Issue 5264: fret diagram nut alignment

Issue 5264: fret diagram nut alignment

This fixes the alignment for negative string-distance.

[Malte Meyn, 2018-01-18 13:53:08]

use sign function from lily-library.scm instead of if clause

[Malte Meyn, 2018-01-18 14:12:30]

align correctly for different size

[Malte Meyn, 2018-01-18 14:24:58]

On 2018/01/18 14:12:30, Malte Meyn wrote:
> align correctly for different size

Try this for testing:

\version "2.19.80"

\include "predefined-guitar-fretboards.ly"

\new FretBoards \with {
  \override FretBoard.size = 10
  \override FretBoard.thickness = 2
  \override FretBoard.fret-diagram-details.string-thickness-factor = 0.2
} \chordmode {
  e
}

[thomasmorley651, 2018-01-18 19:42:01]

I don't think this is the right approach to make left-handed fret-diagrams work.
Ofcourse it cures a single problem while using negative string-distance, but
other problems are shining up as already mentioned.
Instead I think we should disallow negative string-distance, or rather (because
LilyPond does no type-checking on sub-properties) always use the (abs ..).
For the left-handed fret-diagrams, why not place strings (and frets) correctly
right from the start and let do the already existing code all the other work?
I'll post a patch following this route on the tracker.

[Carl, 2018-01-18 19:52:21]

On 2018/01/18 19:42:01, thomasmorley651 wrote:
> I don't think this is the right approach to make left-handed fret-diagrams
work.
> Ofcourse it cures a single problem while using negative string-distance, but
> other problems are shining up as already mentioned.
> Instead I think we should disallow negative string-distance, or rather
(because
> LilyPond does no type-checking on sub-properties) always use the (abs ..).
> For the left-handed fret-diagrams, why not place strings (and frets) correctly
> right from the start and let do the already existing code all the other work?
> I'll post a patch following this route on the tracker.

I agree that the negative string-distance is not the right way to create
left-handed fret diagrams.

The proper approach is to introduce a property that indicates the diagram should
be left-handed, and to make the stencil-coordinates function in
scm/fret-diagrams.scm respect that property.

[thomasmorley651, 2018-01-18 20:00:03]

> The proper approach is to introduce a property that indicates the diagram
should
> be left-handed, and to make the stencil-coordinates function in
> scm/fret-diagrams.scm respect that property.

That's exactly what I'm trying to do with my patch on the tracker