1355519 - Can IMEContentObserver treat HTML editor as multiple editors if it's too big?

Status: NEW

(Core :: DOM: UI Events & Focus Handling, enhancement, P3)

Description

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Currently, IMEContentObserver treats all contents in an HTML editor as an editor.

However, this may cause performance and footprint issue (especially on e10s mode) if the editor has too many contents. As far as I know, Word treats one page is an editor for preventing performance issue if there are too many pages.

From the point of view of IME, text outside current "paragraph" isn't so important. Using all text in an editor may make the conversion of IME improve, but it's not as important as current paragraph.

So, you can say, IMEContentObserver should treat nearest block ancestor is an editor.

However, there are some problems:

1. When caret moves across blocks, it causes sync IPC due to NotifyIMEFocus.
2. When selection crosses multiple blocks, what should we do?

#1 should be fixed with bug 1349255.

#2 might be solved with ignoring outside of first block in the selection. However, after replacing selected text, blocks will be merged. Then, IMEContentObserver needs to notify IME of appending text which was in the last block of the selection.

Perhaps, there could be more issues. Any ideas?

Comment 1

[Sylvestre Ledru [:Sylvestre]]

Moving to p3 because no activity for at least 1 year(s).
See https://github.com/mozilla/bug-handling/blob/master/policy/triage-bugzilla.md#how-do-you-triage for more information

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

Masayuki,  have you seen this causing real world issues? And how hard would this be to fix somehow?
(Just trying to figure out what kind of qf priority this should have)

Comment 3

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Well, I tried to reproduce the symptom with big editable content and IME, but in my environment, I cannot reproduce the slowness (although, for building Firefox, not slow machine). Anyway, this is really difficult challenge, so, I don't think we need to fix this soon.