Re: Plass, Michael Frederick: Optimal Pagination Techniques for Automatic Typesetting Systems
Hi Fop Team, Simon Pepping a écrit : On Thu, Mar 03, 2005 at 08:19:24AM -0700, Victor Mote wrote: Jeremias Maerki wrote: While looking for material on page breaking I found several references to this document: http://wwwlib.umi.com/dissertations/fullcit/8124134 Does anyone know if it's worth ordering and waiting for it? By looking for this reference, I found the following article: www.pi6.fernuni-hagen.de/publ/tr234.pdf It's entitled 'On the Pagination of Complex Documents' (actually it's also referencing Plass). I've read parts of this article and it seems interesting. It's well written, quite easy to understand and provides a better algorithm than TeX's one. And it's also more recent. It doesn't agree with Plass about the NP-hard problem of page layout. Indeed that depends on the formula we are using to estimate the badness of a layout. It proposes another formula which seems more reasonable and better corresponds to a reader's expectations. Perhaps it could provide a good basis? I don't have Knuth's 'Digital Typography' (I'm considering purchasing it). It may be worthwhile to compare this article with what is in the book. The TeX program is described in 'TeX The Program'. That text is weaved into the program code according to Knuth's literate programming system. It can be freely extracted from the program code. I've already done it, and AFAICT it's not easy to find the way in all the TeX stuff (actually nothing is easy with TeX ;-)). I can send you the pdf file if you want, feel free to ask me. Be warned, though: it's a 535 pages (!) document that entirely describes the TeX program. I've started looking into it, and, well, it's rather cryptic. It's very close to the implementation, it seems to be difficult to get a general idea of what it's doing. But I'll investigate a bit more. And, as Simon wrote, TeX is excellent in line-breaking but not as good in page-breaking. It was implemented in the early 80's when memory was expensive. However, it was written with typographic quality in mind, and that's why it may be a good idea to try getting some hints from it. Vincent
Re: border-before-width length-conditional
Jeremias Maerki a écrit : Am I right that for a table-cell in collapsing border model the conditional part of a length-conditional (ex. in border-before-width) has no effect (i.e. is ignored)? I would answer no, actually not exactly. If I understand the spec correctly, the conditional part has an effect only if the generated area begins an ancestor reference area. Let's take the example of border-before. If there is a cell before the current cell we don't care about the conditionality: we just have to chose between this border, the border-after of the preceding cell, and the border-after and border-before of the containing table-rows. Now if the table has to be broken at the end of a page and the current cell begins a new page (and no border is specified for the table-row), in this case the conditionality has to be taken in consideration. Because the cell would be a leading edge in the normal-flow-reference-area of the page, as defined at the end of section 4.2.5, Stacking Constraints. Does it answer your question? I may have missed something, I have not carefully studied this aspect of the spec nor the border-collapsing model. Hope this helps, Vincent
Re: representative example needed [was in fop-user]
Glen Mazza a écrit : So I think we should wait on this until the W3C makes up its own stylesheet without extensions, and makes the same stylesheet publicly available for any XSL processor to run. OK. I personally don't feel capable of writing a stylesheet from scratch: I'm not familiar enough with XSLT. I would leave this task to someone other (Jay Bryant for example said on fop-user he could write a stylesheet). I'd prefer to contribute to Fop in some other way. What may be more cool--and a much better selling point for FOP anyway--is for the Docbook XSL/PDF stylesheets to work well with 1.0 (0.20.5 already does a pretty good job with Docbook PDF generation.) I think that's a nicer target than the RenderX stylesheet, much more practical for our user base, and avoids the copyright headaches. But it is indeed a lot more work. Well, I could do some work here. I'm already using Docbook to write some documents and I have played a bit with the fo stylesheet. For any improvement of that stylesheet I should perhaps rather refer to the Docbook developers. However, IMHO it wouldn't be very useful to hack Docbook's stylesheets in order to work around Fop's currents flaws. The development of the HEAD branch is evolving quite quickly and any stylesheet improvement would be rather temporary. Bug reports on Docbook files would perhaps be more useful. Again, I would rather contribute to Fop by providing patches. But if you all maintain that it would be really, really useful I can do it ;-) We don't care much for making changes to 0.20.5 anymore. We focus on 1.0. I know. That was just because Jeremias and Clay spoke about a comparison between Fop 0.20.5 and Fop 1.0dev. Fop 1.0dev (freshly checked out) crashes with a NoSuchMethodError. Now *that* is of interest for us. I can provide details if needed (in form of a Bugzilla entry?). Sure for 1.0, please. I'll try to isolate the problem and reduce the fo file as much as possible. Then I'll file a bug report, and, well, if I can, provide a patch... No--because again we don't want it anywhere on our site--please don't send it to us--it is RenderX's stylesheet, not ours. It is better not to even look at it, lest our ideas for a similar stylesheet end up coming from their work. OK, I forget it. You would be most welcome here. I really would be glad to help. Sadly I don't have much time to devote to Fop. I've begun to read the XSL spec and dive into Fop code. I'll still need some time before being able to provide patches. Hope you'll hear about me soon... (BTW, checked your ENSEEIHT website -- looks like a wonderful place for a person to grow.) Well, at least it's a good place to learn computer science (perhaps not as good to learn english, though ;-( ). Cheers, Vincent
Re: representative example needed [was in fop-user]
[Web Maestro Clay] It would be *great* if some enterprising and generous developer could spend the time to generate FOP-based XSL-FO documents from the XML, XSLT and XPath specs. In fact, that would be a useful tool for comparing how fop-0.20.5 compares to fop-1.0-dev (the FOP re-design/TRUNK branch). Unfortunately, that hasn't been a priority up to this point. Perhaps it could become a priority in the future. [Jeremias] Oh, it would be so cool if we could have our own PDF of the XSL 1.0 specification [1]. The official PDF was created by RenderX. I thought about doing a stylesheet for that myself but I'm currently so busy coding on FOP 1.0dev that I'd be more than happy if someone from the user community could do that. It would also be interesting to compare FOP 0.20.5 and FOP 1.0dev which is under development. Hi Fop team, would there be anything wrong with using RenderX' XSLT stylesheet to produce a pdf whith Fop? As I read this thread on fop-user a week ago, I wondered whether RenderX released the stylesheet they used to produce the official pdf of the XSL recommendation. Indeed they provided an xmlspec2fo stylesheet on their website [1], but now it seems to have disappeared (the site seems to have been refactored). Anyway, I have it on my disk and tried to run Fop over it. Well, bad news so far ;-( Fop 0.20.5 stops at p.16 whith an error message (Flow 'xsl-region-body' does not map to the region-body in page-master 'blank-page'). This is the page where there is just This page is intentionally left blank. Fop 1.0dev (freshly checked out) crashes with a NoSuchMethodError. As it was just a quick test, I didn't remove Xep extensions; this may be the cause of the crash. I can provide details if needed (in form of a Bugzilla entry?). I could adapt the stylesheet to introduce Fop extensions (at least for the 0.20.5 version, I don't think they are available in 1.0dev?), and perhaps to circumvent Fop's current flaws. If it may be useful to the Fop team I would be glad to help. However, I wonder whether we can use RenderX' stylesheet as a basis. I'm not very familiar with legal issues. So far the stylesheet was available on their website; there is just a copyright statement (© RenderX , 1999-2001) at the beginning of the file. What is your opinion? Vincent [1] http://www.renderx.com/xmlspec.html
