DelayAction.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/WeakObjectPtr.h"
#include "Engine/LatentActionManager.h"
#include "LatentActions.h"
 
// FDelayAction
// A simple delay action; counts down and triggers it's output link when the time remaining falls to zero
class FDelayAction : public FPendingLatentAction
{
public:
    float TimeRemaining;
    FName ExecutionFunction;
    int32 OutputLink;
    FWeakObjectPtr CallbackTarget;
 
    FDelayAction(float Duration, const FLatentActionInfo& LatentInfo)
        : TimeRemaining(Duration)
        , ExecutionFunction(LatentInfo.ExecutionFunction)
        , OutputLink(LatentInfo.Linkage)
        , CallbackTarget(LatentInfo.CallbackTarget)
    {
    }
 
    virtual void UpdateOperation(FLatentResponse& Response) override
    {
        TimeRemaining -= Response.ElapsedTime();
        Response.FinishAndTriggerIf(TimeRemaining <= 0.0f, ExecutionFunction, OutputLink, CallbackTarget);
    }
 
#if WITH_EDITOR
    // Returns a human readable description of the latent operation's current state
    virtual FString GetDescription() const override
    {
        static const FNumberFormattingOptions DelayTimeFormatOptions = FNumberFormattingOptions()
            .SetMinimumFractionalDigits(3)
            .SetMaximumFractionalDigits(3);
        return FText::Format(NSLOCTEXT("DelayAction", "DelayActionTimeFmt", "Delay ({0} seconds left)"), FText::AsNumber(TimeRemaining, &DelayTimeFormatOptions)).ToString();
    }
#endif
};
 
 
class FDelayUntilNextTickAction : public FPendingLatentAction
{
public:
    uint8 InitialFrameParity; // engine frame parity when this action was created (0=even, 1=odd)
    FName ExecutionFunction;
    int32 OutputLink;
    FWeakObjectPtr CallbackTarget;
 
    FDelayUntilNextTickAction(const FLatentActionInfo& LatentInfo)
        : InitialFrameParity((uint8)GFrameCounter & 1)
        , ExecutionFunction(LatentInfo.ExecutionFunction)
        , OutputLink(LatentInfo.Linkage)
        , CallbackTarget(LatentInfo.CallbackTarget)
    {
    }
 
    virtual void UpdateOperation(FLatentResponse& Response) override
    {
        const bool bShouldFinish = !LatentActionCVars::GuaranteeEngineTickDelay || (((uint8)GFrameCounter & 1) != InitialFrameParity);
        Response.FinishAndTriggerIf(bShouldFinish, ExecutionFunction, OutputLink, CallbackTarget);
    }
 
#if WITH_EDITOR
    // Returns a human readable description of the latent operation's current state
    virtual FString GetDescription() const override
    {
        return NSLOCTEXT("DelayUntilNextTickAction", "DelayUntilNextTickActionFmt", "Delay for one tick").ToString();
    }
#endif
};
 
// A variant of the simple delay action that guarantees a delay until the next engine frame
class FDelayUntilNextFrameAction : public FDelayUntilNextTickAction
{
public:
    FDelayUntilNextFrameAction(const FLatentActionInfo& LatentInfo)
        : FDelayUntilNextTickAction(LatentInfo)
    {
    }
 
    virtual void UpdateOperation(FLatentResponse& Response) override
    {
        const bool bHasFrameAdvanced = ((uint8)GFrameCounter & 1) != InitialFrameParity;
        Response.FinishAndTriggerIf(bHasFrameAdvanced, ExecutionFunction, OutputLink, CallbackTarget);
    }
 
#if WITH_EDITOR
    // Returns a human readable description of the latent operation's current state
    virtual FString GetDescription() const override
    {
        return NSLOCTEXT("DelayUntilNextFrameAction", "DelayUntilNextFrameActionFmt", "Delay for one engine frame").ToString();
    }
#endif
};