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temporal: update comment on a method that suggest not using it; provide TempoMap::quarters_per_minute_at ()

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This commit is contained in:
Paul Davis 2021-11-12 10:47:21 -07:00
parent 4f3bf37680
commit a0e134e1b3
1 changed files with 13 additions and 4 deletions
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17
libs/temporal/temporal/tempo.h
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@ -408,11 +408,12 @@ class /*LIBTEMPORAL_API*/ TempoPoint : public Tempo, public tempo_hook, public v
LIBTEMPORAL_API samplepos_t sample_at (Beats const & qn) const { return Temporal::superclock_to_samples (superclock_at (qn), TEMPORAL_SAMPLE_RATE); }
LIBTEMPORAL_API superclock_t superclocks_per_note_type_at (timepos_t const &) const;
/* This method should be used only for display purposes, and even
* then, only when absolutely necessary. It returns a double
* representation of the tempo, and we do not want to be using such
* representations ever, if we could.
/* XXX at some point, we have had discussions about representing tempo
* as a rational number rather than a double. We have not reached that
* point yet (Nov 2021), and so at this point, this method is the
* canonical way to get "bpm at position" from a TempoPoint object.
*/
LIBTEMPORAL_API double note_types_per_minute_at_DOUBLE (timepos_t const & pos) const {
return (superclock_ticks_per_second * 60.0) / superclocks_per_note_type_at (pos);
}
@ -768,6 +769,14 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
LIBTEMPORAL_API TempoPoint const* previous_tempo (TempoPoint const &) const;
/* convenience function that hides some complexities behind fetching
* the bpm at position
*/
LIBTEMPORAL_API double quarters_per_minute_at (timepos_t const & pos) const {
TempoPoint const & tp (tempo_at (pos));
return tp.note_types_per_minute_at_DOUBLE (pos) * (4.0 / tp.note_type());
}
/* convenience function */
LIBTEMPORAL_API BBT_Time round_to_bar (BBT_Time const & bbt) const {
return metric_at (bbt).meter().round_to_bar (bbt);