[Bug] File previews flicker when visual-line-fill-column-mode is enabled

[lyndhurst]

Bug description

Org files with lines longer than fill-column value flicker in the preview pane when visual-line-fill-column-mode is enabled in org-mode. I have not tested with other file types.

I also noticed that switching focus to the preview pane stops the flickering even after switching back to the dired pane, the preview remains still. The flickering starts again if I open a minibuffer, or a dirvish menu UI.

I tested with visible-mode on and off, it made no difference.

Steps to reproduce

1. Make sure visual-line-fill-column-mode is enabled in org-mode
2. Open an org file in Emacs
3. Fill it with lines longer than the local value of fill-column
4. Call dirvish
5. The file in the preview pane should be flickering at this point

This is how visual-mode is configured in my configuration file:

(add-hook! 'org-mode-hook
           #'visual-line-fill-column-mode
           (setq-local fill-column 70)
           )

The flickering also happens when using the default fill-column value (commenting the setq-local line above), and it is even worse when using visual-line along with visual-fill-column as follows:

(add-hook! 'org-mode-hook
           #'visual-line-mode
           #'visual-fill-column-mode
           (setq-local fill-column 70)
           )

Expected behavior

The Org file preview should remain still.

OS

Linux

Emacs Version

29

Emacs Configurations

Doom Emacs

Error callstack

Anything else

Thanks for your time, and a great package.

[alexluigit]

I tested your config with doom with Emacs31 and can not reproduce. Are you using dirvish from :emacs dired module or the latest commit from this repo?

[lyndhurst]

Thanks for having a look at it.

It is installed using :emacs dired indeed. I did a complete upgrade/rebuild of my packages a few days ago. This is the output from describe-package:

Package: dirvish
Source: Straight
Pinned: 5f04619
Build: grafted, HEAD -> main, replaced 5f04619 2024-08-07 16:19:34 -0400
Build location: ~/.emacs.d/.local/straight/build-29.4/dirvish/
Repo location: ~/.emacs.d/.local/straight/repos/dirvish/
Recipe: (:host github :repo "hlissner/dirvish" :files
(:defaults "extensions/*.el" "dirvish-pkg.el")
:package "dirvish" :type git :local-repo "dirvish")
Homepage: https://github.com/alexluigit/dirvish
Modules: Declared by the following Doom modules:
:emacs dired (readme)
Configs: This package is configured in the following locations:
modules/emacs/dired/config.el:72:(use-package! dirvish

Maybe I missed something else, but I do not think so, I tested many configurations and files before posting. I do not know if there is a cache mechanism or something, but results can be inconsistent. While I was testing, I noticed that some files that I previewed/browsed without the visual-line-fill-column-mode would display normally in the preview even after restoring the setting, to this day, some of the notes I tested on are displayed in the preview pane as if the mode was disabled.

=== EDIT

I am having a lot of trouble making sense of this, but I just did some more testing, and I do not know what the normal behaviour should be. I went to other folders to test some more. I have an org-roam folder with a lot of notes, and none of them flicker. They are displayed in the preview as if the visual-line mode was disabled so they do not flicker. Similarly, notes in my Denote folder previewed without visual-line mode do not flicker.

So I guess it leaves me with two questions:

1. Is it normal behavior for Dirvish to ignore the visual-line configuration set by the user in the preview pane?
2. Why is it behaving differently with my Denote notes ?

Denote has a denote-dired-mode to highlight file name components, but the filckering happens even with the mode disabled. I hope you can make more sense of it than I can, or have an idea I could test to find out more,because I am at loss here :)

[alexluigit]

Please let me know if doomemacs/doomemacs#8272 solved this. If not, tweak the dirvish-preview-environment option and see if the issue persists.

[lyndhurst]

Sorry I could not test this weekend. I did a very quick test this morning, but I cannot dig into much further today.

The problem only persists for Org files open in buffers prior to calling Dirvish.

Other files are now displayed steadily, even non Org files already open in buffers (tested with Elisp only). I could not isolate any other common characteristic between Org files still affected except being open in buffers (tried large files, files with title only, folded, unfolded...).

Finally, I did not understand at first glance the dirvish-preview-environment elements, maybe I should read the Consult preview variables doc string later.

Please let me know if you need more info, thanks for following up 👍

[lyndhurst]

In case this is helpful, I noticed today that flickering previews affect files open in buffers only, but I think it might be linked to the visual-line-fill-column-mode after all.

Taking a closer look, previews of files open in buffer honor/respect the visual-line..mode, previews of files that are not open in buffers are displayed without any kind of line wrapping.

[alexluigit]

I see. Thanks for the feedback, will try to fix this soon.

[alexluigit]

Please let me if 8a2aafd fixed this.

[lyndhurst]

I tried to make it flicker as much as I could, it seems fixed for me.
Unfolded open buffers I tried were displayed folded in the preview pane, but I could not notice anything else out of the ordinary.

I will let you know if it happens again after using it for longer, and do not hesitate if you need more info.
Thanks for taking care of it 👍

[alexluigit]

Unfolded open buffers I tried were displayed folded in the preview pane, but I could not notice anything else out of the ordinary.

This is expected since they are newly generated read-only buffers, it does not reuse your existing buffers.

Feel free to report back if the same issue occurs.