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Posted to fop-dev@xmlgraphics.apache.org by bu...@apache.org on 2011/10/07 17:24:26 UTC
DO NOT REPLY [Bug 51993] New: Incorrect line-height for fo:inline
inside fo:block
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
Bug #: 51993
Summary: Incorrect line-height for fo:inline inside fo:block
Product: Fop
Version: 1.0
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P2
Component: general
AssignedTo: fop-dev@xmlgraphics.apache.org
ReportedBy: tiagobellotorres@gmail.com
Classification: Unclassified
Created attachment 27728
--> https://issues.apache.org/bugzilla/attachment.cgi?id=27728
FO file that reproduces the issue.
When I place an "fo:inline" element which specifies a small font-size inside an
"fo:block" element, the line-height in the rendered PDF looks bigger than
necessary. Here's a code snippet of my FO:
<fo:block>
<fo:inline font-size="7pt">Lorem ipsum dolor sit amet, consectetur adipisicing
elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut
enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip
ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate
velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat
cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est
laborum.</fo:inline>
</fo:block>
In contrast, when I just have an "fo:block" which specifies the font-size, the
line-height in the rendered PDF looks correct. For example:
<fo:block font-size="7pt">
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor
incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis
nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu
fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
culpa qui officia deserunt mollit anim id est laborum.
</fo:block>
I believe this problem is related to the fact that FOP assumes a default
font-size (or line-height) for the "fo:block", which turns out to be too large
in the example I showed.
This issue has been discussed on the mailing list, but I haven't found bug
reports:
http://osdir.com/ml/fop-users-xmlgraphics.apache.org/2011-02/msg00114.html
I'm also attaching an FO file which reproduces the behavior I described.
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #6 from Glenn Adams <gl...@skynav.com> 2012-04-09 14:53:09 UTC ---
(In reply to comment #5)
> Glenn, I've attached the files you requested. I'm also changing the bug status
> to NEW.
thanks, this should be sufficient to proceed with work on a fix!
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
Glenn Adams <gl...@skynav.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
--- Comment #2 from Glenn Adams <gl...@skynav.com> 2012-04-08 05:25:11 UTC ---
please provide an output PDF file that corresponds with the supplied input FO
file, along with all console output
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #3 from Tiago Torres <ti...@gmail.com> 2012-04-09 14:34:59 UTC ---
Created attachment 28565
--> https://issues.apache.org/bugzilla/attachment.cgi?id=28565
PDF generated by Apache FOP
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #4 from Tiago Torres <ti...@gmail.com> 2012-04-09 14:36:13 UTC ---
Created attachment 28566
--> https://issues.apache.org/bugzilla/attachment.cgi?id=28566
Log written during the PDF generation
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #8 from Tiago Torres <ti...@gmail.com> 2012-04-10 14:44:42 UTC ---
I see. But I didn't specify the line-height or the font-size of the block
element. FOP assumed a "normal" value and this value took precedence over the
natural line-height of a 7pt text, which I indeed specified in the inline
element. I just think it might be confusing for the end-user to have an
implicit value outweighing a value which was explicitly set.
Just for comparison, most browsers will render the following HTML snippet as
expected:
<p><span style="font-size:7pt">Lorem ipsum dolor sit amet, consectetur
adipisicing
elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut
enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip
ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate
velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat
cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est
laborum.</span></p>
In fact, browsers seem to calculate line-height for each line individually
based on the maximum font-size of the line, which sounds reasonable. FOP seems
to do the same in most cases. However, assuming a default line-height for the
block seems to be causing inconsistent results.
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
Glenn Adams <gl...@skynav.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P2 |P3
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #1 from Glenn Adams <gl...@skynav.com> 2012-04-07 01:42:22 UTC ---
resetting P2 open bugs to P3 pending further review
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #12 from Alberto Perri <ap...@operamail.com> 2012-04-18 07:43:17 UTC ---
Created attachment 28631
--> https://issues.apache.org/bugzilla/attachment.cgi?id=28631
keep-together option used correctly
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[Bug 51993] Incorrect line-height for fo:inline inside fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
Glenn Adams <ga...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |CLOSED
--- Comment #13 from Glenn Adams <ga...@apache.org> ---
batch transition resolved+invalid to closed+invalid
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
Tiago Torres <ti...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |NEW
--- Comment #5 from Tiago Torres <ti...@gmail.com> 2012-04-09 14:37:42 UTC ---
Glenn, I've attached the files you requested. I'm also changing the bug status
to NEW.
