UserWidgetPool.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "UserWidget.h"
#include "WidgetTree.h"
#include "Slate/SObjectWidget.h"
 
#include "UserWidgetPool.generated.h"
 
class APlayerController;
 
USTRUCT()
struct FUserWidgetPool
{
    GENERATED_BODY();
 
public:
    FUserWidgetPool() = default;
    UMG_API FUserWidgetPool(UWidget& InOwningWidget);
    UMG_API ~FUserWidgetPool();
 
    UMG_API void SetWorld(UWorld* OwningWorld);
 
    UMG_API void SetDefaultPlayerController(APlayerController* InDefaultPlayerController);
 
    UMG_API void RebuildWidgets();
 
    UMG_API void AddReferencedObjects(FReferenceCollector& Collector);
 
    bool IsInitialized() const { return OwningWidget.IsValid() || OwningWorld.IsValid(); }
    const TArray<UUserWidget*>& GetActiveWidgets() const { return ActiveWidgets; }
 
    template <typename UserWidgetT = UUserWidget>
    UserWidgetT* GetOrCreateInstance(TSubclassOf<UserWidgetT> WidgetClass)
    {
        // Just make a normal SObjectWidget, same as would happen in TakeWidget
        return AddActiveWidgetInternal(WidgetClass,
            [] (UUserWidget* Widget, TSharedRef<SWidget> Content)
            {
                return SNew(SObjectWidget, Widget)[Content];
            });
    }
 
    using WidgetConstructFunc = TFunctionRef<TSharedPtr<SObjectWidget>(UUserWidget*, TSharedRef<SWidget>)>;
 
    template <typename UserWidgetT = UUserWidget>
    UserWidgetT* GetOrCreateInstance(TSubclassOf<UserWidgetT> WidgetClass, WidgetConstructFunc ConstructWidgetFunc)
    {
        return AddActiveWidgetInternal(WidgetClass, ConstructWidgetFunc);
    }
 
    UMG_API void Release(UUserWidget* Widget, bool bReleaseSlate = false);
 
    UMG_API void Release(TArray<UUserWidget*> Widgets, bool bReleaseSlate = false);
 
    UMG_API void ReleaseAll(bool bReleaseSlate = false);
 
    UMG_API void ResetPool();
 
    UMG_API void ReleaseInactiveSlateResources();
 
    UE_DEPRECATED(4.24, "Use ReleaseAllSlateResources instead.")
    void ReleaseSlateResources() { ReleaseAllSlateResources(); }
 
    UMG_API void ReleaseAllSlateResources();
 
private:
    template <typename UserWidgetT = UUserWidget>
    UserWidgetT* AddActiveWidgetInternal(TSubclassOf<UserWidgetT> WidgetClass, WidgetConstructFunc ConstructWidgetFunc)
    {
        if (!ensure(IsInitialized()) || !WidgetClass)
        {
            return nullptr;
        }
 
        UUserWidget* WidgetInstance = nullptr;
        for (UUserWidget* InactiveWidget : InactiveWidgets)
        {
            if (InactiveWidget->GetClass() == WidgetClass)
            {
                WidgetInstance = InactiveWidget;
                InactiveWidgets.RemoveSingleSwap(InactiveWidget);
                break;
            }
        }
 
        UWidget* OwningWidgetPtr = OwningWidget.Get();
        if (!WidgetInstance)
        {
            if (OwningWidgetPtr)
            {
                WidgetInstance = CreateWidget(OwningWidgetPtr, WidgetClass);
            }
            else if (APlayerController* PlayerControllerPtr = DefaultPlayerController.Get())
            {
                WidgetInstance = CreateWidget(PlayerControllerPtr, WidgetClass);
            }
            else
            {
                WidgetInstance = CreateWidget(OwningWorld.Get(), WidgetClass);
            }
        }
 
        if (WidgetInstance)
        {
            ActiveWidgets.Add(WidgetInstance);
            
            // For pools owned by a widget, we never want to construct Slate widgets before the owning widget itself has built any Slate
            if (!OwningWidgetPtr || OwningWidgetPtr->GetCachedWidget().IsValid())
            {
                TSharedPtr<SWidget>& CachedSlateWidget = CachedSlateByWidgetObject.FindOrAdd(WidgetInstance);
                if (!CachedSlateWidget.IsValid())
                {
                    CachedSlateWidget = WidgetInstance->TakeDerivedWidget(ConstructWidgetFunc);
                }
            }
        }
 
        return Cast<UserWidgetT>(WidgetInstance);
    }
 
    UPROPERTY(Transient)
    TArray<TObjectPtr<UUserWidget>> ActiveWidgets;
    
    UPROPERTY(Transient)
    TArray<TObjectPtr<UUserWidget>> InactiveWidgets;
 
    TWeakObjectPtr<UWidget> OwningWidget;
    TWeakObjectPtr<UWorld> OwningWorld;
    TWeakObjectPtr<APlayerController> DefaultPlayerController;
    TMap<UUserWidget*, TSharedPtr<SWidget>> CachedSlateByWidgetObject;
};