Hashing page pixmaps instead of file to preserve annotations across common pdf alterations.

[rossikos]

I love Sioyek, but I have a major pain point: any change to the pdf that alters its md5 hash (e.g. changing outline or embedding annotations) will become incompatible with its sioyek annotations in the database upon changing the file path.

Sioyek mitigates some of this issue by caching the hash. However if the path is changed, you have to do something like:

update highlights set hash='NEW_HASH' where hash='OLD_HASH'       -- local.db
update document_hash set hash='NEW_HASH' where hash='OLD_HASH'    -- shared.db

every time a slight but hash-altering change is made, which really decreases usability.

I believe it would be more expedient to hash fixed-size pixmaps of the document pages instead, thus allowing Sioyek annotations to be preserved across many of the common changes.

Not sure how much overhead this would create when opening new pdfs, but caching the hashes should be an acceptable mitigation.

Any thoughts?

[ahrm]

There are many issues with this idea, including but not limited to:

1. Performance
2. There are many documents with empty pages, which will have the same hash
3. We can't load a document's annotations until we render every single page in the document