Re: Vertical spacing regression !?

[Joe Neeman]

On Wed, 2010-06-30 at 07:04 +0200, David Kastrup wrote:
> Joe Neeman <address@hidden> writes:
> 
> > On Tue, 2010-06-29 at 20:23 +0200, Arno Waschk wrote:
> >> can't we have correct heights say for every bar (which must be computed 
> >> later anyway) with clever caching so we have them ready when the final 
> >> layout is made?
> > No. For example, we don't know if a bar will have its clef displayed
> > until after line-breaking. Also, the vertical collision avoidance means
> > that in { c1^"long long markup" c1^"long long markup" }, we cannot
> > calculate the height of the second bar without considering the first bar
> > too (and the answer will change if they are on different lines).
> 
> Maybe I am dull, but we need the line heights (or skyline) for a given
> line breakpoint sequence, and a given line breakpoint sequence has a
> given skyline for each line.

No, we don't compute the full skyline for a sequence of breakpoints,
because doing so would require performing the full horizontal layout
first. My point is that it isn't possible to get _completely_ accurate
height estimates unless we do the complete layout for every possible
line-breaking configuration.

Cheers,
Joe