xmlgraphics-fop-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Apache Wiki <wikidi...@apache.org>
Subject [Xmlgraphics-fop Wiki] Update of "MultiColumnLayout" by JeremiasMaerki
Date Mon, 11 Jul 2005 16:51:53 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Xmlgraphics-fop Wiki" for change notification.

The following page has been changed by JeremiasMaerki:
http://wiki.apache.org/xmlgraphics-fop/MultiColumnLayout

The comment on the change is:
Some notes about the implementation and the current status

------------------------------------------------------------------------------
  
  = Topics =
  
-  * While creating the element list we have to be on the lookout for changing ''span'' values.
When a chance is encountered, the creation of the element list has to be stopped, the content
generated up to the point of the change, then restarted with the new IPD.
+  * While creating the element list we have to be on the lookout for changing ''span'' values.
When a chance is encountered, the creation of the element list has to be stopped, the content
generated up to the point of the change, then restarted with the new IPD. ('''solved''')
  
-  * When a span change occurs, the columns have to be balanced. That means we actually don't
have a fixed available BPD. The BPD used by a set of columns before a "span-change" depends
on the break decisions.
+  * When a span change occurs, the columns have to be balanced. That means we actually don't
have a fixed available BPD. The BPD used by a set of columns before a "span-change" depends
on the break decisions. ('''solved''', may have to be improved if it turns out not to be good
enough)
  
-  * column breaks need to be handled appropriately.
+  * column breaks need to be handled appropriately. ('''solved''')
+ 
+  * Handling footnotes on multi-column pages and mixed single-/multicolumn pages ('''OPEN''')
  
  = Ideas =
  
  Column balancing can probably be handled by using a special badness functions which forces
breaks that result in more or less balanced columns. The effective BPD of the column set will
then be the maximum of all the used BPDs in the set.
  
+ = Implementation =
+ 
+ Most changes happened in PageSequenceLayoutManager which is responsible to handle span changes
and to initiate column balancing using a special subclass of PageBreakingAlgorithm, called
BalancingColumnBreakingAlgorithm, which essentially replaces the badness/demerit function
for the breaking algorithm to encourage choosing breaks that result in balanced columns. The
PageViewportProvider (in PSLM) was adjusted to report the correct available BPD in mixed single-/multicolumn
situations.
+ 
+ = Open problems =
+ 
+ Footnotes always span the whole width of the region-body so footnotes from every column
add up on the space used by footnotes. The difficulty is the fact that you might get a footnote
on the second column while you more or less decided on the break position on the first column
already. The code currently doesn't decide on the right breaks on the non-last columns. Luca
suggested a possible approach: [1]
+ 
+ [1] http://mail-archives.apache.org/mod_mbox/xmlgraphics-fop-dev/200506.mbox/%3cPine.LNX.4.62.0506281836390.12967@malatesta.cs.unibo.it%3e
+ 

---------------------------------------------------------------------
To unsubscribe, e-mail: fop-commits-unsubscribe@xmlgraphics.apache.org
For additional commands, e-mail: fop-commits-help@xmlgraphics.apache.org


Mime
View raw message