BeatsSnapFunctions.cpp

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/*  SPDX-License-Identifier: GPL-2.0-or-later */
/*!********************************************************************
 
  Audacity: A Digital Audio Editor
 
  BeatsSnapFunctions.cpp
 
  Dmitry Vedenko
 
**********************************************************************/
 
#include "ProjectTimeSignature.h"
 
#include "SnapUtils.h"
 
namespace
{
/*
bps = tempo / 60
1/lower takes 1/bps
*/
 
double SnapToBar(const AudacityProject& project)
{
   auto& timeSignature = ProjectTimeSignature::Get(project);
   
   const auto barDuration = timeSignature.GetBarDuration();
   const auto multiplier = 1 / barDuration;
 
   return multiplier;
}
 
MultiplierFunctor SnapToBeat(int divisor)
{
   return [divisor](const AudacityProject& project)
   {
      auto& timeSignature = ProjectTimeSignature::Get(project);
 
      const auto quarterDuration = timeSignature.GetQuarterDuration();
      // DV: It was decided that for the time being,
      // BPM sets the duration for quarter notes.
      // For this reason, `cfg.timeSignature.second` is ignored
      const auto fracDuration = quarterDuration * 4.0 / divisor;
      const auto multiplier = 1.0 / fracDuration;
 
      return multiplier;
   };
}
 
MultiplierFunctor SnapToTriplets(int divisor)
{
   return [divisor](const AudacityProject& project)
   {
      auto& timeSignature = ProjectTimeSignature::Get(project);
 
      const auto quarterDuration = 60.0 / timeSignature.GetTempo();
      const auto tripletDivisor = 3 * (divisor / 2);
      const auto fracDuration = quarterDuration * 4.0 / tripletDivisor;
      const auto multiplier = 1.0 / fracDuration;
 
      return multiplier;
   };
}
 
SnapRegistryItemRegistrator beats {
   SnapFunctionItems( "beats",
      SnapFunctionGroup(
         /* i18n-hint: The music theory "beat"*/
         "beats", { XO("Beats"), true },
         /* i18n-hint: The music theory "bar"*/
         TimeInvariantSnapFunction("bar", XO("Bar"), SnapToBar),
         TimeInvariantSnapFunction("bar_1_2", XO("1/2"), SnapToBeat(2)),
         TimeInvariantSnapFunction("bar_1_4", XO("1/4"), SnapToBeat(4)),
         TimeInvariantSnapFunction("bar_1_8", XO("1/8"), SnapToBeat(8)),
         TimeInvariantSnapFunction("bar_1_16", XO("1/16"), SnapToBeat(16)),
         TimeInvariantSnapFunction("bar_1_32", XO("1/32"), SnapToBeat(32)),
         TimeInvariantSnapFunction("bar_1_64", XO("1/64"), SnapToBeat(64)),
         TimeInvariantSnapFunction("bar_1_128", XO("1/128"), SnapToBeat(128))),
      SnapFunctionGroup(
         /* i18n-hint: The music theory "triplet"*/
         "triplets", { XO("Triplets"), true },
         TimeInvariantSnapFunction(
            "triplet_1_2", XO("1/2 (triplets)"), SnapToTriplets(2)),
         TimeInvariantSnapFunction(
            "triplet_1_4", XO("1/4 (triplets)"), SnapToTriplets(4)),
         TimeInvariantSnapFunction(
            "triplet_1_8", XO("1/8 (triplets)"), SnapToTriplets(8)),
         TimeInvariantSnapFunction(
            "triplet_1_16", XO("1/16 (triplets)"), SnapToTriplets(16)),
         TimeInvariantSnapFunction(
            "triplet_1_32", XO("1/32 (triplets)"), SnapToTriplets(32)),
         TimeInvariantSnapFunction(
            "triplet_1_64", XO("1/64 (triplets)"), SnapToTriplets(64)),
         TimeInvariantSnapFunction(
            "triplet_1_128", XO("1/128 (triplets)"), SnapToTriplets(128)))
   ),
   Registry::Placement { {}, { Registry::OrderingHint::Begin } }
};
 
}