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Posted to fop-dev@xmlgraphics.apache.org by bu...@apache.org on 2010/08/23 11:56:10 UTC
DO NOT REPLY [Bug 49801] New: Region-Body Column balancing incorrect
if content is table with header
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
Summary: Region-Body Column balancing incorrect if content is
table with header
Product: Fop
Version: 1.0
Platform: PC
Status: NEW
Severity: major
Priority: P2
Component: page-master/layout
AssignedTo: fop-dev@xmlgraphics.apache.org
ReportedBy: a.kovacs@i-docs.com
To reproduce bug please do the following:
Use:
<fo:region-body region-name="PageBody" column-count="2" />
Fill the region-body with content like :
<fo:block span="none" > ...(content is table with header) ..
<fo:block span="all"> ... (one line (summary)) ..
If the content is made of normal blocks the columns are balanced before the
span="all" summary line.
like:
123456 456789
234567 567890
345678 678901
Summary: 1234567890
If the content is a table without headers the columns are balanced correct.
like:
123456 456789
234567 567890
345678 678901
Summary: 1234567890
If the content is a table with header the columns are not balanced correct.
(the right one is shorter.)
Header Header
123456 567890
234567 678901
345678
456789
Summary: 1234567890
The "computeDemerits()" algorithm is wrong in class
"BalancingColumnBreakingAlgorithm".
The "fullLen" value is to short. Exactly the replicated header width is
missing. In the "par" list the header is contained only once although the
header is displayed in every column. (in the example twice)
Solution could be to place the header as many times in the "par" list as many
columns exist, or to count the existing one header as many times as needed.
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #3 from Jeremias Maerki <je...@apache.org> 2010-09-06 09:46:13 EDT ---
I've been asked to look closer into this, and after about 10 hours spent
brooding over it and consulting the "Digital Typography" book I'm no closer to
solving it. I've been able to calculate the demerits which I expected to result
in the right break decision (for one case), but the algorithm still chose
another breaking point for reasons I just don't understand. The
BalancingColumnBreakingAlgorithm class was some kind of hack to begin with
which I knew had some short-comings. That is now pretty obvious, and I don't
know how to proceed. I have to give up for now since this is simply a bit too
high for me. I'll copy my local changes away so if anyone wants to give it a
shot, I can provide them. But I'm not sure if they would really help.
If anyone can help Adam, please get in touch with him.
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[Bug 49801] [PATCH] Region-Body Column balancing incorrect if
content is table with header
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #17 from Robert Meyer <rm...@hotmail.co.uk> ---
Created attachment 29655
--> https://issues.apache.org/bugzilla/attachment.cgi?id=29655&action=edit
Sample list of test column balancing fo files
A zip containing a list of sample column balancing FO files
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #5 from Andreas L. Delmelle <ad...@apache.org> 2011-02-04 13:27:07 EST ---
Additionally, it's not only fullLen which is off, but obviously also partLen
and restLen, for the same reason (calcContentLength()). There will be cases
where the header will have to be taken into account for partLen, but not for
restLen or vice versa, and cases where it will need to be counted for both.
Currently, the algorithm operates as if the header and footer only count for
the part where the table happens to end.
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #11 from Alex Giotis <al...@gmail.com> 2012-04-23 22:49:00 UTC ---
Even though this is not explicitly specified in XSL-FO 1.X, columns are
expected to be balanced. For our documents, unbalanced columns, are not an
acceptable output. Unfortunately, we were not able to find a solution. I can
only attach a small patch of a dirty hack that gives the desired result for the
initially attached test file, has been working well for us for the last 2 years
and (of course) passes all the unit tests.
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[Bug 49801] Region-Body Column balancing incorrect if content is
table with header
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #16 from Robert Meyer <rm...@hotmail.co.uk> ---
Created attachment 29653
--> https://issues.apache.org/bugzilla/attachment.cgi?id=29653&action=edit
New column balancing algorithm implementation
This patch is a re-write of the coloumn balancing algorithm to fix the issues
that existed within the old code. We have been working on this for the last
couple of weeks and has been a team effort by me, Luis Bernado and Vincent
Hennebert.
It passes all unit tests and renders not only the tests above correctly but
also many others we have thrown at it. I will post another zip attachment
containing sample balancing fo's for you to try should you wish.
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #1 from a.kovacs@i-docs.com 2010-08-23 06:05:19 EDT ---
Created an attachment (id=25928)
--> (https://issues.apache.org/bugzilla/attachment.cgi?id=25928)
test file
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
Glenn Adams <gl...@skynav.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|major |normal
--- Comment #8 from Glenn Adams <gl...@skynav.com> 2012-04-07 01:37:32 UTC ---
resetting severity from major to normal pending further review
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
Glenn Adams <ga...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P5
Severity|normal |enhancement
--- Comment #10 from Glenn Adams <ga...@apache.org> 2012-04-21 05:33:07 UTC ---
lowering priority and changing to enhancement since (1) a fix is likely to
require a fairly significant design change and (2) column balancing is a
(potential) XSL-FO 2.0 feature [1], not an XSL-FO 1.X feature;
[1] http://www.w3.org/TR/xslfo20-req/#N66487
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
alpapad@gmail.com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |alpapad@gmail.com
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
content is table with header
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
Jeremias Maerki <je...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
OS/Version| |All
--- Comment #2 from Jeremias Maerki <je...@apache.org> 2010-08-30 09:52:53 EDT ---
The algorithm does indeed not take the penalty width at the break point into
account. I've experimented for about an hour but still haven't found a
solution. That class is a hack by itself right now. I have never found a really
good algorithm for calculating the demerits for column balancing. I guess this
needs another serious review.
