On 10.03.2005 16:15:10 Victor Mote wrote: > Jeremias Maerki wrote: > > > I got my copy of Michael Plass' dissertation today. A cursory > > overview shows that this document will provide some insight > > on using Knuth element model for page breaking but it also > > makes clear that we still have to come up with solutions for > > certain tricky problems that he didn't have to deal with back > > then. At any rate, the dissertation seems more helpful than > > the two documents we found by Brüggemann-Klein, Klein and Wohlfeil. > > Hi Jeremias: > > I got my copy yesterday and spent some time in it as well. I wanted to weave > some thoughts about it into the thread from a few days ago that dealt with > this same topic. In that thread, you raised the same two issues that I have > been troubled about for page-breaking: 1) differing page IPDs, and 2) > side-floats. > > WRT differing page IPDs, I think it is probably very acceptable in almost > every case to simply change the rules. IOW, If you want to use layout > strategy X, you must do so on a page-sequence-master that has all page IPDs > the same and that uses the same column-count. (Plass acknowledges that the > problem to be solved is two-dimensional, but specifically says that his > algorithm is one-dimensional.) Whether dealing with business forms > (invoices, purchase orders, etc.) or high-end book publishing (I have > experience with both), I cannot think of a use case for differing IPDs on > pages in the same page-sequence. If the goal is 100% standard compliance, > this isn't good enough. However, if the goal is to get some work done for a > client, and it doesn't hinder future 100% compliance, then this would be the > way I would address it.
A fact is that FOP 0.20.5 had no problems with differing available IPDs. With Luca's suggestions I think we can (auto-)configure the page breaking algorithm (read: no separate layout strategy) so it can handle differing IPDs. > Side-floats are another story. Plass addresses them by adding a new > primitive to the box/glue/penalty model, called "insert" (page 15). However, > I thought the following was pretty interesting as well, drawn from the last > paragraph of his dissertation: > > "There are other ways of incorporating approximations into the pagination > routine; for instance, inset figures could be handled satisfactorily by > doing the pagination as if they were full width figures with the same area > as the original figures; afterwards the paragraphs could be re-broken in > order to fit them around the figures. The optimizing line breaking algorithm > would be helpful in this regard, since it could break the text on the page > in such a way that it would come out to the right number of lines. Layout > artists traditionally use approximate copyfitting techniques to do such > tasks, so methods like this hold much promise." > > So, if an insert requiring 4 square inches is required, and the IPD is six > inches, add 2/3 of an inch to the BPD of the block, do your copyfitting, > then come back and lay the block out properly later. > > After thinking through all of these papers and ideas, I am more convinced > than ever of the utility of pluggable layout. But I guess you guys like > branches better :-) Jeremias Maerki
