[css-break] define breaking of floats

[dbaron]

The current breaking specification doesn't appear to define a lot of detail for breaking of floats. I think a definition ought to answer at least the following questions (which are written assuming writing-mode: horizontal-tb):

• how do the rules for float placement interact with fragmentation, particularly when the widths of the fragments are different? For example:
  • if there are two floats at the bottom of a fragment that need to be continued in the next fragment, but they don't both fit in its width, which one goes first? (I would assume the earlier one in the document order.)
  • if a float doesn't fit within a fragment and it needs to begin in a later fragment, is it possible to place any other floats before it begins? (I would assume not.) In what order do such continued floats begin? (I'd again assume document order.)
• If a float's containing block does not exist in the fragment in which (part of) the float is, how are the edges of that containing block defined?

[fantasai]

I think the first set of questions should be answered in https://www.w3.org/TR/css-break-3/#varying-size-boxes ? Certainly there's an example of exactly the cases you describe.

[dbaron]

There's an example, sure, but not definitions. And the example only covers part, since it doesn't really explain what led to the order of the later fragments.

[fantasai]

The normative prose is: “Fragments of boxes that began on a previous fragmentainer must obey placement rules with the additional constraint that fragments must not be positioned above the block-start edge of the fragmentainer.”

The float-placement rules invoke document order, and fragments must obey the placement rules.