Convert leaves to a list of QEvent objects. If the leaves have no effective tempo, tempo must be a TempoMark.
abjad> from abjad.tools.quantizationtools import tempo_scaled_leaves_to_q_events
abjad> source = Staff("c'4 r4. e'8 <g' b' d'' fs''>2")
abjad> source_tempo = contexttools.TempoMark((1, 4), 55)
abjad> tempo_scaled_leaves_to_q_events(source[:], tempo = source_tempo)
[QEvent(Offset(0, 1), 0), QEvent(Offset(12000, 11), None), QEvent(Offset(30000, 11), 4), QEvent(Offset(36000, 11), (7, 11, 14, 18)), QEvent(Offset(60000, 11), None)]
Return a list of QEvent objects.