Folding regions

[9vult]

My thoughts on a non-Extradata-based fold (region) system

As far as I can tell, using Extradata for regions has the benefit of being largely invisible, but it seems to cause more issues than it solves. For starters, you can't add events to the end of the region. You also can't move the start and end of the region around without recreating it, and there's a whole host of miscellaneous issues stemming from the extradata usage, like opening and closing a region not being a idempotent change.

Alternatively, we could use a "physical" barrier - events themselves. Consider the following:

Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Outside
Comment:  0,0:00:00.00,0:00:05.00,Default,,0,0,0,,#region
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Inside!
Comment:  0,0:00:00.00,0:00:05.00,Default,,0,0,0,,#endregion
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Outside

Using events as region barriers has several benefits. Most importantly, they can be easily moved around the file, modifications can be performed by an editor that doesn't support the region format without breaking them, and they're easily added, spotted, and removed (again, even by nonsupporting editors).

Regions could be optionally named:

Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Outside
Comment:  0,0:00:00.00,0:00:05.00,Default,,0,0,0,,#region My cool sign
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Inside!
Comment:  0,0:00:00.00,0:00:05.00,Default,,0,0,0,,#endregion My cool sign (closing name optional) 
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Outside

And there are a few possible options for supporting open/close in an open and idempotent manner. One possibility would be to use the Actor field:

Comment: 0,0:00:00.00,0:00:05.00,Default,region:closed,0,0,0,,#region My cool sign

Or something similar.

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Implementation-wise, we would likely need an alternative to

https://github.com/9vult/Ameko/blob/8da7c54753e08c6795e1149efd4e0dec898eb3a6/AssCS/EventManager.cs#L51-L61

where chain is filtered on the event being in an open region.

[petzku]

i don't really see how this is different from how folds are largely currently used? (that is, people generally label their folds' start and end with a commented line—this has the benefit of structuring the file even when the folds are removed). not that the proposal is necessarily a bad idea

opening and closing a region not being a idempotent change.

this is purely because the original implementation (unnecessarily) restricted itself to Aegisub's existing extradata API (which would always provide a new ID for a new entry, since they might not be unique), rather than extending it (allowing edits of extradata rather than creating a new entry)—not at all necessary to using extradata to store this

they can be easily moved around the file, modifications can be performed by an editor that doesn't support the region format without breaking them, and they're easily added, spotted, and removed (again, even by nonsupporting editors).

all of this besides spotting holds for extradata-based folds as well? at least if using commented lines as delimiters (which, again, is not particularly different from this proposed use)

For starters, you can't add events to the end of the region.

only an issue if— okay you get the idea

Implementation-wise, we would likely need an alternative to

surely folds shouldn't change which lines are accessible? or are you talking purely about rendering the lines?

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in short: the idea is maybe good, but the only real “fix” here to how folds are currently implemented in relevant Aegisub versions is forcing the user to use dedicated delimiter lines

[9vult]

surely folds shouldn't change which lines are accessible? or are you talking purely about rendering the lines?

Correct. That getter is used by the GUI to populate the grid, so we would want a complementary one that only returns lines that aren't in collapsed regions.

Wouldn't replace it because otherwise there'd be no way to get the whole list 😅

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The rest of what you say makes sense to me. I do admit I'm not the most experienced with Aegisub's folding (I don't use it much since I don't typeset), so most of my remarks are based on my limited experience and regurgitating what I've seen pass by in various chats lol.

[kametsuu]

That's what Kainote does. It uses actor field for that and empty comment line for description of fold (tree).

For example fold named "Fold example" with two lines in it:

Dialogue: 0,0:00:05.00,0:00:10.00,Default,,0,0,0,,First line (not in fold)
Comment: 0,0:00:10.00,0:00:15.00,Default,[tree_description],0,0,0,,Fold example
Dialogue: 0,0:00:10.00,0:00:15.00,Default,[tree_opened],0,0,0,,Line in fold
Dialogue: 0,0:00:15.00,0:00:20.00,Default,[tree_opened],0,0,0,,Second line in fold
Dialogue: 0,0:00:20.00,0:00:25.00,Default,,0,0,0,,Not in fold

[9vult]

Marking every line in the region with [tree_opened], while making the "check which lines to render" part super easy, is a bad solution IMO. I wonder why they did that?

Not only does it prevent you from using the actor field for anything else, but unless Kainote copies the preceding actor to new lines, wouldn't that mean you have to manually add the flag if you add a line to the fold?

[kametsuu]

I originally thought it was related to the fact that you can hide individual lines in Kainote (which I actually used quite a lot), but it turns out that’s not the case. This feature was created something like 8 years ago when Kainote was heavily restructured and it probably left this way because it just worked anyway, so yeah bad design.

You don’t see that message in the actor field in the program, it gets stripped out. If you use “insert after” or “insert before” on a line that’s inside a fold, the new line will also be placed inside that fold.

Personally, I would go with something like this:

Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Outside
Comment:  0,0:00:00.00,0:00:05.00,Default,[fold_start:some name of fold],0,0,0,,
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Inside
Comment:  0,0:00:00.00,0:00:05.00,Default,[fold_end:some name of fold],0,0,0,,
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Outside

I wouldn’t put #region in the content of line, because I can imagine someone trying to leave a note there (possibly not even in English) and randomly typing that and getting confused by what happened. So IMO, it should be entirely in the actor field.

[9vult]

Yeah I did consider that.

Could allow for inline with the content as well if that was desired for some reason:

Dialogue: 0,0:00:00.00,0:00:05.00,Default,[fold_start:some name of fold],0,0,0,,Inside of fold

Same with the ending

Though this ofc brings back the "not easy to add lines to the end" issue, so not a great solution