/// <returns>
/// Returns a collection which is the projection of this collection onto the defined periodic function.
/// </returns>
/// <remarks>
/// The object on which this method is called is a timeline's parent's collection of intervals.
/// The periodic collection passed via parameters describes the active/fill periods of the timeline.
/// The output is the projection of (this) object using the parameter function of the timeline.
///
/// We assume this function is ONLY called when this collection overlaps the active zone.
///
/// The periodic function maps values from domain to range within its activation period of [beginTime, endTime);
/// in the fill period [endTime, endTime+fillDuration) everything maps to a constant post-fill value, and outside of
/// those periods every value maps to null.
///
/// The projection process can be described as three major steps:
///
/// (1) NORMALIZE this collection: offset the TIC's coordinates by BeginTime and scale by SpeedRatio.
///
/// (2) FOLD this collection. This means we convert from parent-time coordinate space into the space of
/// a single simpleDuration for the child. This is equivalent to "cutting up" the parent TIC into
/// equal-length segments (of length Period) and overlapping them -- taking their union. This lets us
/// know exactly which values inside the simpleDuration we have reached on the child. In the case of
/// autoreversed timelines, we do the folding similiar to folding a strip of paper -- alternating direction.
///
/// (3) WARP the resulting collection. We now convert from simpleDuration domain coordinates into
/// coordinates in the range of the timeline function. We do this by applying the "warping" effects of
/// acceleration, and deceleration.
///
/// In the special case of infinite simple duration, we essentially are done after performing NORMALIZE,
/// because no periodicity or acceleration is present.
///
/// In the ultimate degenerate case of zero duration, we terminate early and project the zero point.
///
/// </remarks>
/// <param name="projection">An empty output projection, passed by reference to allow TIC reuse.</param>
/// <param name="beginTime">Begin time of the periodic function.</param>
/// <param name="endTime">The end (expiration) time of the periodic function. Null indicates positive infinity.</param>
/// <param name="fillDuration">The fill time appended at the end of the periodic function. Zero indicates no fill period. Forever indicates infinite fill period.</param>
/// <param name="period">Length of a single iteration in the periodic collection.</param>
/// <param name="appliedSpeedRatio">Ratio by which to scale down the periodic collection.</param>
/// <param name="accelRatio">Ratio of the length of the accelerating portion of the iteration.</param>
/// <param name="decelRatio">Ratio of the length of the decelerating portion of the iteration.</param>
/// <param name="isAutoReversed">Indicates whether reversed arcs should follow after forward arcs.</param>
internal void ProjectOntoPeriodicFunction(ref TimeIntervalCollection projection,
TimeSpan beginTime, Nullable<TimeSpan> endTime,
Duration fillDuration, Duration period,
double appliedSpeedRatio, double accelRatio, double decelRatio,
bool isAutoReversed)
{
Debug.Assert(projection.IsEmpty);
Debug.Assert(!_invertCollection); // Make sure we never leave inverted mode enabled
Debug.Assert(!endTime.HasValue || beginTime <= endTime); // Ensure legitimate begin/end clipping parameters
Debug.Assert(!IsEmptyOfRealPoints); // We assume this function is ONLY called when this collection overlaps the active zone. So we cannot be empty.
Debug.Assert(!endTime.HasValue || endTime >= _nodeTime[0]); // EndTime must come at or after our first node (it can be infinite)
Debug.Assert(_nodeTime[_count - 1] >= beginTime); // Our last node must come at least at begin time (since we must intersect the active period)
Debug.Assert(endTime.HasValue || fillDuration == TimeSpan.Zero); // Either endTime is finite, or it's infinite hence we cannot have any fill zone
Debug.Assert(!period.HasTimeSpan || period.TimeSpan > TimeSpan.Zero || (endTime.HasValue && beginTime == endTime)); // Check the consistency of degenerate case where simple duration is zero; expiration time should equal beginTime
Debug.Assert(!_nodeIsInterval[_count - 1]); // We should not have an infinite domain set
// We initially project all intervals into a single period of the timeline, creating a union of the projected segments.
// Then we warp the time coordinates of the resulting TIC from domain to range, applying the effects of speed/accel/decel
bool nullPoint = _containsNullPoint // Start by projecting the null point directly, then check whether we fall anywhere outside of the active and fill period
|| _nodeTime[0] < beginTime // If we intersect space before beginTime, or...
|| (endTime.HasValue && fillDuration.HasTimeSpan // ...the active and fill periods don't stretch forever, and...
&& (_nodeTime[_count - 1] > endTime.Value + fillDuration.TimeSpan // ...we intersect space after endTime+fill, or...
|| (_nodeTime[_count - 1] == endTime.Value + fillDuration.TimeSpan // ...as we fall right onto the end of fill zone...
