slurs avoid stafflines: move far enough; issue 3628

slurs avoid stafflines: move far enough; issue 3628

Suggestion from Janek Warchoł to account for the fact that the curve
of a slur moves less than its control points, and to consider flattening
as well as increasing the curve.

[janek, 2013-12-06 22:31:01]

Hi,

i'm very busy with other LilyPond stuff, but would like to give this patch a
closer look.  May i ask to prolong the contdown for it until tomorrow 12:00?

Janek

[janek, 2013-12-07 17:04:00]

There's one nitpick, other than that it can go.  There are some things i would
do in another way, but there's no sense wasting time discussing them.  I'll just
make a new patch if i'll have the time.

thanks, and i'm sorry that it took so long!
Janek

https://codereview.appspot.com/35310043/diff/1/lily/slur-configuration.cc
File lily/slur-configuration.cc (right):

https://codereview.appspot.com/35310043/diff/1/lily/slur-configuration.cc#new...
lily/slur-configuration.cc:64: : state.parameters_.gap_to_staffline_outside_);
You forgot about staffline thickness:

mus = \relative c'' {
  \override Slur.details.gap-to-staffline-inside = #0.05
  \override Slur.details.gap-to-staffline-outside = #0.05
  \slurUp
  a2( a)
  e1( a)
}
\markup \scale #'(3 . 3) {
  \score {
    \mus
    \layout { }
  }
}

will result in slurs touching stafflines.

[Keith, 2013-12-07 19:49:42]

https://codereview.appspot.com/35310043/diff/1/lily/slur-configuration.cc
File lily/slur-configuration.cc (right):

https://codereview.appspot.com/35310043/diff/1/lily/slur-configuration.cc#new...
lily/slur-configuration.cc:64: : state.parameters_.gap_to_staffline_outside_);
On 2013/12/07 17:04:00, janek wrote:
> You forgot about staffline thickness:

I was ignoring line thicknesses.  There is the line-width for the staff-lines
and for the outline of the slur itself. I don't want to look up grob-properties
for every potential slur in the beauty contest, so I cached the layout
line-thickness in slur-scoring. The tapering of the slur is a bigger effect, so
I accounted for that as well.

[janek, 2013-12-08 10:10:11]

One last question and it can bee pushed (as far as i'm concerned).

Janek

https://codereview.appspot.com/35310043/diff/80001/lily/slur-configuration.cc
File lily/slur-configuration.cc (right):

https://codereview.appspot.com/35310043/diff/80001/lily/slur-configuration.cc...
lily/slur-configuration.cc:66: + state.line_thickness_
The comment says "half of the staffline" but here it's not halved - is this ok?

[Keith, 2013-12-10 17:26:07]

https://codereview.appspot.com/35310043/diff/80001/lily/slur-configuration.cc
File lily/slur-configuration.cc (right):

https://codereview.appspot.com/35310043/diff/80001/lily/slur-configuration.cc...
lily/slur-configuration.cc:66: + state.line_thickness_
On 2013/12/08 10:10:11, janek wrote:
> The comment says "half of the staffline" but here it's not halved - is this
ok?

It says "half for the staff line, half for the slur outline" each of those
halves being half a line-thickness.  Two halves add to one, so there is a full
thine-thickness added in the code.