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03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/Enum/EnumDisplayNameFn/EnumDisplayNameFn.md

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+# EnumDisplayNameFn
+
+- **功能描述：** 在Runtime下为枚举字段提供自定义名称的函数回调
+- **使用位置：** UENUM
+- **引擎模块：** Enum Property
+- **元数据类型：** string="abc"
+- **常用程度：** ★★
+
+只在Runtime下生效，在Editor下依然不起作用。
+
+## 测试代码：
+
+```cpp
+//[EMyEnum_CustomDisplay	Enum->Field->Object	/Script/Insider.EMyEnum_CustomDisplay]
+//(BlueprintType = true, EnumDisplayNameFn = GetMyEnumCustomDisplayName, First.Name = EMyEnum_CustomDisplay::First, IsBlueprintBase = true, ModuleRelativePath = Enum/MyEnum_Test.h, Second.Name = EMyEnum_CustomDisplay::Second, Third.Name = EMyEnum_CustomDisplay::Third)
+//	ObjectFlags:	RF_Public | RF_Transient 
+//	Outer:	Package /Script/Insider
+//	EnumFlags:	EEnumFlags::None
+//	EnumDisplayNameFn:	6adb4804
+//	CppType:	EMyEnum_CustomDisplay
+//	CppForm:	EnumClass
+//{
+//	First = 0,
+//	Second = 1,
+//	Third = 2,
+//	EMyEnum_MAX = 3
+//};
+
+UENUM(Blueprintable, meta = (EnumDisplayNameFn = "GetMyEnumCustomDisplayName"))
+enum class EMyEnum_CustomDisplay :uint8
+{
+	First,
+	Second,
+	Third,
+};
+
+extern FText GetMyEnumCustomDisplayName(int32 val);
+
+FText GetMyEnumCustomDisplayName(int32 val)
+{
+	EMyEnum_CustomDisplay enumValue = (EMyEnum_CustomDisplay)val;
+	switch (enumValue)
+	{
+	case EMyEnum_CustomDisplay::First:
+		return FText::FromString(TEXT("My_First"));
+	case EMyEnum_CustomDisplay::Second:
+		return FText::FromString(TEXT("My_Second"));
+	case EMyEnum_CustomDisplay::Third:
+		return FText::FromString(TEXT("My_Third"));
+	default:
+		return FText::FromString(TEXT("Invalid MyEnum"));
+	}
+}
+```
+
+## 测试蓝图：
+
+![Untitled](Untitled.png)
+
+EnumDisplayNameFn 的函数设置是在gen.cpp中完成的，因此并不需要成为UFUNCTION。
+
+```cpp
+const UECodeGen_Private::FEnumParams Z_Construct_UEnum_Insider_EMyEnum_CustomDisplay_Statics::EnumParams = {
+	(UObject*(*)())Z_Construct_UPackage__Script_Insider,
+	GetMyEnumCustomDisplayName,             //这里！！！
+	"EMyEnum_CustomDisplay",
+	"EMyEnum_CustomDisplay",
+	Z_Construct_UEnum_Insider_EMyEnum_CustomDisplay_Statics::Enumerators,
+	RF_Public|RF_Transient|RF_MarkAsNative,
+	UE_ARRAY_COUNT(Z_Construct_UEnum_Insider_EMyEnum_CustomDisplay_Statics::Enumerators),
+	EEnumFlags::None,
+	(uint8)UEnum::ECppForm::EnumClass,
+	METADATA_PARAMS(UE_ARRAY_COUNT(Z_Construct_UEnum_Insider_EMyEnum_CustomDisplay_Statics::Enum_MetaDataParams), Z_Construct_UEnum_Insider_EMyEnum_CustomDisplay_Statics::Enum_MetaDataParams)
+};
+```
+
+## 原理代码：
+
+```cpp
+
+/FText UEnum::GetDisplayNameTextByIndex(int32 NameIndex) const
+{
+	FString RawName = GetNameStringByIndex(NameIndex);
+
+	if (RawName.IsEmpty())
+	{
+		return FText::GetEmpty();
+	}
+
+#if WITH_EDITOR
+	FText LocalizedDisplayName;
+	// In the editor, use metadata and localization to look up names
+	static const FString Namespace = TEXT("UObjectDisplayNames");
+	const FString Key = GetFullGroupName(false) + TEXT(".") + RawName;
+
+	FString NativeDisplayName;
+	if (HasMetaData(TEXT("DisplayName"), NameIndex))
+	{
+		NativeDisplayName = GetMetaData(TEXT("DisplayName"), NameIndex);
+	}
+	else
+	{
+		NativeDisplayName = FName::NameToDisplayString(RawName, false);
+	}
+
+	if (!(FText::FindText(Namespace, Key, /*OUT*/LocalizedDisplayName, &NativeDisplayName)))
+	{
+		LocalizedDisplayName = FText::FromString(NativeDisplayName);
+	}
+
+	if (!LocalizedDisplayName.IsEmpty())
+	{
+		return LocalizedDisplayName;
+	}
+#endif
+	//Runtime下到这里
+	if (EnumDisplayNameFn)
+	{
+		return (*EnumDisplayNameFn)(NameIndex);
+	}
+
+	return FText::FromString(GetNameStringByIndex(NameIndex));
+}
+```