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Posted to fop-users@xmlgraphics.apache.org by Sebastien <ka...@gmail.com> on 2008/11/05 16:49:56 UTC
Image overflow in FOP
Hi !
I'm using FOP 0.95 to generate a PDF from an XML document.
I'm using XSL-FO to make the transformation and i'm having
difficulties with images, especially making them to fit within page or
to jump over the next one.
All these images are SVG (within instream-foreign-object). The SVG is
made of a large JPG background imported with <svg:image> and one or
several <svg:path> or other basic shapes.
The only constraint i want for the images is to fit the page width,
and conserve aspect ratio.
That i managed to achieve it. But the problem is that the image
overflow the page height whenever there isn't enough room left at the
end of the page. Here is a screenshot of what the problem is:
http://img444.imageshack.us/my.php?image=imageoverflowbj6.png
What i want to do is making FOP to do a page-break when the image
can't fit into the page.
I tried every combinations of keep constraints with no luck.
I even tried to fix (or remove) the width and the height on the
instream-foreign-object but FOP still doesn't want to jump to the next
page :'(
Here are some screenshots of the result:
- without width
http://img241.imageshack.us/my.php?image=imageoverflowwidthaz5.png
- with smaller height (but still big enough to make the image bigger
than the space left at the end of page)
http://img504.imageshack.us/my.php?image=imageoverflowheightjs7.png
We can see that the image is very well scaled up/down but i can't make
FOP to break-page :'(
Here is the incriminated piece of code (corresponding to the first screenshot)
<fo:block>
<fo:instream-foreign-object width="100%" content-width="scale-to-fit"
content-height="scale-to-fit">
<svg:svg viewBox="519025 -6702573 5363 4051" height="2430px" width="3219px">
<svg:image height="4051" width="5363" y="-6702573" x="519025"
xlink:href="file:///C:\bdd\docs\cartes\Scan25_Georef.jpg" />
[some paths, rects and texts]
</svg:svg>
</fo:instream-foreign-object>
</fo:block>
It seems like one of the FOP known issue in the LayoutEngine, but i'm
not quite sure because i use instream-foreign-object instead of
external-graphic:
http://xmlgraphics.apache.org/fop/knownissues.html#Layout+Engine
(external-graphic don't shrink)
My questions are:
- is it possible to do what i want (having a page-break whenever it's
needed) with instream-foreign-object (and with FOP) ?
- in case it's not, how could i calculate the space left at the end
of page to decide whether i put a break-before="page" on the
corresponding block or not ? I saw some xpath in FOP testcases which
tried to access some kind of "internal properties" like viewports
etc... and i wondered whether it's possible for me to use these path
to retrieve the remaining free space (and for my culture: are these
paths part of the standard or specific to FOP ?)
Thanks in advance for your help, i'm stuck with this issue for days...
Some ressources i found (and tried whenever it applied to my pb, but
with no luck):
http://www.nabble.com/Image-overflow-td5982795.html
http://www.nabble.com/0.94-AND-0.95b-Images-to17627201.html#a17629647
For those who can understand french, here is a more detailed
description of my problem:
http://forum.hardware.fr/hfr/Programmation/XML-XSL/debordement-image-generer-sujet_118855_1.htm
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Re: Image overflow in FOP
Posted by Sebastien <ka...@gmail.com>.
> Without seeing your FO to fully understand what you're doing it is a bit
> difficult to offer further suggestions. Usually, watermarks are best
> painted using block-containers (absolute-position="fixed") inside the
> region-before. Or you can use the background-image property on the
> region-body.
>
I needed conditional watermarking, so i managed to work this out with
the xsl-region-before. Thanks ;)
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Re: Image overflow in FOP
Posted by Jeremias Maerki <de...@jeremias-maerki.ch>.
On 05.11.2008 20:22:27 Sebastien wrote:
> Thank you for your answer !
>
> > Here's what I would do: Enable the i-f-o behaviour as in your first
> > screenshot, then remove all keeps. That should avoid the overflow. Then
> > add keep-with-next or keep-together one step after the other. I'm pretty
> > sure that you've just overdone the keeps. Please note that
> > keep-*="always" doesn't allow FOP to break the content appart.
> >
> I removed all the keeps in my entire document (i searched in the .fo
> output to be sure) but this didn't solve the problem unfortunately :(
>
> Actually, i even put some break-before (and even break-after for...