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #4 from Andreas L. Delmelle <ad...@apache.org> 2011-02-04 13:18:28 EST ---
Created an attachment (id=26606)
--> (https://issues.apache.org/bugzilla/attachment.cgi?id=26606)
altered test case
The fullLen in computeDemerits() is indeed off, because
ElementListUtils.calcContentLength() naively sums box and glue lengths. It just
counts the header box once, and does not contain any logic to take into account
possible special behavior of the penalties. Adding the header box multiple
times to the list will not immediately solve the issue.
Question that needs to be answered in order to do that: how many times would it
need to be duplicated? Answer: the number of times the table is broken plus 1.
But we don't know that number, at that point... That is precisely the reason
the table-layout code only adds the box once.
See also the attached altered test case for a slightly more complicated
example. The first and last table's headers only need to be counted once, while
the header and footer of the second table need to be counted --how many times?
The algorithm currently only breaks once.
Seems like the chicken and the egg... :-/
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
content is table with header
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
Alex Giotis <al...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |alex.giotis@gmail.com
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
content is table with header
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
Glenn Adams <gl...@skynav.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P2 |P3
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #13 from Alex Giotis <al...@gmail.com> 2012-04-23 22:53:48 UTC ---
Created attachment 28663
--> https://issues.apache.org/bugzilla/attachment.cgi?id=28663
Current output PDF
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #12 from Alex Giotis <al...@gmail.com> 2012-04-23 22:51:58 UTC ---
Created attachment 28662
--> https://issues.apache.org/bugzilla/attachment.cgi?id=28662
Dirty hack
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #15 from Alex Giotis <al...@gmail.com> 2012-04-23 23:00:30 UTC ---
The patch is against revision 1329104 of trunk.
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #14 from Alex Giotis <al...@gmail.com> 2012-04-23 22:54:46 UTC ---
Created attachment 28664
--> https://issues.apache.org/bugzilla/attachment.cgi?id=28664
Expected output PDF (after patch)
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #9 from Glenn Adams <gl...@skynav.com> 2012-04-07 01:42:15 UTC ---
resetting P2 open bugs to P3 pending further review
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[Bug 49801] [PATCH] Region-Body Column balancing incorrect if
content is table with header
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
Robert Meyer <rm...@hotmail.co.uk> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|Region-Body Column |[PATCH] Region-Body Column
|balancing incorrect if |balancing incorrect if
|content is table with |content is table with
|header |header
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[Bug 49801] [PATCH] Region-Body Column balancing incorrect if
content is table with header
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #18 from Alex Giotis <al...@gmail.com> ---
Great work !!
I tested it with a multi-page complex layout and it is working very well.
Luckily for us, I see the same output as with the hack I had attached. Next
week, a colleague will execute more tests on other documents with complex
layout and will check some corner cases. I will add a comment if something
comes up.
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DO NOT REPLY [Bug 49801] Region-Body Column balancing incorrect if
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #7 from Andreas L. Delmelle <ad...@apache.org> 2011-03-21 15:27:29 EDT ---
Thinking more about a possible fix, I am suddenly asking myself why we would
even fiddle with the demerits at all to balance columns. Playing with the
demerits alone is not enough to make a break more/less favorable. Ultimately,
the adjustment ratio is a deciding factor too, and that is based on the
difference between available width and the width of the line.
Since the algorithm works with the full bpd of the page as line-width, this is
bound to cause the algorithm to 'ignore' the better demerits at some points.
In a way, that feels like we could handle column-balancing better by (also)
forcing the available line-width down to the minimal width needed by the
content (i.e. taking into account pieces that must be kept together within the
same column).
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Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=49801
--- Comment #6 from Andreas L. Delmelle <ad...@apache.org> 2011-02-08 15:19:45 EST ---
Just thought of similar potential issues, due to the limitations of
ElementListUtils.calcContentLength(), but unrelated to column-balancing per se,
that are to be expected in list-items and table-cells.
More precisely those that have a table with header and/or footer as a
descendant, and are divided over more than one column/page.
For lists, problems may arise in
ListItemLayoutManager.getCombinedKnuthElementsForListItem(), I think, where the
calculated lengths could prove to be wrong (due to the content eventually being
broken at least once).
For table-cells, similarly, the totalLength in the ActiveCell constructor might
be too low if the cell contains a long nested table that causes multiple
breaks...
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