1288983 - Break text frames for force line break inside earlier

Status: NEW

(Core :: Layout: Text and Fonts, defect, P3)

Description

[Xidorn Quan [:xidorn] UTC+10]

We sometimes run into O(N^2) algorithm for processing text runs (e.g. bug 1288938), and shorter text run would make those issues happen less frequently.

I suggest we have the frame constructor split text frames which has force line break inside, so that when we are creating text runs, frames are already short enough, and we wouldn't ever create text run which is across any force line break.

Comment 1

[Xidorn Quan [:xidorn] UTC+10]

I wonder if we split the text frame in nsCSSFrameConstructor::ConstructTextFrame, do we still need the current code in nsTextFrame::ReflowText to find newlines.

Comment 2

[Xidorn Quan [:xidorn] UTC+10]

Looks like we would still need that in case the data is changed dynamically.

I guess we may want to move the newline cache to frame property table, so that we avoid an allocation (because it is just one integer then), and we should be able to skip more rescanning. (The invalidation could take some time, but we need an O(n) in CharacterDataChanged anyway).