SlateAttribute.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Misc/Attribute.h"
#include "Misc/EnumClassFlags.h"
#include "Templates/EqualTo.h"
#include "Widgets/InvalidateWidgetReason.h"
 
#include <type_traits>
 
#ifndef UE_SLATE_WITH_MEMBER_ATTRIBUTE_DEBUGGING
    #define UE_SLATE_WITH_MEMBER_ATTRIBUTE_DEBUGGING 0
#endif
#ifndef UE_SLATE_WITH_ATTRIBUTE_INITIALIZATION_ON_BIND
    #define UE_SLATE_WITH_ATTRIBUTE_INITIALIZATION_ON_BIND 0
#endif
#ifndef UE_SLATE_WITH_ATTRIBUTE_NAN_DIAGNOSTIC
    #define UE_SLATE_WITH_ATTRIBUTE_NAN_DIAGNOSTIC DO_ENSURE
#endif
 
class SWidget;
 
enum class ESlateAttributeBindAction
{
    None = 0, // Do nothing when an attribute is bound.
    Initialize = 1, // Initialize the attribute value from the binding.
};
ENUM_CLASS_FLAGS(ESlateAttributeBindAction)
#if UE_SLATE_WITH_ATTRIBUTE_INITIALIZATION_ON_BIND
#   define UE_SLATE_WITH_ATTRIBUTE_DEFAULT_INITIALIZATION_ACTION ESlateAttributeBindAction::Initialize
#else
#   define UE_SLATE_WITH_ATTRIBUTE_DEFAULT_INITIALIZATION_ACTION ESlateAttributeBindAction::None
#endif
 
struct FSlateAttributeBase
{
    template<typename T>
    constexpr static bool IsInvalidateWidgetReasonSupported(T Reason)
    {
        return false;
    }
    constexpr static bool IsInvalidateWidgetReasonSupported(EInvalidateWidgetReason Reason)
    {
        return (Reason & (EInvalidateWidgetReason::ChildOrder | EInvalidateWidgetReason::AttributeRegistration)) == EInvalidateWidgetReason::None;
    }
};
 
 
template<typename ComparePredicate = TEqualTo<>>
struct TSlateAttributeComparePredicate
{
    template<typename ObjectType>
    static bool IdenticalTo(const SWidget&, ObjectType&& Lhs, ObjectType&& Rhs)
    {
        // If you have an error here, do you have a operator== const?
        return ComparePredicate{}(Forward<ObjectType>(Lhs), Forward<ObjectType>(Rhs));
    }
};
 
 
struct TSlateAttributeFTextComparePredicate
{
    static bool IdenticalTo(const SWidget&, const FText& Lhs, const FText& Rhs)
    {
        return Lhs.IdenticalTo(Rhs, ETextIdenticalModeFlags::DeepCompare | ETextIdenticalModeFlags::LexicalCompareInvariants);
    }
};
 
 
template<EInvalidateWidgetReason InvalidationReason>
struct TSlateAttributeInvalidationReason
{
    static_assert(FSlateAttributeBase::IsInvalidateWidgetReasonSupported(InvalidationReason), "The invalidation is not supported by the SlateAttribute.");
    static constexpr EInvalidateWidgetReason GetInvalidationReason(const SWidget&) { return InvalidationReason; }
};
 
 
template<typename ObjectType>
struct TSlateDeprecatedTAttribute
{
    TSlateDeprecatedTAttribute() = default;
 
    using FGetter = typename TAttribute<ObjectType>::FGetter;
 
    template<typename OtherType>
    TSlateDeprecatedTAttribute(const OtherType& InInitialValue) { }
 
    TSlateDeprecatedTAttribute(ObjectType&& InInitialValue) { }
 
    template<class SourceType>
    TSlateDeprecatedTAttribute(TSharedRef<SourceType> InUserObject, typename FGetter::template TConstMethodPtr< SourceType > InMethodPtr) {}
 
    template< class SourceType >
    TSlateDeprecatedTAttribute(SourceType* InUserObject, typename FGetter::template TConstMethodPtr< SourceType > InMethodPtr) { }
 
    bool IsSet() const { return false; }
 
    template<typename OtherType>
    void Set(const OtherType& InNewValue) {}
 
    const ObjectType& Get(const ObjectType& DefaultValue) const { return DefaultValue; }
    const ObjectType& Get() const { static ObjectType Temp; return Temp; }
    FGetter GetBinding() const { return false; }
 
    void Bind(const FGetter& InGetter) {}
    template<class SourceType>
    void Bind(SourceType* InUserObject, typename FGetter::template TConstMethodPtr< SourceType > InMethodPtr) {}
    bool IsBound() const { return false; }
 
    bool IdenticalTo(const TAttribute<ObjectType>& InOther) const { return false; }
};
 
// IWYU pragma: begin_exports
#include "Types/Attributes/SlateAttributeDefinition.inl"
#include "Types/Attributes/SlateAttributeBase.inl"
 
#include "Types/Attributes/SlateAttributeContained.inl"
#include "Types/Attributes/SlateAttributeManaged.inl"
#include "Types/Attributes/SlateAttributeMember.inl"
// IWYU pragma: end_exports