Re: [Patch] Fix #1333: beamed multi-note acciaccaturas (issue3169041)

[v . villenave]

On 2010/11/18 19:59:23, Neil Puttock wrote:
> Hi Valentin,

Hi Carl, hi Neil, thank for stopping by! :-)
Graham: that's the reason why I uploaded a new patch set, but it didn't
succeed either.  I'm having some kind of a WTF situation here.

> I'm afraid I share Carl's concerns here

I think he's right too. I wanted to take this as a chance to "correct"
the way grace-functions are defined now, which I don't really like
(having to define startGrace and stopGrace as empty expressions?
really?). And I was confident that this could be handled with a
straightforward convert-ly rule. However, you're both right in pointing
out that it might be an unnecessary risk.

> though to my mind the most pressing
> issue is how the slash is rendered.  I don't think it's enough to
simply use a
> stencil override, since it makes it too difficult for users to tweak
the
> appearance.

Hence the "workaround" part that I did mention in my description.  I did
see it as a temporary hack, or more appropriately, a proof-of-concept,
until we could have a genuinely proper solution (see below).

> I think rendering the slash with support for tweaking its appearance
in a
> consistent manner demands an implementation as a separate grob.

Unfortunately, this is precisely where I'm out of my league.  My secret
hope was that something like the harp-pedal thing would happen, i.e. my
initial "naive" effort could entice proper programmers into implementing
something nicer in the future :-)

That being said, I'd be happy to play ball and give this a go: if you
were to implement such a grob (I'm guessing something like
BeamedMultiAcciaccaturaInitialStemSlash, only shorter ;-), where would
you start? Would it require a glyph, like what we're doing with
non-beamed acciaccaturas, or would a simple line be enough? And how
would you compute the angle of the slash?

(Besides, I'm concerned with the overhead/bloat/namespace pollution/etc.
Would this grob really need to be added to the Stem_engraver by default?
It would be used quite rarely, I think.)

Bonus question: if we were to have an AcciaccaturaSlash grob, then would
we still need the current implementation for slashed single notes (e.g.
combining a slash glyph with the flag glyph, etc.)? Or could we use the
same grob in both cases for visual consistency?

... Duh. I thought I was out of my league before, but it's even worse
now :(

Cheers,
Valentin.

http://codereview.appspot.com/3169041/