[Simon Pepping]


I see you also solved another problem, viz. that fo:layout-master-set
did not return a proper IPD.

Correct. There are, I'm certain, many more cases where the layout managers does not yet set all the dimensions needed to resolve all the different percentages.

However, I am not happy with your
solution. During the layout process, you feed the page dimensions back
into the FO tree, in PageLayoutManager.createPageAreas.

Yes, and in BlockLayoutManager and in all the other LM that defines base length for percentages.

I think it
would be a better design if, in order to resolve the percent-based
properties, you would not climb the FO tree but the Area tree. That
avoids feeding back results from the Area tree into the FO tree.

The XSL spec says (XSL-PR/slice3.html#section-N1208-Conceptual-Procedure):

'The formatting object supplies parameters to its children based on the
traits of areas already in the area tree, possibly including areas
generated by the formatting object or its ancestors.'

Holding those parameters in the FO tree is one solution. Extracting
them from the area tree layed out up to that point is another

But there is *no* areas layed out or even created at the point where we need resolved length. When getNextBreakPoss is called, we only have a series of BreakPoss's stored in different layout managers.

The Area objects are created much later when we have BreakPoss's for an entire page. PageLM then calls addAreas which recursively creates all the areas for the page.

which has the advantage that it does not load the FO tree
with information that it does not need to have.

I initially had a separate PropertyContext object where the length was stored. The FO element then had a reference to the PropertyContext and there was a PropertyContext for every FO. But since there was a one-to-one correspondence between the FO's and the PropertyContexts I decided to put the information directly in the FO's instead.

Somehow, in our current design, the information must be stored in an object that exists:

- when the properties are parsed.
- when the break possibilities are created.

The FO nodes fulfills both requirements.

Perhaps the dimensions should be stored in the layout manager tree but the LM tree is not available when the the properties are parsed and there is no way to get from a FO to the LM's that the FO creates.


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