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
Glenn Adams <ga...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |INVALID
--- Comment #9 from Glenn Adams <ga...@apache.org> 2012-04-10 16:34:04 UTC ---
(In reply to comment #8)
> I see. But I didn't specify the line-height or the font-size of the block
> element. FOP assumed a "normal" value and this value took precedence over the
> natural line-height of a 7pt text, which I indeed specified in the inline
> element. I just think it might be confusing for the end-user to have an
> implicit value outweighing a value which was explicitly set.
>
> In fact, browsers seem to calculate line-height for each line individually
> based on the maximum font-size of the line, which sounds reasonable. FOP seems
> to do the same in most cases. However, assuming a default line-height for the
> block seems to be causing inconsistent results.
Keep in mind the semantics of the line-stacking-strategy property, which
defaults to max-height and not line-height. The CSS semantics default to
line-height, not max-height, so this is a difference between XSL-FO and CSS.
Further, at this time, FOP does not support the line-height value. That is, FOP
at present supports only max-height and font-height strategies. In the former
case, the maximum line rectangle applies (i.e., the maximum needed to contain
the line's inline areas) in the latter case, the text-altitude/depth properties
(or font metrics) apply, where the font/font-size that applies to the parent
block is what determines the font metric flavors of altitude/default.
See XSL-FO Section 4.5 Line Areas [1] for more detail.
Also, in case of max-height and font-height strategy, the space-{before,after}
of the generated line areas is set to the half leading trait value [2].
My conclusion is that the current behavior is not a bug.
[1] http://www.w3.org/TR/2006/REC-xsl11-20061205/#area-line
[2] http://www.w3.org/TR/2006/REC-xsl11-20061205/#fo_block
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #7 from Manuel Mall <ma...@apache.org> 2012-04-10 09:35:47 UTC ---
I am not sure if this is actually a bug. The line building rules in the spec
are anything but easy to understand. For example it says for the line-height
property: "If the property is set on a block-level element whose content is
composed of inline-level elements, it specifies the minimal height of each
generated inline box." In the example given the line-height property value on
the fo:block would be "normal" meaning in the FOP implementation the calculated
value for line-height set on the fo:block would be 1.2 * font-size. Therefore
following the stated rule this would be the minimum height applied to all
generated inline areas. The reasoning behind this is also stated in the spec:
"Generally, when there is only one value of "line-height" for all inline boxes
in a paragraph (and no tall images), the above will ensure that baselines of
successive lines are exactly "line-height" apart. This is important when
columns of text in different fonts have to be aligned, for example in a table."
I could easily be wrong in my interpretation here but this is my recollection
on how this behaviour came about.
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #10 from Manuel Mall <ma...@apache.org> 2012-04-10 17:16:05 UTC ---
(In reply to comment #9)
> (In reply to comment #8)
...
> Further, at this time, FOP does not support the line-height value. That is, FOP
> at present supports only max-height and font-height strategies.
There was a discussion many years ago questioning if the above statement is
actually correct:
http://mail-archives.apache.org/mod_mbox/xmlgraphics-fop-dev/200701.mbox/%3C20070112114529.AFE1.DEV@jeremias-maerki.ch%3E
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DO NOT REPLY [Bug 51993] Incorrect line-height for fo:inline inside
fo:block
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=51993
--- Comment #11 from Glenn Adams <ga...@apache.org> 2012-04-10 17:35:05 UTC ---
(In reply to comment #10)
> (In reply to comment #9)
> > (In reply to comment #8)
> ...
> > Further, at this time, FOP does not support the line-height value. That is, FOP
> > at present supports only max-height and font-height strategies.
>
> There was a discussion many years ago questioning if the above statement is
> actually correct:
> http://mail-archives.apache.org/mod_mbox/xmlgraphics-fop-dev/200701.mbox/%3C20070112114529.AFE1.DEV@jeremias-maerki.ch%3E
thanks for pointing that out; i certainly agree it is a complex area of the
spec, and what FOP actually implements may or may not comply; i would have to
speculate that the current FOP test cases do not adequately cover the range of
different line stacking behaviors
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