69 lines
2.3 KiB
Markdown
69 lines
2.3 KiB
Markdown
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# BlueprintReadOnly
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- **功能描述：** 此属性可由蓝图读取，但不能被修改。
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- **元数据类型：** bool
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- **引擎模块：** Blueprint
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- **作用机制：** 在PropertyFlags中加入[CPF_BlueprintVisible](../../../../Flags/EPropertyFlags/CPF_BlueprintVisible.md), [CPF_BlueprintReadOnly](../../../../Flags/EPropertyFlags/CPF_BlueprintReadOnly.md)
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- **常用程度：** ★★★★★
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此属性可由蓝图读取，但不能被修改。此说明符与 BlueprintReadWrite 说明符不兼容。
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## 示例代码：
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```cpp
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public:
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//PropertyFlags: CPF_BlueprintVisible | CPF_ZeroConstructor | CPF_IsPlainOldData | CPF_NoDestructor | CPF_HasGetValueTypeHash | CPF_NativeAccessSpecifierPublic
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UPROPERTY(BlueprintReadWrite, Category = Blueprint)
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int32 MyInt_ReadWrite = 123;
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//PropertyFlags: CPF_BlueprintVisible | CPF_BlueprintReadOnly | CPF_ZeroConstructor | CPF_IsPlainOldData | CPF_NoDestructor | CPF_HasGetValueTypeHash | CPF_NativeAccessSpecifierPublic
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UPROPERTY(BlueprintReadOnly, Category = Blueprint)
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int32 MyInt_ReadOnly = 123;
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```
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## 示例效果：
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指定蓝图中只读：
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## 原理：
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有CPF_BlueprintVisible 就可以Get
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加上CPF_BlueprintReadOnly 后就不能修改。
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```cpp
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EPropertyAccessResultFlags PropertyAccessUtil::CanGetPropertyValue(const FProperty* InProp)
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{
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if (!InProp->HasAnyPropertyFlags(CPF_Edit | CPF_BlueprintVisible | CPF_BlueprintAssignable))
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{
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return EPropertyAccessResultFlags::PermissionDenied | EPropertyAccessResultFlags::AccessProtected;
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}
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return EPropertyAccessResultFlags::Success;
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}
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FBlueprintEditorUtils::EPropertyWritableState FBlueprintEditorUtils::IsPropertyWritableInBlueprint(const UBlueprint* Blueprint, const FProperty* Property)
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{
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if (Property)
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{
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if (!Property->HasAnyPropertyFlags(CPF_BlueprintVisible))
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{
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return EPropertyWritableState::NotBlueprintVisible;
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}
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if (Property->HasAnyPropertyFlags(CPF_BlueprintReadOnly))
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{
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return EPropertyWritableState::BlueprintReadOnly;
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}
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if (Property->GetBoolMetaData(FBlueprintMetadata::MD_Private))
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{
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const UClass* OwningClass = Property->GetOwnerChecked<UClass>();
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if (OwningClass->ClassGeneratedBy.Get() != Blueprint)
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{
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return EPropertyWritableState::Private;
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}
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}
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}
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return EPropertyWritableState::Writable;
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}
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```
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