I had the following hook:

(add-hook 'image-mode-hook 'imagex-sticky-maximize)

imagex-sticky-maximize is a function that maximizes the image to the borders of the window. I prefer to see my images to his fullest inside the window.

This works fine so far. But I noticed that Emacs crashes if the next file is a *.gif file. So disabling the imagex-sticky-maximize helps. But I would like to enable that function when the file is a *.PNG, or *.JPG or *.TIFF image.

So I was looking for a solution. I know you have the auto-mode-alist. When you declare something like this:

(add-to-list 'auto-mode-alist '("\\.clj$\\'" . paredit-mode))

Then paredit mode will be called as minor mode, when you open file with the extension *.clj. This works only for minor modes. I was looking for a sort of auto-function-alist, that calls imagex-sticky-maximize when a specifix extension is being opened. However, I couldn't find anything of this.

Any suggestion in that direction would be appreciated.

1 Answer 1


You can easily write your own function that checks the extension of the file name of the current buffer, and call a function if it does (or doesn't) match.

For example (warning: untested):

(defun my-image-mode-hook ()
  (let ((name (buffer-file-name)))
    (when name
      (let ((ext (file-name-extension name)))
        (unless (string= (downcase ext) "gif")
(add-hook 'image-mode-hook 'my-image-mode-hook)
  • Thanks for your suggestion. It would be a good idea indeed. Your function doesn't nothing by the way, you need to (add-hook 'image-mode-hook 'my-image-mode-hook).
    – ReneFroger
    Oct 19, 2015 at 14:45
  • @ReneFroger, thanks, answer updated! (Damn you auto completion...) Oct 19, 2015 at 14:53

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