58 lines
1.9 KiB
Markdown
58 lines
1.9 KiB
Markdown
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# BindWidgetOptional
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- **功能描述：** 指定在C++类中该Widget属性可以绑定到UMG的某个同名控件，也可以不绑定。
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- **使用位置：** UPROPERTY
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- **引擎模块：** Widget Property
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- **元数据类型：** bool
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- **限制类型：** UWidget子类里属性
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- **关联项：** [BindWidget](../BindWidget/BindWidget.md)
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- **常用程度：** ★★★
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指定在C++类中该Widget属性可以绑定到UMG的某个同名控件，也可以不绑定。
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大致作用和BindWidget一样，区别是：
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- BindWidgetOptional顾名思义是可选的，意思是UMG里即使不定义该控件在编译的时候也不会报错。编译会通过，但是会提示警告缺少控件。
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-
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- 和不加BindWidgetOptional的控件同名属性的区别是，前者在UMG里定义同名控件的时候不会报错，但后者是会提示同名冲突报错。
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BindWidgetOptional的写法有两种：
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BindWidgetOptional可以看作是BindWidget和OptionalWidget的合并版。
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```cpp
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UCLASS(BlueprintType)
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class INSIDER_API UMyProperty_BindWidget :public UUserWidget
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{
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GENERATED_BODY()
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UPROPERTY(EditAnywhere, BlueprintReadWrite)
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class UTextBlock* MyTextBlock_SameName;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (BindWidgetOptional))
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class UTextBlock* MyTextBlock_Optional1;
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UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (BindWidget, OptionalWidget))
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class UTextBlock* MyTextBlock_Optional2;
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};
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```
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## 测试效果：
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## 原理：
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```cpp
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bool FWidgetBlueprintEditorUtils::IsBindWidgetProperty(const FProperty* InProperty, bool& bIsOptional)
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{
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if ( InProperty )
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{
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bool bIsBindWidget = InProperty->HasMetaData("BindWidget") || InProperty->HasMetaData("BindWidgetOptional");
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bIsOptional = InProperty->HasMetaData("BindWidgetOptional") || ( InProperty->HasMetaData("OptionalWidget") || InProperty->GetBoolMetaData("OptionalWidget") );
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return bIsBindWidget;
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}
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return false;
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}
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```
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