WidgetTree.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "UObject/Object.h"
#include "Templates/SubclassOf.h"
#include "Widgets/SWidget.h"
#include "Components/Widget.h"
#include "Components/PanelWidget.h"
#include "Components/NamedSlotInterface.h"
#include "Blueprint/UserWidget.h"
 
#include "WidgetTree.generated.h"
 
UCLASS(MinimalAPI)
class UWidgetTree : public UObject, public INamedSlotInterface
{
    GENERATED_UCLASS_BODY()
 
public:
 
    // Begin UObject
    UMG_API virtual UWorld* GetWorld() const override;
    // End UObject
 
    UMG_API UWidget* FindWidget(const FName& Name) const;
 
    UMG_API UWidget* FindWidget(TSharedRef<SWidget> InWidget) const;
 
    template <typename WidgetT>
    inline WidgetT* FindWidget(const FName& Name) const
    {
        return Cast<WidgetT>(FindWidget(Name));
    }
 
    UMG_API bool RemoveWidget(UWidget* Widget);
 
    static UMG_API class UPanelWidget* FindWidgetParent(UWidget* Widget, int32& OutChildIndex);
 
    static UMG_API UWidget* FindWidgetChild(UPanelWidget* ParentWidget, FName ChildWidgetName, int32& OutChildIndex);
 
    static UMG_API int32 FindChildIndex(const UPanelWidget* ParentWidget, const UWidget* ChildWidget);
 
    UMG_API void GetAllWidgets(TArray<UWidget*>& Widgets) const;
 
    static UMG_API void GetChildWidgets(UWidget* Parent, TArray<UWidget*>& Widgets);
 
    static UMG_API bool TryMoveWidgetToNewTree(UWidget* Widget, UWidgetTree* DestinationTree);
 
    UMG_API void ForEachWidget(TFunctionRef<void(UWidget*)> Predicate) const;
 
    UMG_API void ForEachWidgetAndDescendants(TFunctionRef<void(UWidget*)> Predicate) const;
 
    static UMG_API void ForWidgetAndChildren(UWidget* Widget, TFunctionRef<void(UWidget*)> Predicate);
 
    void ForEachWidgetUntil(TFunctionRef<bool(UWidget*)> Predicate) const;
 
    static UMG_API bool ForEachWidgetAndChildrenUntil(UWidget* Widget, TFunctionRef<bool(UWidget*)> Predicate);
 
 
    template <typename WidgetT>
    [[nodiscard]] inline WidgetT* ConstructWidget(TSubclassOf<WidgetT> WidgetClass = WidgetT::StaticClass(), FName WidgetName = NAME_None)
    {
        if(WidgetClass != nullptr)
        {
            if constexpr(std::is_base_of_v<UUserWidget, WidgetT>)
            {
                return CreateWidget<WidgetT>(this, *WidgetClass, WidgetName);
            }
            else
            {
                static_assert(std::is_base_of_v<UWidget, WidgetT>, "WidgetTree::ConstructWidget can only create UWidget objects.");
                return NewObject<WidgetT>(this, WidgetClass, WidgetName, RF_Transactional);
            }
        }
 
        return nullptr;
    }
 
    // INamedSlotInterface
    //----------------------------------------------------------------------------------------
    
    UMG_API virtual void GetSlotNames(TArray<FName>& SlotNames) const override;
 
    UMG_API virtual UWidget* GetContentForSlot(FName SlotName) const override;
 
    UMG_API virtual void SetContentForSlot(FName SlotName, UWidget* Content) override;
 
    //----------------------------------------------------------------------------------------
 
    // UObject interface
    UMG_API virtual void PreSave(FObjectPreSaveContext ObjectSaveContext) override;
    UMG_API virtual void PostLoad() override;
    // End of UObject interface
 
public:
    UPROPERTY(Instanced)
    TObjectPtr<UWidget> RootWidget;
 
    UPROPERTY()
    TMap<FName, TObjectPtr<UWidget>> NamedSlotBindings;
 
protected:
 
#if WITH_EDITORONLY_DATA
    UPROPERTY(Instanced)
    TArray< TObjectPtr<UWidget> > AllWidgets;
#endif
};