I have an image generated by plantuml which I open in an Image mode buffer. I want to use Auto-Revert mode so it auto-refreshes, but it doesn't seem to work on Image mode buffers for some reason. Is there something I'm missing?
3 Answers
As someone who just had this problem, I found another solution: auto-image-file-mode
. What it does is automatically make sure the file is in image mode instead of binary, so enable both that and auto-revert-mode
and everything works as expected. Emacs 24.4.1
Source: http://osdir.com/ml/bug-gnu-emacs-gnu/2014-01/msg01061.html

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You don't provide much information about what you are doing or what you are seeing. Try to give a step-by-step recipe, preferably starting from emacs -Q
, and say what you expect versus what you see.
Does manually reverting the buffer work (M-x revert-buffer
, after setting the current buffer to the image buffer)? If so, then investigate what is different about auto-reversion.
Are you using global-auto-revert-mode
? If not, is your image buffer on auto-revert-buffer-list
? If not, then that would explain things: auto-revert-mode
adds the current buffer to that list, and auto-revert-buffers
reverts buffers that are on that list.
I'm no expert on image-mode
, but searching for revert
in image-mode.el
I see function image-after-revert-hook
. If it were I, I might start by M-x debug-on-entry image-after-revert-hook
(after loading image-mode.el
, not image-mode.elc
), and then stepping through the debugger (e.g., using d
).
(A wild guess tells me that that function is not even called, and that the image buffer is not a candidate for reverting. See above. Maybe try global-auto-revert-mode
, to start with.)

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I tried opening a png in emacs, enabling auto-revert-mode
and then from a shell, copying another image over it and then replacing that file with a copy of the original png.
What I found is that the file is sometimes updated to the new files binary contents, but not the rendered content. If it opens the binary content, try using C-c C-c to convert it to an image.
After doing that conversion at least once, it starts auto-reverting as I would expect by keeping it an image.
Note: I tried this with Emacs 25.1, so it may be a new feature. What version are you using?

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24.3 - time to update! I used to stay on the source head or near it, but the release version is pretty good these days. – Mark Nov 02 '14 at 10:20