ComponentReregisterContext.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Containers/IndirectArray.h"
#include "RenderingThread.h"
#include "UObject/UObjectIterator.h"
#include "Engine/World.h"
 
ENGINE_API DECLARE_LOG_CATEGORY_EXTERN(LogActorComponent, Log, All);
 
class FComponentReregisterContextBase
{
protected:
    TSet<FSceneInterface*>* ScenesToUpdateAllPrimitiveSceneInfos = nullptr;
 
    //Unregisters the Component and returns the world it was registered to.
    ENGINE_API UWorld* UnRegister(UActorComponent* InComponent);
 
    //Reregisters the given component on the given scene
    ENGINE_API void ReRegister(UActorComponent* InComponent, UWorld* InWorld);
};
 
class FComponentReregisterContext : public FComponentReregisterContextBase
{
private:
    TWeakObjectPtr<UActorComponent> Component;
    TWeakObjectPtr<UWorld> World;
public:
    FComponentReregisterContext(UActorComponent* InComponent, TSet<FSceneInterface*>* InScenesToUpdateAllPrimitiveSceneInfos = nullptr)
        : World(nullptr)
    {
        ScenesToUpdateAllPrimitiveSceneInfos = InScenesToUpdateAllPrimitiveSceneInfos;
 
        World = UnRegister(InComponent);
        // If we didn't get a scene back NULL the component so we dont try to
        // process it on destruction
        Component = World.IsValid() ? InComponent : nullptr;
    }
 
    ~FComponentReregisterContext()
    {
        if( Component.IsValid() && World.IsValid() )
        {
            ReRegister(Component.Get(), World.Get());
        }
    }
};
 
 
/* Pairing of UActorComponent and its UWorld. Used only by FMultiComponentReregisterContext
 * for tracking purposes 
 */
struct FMultiComponentReregisterPair
{
    UActorComponent* Component;
    UWorld* World;
 
    FMultiComponentReregisterPair(UActorComponent* _Component, UWorld* _World) : Component(_Component), World(_World) {}
};
 
 
class FMultiComponentReregisterContext : public FComponentReregisterContextBase
{
private:
    TArray<FMultiComponentReregisterPair> ComponentsPair;
    
public:
    FMultiComponentReregisterContext(const TArray<UActorComponent*>& InComponents)
    {
        // Unregister each component and cache resulting scene
        for (UActorComponent* Component : InComponents)
        {
            UWorld* World = UnRegister(Component);
            if(World)
            {
                ComponentsPair.Push( FMultiComponentReregisterPair(Component, World) );
            }
        }
    }
 
    ~FMultiComponentReregisterContext()
    {
        //Re-register each valid component pair that we unregistered in our constructor
        for(auto Iter = ComponentsPair.CreateIterator(); Iter; ++Iter)
        {
            FMultiComponentReregisterPair& pair = (*Iter);
            if(pair.Component)
            {
                ReRegister(pair.Component, pair.World);
            }
        }
    }
};
 
class FGlobalComponentReregisterContext
{
public:
    ENGINE_API FGlobalComponentReregisterContext();
    
    FGlobalComponentReregisterContext(const TArray<UClass*>& ExcludeComponents);
 
    ENGINE_API ~FGlobalComponentReregisterContext();
 
    static int32 ActiveGlobalReregisterContextCount;
 
private:
    TIndirectArray<FComponentReregisterContext> ComponentContexts;
 
    TSet<FSceneInterface*> ScenesToUpdateAllPrimitiveSceneInfos;
 
    void UpdateAllPrimitiveSceneInfos();
};
 
template<class ComponentType>
class TComponentReregisterContext
{
public:
    TComponentReregisterContext()
    {
        // wait until resources are released
        FlushRenderingCommands();
 
        // Reregister all components of the templated type.
        for(TObjectIterator<ComponentType> ComponentIt;ComponentIt;++ComponentIt)
        {
            ComponentContexts.Add(new FComponentReregisterContext(*ComponentIt, &ScenesToUpdateAllPrimitiveSceneInfos));
        }
 
        UpdateAllPrimitiveSceneInfos();
    }
 
    ~TComponentReregisterContext()
    {
        UpdateAllPrimitiveSceneInfos();
    }
 
private:
    TIndirectArray<FComponentReregisterContext> ComponentContexts;
 
    TSet<FSceneInterface*> ScenesToUpdateAllPrimitiveSceneInfos;
 
    void UpdateAllPrimitiveSceneInfos()
    {
        UpdateAllPrimitiveSceneInfosForScenes(MoveTemp(ScenesToUpdateAllPrimitiveSceneInfos));
 
        check(ScenesToUpdateAllPrimitiveSceneInfos.Num() == 0);
    }
};