> the fun ?) everywhere in the encapsulating block hierarchy to force
> the page break ! But, these two didn't work either whereas they have
> worked in my previous test ! (i decided to drop this issue for a while
> because i thought i would be able to hack it easily later...)
>
> And that made me think of something i changed between my old test and now:
> 1) i ran into memory trouble before because the whole PDF was a unique
> page-sequence, so i decided to divide it into multiple page-sequences.
> It solved my memory problem and the style was more elegant. So i tried
> reverting theses changes having one single page-sequence again... no
> luck, still the overflow.
> 2) i needed a watermark on some of my pages (something like "top
> secret" stuff) and i chose an "XML" solution again by using SVG. It
> was more convenient because i was able to rotate the text and repeat
> it as much as i wanted. The issue was to render it as a "watermark"
> ie. all over the page and behind the content. I chose to use a
> block-container to encapsulate all the item, including the map (an
> item is "Cheminée DALKIA" for instance, it has several fields entitled
> in green boxes and eventually a map, as you can see in the
> screenshots) and i attached the watermark.svg as its background-image.
> This worked great, and was much more elegant than the other solutions
> i saw about watermarks. Same test as before: i removed the
> block-container and... it worked !!!!
>
> I then re-added the keep-with-next between the green boxes and the map
> and everything is now working very well. I just have to think about
> another solution for the watermark, which really is a less important
> issue than the one you helped me solve.
Without seeing your FO to fully understand what you're doing it is a bit
difficult to offer further suggestions. Usually, watermarks are best
painted using block-containers (absolute-position="fixed") inside the
region-before. Or you can use the background-image property on the
region-body.
> > Looking at your layout you'd probably have a keep-with-next on the green
> > bar to keep the bar with the following image. But it (probably) makes no
> > sense to glue the green bars together.
> >
> That's correct ;)
>
>
> Well, thank you so much for you help. Even if the keeps were not the
> direct cause of the problem, i did abuse of them a little so i cleaned
> up my document. More important, it put me on the tracks to find out
> the solution.
> If you still have time to answer or some nice doc to point me to, I'd
> like to know how block-container works, why it screwed the
> page-breaking and how/when to use it. I think I didn't fully
> understand the W3C spec about it.
Hey, even after all this years developing on FOP I can't say that I
"fully" understand the XSL spec. But it's still (obviously) my main
piece of reference.
Jeremias Maerki
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Re: Image overflow in FOP
Posted by Sebastien <ka...@gmail.com>.
Thank you for your answer !
> Here's what I would do: Enable the i-f-o behaviour as in your first
> screenshot, then remove all keeps. That should avoid the overflow. Then
> add keep-with-next or keep-together one step after the other. I'm pretty
> sure that you've just overdone the keeps. Please note that
> keep-*="always" doesn't allow FOP to break the content appart.
>
I removed all the keeps in my entire document (i searched in the .fo
output to be sure) but this didn't solve the problem unfortunately :(
Actually, i even put some break-before (and even break-after for...
the fun ?) everywhere in the encapsulating block hierarchy to force
the page break ! But, these two didn't work either whereas they have
worked in my previous test ! (i decided to drop this issue for a while
because i thought i would be able to hack it easily later...)
And that made me think of something i changed between my old test and now:
1) i ran into memory trouble before because the whole PDF was a unique
page-sequence, so i decided to divide it into multiple page-sequences.
It solved my memory problem and the style was more elegant. So i tried
reverting theses changes having one single page-sequence again... no
luck, still the overflow.
2) i needed a watermark on some of my pages (something like "top
secret" stuff) and i chose an "XML" solution again by using SVG. It
was more convenient because i was able to rotate the text and repeat
it as much as i wanted. The issue was to render it as a "watermark"
ie. all over the page and behind the content. I chose to use a
block-container to encapsulate all the item, including the map (an
item is "Cheminée DALKIA" for instance, it has several fields entitled
in green boxes and eventually a map, as you can see in the
screenshots) and i attached the watermark.svg as its background-image.
This worked great, and was much more elegant than the other solutions
i saw about watermarks. Same test as before: i removed the
block-container and... it worked !!!!
I then re-added the keep-with-next between the green boxes and the map
and everything is now working very well. I just have to think about
another solution for the watermark, which really is a less important
issue than the one you helped me solve.
> Looking at your layout you'd probably have a keep-with-next on the green
> bar to keep the bar with the following image. But it (probably) makes no
> sense to glue the green bars together.
>
That's correct ;)
Well, thank you so much for you help. Even if the keeps were not the
direct cause of the problem, i did abuse of them a little so i cleaned
up my document. More important, it put me on the tracks to find out
the solution.
