ISSUE-99: What happens when fill operations are blocked (related to Issue 98)

clear semantics

What happens when fill operations are blocked (related to Issue 98)

TTML 1.0
Raised by:
Sean Hayes
Opened on:
The current semantics are not actually very clear as to what happens when fill operations are blocked (there is no explicit part to B.5.1 which matches the condition: “the fill buffer is non-empty and contains sufficient content to compose a fill unit but insufficient space is present to accommodate it”. Presumably step 1 is skipped, and the timer is reset in step 2, so the fill remains pending, which implies that under some conditions, some content may never get flowed into the region. Again this seems to be due to the presence of an independent clear cycle.

I suggest that if the clear is initiated only by the fill/overflow condition, then these issues could be avoided by the algorithm:

Fill timer expires ->
While there is insufficient room to fit one fill unit into region
Use clear operation to remove one clear unit
Use reflow operation to adjust spacing if necessary
Use fill operation to flow one fill unit into region

Which also helps with the condition when the clear unit is smaller than the fill unit.

Related Actions Items:
No related actions
Related emails:
  1. Agenda for meeting 22-05-09 (from on 2009-05-22)
  2. ISSUE-99 (clear semantics): What happens when fill operations are blocked (related to Issue 98) [DFXP 1.0] (from on 2009-05-15)

Related notes:

resolved in TTAF1-DFXP WD Editor's Copy Update - 20090529

Glenn Adams, 29 May 2009, 04:33:20

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