Source/core/animation/TimedItemCalculations.h

/*
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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#ifndef TimedItemCalculations_h
#define TimedItemCalculations_h

#include "core/animation/TimedItem.h"
#include "core/animation/Timing.h"
#include "core/platform/animation/AnimationUtilities.h"
#include "wtf/MathExtras.h"

namespace WebCore {

static inline double calculateActiveTime(double activeDuration, double localTime, double startTime, const Timing& specified)
{
    ASSERT(activeDuration >= 0);
    ASSERT(std::isfinite(startTime));

    if (isNull(localTime))
        return nullValue();

    if (localTime < specified.startDelay) {
        if (specified.fillMode == Timing::FillModeBackwards || specified.fillMode == Timing::FillModeBoth)
            return 0;
        return nullValue();
    }

    if (localTime < startTime + activeDuration)
        return localTime - specified.startDelay;

    if (specified.fillMode == Timing::FillModeForwards || specified.fillMode == Timing::FillModeBoth)
        return activeDuration;

    return nullValue();
}

static inline double calculateScaledActiveTime(double activeDuration, double activeTime, double startOffset, const Timing& specified)
{
    ASSERT(activeDuration >= 0);
    ASSERT(startOffset >= 0);

    if (isNull(activeTime))
        return nullValue();

    ASSERT(activeTime >= 0);

    return (specified.playbackRate < 0 ? activeTime - activeDuration : activeTime) * specified.playbackRate + startOffset;
}

static inline bool endsOnIterationBoundary(double iterationCount, double iterationStart)
{
    return !fmod(iterationCount + iterationStart, 1);
}

static inline double calculateIterationTime(double iterationDuration, double repeatedDuration, double scaledActiveTime, double startOffset, const Timing& specified)
{
    ASSERT(iterationDuration >= 0);
    ASSERT(repeatedDuration == iterationDuration * specified.iterationCount);

    if (isNull(scaledActiveTime))
        return nullValue();

    ASSERT(scaledActiveTime >= 0);
    ASSERT(scaledActiveTime <= repeatedDuration + startOffset);

    if (!iterationDuration)
        return 0;

    if (scaledActiveTime - startOffset == repeatedDuration && specified.iterationCount && endsOnIterationBoundary(specified.iterationCount, specified.iterationStart))
        return iterationDuration;

    return fmod(scaledActiveTime, iterationDuration);
}

static inline double calculateCurrentIteration(double iterationDuration, double iterationTime, double scaledActiveTime, const Timing& specified)
{
    ASSERT(iterationDuration >= 0);
    ASSERT(isNull(iterationTime) || iterationTime >= 0);

    if (isNull(scaledActiveTime))
        return nullValue();

    ASSERT(iterationTime >= 0);
    ASSERT(iterationTime <= iterationDuration);
    ASSERT(scaledActiveTime >= 0);

    if (!scaledActiveTime)
        return 0;

    if (!iterationDuration)
        return floor(specified.iterationStart + specified.iterationCount);

    if (iterationTime == iterationDuration)
        return specified.iterationStart + specified.iterationCount - 1;

    return floor(scaledActiveTime / iterationDuration);
}

static inline double calculateDirectedTime(double currentIteration, double iterationDuration, double iterationTime, const Timing& specified)
{
    ASSERT(isNull(currentIteration) || currentIteration >= 0);
    ASSERT(iterationDuration > 0);

    if (isNull(iterationTime))
        return nullValue();

    ASSERT(currentIteration >= 0);
    ASSERT(iterationTime >= 0);
    ASSERT(iterationTime <= iterationDuration);

    const bool currentIterationIsOdd = fmod(currentIteration, 2) >= 1;
    const bool currentDirectionIsForwards = specified.direction == Timing::PlaybackDirectionNormal
        || (specified.direction == Timing::PlaybackDirectionAlternate && !currentIterationIsOdd)
        || (specified.direction == Timing::PlaybackDirectionAlternateReverse && currentIterationIsOdd);

    return currentDirectionIsForwards ? iterationTime : iterationDuration - iterationTime;
}

static inline double calculateTransformedTime(double currentIteration, double iterationDuration, double iterationTime, const Timing& specified)
{
    ASSERT(isNull(currentIteration) || currentIteration >= 0);
    ASSERT(iterationDuration > 0);
    ASSERT(isNull(iterationTime) || (iterationTime >= 0 && iterationTime <= iterationDuration));

    double directedTime = calculateDirectedTime(currentIteration, iterationDuration, iterationTime, specified);
    return specified.timingFunction ?
        iterationDuration * specified.timingFunction->evaluate(directedTime / iterationDuration, accuracyForDuration(iterationDuration)) :
        directedTime;
}

} // namespace WebCore

#endif