88 lines
2.7 KiB
Markdown
88 lines
2.7 KiB
Markdown
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# FieldNotify
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- **功能描述：** 为该函数创建一个FieldNotify的绑定点。
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- **元数据类型：** bool
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- **引擎模块：** UHT
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- **限制类型：** ViewModel里的函数
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- **常用程度：** ★★★
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为该函数创建一个FieldNotify的绑定点。
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需要注意的是，如果是Get函数则其返回值改变的时候，需要在别的触发改变的地方手动广播事件。正如下面的代码UE_MVVM_BROADCAST_FIELD_VALUE_CHANGED(GetHPPercent);所做的。
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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 UMyViewModel :public UMVVMViewModelBase
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{
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GENERATED_BODY()
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protected:
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UPROPERTY(BlueprintReadWrite, FieldNotify, Getter, Setter, BlueprintSetter = SetHP)
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float HP = 1.f;
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UPROPERTY(BlueprintReadWrite, FieldNotify, Getter, Setter, BlueprintSetter = SetMaxHP)
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float MaxHP = 100.f;
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public:
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float GetHP()const { return HP; }
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UFUNCTION(BlueprintSetter)
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void SetHP(float val)
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{
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if (UE_MVVM_SET_PROPERTY_VALUE(HP, val))
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{
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UE_MVVM_BROADCAST_FIELD_VALUE_CHANGED(GetHPPercent);
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}
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}
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float GetMaxHP()const { return MaxHP; }
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UFUNCTION(BlueprintSetter)
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void SetMaxHP(float val)
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{
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if (UE_MVVM_SET_PROPERTY_VALUE(MaxHP, val))
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{
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UE_MVVM_BROADCAST_FIELD_VALUE_CHANGED(GetHPPercent);
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}
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}
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//You need to manually notify that GetHealthPercent changed when CurrentHealth or MaxHealth changed.
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UFUNCTION(BlueprintPure, FieldNotify)
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float GetHPPercent() const
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{
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return (MaxHP != 0.f) ? HP / MaxHP : 0.f;
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}
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};
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```
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## 测试效果：
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可见GetHPPercent有生成一个FIELD。
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```cpp
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//MyViewModel.generated.h
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#define FID_GitWorkspace_Hello_Source_Insider_Property_MVVM_MyViewModel_h_12_FIELDNOTIFY \
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UE_FIELD_NOTIFICATION_DECLARE_CLASS_DESCRIPTOR_BEGIN(INSIDER_API ) \
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UE_FIELD_NOTIFICATION_DECLARE_FIELD(HP) \
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UE_FIELD_NOTIFICATION_DECLARE_FIELD(MaxHP) \
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UE_FIELD_NOTIFICATION_DECLARE_FIELD(GetHPPercent) \
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UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD_BEGIN(HP) \
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UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD(MaxHP) \
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UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD(GetHPPercent) \
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UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD_END() \
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UE_FIELD_NOTIFICATION_DECLARE_CLASS_DESCRIPTOR_END();
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//MyViewModel.gen.cpp
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UE_FIELD_NOTIFICATION_IMPLEMENT_FIELD(UMyViewModel, HP)
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UE_FIELD_NOTIFICATION_IMPLEMENT_FIELD(UMyViewModel, MaxHP)
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UE_FIELD_NOTIFICATION_IMPLEMENT_FIELD(UMyViewModel, GetHPPercent)
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UE_FIELD_NOTIFICATION_IMPLEMENTATION_BEGIN(UMyViewModel)
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UE_FIELD_NOTIFICATION_IMPLEMENT_ENUM_FIELD(UMyViewModel, HP)
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UE_FIELD_NOTIFICATION_IMPLEMENT_ENUM_FIELD(UMyViewModel, MaxHP)
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UE_FIELD_NOTIFICATION_IMPLEMENT_ENUM_FIELD(UMyViewModel, GetHPPercent)
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UE_FIELD_NOTIFICATION_IMPLEMENTATION_END(UMyViewModel);
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```
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## 蓝图效果：
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进度条可以绑定到GetHPPercent。
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