FrameNumber.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Math/NumericLimits.h"
#include "Math/UnrealMathUtility.h"
#include "Templates/EnableIf.h"
#include "Templates/UnrealTypeTraits.h"
 
class FArchive;
template <typename NumericType> struct TNumericLimits;
 
/**
 * Typesafe 32-bit signed frame number. Defined in this way to prevent erroneous float->int conversions and afford type-safe operator overloading.
 */
struct FFrameNumber
{
    constexpr FFrameNumber()
        : Value(0)
    {}
 
    /**
     * Implicit construction from a signed integer frame number, whilst disallowing any construction from other types.
     */
    template<typename T, typename U = typename TEnableIf<std::is_same_v<T, int32>>::Type>
    constexpr FFrameNumber(T /*int32*/ InValue)
        : Value(InValue)
    {}
 
    /**
     * Serializes the given FrameNumber from or into the specified archive.
     *
     * @param Ar            The archive to serialize from or into.
     * @param FrameNumber   The bound to serialize.
     * @return The archive used for serialization.
     */
    friend FArchive& operator<<(FArchive& Ar, FFrameNumber& FrameNumber);
 
    bool Serialize(FArchive& Ar);
 
    FFrameNumber& operator+=(FFrameNumber RHS)                    { Value += RHS.Value; return *this; }
    FFrameNumber& operator-=(FFrameNumber RHS)                    { Value -= RHS.Value; return *this; }
    FFrameNumber& operator%=(FFrameNumber RHS)                    { Value %= RHS.Value; return *this; }
 
    FFrameNumber& operator++()                                    { ++Value; return *this; }
    FFrameNumber& operator--()                                    { --Value; return *this; }
 
    FFrameNumber operator++(int32)                                { FFrameNumber Ret = *this; ++Value; return Ret; }
    FFrameNumber operator--(int32)                                { FFrameNumber Ret = *this; --Value; return Ret; }
 
    friend bool operator==(FFrameNumber A, FFrameNumber B)        { return A.Value == B.Value; }
    friend bool operator!=(FFrameNumber A, FFrameNumber B)        { return A.Value != B.Value; }
 
    friend bool operator< (FFrameNumber A, FFrameNumber B)        { return A.Value < B.Value; }
    friend bool operator> (FFrameNumber A, FFrameNumber B)        { return A.Value > B.Value; }
    friend bool operator<=(FFrameNumber A, FFrameNumber B)        { return A.Value <= B.Value; }
    friend bool operator>=(FFrameNumber A, FFrameNumber B)        { return A.Value >= B.Value; }
 
    friend FFrameNumber operator+(FFrameNumber A, FFrameNumber B) { return FFrameNumber(A.Value + B.Value); }
    friend FFrameNumber operator-(FFrameNumber A, FFrameNumber B) { return FFrameNumber(A.Value - B.Value); }
    friend FFrameNumber operator%(FFrameNumber A, FFrameNumber B) { return FFrameNumber(A.Value % B.Value); }
 
    friend FFrameNumber operator-(FFrameNumber A)                 { return FFrameNumber(-A.Value); }
 
    friend FFrameNumber operator*(FFrameNumber A, float Scalar)   { return FFrameNumber(static_cast<int32>(FMath::Clamp(FMath::FloorToDouble(double(A.Value) * Scalar), (double)TNumericLimits<int32>::Min(), (double)TNumericLimits<int32>::Max()))); }
    friend FFrameNumber operator/(FFrameNumber A, float Scalar)   { return FFrameNumber(static_cast<int32>(FMath::Clamp(FMath::FloorToDouble(double(A.Value) / Scalar), (double)TNumericLimits<int32>::Min(), (double)TNumericLimits<int32>::Max()))); }
 
    friend inline uint32 GetTypeHash(FFrameNumber A)
    {
        return A.Value;
    }
 
    /**
     * The value of the frame number
     */
    int32 Value;
};
 
template<>
struct TNumericLimits<FFrameNumber>
{
    typedef FFrameNumber NumericType;
 
    static constexpr NumericType Min()
    {
        return MIN_int32;
    }
 
    static constexpr NumericType Max()
    {
        return MAX_int32;
    }
 
    static constexpr NumericType Lowest()
    {
        return Min();
    }
};