Re: Slur with left and/or right arrow head

[Lukas-Fabian Moser]

Hi Aaron and Harm,

> > I started to implement the functionality, finally I more or less
> > rewrote anything.
> > As David K once said: rewriting all means at least knowing where the 
> > bugs are...
>
> There is an annoying optical issue where using the angle of the curve 
> at the end points does not work well for an arrow head that partially 
> overlaps the curve.  Instead, one needs to consider the slope of the 
> curve a little inwards from the ends so that the arrow appears to be 
> aligned properly.
>
> I took a stab at patching your code to address this.  This involved 
> some additional computational work for various metrics of a Bezier 
> curve.  See the attached files.

Wow - that's just amazing. Thanks to both of you!!

As to the interface: For, e.g., Glissandos, an arrow tip (not as 
beautiful as your Slur arrow) is activated by issuing \overriding 
Glissando.bound-details.left.arrow = ##t. I asked myself whether it's 
good to have this difference in the interface for Slur arrows where you 
use details instead of bound-details and a signed value (#LEFT and 
#RIGHT), seeing that Slur.details.arrow-right = #LEFT doesn't give a 
reasonable result anyway (at the moment). But I do not really know what 
the conceptual difference of details vs. bound-details is, anyway.

Harm, the old code for outside-staff-curve still works with this 
solution, so it could be re-used if needed (might be appropriate for my 
use case).

Concerning my request for "the option to have an arrow tip at both ends 
of the Slur": This is now already implemented since left and right arrow 
tip can be activated independently and/or simultaneously.

I'm undecided as to the desired behaviour with broken Slurs. For me, 
it's all about graphical annotations in very short "scores" in a music 
theory setting where I'll make sure that there are no line-breaks 
anyway. But of course there might be good reasons to use 
slurs-with-arrow-tips in "real life" scores where one might wish for a 
reasonable handling of arrowed broken slurs. I can imagine three 
possibilities:

a) arrow head only at the last (resp. first for arrow-left) broken slur

b) arrow head at each broken curve (current situation)
b') arrow head at each broken curve, but partly dashed slur at breaking 
points. I try to sketch this in attached image.

To be clear: I do not need this functionality at all, but only wanted to 
give an input regarding the possibly reasonable design behaviours. What 
do you think?

Lukas

broken-arrowed-slur.png
Description: PNG image