This wasn't necessary before since the internal representation of
folds is be checked for consistency after each commit, but after the
switch to extradata fold operations would leave the extradata in an
invalid state. This isn't technically a problem, but it does leave more
extradata entries lying around than necessary, and it can trip up
automation scripts that aren't prepared for inconsistent fold state.
This makes the internal juggling of fold data even more complicated, but
it has a number of advantages:
- Folds will preserved even when opening the file with Aegisub builds
that don't know about folding.
- Folds will be preserved by automation scripts that re-insert every
line.
- Folds do not break when adding or deleting lines in a text editor or
some other editor, as long as the lines involving folds aren't
touched.
- In particular, merging changes using tools like git will not break
folds.
- Copy/pasting folds also keeps the folds to some extent. This is
impossible to solve in full generality, but simple cases like
cut/pasting a folded section somewhere else work, as long as the file
isn't saved in between.
- This will give automation scripts full access to folding without
needing to set up any additional API functions.
Line folds are managed using metadata of AssDialogue elements, and
saved in the project properties. They only affect the appearance of the
subtitle grid, and have no impact on other line operations.
arch1t3cht