QualifiedFrameTime.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Misc/FrameRate.h"
#include "Misc/FrameTime.h"
#include "Misc/Timecode.h"
 
/**
 * A frame time qualified by a frame rate context
 */
struct FQualifiedFrameTime
{
 
    /**
     * Default construction for UObject purposes
     */
    FQualifiedFrameTime()
        : Time(0), Rate(24, 1)
    {}
 
    /**
     * User construction from a frame time and its frame rate
     */
    FQualifiedFrameTime(const FFrameTime& InTime, const FFrameRate& InRate)
        : Time(InTime), Rate(InRate)
    {}
 
    /**
     * User construction from a timecode and its frame rate
     */
    FQualifiedFrameTime(const FTimecode& InTimecode, const FFrameRate& InRate)
        : Time(InTimecode.ToFrameNumber(InRate))
        , Rate(InRate)
    {
    }
 
public:
 
    /**
     * Convert this frame time to a value in seconds
     */
    double AsSeconds() const
    {
        return Time / Rate;
    }
 
    /**
     * Convert this frame time to a different frame rate
     */
    FFrameTime ConvertTo(FFrameRate DesiredRate) const
    {
        return  FFrameRate::TransformTime(Time, Rate, DesiredRate);
    }
 
    /**
     * Create an FTimecode from this qualified frame time.
     *
     * Any subframe value in the frame time will be ignored.
     * Whether or not the returned timecode is a drop-frame timecode will be determined by the qualified frame time's frame rate
     * and the CVar specifying whether to generate drop-frame timecodes by default for supported frame rates.
     */
    FTimecode ToTimecode() const
    {
        return FTimecode::FromFrameNumber(Time.FloorToFrame(), Rate);
    }
 
    /**
     * Create an FTimecode from this qualified frame time. Optionally supports creating a drop-frame timecode,
     * which drops certain timecode display numbers to help account for NTSC frame rates which are fractional.
     *
     * @param bDropFrame    If true, the returned timecode will drop the first two frames on every minute (except when Minute % 10 == 0).
     *     This is only valid for NTSC framerates (29.97, 59.94) and will assert if you try to create a drop-frame timecode
     *     from a non-valid framerate. All framerates can be represented by non-drop timecode.
     */
    FTimecode ToTimecode(bool bDropFrame) const
    {
        return FTimecode::FromFrameNumber(Time.FloorToFrame(), Rate, bDropFrame);
    }
 
public:
 
    /** The frame time */
    FFrameTime Time;
 
    /** The rate that this frame time is in */
    FFrameRate Rate;
};