78 lines
2.8 KiB
Markdown
78 lines
2.8 KiB
Markdown
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# EditCondition
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- **功能描述：** 给一个属性指定另外一个属性或者表达式来作为是否可编辑的条件。
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- **使用位置：** UPROPERTY
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- **引擎模块：** DetailsPanel
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- **元数据类型：** string="abc"
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- **关联项：** [EditConditionHides](../EditConditionHides/EditConditionHides.md), [InlineEditConditionToggle](../InlineEditConditionToggle/InlineEditConditionToggle.md), [HideEditConditionToggle](../HideEditConditionToggle/HideEditConditionToggle.md)
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- **常用程度：** ★★★★★
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给一个属性指定另外一个属性或者表达式来作为是否可编辑的条件。
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- 表达式里引用的属性必须得是同一个类或结构范围内的。
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## 测试代码：
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```cpp
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UCLASS(BlueprintType)
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class INSIDER_API UMyProperty_EditCondition_Test :public UObject
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{
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GENERATED_BODY()
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public:
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Property)
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bool MyBool;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Property)
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int32 MyInt = 123;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Property, meta = (EditCondition = "MyBool"))
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int32 MyInt_EditCondition = 123;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Property, meta = (EditCondition = "!MyBool"))
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int32 MyInt_EditCondition_Not = 123;
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public:
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = PropertyExpression)
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int32 MyFirstInt = 123;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = PropertyExpression)
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int32 MySecondInt = 123;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = PropertyExpression, meta = (EditCondition = "(MyFirstInt+MySecondInt)==500"))
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int32 MyInt_EditConditionExpression = 123;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = PropertyExpression, meta = (EditCondition = "!((MyFirstInt+MySecondInt)==500)"))
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int32 MyInt_EditConditionExpression_Not = 123;
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};
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```
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## 测试结果：
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- 可以通过bool单个属性来控制其他属性是否可以编辑
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- 也可以通过一个表达式引入更复杂的计算机制来决定是否来编辑。
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## 原理：
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在细节面板的属性初始化的时候，会判断该属性EditCondition设置，如果有值，会创建FEditConditionParser来解析表达式然后求值。
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```cpp
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void FPropertyNode::InitNode(const FPropertyNodeInitParams& InitParams)
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{
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const FString& EditConditionString = MyProperty->GetMetaData(TEXT("EditCondition"));
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// see if the property supports some kind of edit condition and this isn't the "parent" property of a static array
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const bool bIsStaticArrayParent = MyProperty->ArrayDim > 1 && GetArrayIndex() != -1;
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if (!EditConditionString.IsEmpty() && !bIsStaticArrayParent)
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{
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EditConditionExpression = EditConditionParser.Parse(EditConditionString);
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if (EditConditionExpression.IsValid())
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{
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EditConditionContext = MakeShareable(new FEditConditionContext(*this));
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}
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}
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}
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```
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