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03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/Component/BlueprintSpawnableComponent/BlueprintSpawnableComponent.md

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+# BlueprintSpawnableComponent
+
+- **功能描述：** 允许该组件出现在Actor蓝图里Add组件的面板里。
+- **使用位置：** UCLASS
+- **引擎模块：** Component Property
+- **元数据类型：** bool
+- **限制类型：** Component类
+- **常用程度：** ★★★★
+
+允许该组件出现在Actor蓝图里Add组件的面板里。
+
+在蓝图节点上，不管有没有BlueprintSpawnableComponent则都是可以添加该组件的。
+
+## 测试代码：
+
+```cpp
+UCLASS(Blueprintable, meta = (BlueprintSpawnableComponent))
+class INSIDER_API UMyActorComponent_Spawnable : public UActorComponent
+{
+	GENERATED_BODY()
+public:
+	UPROPERTY(BlueprintReadWrite, EditAnywhere)
+	float MyFloat;
+};
+
+UCLASS(Blueprintable)
+class INSIDER_API UMyActorComponent_NotSpawnable : public UActorComponent
+{
+	GENERATED_BODY()
+public:
+	UPROPERTY(BlueprintReadWrite, EditAnywhere)
+	float MyFloat;
+};
+```
+
+## 蓝图中效果：
+
+可以看到，在Actor的左边Add的按钮下，UMyActorComponent_Spawnable 可以被添加进去，但是UMyActorComponent_NotSpawnable 被阻止了。但同时也要注意到如果在蓝图中AddComponent节点则是都可以的。
+
+![Untitled](Untitled.png)
+
+![Untitled](Untitled%201.png)
+
+## 原理：
+
+```cpp
+bool FKismetEditorUtilities::IsClassABlueprintSpawnableComponent(const UClass* Class)
+{
+	// @fixme: Cooked packages don't have any metadata (yet; they might become available via the sidecar editor data)
+	// However, all uncooked BPs that derive from ActorComponent have the BlueprintSpawnableComponent metadata set on them
+	// (see FBlueprintEditorUtils::RecreateClassMetaData), so include any ActorComponent BP that comes from a cooked package
+	return (!Class->HasAnyClassFlags(CLASS_Abstract) &&
+			Class->IsChildOf<UActorComponent>() &&
+			(Class->HasMetaData(FBlueprintMetadata::MD_BlueprintSpawnableComponent) || Class->GetPackage()->bIsCookedForEditor));
+}
+```