Image tooltips doesn't work in other buffers

Question

Consider the following content of a file called image-tooltips.el which I source into my .emacs file via load-file. Displaying the image tooltip works if I put a ;\includegraphics{myfile.jpg} into this file after executing eval-buffer.

However if I load a latex-file also including an includegraphics stanza, it doesn't work.

I turned flyspell mode off and also tried to but the following code between a

(add-hook 'LaTeX-mode-hook
 '(lambda ()

;;; code below

))

Here is the content of image-tooltips.el:

(defvar image-tooltip-re (concat  "\\\\includegraphics{\\(?1:.*\\."
                                 (regexp-opt '("png" "PNG" "JPG" "jpeg"
                                               "jpg" "JPEG" "eps" "EPS" "pdf"))
                                 "\\)}")
 "Regexp to match included images")


(defun image-tooltip (window object position)
  (save-excursion
    (goto-char position)
    (let (beg end imgfile img s)
      (while (not (looking-at image-tooltip-re))
        (forward-char -1))
      (setq imgfile (match-string-no-properties 1))
      (when (file-exists-p imgfile)
        (setq img (create-image (expand-file-name imgfile)
                                'imagemagick nil :width 800))
        (propertize "Look in the minibuffer"
                    'display img)))))


(font-lock-add-keywords
 nil
 `((,image-tooltip-re
    0 '(face font-lock-keyword-face
             help-echo image-tooltip))))

(font-lock-fontify-buffer)
(setq x-gtk-use-system-tooltips nil)

;\includegraphics{image.jpg};; works

How can I make this work automatically if I load a tex-file and also if flyspell mode is enabled (the matched strings should be ignored by flyspell and the image should show on mouseover instead).

The code above is a slightly adapted version of Displaying image overlays on image filenames in Emacs

Edit Same problem with the code from https://emacs.stackexchange.com/a/27428/2323.

Edit 2 Here is a minimal .emacs file where I get the problem with John Kitchin's solution that it works only after explicitely reloading latex mode, i.e. load a .tex file (where latex-mode is loaded automatically) the it doesn't work but it works afer an M-x latex-mode. Also if I add an \includegraphics{image.jpg} line it sometimes doesn't recognize it, but after reloading latex mode it works. However it should recognize it without reloading latex-mode.

(require 'package)
(add-to-list 'package-archives 
    '("marmalade" .
      "http://marmalade-repo.org/packages/"))
(add-to-list 'package-archives
             '("melpa" . "http://melpa.milkbox.net/packages/") t)

(setq package-archive-enable-alist '(("melpa" deft magit)))

(package-initialize)

(setq ispell-program-name "hunspell")
(setq ispell-local-dictionary "de_DE")
(setq ispell-local-dictionary-alist
      '(("de_DE" "[[:alpha:]]" "[^[:alpha:]]" "[']" nil nil nil utf-8)
    ("en_US" "[[:alpha:]]" "[^[:alpha:]]" "[']" nil nil nil utf-8)
    ))



(add-hook 'LaTeX-mode-hook 'turn-on-flyspell)
(add-hook 'LaTeX-mode-hook 'flyspell-buffer)



(setq x-gtk-use-system-tooltips nil)

(defvar image-tooltip-re (concat  "\\\\includegraphics{\\(?1:.*\\."
                  (regexp-opt '("png" "PNG" "JPG" "jpeg"
                        "jpg" "JPEG" "eps" "EPS" "pdf"))
                  "\\)}")
  "Regexp to match included images")


(defun image-tooltip (window object position)
  (save-excursion
    (goto-char position)
    (let (beg end imgfile img s)
      (while (not (looking-at image-tooltip-re))
        (forward-char -1))
      (setq imgfile (match-string-no-properties 1))
      (if (file-exists-p imgfile)
      (progn
        (setq img (create-image (expand-file-name imgfile)
                    'imagemagick nil :width 800))
        (propertize "Look in the minibuffer"
            'display img))
    "No file found"))))

(defun img-match (limit)
  "Match bar in at the end of a word."
  (when (re-search-forward image-tooltip-re limit t)
    (flyspell-delete-region-overlays (match-beginning 1)
                     (match-end 1))
    t))

(add-hook 'LaTeX-mode-hook
      (lambda ()
        (font-lock-add-keywords
         nil
         '((img-match 1 '(face font-lock-keyword-face
                   help-echo image-tooltip))))))

Answer 1

You probably want something like this. I think you need a function that matches the img, so you can get the region and remove flyspell overlays. Also you need to modify the add-hook call a bit.

(setq x-gtk-use-system-tooltips nil)

(defvar image-tooltip-re (concat  "\\\\includegraphics{\\(?1:.*\\."
                  (regexp-opt '("png" "PNG" "JPG" "jpeg"
                        "jpg" "JPEG" "eps" "EPS" "pdf"))
                  "\\)}")
  "Regexp to match included images")


(defun image-tooltip (window object position)
  (save-excursion
    (goto-char position)
    (let (beg end imgfile img s)
      (while (not (looking-at image-tooltip-re))
        (forward-char -1))
      (setq imgfile (match-string-no-properties 1))
      (if (file-exists-p imgfile)
      (progn
        (setq img (create-image (expand-file-name imgfile)
                    'imagemagick nil :width 800))
        (message (propertize "Look in the minibuffer"
                 'display img)))
    "No file found"))))

(defun img-match (limit)
  "Match bar in at the end of a word."
  (when (re-search-forward image-tooltip-re limit t)
    (flyspell-delete-region-overlays (match-beginning 1)
                     (match-end 1))
    t))

(add-hook 'LaTeX-mode-hook
      (lambda ()
        (font-lock-add-keywords
         nil
         '((img-match 1 '(face font-lock-keyword-face
                   help-echo image-tooltip))))))