Multi-line text effects (or "the spy strikes back")

[Omikhleia]

My next "easy" package project...

I came across that document, you know, which mentioned a great threat to the world, and solutions to avoid it. But unfortunately...

... The document was, erm, how do you say that in English? Redacted , i think. Or censored by some state agency, anyway 😆

Ok, this might sound very specific... and indeed, I had that kind of "letter" with some censored text... in LibreOffice, initially, I just drew ugly black boxes manually over some (fake) bits of text - but, typesetting it again in another page size, I had to redo them all... So I thought it could be fun to make it better with SILE, and allow those boxes to span over multiple lines automatically so I don't have to bother where line breaks will occur if I change the page size once again, the font, margins or whatever... Very specific need, I admit. Er. Wait... The same small trick could maybe be used for:

• multi-line underlining (though underlining is nearly always bad typography...)
• multi-line strike-through (oh, more interesting to me... In a critical text edition, it could be most welcome, for what it is truly = mark portions of text that the author rejected)
• multi-line hyper-links (cf. pdf:link does not allow line breaks #1239... Oh oh, even more interesting) - well, I am not sure having a repeated link on each line is very neat and the proper way to achieve that, but it would somehow work...

The "trick" so far is so obvious (some new zerohbox-like nodes in the text flow to mark the start and end of a "redaction", a simple SILE.typesetter.breakIntoLines overload to re-process them after the actual regular line-breaking stuff; and if one really wants to cancel the hidden text, an even simpler overload to SILE.typesetter.drawHbox)... Surely, it sounds all too simple... I might have forgotten something ^^ But it's a hella fun anyway 😸

[Omikhleia]

I might have forgotten something

Found one edge case pretty soon. Page breaks with migrating contents (typically footnotes). Things go messy here.

[Omikhleia]

For the record and an update, the core functionality discussed here (= the ability to implement effects spanning multiple lines) is addressed in #1977 - Yep, it took me 2+ years to get there ;)