Preview image file storage location for HTML exports

[karthink]

Leaving preview images in org-persist-dir when exporting Org documents to HTML with tex:dvisvgm or tex:dvipng makes the files non-portable and should be avoided.

As a result, there are two questions:

1. Where do we place the image files relative to the exported HTML document?
2. How is this location specified by the user?

We've been unable to find an intuitive/least-surprise solution to either of the questions. Here is the current system:

And here are a few different options we've considered. There are more possibilities because of the org-persist/temporary storage option (for non-export previews) and the option to inline the images in the HTML document:

Option 1

Option 2

Option 3

[tecosaur]

I'm not a fan of the complexity, but I'm most inclined towards (2) currently, based on the following thought process:

1. Inline images need to be an option
2. Having files locally/next to the .org file seems important for publishing
3. I think it would be undesirable to have to accept a local folder if you want in-buffer previews
4. There are legitimate reasons for wanting to switch between persist/temp preview storage, separately to the axis of publishing concerns

[karthink]

3. I think it would be undesirable to have to accept a local folder if you want in-buffer previews

Based on the number of questions about ltximg/ online, I think many users will want control over where in-buffer previews are placed. The limited choice of org-persist-dir or /tmp is going to annoy them. (Maybe this should be a separate issue?)

[karthink]

I'm not a fan of the complexity, but I'm most inclined towards (2) currently, based on the following thought process:

1. Inline images need to be an option
2. Having files locally/next to the .org file seems important for publishing

I agree broadly, but I'm looking for a better option than all of these, one with fewer arrows. Some modification of option 2 perhaps.

[tecosaur]

Based on the number of questions about ltximg/ online, I think many users will want control over where in-buffer previews are placed. The limited choice of org-persist-dir or /tmp is going to annoy them. (Maybe this should be a separate issue?)

We could have two variables

• org-latex-preview-cache-dir which can be 'persist, 'temp, or a string interpreted as a relative path based on the current org file/publish project.
• :image-dir (or similar) in org-html-latex-image-options, which either works exactly the same way or can only be a string.

[karthink]

Conclusion from discussion: Let's do it, with the name as org-latex-preview-cache for now.

[tecosaur]

Done.