834097 - Simplify nsOverflowContinuationTracker frame list handling

Status: NEW

(Core :: Layout: Block and Inline, defect)

Description

[Mats Palmgren (inactive)]

nsOverflowContinuationTracker can point to either the
ExcessOverflowContinuations list or the OverflowContinuations on the
next-in-flow (stored in mParent).  This seems overly complicated.
I think it would be simpler to always add the frames to the
ExcessOverflowContinuations list and then the next-in-flow can
drain that at the start of its ReflowOverflowContainerChildren.

Comment 1

[Mats Palmgren (inactive)]

fantasai, would this be possible?  Were there any particular reasons you chose
the current design?

Comment 2

[fantasai]

The reason for the current design was to maintain the proper ordering of overflow continuation frames. The draining model used for overflowing frames in the flow works fine as long as the frames on the overflow list are guaranteed to be before the frames already in the next-in-flow. However, this is not true for overflow continuations.

Let me know if that answers your question...

Comment 3

[fantasai]

Example of why the current model is used:
  Imagine block frames A, B, and C exist on page 1.
  A and C have overflow that spills onto page 2, so page two has A' and C' in its list.
  We reflow a second time because someone added content to B.
  B now also overflows, so we need to add B' to page 2.
B' needs to be between A' and C' in page 2's overflow continuation list. If we put it in page 1's overflow list and drained it onto the top of page 2, the ordering would be B', A', C' instead of A', B', C'.