WidgetSlotWithAttributeSupport.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "SlotBase.h"
#include "Layout/ChildrenBase.h"
#include "Types/SlateAttribute.h"
#include "Types/SlateAttributeDescriptor.h"
 
#include <limits>
 
 
template <typename SlotType>
class TWidgetSlotWithAttributeSupport : public TSlotBase<SlotType>, public SlateAttributePrivate::ISlateAttributeContainer
{
private:
    using Super = TSlotBase<SlotType>;
protected:
    using TSlotBase<SlotType>::TSlotBase;
 
    template<typename InObjectType, typename InComparePredicate = TSlateAttributeComparePredicate<>>
    struct TSlateSlotAttribute : public ::SlateAttributePrivate::TSlateContainedAttribute<InObjectType, ::SlateAttributePrivate::FSlateAttributeNoInvalidationReason, InComparePredicate>
    {
        using ::SlateAttributePrivate::TSlateContainedAttribute<InObjectType, ::SlateAttributePrivate::FSlateAttributeNoInvalidationReason, InComparePredicate>::TSlateContainedAttribute;
    };
 
public:
    virtual ~TWidgetSlotWithAttributeSupport()
    {
        if (SWidget* WidgetPtr = Super::GetOwnerWidget())
        {
            RemoveContainerWidget(*WidgetPtr);
        }
    }
 
    void Construct(const FChildren& SlotOwner, typename Super::FSlotArguments&& InArgs)
    {
        checkf(SlotOwner.SupportSlotWithSlateAttribute(), TEXT("The FChildren '%s' does not support SlateSlotAttribute but use a Slot type that does."), *SlotOwner.GetName().ToString());
        checkf(SlotOwner.GetName().IsValid(), TEXT("The FChildren '%s' does not have a valid name."), *SlotOwner.GetName().ToString());
        Super::Construct(SlotOwner, MoveTemp(InArgs));
    }
 
    static void RegisterAttributes(FSlateWidgetSlotAttributeInitializer& AttributeInitializer)
    {
    }
 
    void RequestSortAttribute()
    {
        SWidget* WidgetPtr = Super::GetOwnerWidget();
        ensureAlwaysMsgf(WidgetPtr, TEXT("FSlot needs to be constructed before we modify the FChildren."));
        if (WidgetPtr)
        {
            UpdateContainerSortOrder(*WidgetPtr);
        }
    }
 
 
    //~ Begin ISlateAttributeContainer interface
    virtual SWidget& GetContainerWidget() const override
    {
        SWidget* WidgetPtr = TSlotBase<SlotType>::GetOwnerWidget();
        checkf(WidgetPtr, TEXT("Slot Attributes has to be registered after the FSlot is constructed."));
        return *WidgetPtr;
    }
 
    virtual FName GetContainerName() const override
    {
        return FSlotBase::GetOwner()->GetName();
    }
 
    virtual uint32 GetContainerSortOrder() const override
    {
        check(FSlotBase::GetOwner());
        const int32 NumSlot = FSlotBase::GetOwner()->NumSlot();
        for (int32 Index = 0; Index < NumSlot; ++Index)
        {
            if (&FSlotBase::GetOwner()->GetSlotAt(Index) == this)
            {
                return Index;
            }
        }
#pragma push_macro("UNDEF_MAX")
#undef max
        return std::numeric_limits<uint32>::max();
#pragma pop_macro("UNDEF_MAX")
    }
    //~ End ISlateAttributeContainer interface
};