Re: rewrite Self_alignment_interface (issue 7768043)

[mtsolo]

I'd recommend adding a sort of padding property to the
self-alignment-interface to get it completely there.  That is, imagine
that we right align to a grob and we want to be padded by 0.1  We should
be able to do that.  That'd allow self-alignment-interface to be used
for grobs like InstrumentName.


https://codereview.appspot.com/7768043/diff/46001/lily/new-fingering-engraver.cc
File lily/new-fingering-engraver.cc (right):

https://codereview.appspot.com/7768043/diff/46001/lily/new-fingering-engraver.cc#newcode291
lily/new-fingering-engraver.cc:291: // don't overwrite offset property
if it was overridden by the user
Consider chaining an offset callback here.  See chain_callback and
chain_offset_callback.

https://codereview.appspot.com/7768043/diff/46001/lily/self-alignment-interface.cc
File lily/self-alignment-interface.cc (right):

https://codereview.appspot.com/7768043/diff/46001/lily/self-alignment-interface.cc#newcode152
lily/self-alignment-interface.cc:152:
This would be the place to tack on padding.

https://codereview.appspot.com/7768043/diff/46001/scm/define-grobs.scm
File scm/define-grobs.scm (right):

https://codereview.appspot.com/7768043/diff/46001/scm/define-grobs.scm#newcode143
scm/define-grobs.scm:143: (X-extent . (-0.1 . 0.1)) ;UGH! how to get
ambitusline extent from its stencil?
Why can't you use the standard X extent function given in grob.cc?

https://codereview.appspot.com/7768043/