On May 19, 2008, at 17:08, Vincent Hennebert wrote:

Hi

bonekrusher wrote:
Hi,

Since FOP 0.94 and 0.95 Beta do not have support for Table Continuation Labels, I would like to see if I can possible work on this for the project.

To implement this feature, 4 steps basically need to be performed:
- implement support for fo:retrieve-table-marker in the FO tree;
  I believe this stage is more or less complete

Indeed. I added this recently. The only thing currently incomplete is support for retrieve-table-markers as substitutes for the header/ footer. (It seems like the Recommendation offers the possibility of putting the entire fo:table-header element in a fo:marker... Adrian pointed this out after I committed. As Vincent points out: read /and/ re-read ;-))


<snip />
I can’t help you much regarding how other markers are currently handled,
since I haven’t looked at this part of the code yet.

The key point here is PageSequenceLayoutManager.resolveRetrieveMarker () which is called from AbstractLayoutManager.createChildLMs() (for the subclass StaticContentLayoutManager).

<snip />
However,
org.apache.fop.fo.flow.AbstractRetrieveMarker seems like a good starting
point.

This contains the basic code for cloning the marker. Normally, this should not need any changes (apart from cleaning up some unrelated TODOs...) While it may be of educational value to browse through, it does not contain anything specific wrt the actual marker-resolution. It only contains the mechanism for the marker-duplication: cloning the subtree, evaluating property expressions in the proper context, triggering white-space-handling. This is all done because one fo:marker may be retrieved multiple times into different contexts, so it's important to separate the retrieved copy from the original.

The main challenge in the layoutengine, as I see it is that, for marker-retrieval to work (on page-level), the cells in the table-body have to have 'added' their markers (see AbstractLayoutManager.addMarkersToPage(), which is called from addAreas()). In normal flow-layout, the marker-retrieval is triggered by the StaticContentLayoutManager.createChildLMs(), which is activated / after/ the areas for the Flow have been added to the body-region for the current page-viewport.


Just my 2 cents...

Cheers

Andreas

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