vault backup: 2024-10-12 17:19:45

03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/DetailsPanel/ForceInlineRow/ForceInlineRow.md

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+# ForceInlineRow
+
+- **功能描述：** 强制TMap属性里的结构key和其他Value合并到同一行来显示
+- **使用位置：** UPROPERTY
+- **元数据类型：** bool
+- **关联项：** [EditInline](../EditInline/EditInline.md)
+- **常用程度：** ★
+
+强制TMap属性里的结构key和其他Value合并到同一行来显示。这里要注意的点是：
+
+- 本属性是TMap属性，这样才有Key。TArray或TSet是没有用的。
+- FStruct作为Key，这样源码里的机制才能生效，因为判断的就是Key Property
+- 该FStruct有注册相关的IPropertyTypeCustomization，这样才能自定义该结构的显示UI
+- 该IPropertyTypeCustomization的ShouldInlineKey返回false（默认就是），否则true的话则不管有没有标ForceInlineRow，都会合并成一行
+
+## 测试代码：
+
+```cpp
+public:
+	UPROPERTY(EditAnywhere, BlueprintReadWrite)
+	TMap<FMyCommonStruct, int32> MyStructMap;
+
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (ForceInlineRow))
+	TMap<FMyCommonStruct, int32> MyStructMap_ForceInlineRow;
+
+	UPROPERTY(EditAnywhere, BlueprintReadWrite)
+	TMap<int32, FMyCommonStruct> MyStructMap2;
+
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (ForceInlineRow))
+	TMap<int32, FMyCommonStruct> MyStructMap_ForceInlineRow2;
+	
+	
+
+void FMyCommonStructCustomization::CustomizeHeader(TSharedRef<IPropertyHandle> PropertyHandle, FDetailWidgetRow& HeaderRow, IPropertyTypeCustomizationUtils& CustomizationUtils)
+{
+	HeaderRow.NameContent()[SNew(STextBlock).Text(INVTEXT("This is MyCommonStruct"))];
+
+	TSharedPtr<IPropertyHandle> IntPropertyHandle = PropertyHandle->GetChildHandle(GET_MEMBER_NAME_CHECKED(FMyCommonStruct, MyInt));
+	TSharedPtr<IPropertyHandle> StringPropertyHandle = PropertyHandle->GetChildHandle(GET_MEMBER_NAME_CHECKED(FMyCommonStruct, MyString));
+
+	HeaderRow.ValueContent()
+		[
+			SNew(SHorizontalBox)
+				+ SHorizontalBox::Slot()
+				.Padding(5.0f, 0.0f).AutoWidth()
+				[
+					IntPropertyHandle->CreatePropertyNameWidget()
+				]
+				+ SHorizontalBox::Slot()
+				.Padding(5.0f, 0.0f).AutoWidth()
+				[
+					IntPropertyHandle->CreatePropertyValueWidget()
+				]
+				+ SHorizontalBox::Slot()
+				.Padding(5.0f, 0.0f).AutoWidth()
+				[
+					StringPropertyHandle->CreatePropertyNameWidget()
+				]
+				+ SHorizontalBox::Slot()
+				.Padding(5.0f, 0.0f).AutoWidth()
+				[
+					StringPropertyHandle->CreatePropertyValueWidget()
+				]
+		];
+
+}
+```
+
+## 测试效果：
+
+可以见到MyStructMap的数据项展示就分为了两行。而带有ForceInlineRow之后，数据项UI就合并为一行，显得更加的简洁。
+
+在下面也特别观察到如果把FStruct作为Value，则是没有这个区别的。
+
+![Untitled](Untitled.png)
+
+假如不注册FMyCommonStruct相应的IPropertyTypeCustomization的话，则结构的属性UI采用默认方式显示，则都是分为两行。
+
+![Untitled](Untitled%201.png)
+
+而假如FMyCommonStruct的IPropertyTypeCustomization的ShouldInlineKey返回true，则会导致即使没有ForceInlineRow也会把该拥有该结构作为Key的属性给都合并为一行显示，这个时候就失去ForceInlineRow的作用和区别了。
+
+![Untitled](Untitled%202.png)
+
+## 原理：
+
+该部分逻辑也同样处于在FDetailPropertyRow的构造函数创建过程中，判断是否有GetPropertyKeyNode，则其实是在要求TMap属性。
+
