Re: Vertical spacing regression !?

[Boris Shingarov]

On 06/27/2010 01:25 PM, Joe Neeman wrote:
> On Sun, 2010-06-27 at 06:56 -0400, Boris Shingarov wrote:
>
> > This was discussed on this list only a few weeks ago.  I think we 
> are on
> > our way to get rid of global page*line breaking.
>
> Although I am happy to have an option to do full line-breaking before
> page-breaking, I am very much against getting rid of the line and
> page-breaking interaction. For example, if we did that then we would
> have to scrap the new vertical layout since it relies on being able to
> stretch the systems after the pages are determined. And while I have a
> personal bias against scrapping the vertical layout (since I wrote it),
> I do think that it is a big improvement over the previous layout
> algorithm and I have heard comments to that effect on the lists too.
> Also, the page-turn-breaker can't function without some interaction
> between line- and page-breaking.
I understand the bad effects of divorcing line- from page-breaking.  
Another one (of those which I personally care about) is that it will 
negate the window/orphan handling feature I added.  At least to my 
users, this is important.  And yes, I do agree that the new layout 
algorithm *is* a big improvement over the previous one.

But what do we do about the height estimation problems?  No matter how 
important the positive effects of line/page-breaking interaction are, a 
score with staves cut at the bottom, is unusable.  And a score with the 
opposite problem, is equally unusable.  Can we realistically hope to fix 
enough bugs so that real publications will look usable?  I don't know.  
I started working on the estimations because the user's book suffered 
the problem.  I fixed five, and pulled your fixes for a few.  And yet 
the book is still suffering the same problem.  I know what causes it 
*now*, but I do not know if this is going to be the last one *for this 
book*, and I am now facing problems of customer value when talking about 
fixing height estimation bugs.

So what are we going to do, keep fixing these bugs, under the theory 
that there is only finite number of them?  One thing that makes me 
nervous is that a lot of the time the fixes involve increase of 
computational complexity.  We are moving from simple height estimation 
to more and more complex height estimation; can it be that as we 
approach being more and more correct in our estimation, the complexity 
also approaches that of full layout?