&& _nodeIsPoint[_count - 1] && (endTime > beginTime || fillDuration.TimeSpan > TimeSpan.Zero)))); // ...we may have a point intersection with the stopped zone
// Now consider the main scenarios:
if (endTime.HasValue && beginTime == endTime) // Degenerate case when our active period is a single point; project only the point
{
projection.InitializePoint(TimeSpan.Zero);
}
else // The case of non-zero active duration
{
bool includeFillPeriod = !fillDuration.HasTimeSpan || fillDuration.TimeSpan > TimeSpan.Zero; // This variable represents whether we have a non-zero fill zone
if (period.HasTimeSpan) // We have a finite TimeSpan period and non-zero activation duration
{
TimeIntervalCollection tempCollection = new TimeIntervalCollection();
ProjectionNormalize(ref tempCollection, beginTime, endTime, includeFillPeriod, appliedSpeedRatio);
long periodInTicks = period.TimeSpan.Ticks;
Nullable<TimeSpan> activeDuration;
bool includeMaxPoint;
if (endTime.HasValue)
{
activeDuration = endTime.Value - beginTime;
includeMaxPoint = includeFillPeriod && (activeDuration.Value.Ticks % periodInTicks == 0); // Fill starts at a boundary
}
else
{
activeDuration = null;
includeMaxPoint = false;
}
projection.EnsureAllocatedCapacity(_minimumCapacity);
tempCollection.ProjectionFold(ref projection, activeDuration, periodInTicks, isAutoReversed, includeMaxPoint);
if (accelRatio + decelRatio > 0)
{
projection.ProjectionWarp(periodInTicks, accelRatio, decelRatio);
}
}
else // Infinite period degenerate case; we perform straight 1-1 linear mapping, offset by begin time and clipped
{
ProjectionNormalize(ref projection, beginTime, endTime, includeFillPeriod, appliedSpeedRatio);
}
}
projection._containsNullPoint = nullPoint; // Ensure we have the null point properly set
}
/// <summary>
/// Used for projecting the end of a fill period. When calling, we already know that we intersect the fill period
/// but not the active period.
/// </summary>
/// <returns>
/// Returns a collection which is the projection of the argument point onto the defined periodic function.
/// </returns>
/// <param name="projection">An empty output projection, passed by reference to allow TIC reuse.</param>
/// <param name="beginTime">Begin time of the periodic function.</param>
/// <param name="endTime">The end (expiration) time of the periodic function.</param>
/// <param name="period">Length of a single iteration in the periodic collection.</param>
/// <param name="appliedSpeedRatio">Ratio by which to scale down the periodic collection.</param>
/// <param name="accelRatio">Ratio of the length of the accelerating portion of the iteration.</param>
/// <param name="decelRatio">Ratio of the length of the decelerating portion of the iteration.</param>
/// <param name="isAutoReversed">Indicates whether reversed arcs should follow after forward arcs.</param>
internal void ProjectPostFillZone(ref TimeIntervalCollection projection,
TimeSpan beginTime, TimeSpan endTime, Duration period,
double appliedSpeedRatio, double accelRatio, double decelRatio,
bool isAutoReversed)
{
Debug.Assert(projection.IsEmpty); // Make sure the projection was properly cleared first
Debug.Assert(!_invertCollection); // Make sure we never leave inverted mode enabled
Debug.Assert(beginTime <= endTime); // Ensure legitimate begin/end clipping parameters
Debug.Assert(!IsEmptyOfRealPoints); // We assume this function is ONLY called when this collection overlaps the postfill zone. So we cannot be empty.
Debug.Assert(!period.HasTimeSpan || period.TimeSpan > TimeSpan.Zero || beginTime == endTime); // Check the consistency of degenerate case where simple duration is zero; expiration time should equal beginTime
Debug.Assert(!_nodeIsInterval[_count - 1]); // We should not have an infinite domain set
long outputInTicks;
if (beginTime == endTime) // Degenerate case when our active period is a single point; project only that point
{
outputInTicks = 0;
}
else // The case of non-zero active duration
{
outputInTicks = (long)(appliedSpeedRatio * (double)(endTime - beginTime).Ticks);
if (period.HasTimeSpan) // Case of finite simple duration; in the infinite case we are already done
{
long periodInTicks = period.TimeSpan.Ticks; // Start by folding the point into its place inside a simple duration
if (isAutoReversed)
{
long doublePeriod = periodInTicks << 1; // Fast multiply by 2
outputInTicks = outputInTicks % doublePeriod;
if (outputInTicks > periodInTicks)
{
outputInTicks = doublePeriod - outputInTicks;
}
}
else
{
outputInTicks = outputInTicks % periodInTicks;
if (outputInTicks == 0)
{
outputInTicks = periodInTicks; // If we are at the end, stick to the max value
}
}
if (accelRatio + decelRatio > 0) // Now if we have acceleration, warp the point by the correct amount
{
double dpPeriod = (double)periodInTicks;
double inversePeriod = 1 / dpPeriod;
double halfMaxRate = 1 / (2 - accelRatio - decelRatio); // Constants to simplify
double t;
long accelEnd = (long)(dpPeriod * accelRatio);
long decelStart = periodInTicks - (long)(dpPeriod * decelRatio);
if (outputInTicks < accelEnd) // We are in accel zone
{
t = (double)outputInTicks;
outputInTicks = (long)(halfMaxRate * inversePeriod * t * t / accelRatio);
}
else if (outputInTicks <= decelStart) // We are in the linear zone
{
t = (double)outputInTicks;
outputInTicks = (long)(halfMaxRate * (2 * t - accelRatio));
}
else // We are in decel zone
{
t = (double)(periodInTicks - outputInTicks);
outputInTicks = periodInTicks - (long)(halfMaxRate * inversePeriod * t * t / decelRatio);
}
}
}
}
projection.InitializePoint(TimeSpan.FromTicks(outputInTicks));
}