+接着作为Key的类型，如果是UObject*，则因为NeedsKeyNode一直返回false，则无论如何都会进入MakePropertyEditor的分支。
+
+因此此项测试的类型其实是Struct，这样就必须依赖bInlineRow 和FoundPropertyCustomisation 的配合。这个时候就必须有IPropertyTypeCustomization才会进入分支，而且如果IPropertyTypeCustomization::ShouldInlineKey()返回true，则就不管属性上的ForceInlineRow如何，都会进入分支。否则就靠属性上的ForceInlineRow，这个时候才是这个Meta发挥作用的时候。
+
+```cpp
+FDetailPropertyRow::FDetailPropertyRow(TSharedPtr<FPropertyNode> InPropertyNode, TSharedRef<FDetailCategoryImpl> InParentCategory, TSharedPtr<FComplexPropertyNode> InExternalRootNode)
+{
+	if (PropertyNode->GetPropertyKeyNode().IsValid())
+	{							
+		TSharedPtr<IPropertyTypeCustomization> FoundPropertyCustomisation = GetPropertyCustomization(PropertyNode->GetPropertyKeyNode().ToSharedRef(), ParentCategory.Pin().ToSharedRef());
+	
+		bool bInlineRow = FoundPropertyCustomisation != nullptr ? FoundPropertyCustomisation->ShouldInlineKey() : false;
+	
+		static FName InlineKeyMeta("ForceInlineRow");
+		bInlineRow |= InPropertyNode->GetParentNode()->GetProperty()->HasMetaData(InlineKeyMeta);
+	
+		// Only create the property editor if it's not a struct or if it requires to be inlined (and has customization)
+		if (!NeedsKeyNode(PropertyNodeRef, InParentCategory) || (bInlineRow && FoundPropertyCustomisation != nullptr))
+		{
+			CachedKeyCustomTypeInterface = FoundPropertyCustomisation;
+			
+			MakePropertyEditor(PropertyNode->GetPropertyKeyNode().ToSharedRef(), Utilities, PropertyKeyEditor);
+		}
+	}
+}
+
+bool FDetailPropertyRow::NeedsKeyNode(TSharedRef<FPropertyNode> InPropertyNode, TSharedRef<FDetailCategoryImpl> InParentCategory)
+{
+	FStructProperty* KeyStructProp = CastField<FStructProperty>(InPropertyNode->GetPropertyKeyNode()->GetProperty());
+	return KeyStructProp != nullptr;
+}
+```
+
+源码里使用的例子：
+
+在源码里搜索发现到该例子，但实际上其实这里HLODSetups上的ForceInlineRow并不能起作用。
+
+```cpp
+USTRUCT()
+struct FRuntimePartitionDesc
+{
+	GENERATED_USTRUCT_BODY()
+
+#if WITH_EDITORONLY_DATA
+	/** Partition class */
+	UPROPERTY(EditAnywhere, Category = RuntimeSettings)
+	TSubclassOf<URuntimePartition> Class;
+
+	/** Name for this partition, used to map actors to it through the Actor.RuntimeGrid property  */
+	UPROPERTY(EditAnywhere, Category = RuntimeSettings, Meta = (EditCondition = "Class != nullptr", HideEditConditionToggle))
+	FName Name;
+
+	/** Main partition object */
+	UPROPERTY(VisibleAnywhere, Category = RuntimeSettings, Instanced, Meta = (EditCondition = "Class != nullptr", HideEditConditionToggle, NoResetToDefault, TitleProperty = "Name"))
+	TObjectPtr<URuntimePartition> MainLayer;
+
+	/** HLOD setups used by this partition, one for each layers in the hierarchy */
+	UPROPERTY(EditAnywhere, Category = RuntimeSettings, Meta = (EditCondition = "Class != nullptr", HideEditConditionToggle, ForceInlineRow))
+	TArray<FRuntimePartitionHLODSetup> HLODSetups;
+#endif
+
+#if WITH_EDITOR
+	void UpdateHLODPartitionLayers();
+#endif
+};
+```