If you still have time to answer or some nice doc to point me to, I'd
like to know how block-container works, why it screwed the
page-breaking and how/when to use it. I think I didn't fully
understand the W3C spec about it.
Cheers !
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Re: Image overflow in FOP
Posted by Jeremias Maerki <de...@jeremias-maerki.ch>.
Comments inline...
On 05.11.2008 16:49:56 Sebastien wrote:
> Hi !
> I'm using FOP 0.95 to generate a PDF from an XML document.
> I'm using XSL-FO to make the transformation and i'm having
> difficulties with images, especially making them to fit within page or
> to jump over the next one.
> All these images are SVG (within instream-foreign-object). The SVG is
> made of a large JPG background imported with <svg:image> and one or
> several <svg:path> or other basic shapes.
> The only constraint i want for the images is to fit the page width,
> and conserve aspect ratio.
> That i managed to achieve it. But the problem is that the image
> overflow the page height whenever there isn't enough room left at the
> end of the page. Here is a screenshot of what the problem is:
> http://img444.imageshack.us/my.php?image=imageoverflowbj6.png
>
> What i want to do is making FOP to do a page-break when the image
> can't fit into the page.
> I tried every combinations of keep constraints with no luck.
> I even tried to fix (or remove) the width and the height on the
> instream-foreign-object but FOP still doesn't want to jump to the next
> page :'(
> Here are some screenshots of the result:
> - without width
> http://img241.imageshack.us/my.php?image=imageoverflowwidthaz5.png
> - with smaller height (but still big enough to make the image bigger
> than the space left at the end of page)
> http://img504.imageshack.us/my.php?image=imageoverflowheightjs7.png
>
> We can see that the image is very well scaled up/down but i can't make
> FOP to break-page :'(
>
> Here is the incriminated piece of code (corresponding to the first screenshot)
> <fo:block>
> <fo:instream-foreign-object width="100%" content-width="scale-to-fit"
> content-height="scale-to-fit">
> <svg:svg viewBox="519025 -6702573 5363 4051" height="2430px" width="3219px">
> <svg:image height="4051" width="5363" y="-6702573" x="519025"
> xlink:href="file:///C:\bdd\docs\cartes\Scan25_Georef.jpg" />
> [some paths, rects and texts]
> </svg:svg>
> </fo:instream-foreign-object>
> </fo:block>
I think that looks fine.
> It seems like one of the FOP known issue in the LayoutEngine, but i'm
> not quite sure because i use instream-foreign-object instead of
> external-graphic:
> http://xmlgraphics.apache.org/fop/knownissues.html#Layout+Engine
> (external-graphic don't shrink)
No, that's the inability of FOP to shrink the image vertically if
there's not enough room. That's not the same as the requirement you've
stated above.
> My questions are:
> - is it possible to do what i want (having a page-break whenever it's
> needed) with instream-foreign-object (and with FOP) ?
IMO, the instream-foreign-object part is already correct (first
screenshot) but you've got the keeps wrong.
> - in case it's not, how could i calculate the space left at the end
> of page to decide whether i put a break-before="page" on the
> corresponding block or not ? I saw some xpath in FOP testcases which
> tried to access some kind of "internal properties" like viewports
> etc... and i wondered whether it's possible for me to use these path
> to retrieve the remaining free space (and for my culture: are these
> paths part of the standard or specific to FOP ?)
Nah, that's really FOP's job.
> Thanks in advance for your help, i'm stuck with this issue for days...
>
> Some ressources i found (and tried whenever it applied to my pb, but
> with no luck):
> http://www.nabble.com/Image-overflow-td5982795.html
> http://www.nabble.com/0.94-AND-0.95b-Images-to17627201.html#a17629647
>
> For those who can understand french, here is a more detailed
> description of my problem:
> http://forum.hardware.fr/hfr/Programmation/XML-XSL/debordement-image-generer-sujet_118855_1.htm
Here's what I would do: Enable the i-f-o behaviour as in your first
screenshot, then remove all keeps. That should avoid the overflow. Then
add keep-with-next or keep-together one step after the other. I'm pretty
sure that you've just overdone the keeps. Please note that
keep-*="always" doesn't allow FOP to break the content appart.
Looking at your layout you'd probably have a keep-with-next on the green
bar to keep the bar with the following image. But it (probably) makes no
sense to glue the green bars together.
HTH & good luck
Jeremias Maerki
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