public static BpmGraph ParseBars(List <BarSection> barSections)
{
//In this context, 'time' = bar (beat is still beat)
barSections.Sort((a, b) => a.StartBar.CompareTo(b.StartBar));
var barToBeatSections = new List <BpmSection>();
double maxBar = 100_000;
var lastBarSection = new BpmSection(0, maxBar, 0, maxBar * 4);//default bar section for default Beats Per Bar of 4
barToBeatSections.Add(lastBarSection);
foreach (var bar in barSections)
{
double startBeat = lastBarSection.BeatAt(bar.StartBar);
double endBeat = (maxBar - bar.StartBar) * bar.NewBeatsPerBar + startBeat;
var section = new BpmSection(bar.StartBar, maxBar, startBeat, endBeat);
//modify the last section to end here
lastBarSection.EndBeat = startBeat;
lastBarSection.EndTime = bar.StartBar;
Assert.AreApproximatelyEqual(bar.NewBeatsPerBar, (float)section.Slope());
barToBeatSections.Add(section);
lastBarSection = section;
}
return(new BpmGraph(barToBeatSections));
}
public double BeatAt(double time)
{
//check if last entry is valid for efficiency
if (_beatCache != null && _beatCache.EndTime >= time && _beatCache.StartTime <= time)
{
return(_beatCache.BeatAt(time));//reuse cache
}
//(trivial) edge case
if (BpmSections.Count == 1)
{
return(BpmSections[0].BeatAt(time));
}
//binary search
int min = 0;
int max = BpmSections.Count - 1;
while (true)//will break when found
{
int midpt = (min + max) / 2;
if (max - min == 1)//right next to each other
{
if (BpmSections[min].TimeInBounds(time))
{
_beatCache = BpmSections[min];
return(BpmSections[min].BeatAt(time));
}
else
{
_beatCache = BpmSections[max];
return(BpmSections[max].BeatAt(time));
}
}
BpmSection mid = BpmSections[midpt];
if (mid.EndTime > time)
{
max = midpt;
}
else if (mid.StartTime < time)
{
min = midpt;
}
else
{
_beatCache = mid;
return(mid.BeatAt(time));
}
}
}