def visit_Slur(self, slur):
"""
Attempt to pitch-bend to victory.
Also apply shortening to the tail of the slur.
"""
def fail():
# Cut the tail off the end and return the whole shebang.
last, rest = self.shorten(slur.exprs[-1])
return Music(slur.exprs[:-1] + [last, rest]), False
# If we can't do legato on this instrument, bail.
if not can_legato(self.inst):
return fail()
first = slur.exprs[0]
exprs = slur.exprs[1:]
for expr in exprs:
if abs(expr.pitch - first.pitch) > 12:
# Bail.
return fail()
first = first._replace(
duration=sum(expr.duration for expr in slur.exprs))
first, rest = self.shorten(first)
offset = 0
out = [first]
for expr in exprs:
offset += expr.duration
out.append(PitchBend(offset,
(8191 // 12) * (expr.pitch - first.pitch)))
out.append(rest)
return Music(out), False
def test_guitar_can_legato(self):
self.assertTrue(can_legato("overdriven guitar"))
def test_piano_cannot_legato(self):
self.assertFalse(can_legato("acoustic grand"))
