[prev in list] [next in list] [prev in thread] [next in thread] 

List:       fop-dev
Subject:    [jira] [Commented] (FOP-2293) Whitespace management extension
From:       "Vincent Hennebert (JIRA)" <jira () apache ! org>
Date:       2014-03-31 9:36:17
Message-ID: JIRA.12665478.1377509696013.35307.1396258577059 () arcas
[Download RAW message or body]


    [ https://issues.apache.org/jira/browse/FOP-2293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13955050#comment-13955050 \
] 

Vincent Hennebert commented on FOP-2293:
----------------------------------------

Hi Seifeddine,

at first I was doubtful that your approach would work, but after a more in-depth \
study I think it should do the job. It's actually quite clever and we're at the edge \
of what we can do with the Knuth algorithm; hopefully it won't cause conflicts with \
other features but as of now I can't see any. Well done anyway!

A few comments:
* In BestFitPenalty: this penaltyIndex field should ideally be removed as it \
introduces unwelcome mutability. IIC all you need is a reference to the \
BestFitPenalty instance? In which case you can probably just turn Variant into an \
instance class (remove the static keyword) and add some getPenalty method that return \
                BestFitPenalty.this
* In PageBreakingAlgorithm:
  * Isn't the javadoc for pendingVariant misleading: is it all descendant nodes or \
                just the next one?
  * BestPageRecords: there's no need to override reset AFAIU?
  * computeDifference: you should also add the size of the pending variant if \
{{element}} is a glue (although I don't believe it ever happens in page breaking that \
we are breaking at a glue since they are always preceded by penalties —but better \
safe than sorry).

It remains to make it work when there are several multi-switch on the same page. IIC \
it doesn't work at the moment. Maybe you can take advantage of the fact that the \
first variant will be the one that will be selected by default. So only when we break \
at a BestFitPenalty do you need to know what variant has been selected if any. Then, \
on active nodes, instead of storing the pending variant, you can just add the widths \
of the variants that are on the page.

Thanks for your patch!
Vincent

> Whitespace management extension
> -------------------------------
> 
> Key: FOP-2293
> URL: https://issues.apache.org/jira/browse/FOP-2293
> Project: Fop
> Issue Type: New Feature
> Components: general
> Affects Versions: trunk
> Reporter: Seifeddine Dridi
> Priority: Minor
> Labels: XSL-FO
> Fix For: trunk
> 
> Attachments: FO_multi-switch_best-fit_ext_rev10.patch, \
> FO_multi-switch_best-fit_ext_rev2.patch, FO_multi-switch_best-fit_ext_rev3.patch, \
> FO_multi-switch_best-fit_ext_rev4.patch, FO_multi-switch_best-fit_ext_rev5.patch, \
> FO_multi-switch_best-fit_ext_rev6.patch, FO_multi-switch_best-fit_ext_rev7.patch, \
> FO_multi-switch_best-fit_ext_rev8.patch, FO_multi-switch_best-fit_ext_rev9.patch, \
> FO_multi-switch_test.fo, FO_multi-switch_with_best-fit_extension.patch, bestfit.fo, \
> doc.pdf, empty-last-page.fo, multi-switch-testcases.zip, multi-switch_bestfit.fo, \
> multiple-feasible-nodes.fo, patch-rev1.1.patch, patch-rev1.patch, patch-rev2.patch, \
> patch.patch, two-valid-variants.fo 
> 
> I have been working on an extension for whitespace management, similar to what's \
> described here: http://wiki.apache.org/xmlgraphics-fop/WhitespaceManagement The \
> logic of the extension is very simple: the user defines a set of alternatives that \
> he wishes to insert at the end of a page, then if there is enough space left, FOP \
> will pick the alternative that best matches the user's selection criteria (first \
> fit, smallest fit, biggest fit). This is my first work on FOP and it took me almost \
> 2 months to reach this stage in development. But it's not the end of course, so I'm \
> relying on your feedback to improve it. Thank you



--
This message was sent by Atlassian JIRA
(v6.2#6252)


[prev in list] [next in list] [prev in thread] [next in thread]