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From Apache Wiki <wikidi...@apache.org>
Subject [Xmlgraphics-fop Wiki] Update of "PageLayout/InfluenceOfPageSizesOnAlgorithm" by JeremiasMaerki
Date Wed, 09 Aug 2006 08:24:15 GMT
Dear Wiki user,

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The following page has been changed by JeremiasMaerki:

The comment on the change is:
Planning on implementing this

  It remains to be determined if side-floats have an impact here. Probably not, since they
mostly affect only the present page and there only the line-breaking.
- Example of such a document: attachment:alternating-page-sizes.fo.xml, attachment:alternating-page-sizes.pdf
+ Example of such a document: http://people.apache.org/~jeremias/fop/alternating-page-sizes.fo,
- [1] Br├╝ggemann-Klein, Klein, Wohlfeil: On the Pagination of Complex Documents, www.pi6.fernuni-hagen.de/publ/tr234.pdf
+ [1] Br├╝ggemann-Klein, Klein, Wohlfeil: On the Pagination of Complex Documents, http://www.pi6.fernuni-hagen.de/publ/tr234.pdf
+ ----
+ = Details to consider when implementing "changing available IPD" in FOP Trunk =
+ Here are some points we should look into when we're planning on implementing support for
"changing available IPD" in FOP Trunk:
+  * The algorithm for page breaking has to be changed from total-fit to best-fit, either
be modifying the existing breaking algorithm in the !PageBreakingAlgorithm subclass to behave
like best-fit or by implementing a new algorithm based on Donald Knuths description.
+  * The LMs have to be restartable. Line breaks become invalid when the available IPD changes
and they have to be recalculated, so the LMs have to be able to setup at an earlier point
and restart element list generation from there. We probably need something similar to what
we had before introducing the Knuth approach (see [http://svn.apache.org/viewvc/xmlgraphics/fop/tags/Before_Merge_KnuthStylePageBreaking_Branch/src/java/org/apache/fop/layoutmgr/LayoutManager.java?view=markup
resetPosition() methods]). Looks like we removed that prematurely.
+    * The table and list LMs currently don't support even resuming element list generation
after a hard break as the other LMs do.
+  * A suitable approach has to be found so that not too many precalculated elements have
to be discarded when the available IPD changes.
+  * We have to investigate how the change of the page breaking algorithm has impact on features
such as footnotes, floats and page-position="last".
+  * Column balancing for multi-columns documents relies on the total-fit algorithm. We will
have to find a different approach here.
+  * The table LM have to be able deal with changing IPD. The columns setup, for example,
may change from page to page for a table that spans multiple pages, especially if auto table
layout is active.

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