Limit the angle of broken hairpins

[Urs Liska]

Hi,

as brought up in 
http://lists.gnu.org/archive/html/lilypond-user/2018-09/msg00236.html 
broken hairpins look ugly when they are too short. This is (as pointed 
out by Harm) due to the fact that the heights at the broken edges are 
hardcoded in the C++ function printing the hairpin.

I suggest a two-fold remedy:

1) limit the heights at the broken edges so the height/width ratio of 
the sibling doesn't exceed a certain value (I'd start with 1/2)

2) make that ratio and the broken-heights values user-settable as grob 
properties.

I've given it a partial try that can be seen at 
https://github.com/lilypond/lilypond/pull/4. This commit (hopefully) 
implements part 1) of the above. I've also attached the patch. Since I 
don't have a working build environment right now I couldn't test this 
code, but it should be straightforward, I think.

I would be glad if someone could add the code to create the grob 
properties (should be little work but not if you have to first look 
everything up like me) in order to upload it for review later.

Urs

0001-Limit-angle-of-broken-hairpins.patch
Description: Text Data

encore.png
Description: PNG image