ((load-path (image-load-path-for-library "mh-e" "mh-logo.xpm"))
           (image-load-path (cons (car load-path)
                                  (when (boundp 'image-load-path)
                                    image-load-path))))
      (mh-tool-bar-folder-buttons-init))

View in manual

Probably introduced at or before Emacs version 22.1.

Aliases

mh-image-load-path-for-library (obsolete since 29.1)

Source Code

;; Defined in /usr/src/emacs/lisp/image.el.gz
(defun image-load-path-for-library (library image &optional path no-error)
  "Return a suitable search path for images used by LIBRARY.

It searches for IMAGE in `image-load-path' (excluding
\"`data-directory'/images\") and `load-path', followed by a path
suitable for LIBRARY, which includes \"../../etc/images\" and
\"../etc/images\" relative to the library file itself, and then
in \"`data-directory'/images\".

Then this function returns a list of directories which contains
first the directory in which IMAGE was found, followed by the
value of `load-path'.  If PATH is given, it is used instead of
`load-path'.

If NO-ERROR is non-nil and a suitable path can't be found, don't
signal an error.  Instead, return a list of directories as before,
except that nil appears in place of the image directory.

Here is an example that uses a common idiom to provide
compatibility with versions of Emacs that lack the variable
`image-load-path':

    ;; Shush compiler.
    (defvar image-load-path)

    (let* ((load-path (image-load-path-for-library \"mh-e\" \"mh-logo.xpm\"))
           (image-load-path (cons (car load-path)
                                  (when (boundp \\='image-load-path)
                                    image-load-path))))
      (mh-tool-bar-folder-buttons-init))"
  (unless library (error "No library specified"))
  (unless image   (error "No image specified"))
  (let (image-directory image-directory-load-path)
    ;; Check for images in image-load-path or load-path.
    (let ((img image)
          (dir (or
                ;; Images in image-load-path.
                (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 `image-directory'
      ;; accordingly.
      (when dir
        (setq dir (file-name-directory dir))
        (while (setq parent (file-name-directory img))
          (setq img (directory-file-name parent)
                dir (expand-file-name "../" dir))))
      (setq image-directory-load-path dir))

    ;; If `image-directory-load-path' isn't Emacs's image directory,
    ;; it's probably a user preference, so use it. Then use a
    ;; relative setting if possible; otherwise, use
    ;; `image-directory-load-path'.
    (cond
     ;; User-modified image-load-path?
     ((and image-directory-load-path
           (not (equal image-directory-load-path
                       (file-name-as-directory
                        (expand-file-name "images" data-directory)))))
      (setq image-directory image-directory-load-path))
     ;; Try relative setting.
     ((let (library-name d1ei d2ei)
        ;; First, find library in the load-path.
        (setq library-name (locate-library library))
        (if (not library-name)
            (error "Cannot find library %s in load-path" library))
        ;; And then set image-directory relative to that.
        (setq
         ;; Go down 2 levels.
         d2ei (file-name-as-directory
               (expand-file-name
                (concat (file-name-directory library-name) "../../etc/images")))
         ;; Go down 1 level.
         d1ei (file-name-as-directory
               (expand-file-name
                (concat (file-name-directory library-name) "../etc/images"))))
        (setq 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)))))
     ;; Use Emacs's image directory.
     (image-directory-load-path
      (setq image-directory image-directory-load-path))
     (no-error
      (message "Could not find image %s for library %s" image library))
     (t
      (error "Could not find image %s for library %s" image library)))

    ;; Return an augmented `path' or `load-path'.
    (nconc (list image-directory)
           (delete image-directory (copy-sequence (or path load-path))))))