518665 - Make nsBlockFrame's overflow store an nsFrameList, not just lines

Status: RESOLVED DUPLICATE of bug 728908

(Core :: Layout, defect, P3)

Description

[Boris Zbarsky [:bzbarsky]]

See bug 512471 comment 5.

I guess the idea would be that Set/Get/RemoveOverflowLines would take a pointer to a struct, not to an nsLineList*, and that struct would contain an nsLineList* and an nsFrameList.

Would allocating this struct from the presshell's arena be reasonable?  I expect we'd be doing this a fair amount, and we have a prescontext in DestroyOverflowLines and the like already....

Comment 1

[fantasai]

Alternatively, you could just construct the nsFrameList on the fly in the places it's needed. We do that in GetChildList.

Comment 2

[fantasai]

Sorry, I guess I wasn't cleary: in that case, it doesn't need to be dynamically-allocated.

Comment 3

[Boris Zbarsky [:bzbarsky]]

I thought the whole point here was to get rid of the GetChildList code in question.

Comment 4

[fantasai]

I was suggesting to shift that into GetOverflowLines() so that GetOverflowLines()'s caller can request a frame list along with the line list. There's a couple places where we call GetOverflowLines just to check if we have lines, and there's others where we're manipulating the frame list; in the latter case we should have a frame list to manipulate.

But I guess that still doesn't get us const& nsFrameList for GetChildList...

Comment 5

[Boris Zbarsky [:bzbarsky]]

Right.  And creating an nsFrameList when we don't need one is not a good idea, since it's an O(N) in number of frames operation now...

Comment 6

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

We've stored overflow in a FrameLines struct containing nsFrameList and nsLineList. This is done in bug 728908.

Re comment 4:

But I guess that still doesn't get us const& nsFrameList for GetChildList...

This is fixed by bug 728906.