[Lilypond-auto] [LilyIssues-auto] [testlilyissues:issues] #5210 LyricHyp

The problem with "We also silently correct some minor/coding problems:" is that a number of those corrections are problematic. For one thing, changing all code defaults for robustX2scm to the defaults in the grobs is not serving any purpose: the intent for robustX2scm is to avoid crashes. Providing/tracking best behavior suddenly makes for two places where defaults have to be updated, and they are only documented at the Scheme side. If a value requires fine-tuning/explanation, it should be set and documented with the grob, not hardcoded in C++.

'padding might be 0.0, but a negative 'padding is ignored and 0.07 is used instead.

creates a discontinuity. That's inscrutable behavior for calculated values, particularly if calculated values may end up to be numerically zero (consequently small negative values). So if there is sensible behavior for zero values but no sensible behavior for negative values, the default fallback should be 0 rather than 0.07.

Having this in a separate review makes it reasonably easy to find the culprit. Washing everything up in a single review makes it hard for the reviewer.

Then you change the behavior of dash-period with the argument

 If you don't want a dash, you should

omit "--".

but -- is semantic information that may be used for other purposes (and it is being used for alignment if I remember correctly). Omitting it is an indication that one is talking about separate words which may not always be the case.

So a big "fix hyphens" patch makes it hard to review things, and hard to deal with separate things as separate things when problems are reported. We have in some cases reverted patches when that was the fastest option to recover from disruptive changes, and cramming everything into one patch/commit then causes a whole lot more of a disruption.

[issues:#5210] LyricHyphen improvements: Accept hyphen markup, fuzzy-metrics

Status: Started
Created: Wed Oct 04, 2017 11:37 AM UTC by Knut Petersen
Last Updated: Fri Oct 06, 2017 10:28 AM UTC
Owner: Knut Petersen

LyricHyphen: Use markup as hyphen, introduce 'fuzzy-metrics

We use a LyricHyphen grob constructed from rounded-boxes.
That is fine with a lot of fonts, but it is ugly if you use
e.g. Minion, a font that resembles handwriting, or a font
of the Fraktur family.

If a song with multiple stanzas is engraved, the position of
hyphens is far from optimal, especially at the start and end
of lines.

This patch

allows to use an arbitrary markup instead of the default
rounded-box-dash that was used in lilypond for ages.
In the most simple case, if you want to use the hyphen
of the lyric font, simply set 'text to "-".
As it is impossible to shorten a markup, 'minimum-distance
is ignored if it is below the natural width of the markup
+ 2 * padding.
implements a booloean property 'fuzzy-metrics. If set to #t,
'dash-period is only taken as a start value for calculating
the number of individual hyphens to use. That value might
be increased if the space between the borders and the first
hyphen is big, and it will be increased if the result is an
even number of hyphens. With this algorithm it is probable
that the small variations of the length of syllables in
stanzas at a given moment will not change the number of
hyphens choosen. As long as the number of hyphens used is
equal, the output is much nicer than with the old code,
A single hyphen will be centered, otherwise the distance
between the first/last hyphen and the adjacent syllable will
be ('padding + 'length) and a period that distributes the
other hyphens evenly is used. If we are at a line break,
the adjacent hyphen will be separated from the border only
by 'padding.

As long as neither 'text nor 'fuzzy-metrics is used, the output
is identical or similar to the old style. The number of hyphens
used might change as padding is always obeyed, it might change
as we reserve enough space at the end of a line for a shortend
rounded-box hyphen. That way a hyphen never will stick out to
the right of a system.

We also silently correct some minor/coding problems:

A 'length below 'minimum-length will be interpreted
as'minimum-length.
A 'dash-period below 'length will be ignored and
'length*1.5 will be used. That's ugly but much
easier to spot than a missing hyphen. At other places
a negative dash-period means "do not print", but here
this is nonsense. If you don't want a dash, you should
omit "--".
'padding might be 0.0, but a negative 'padding is
ignored and 0.07 is used instead.
the defaults used with robust_scm2double were changed
according to the defaults defined in define-grobs.scm.

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From:	Auto mailings of changes to Lily Issues via Testlilyissues-auto
Subject:	[Lilypond-auto] [LilyIssues-auto] [testlilyissues:issues] #5210 LyricHyphen improvements: Accept hyphen markup, fuzzy-metrics
Date:	Fri, 06 Oct 2017 19:58:33 +0000