UE5 C++（十二）— 委托（代理）、多播委托

这里写目录标题

介绍
- 定义
- 声明委托
- 绑定委托
- 执行委托
单播委托
多播委托
动态多播代理

介绍

这个官网上有很详细介绍，这里介绍几个点

定义

委托是一种泛型但类型安全的方式，可在C++对象上调用成员函数。可使用委托动态绑定到任意对象的成员函数，之后在该对象上调用函数，即使调用程序不知对象类型也可进行操作。复制委托对象很安全。你也可以利用值传递委托，但这样操作需要在堆上分配内存，因此通常并不推荐。请尽量通过引用传递委托。

声明委托

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UDELEGATE(BlueprintAuthorityOnly)
DECLARE_DYNAMIC_MULTICAST_DELEGATE_FourParams(FInstigatedAnyDamageSignature, float, Damage, const UDamageType*, DamageType, AActor*, DamagedActor, AActor*, DamageCauser);

绑定委托

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MyDelegate.BindRaw( &MyFunction, true, 20 );

执行委托

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WriteToLogDelegate.Execute(TEXT("Delegates are great!"));

单播委托

单播委托只能绑定一个函数

创建一个C++类 MyDelegateActor

MyDelegateActor.h


#pragma once#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "MyDelegateActor.generated.h"DECLARE_DELEGATE(NoParamDelegate);//声明一个无参委托
DECLARE_DELEGATE_OneParam(OneParamDelegate, int32);//声明一个有一个int32参数的委托
DECLARE_DELEGATE_TwoParams(TwoParamsDelegate, int32, FString);//声明一个有一个int32参数和一个FString参数的委托
DECLARE_DELEGATE_RetVal(int32, RetValDelegate);//声明一个有返回值的委托UCLASS()
class DEMO_API AMyDelegateActor : public AActor
{GENERATED_BODY()public:	// Sets default values for this actor's propertiesAMyDelegateActor();protected:// Called when the game starts or when spawnedvirtual void BeginPlay() override;public:	// Called every framevirtual void Tick(float DeltaTime) override;NoParamDelegate NoParamDelegate;//声明一个无参委托OneParamDelegate OneParamDelegate;//声明一个有一个int32参数的委托TwoParamsDelegate TwoParamsDelegate;//声明一个有一个int32参数和一个FString参数的委托RetValDelegate RetValDelegate;//声明一个有返回值的委托void NoParamDelegateFunc();//无参委托函数void OneParamDelegateFunc(int32 Param);//有一个int32参数的委托函数void TwoParamsDelegateFunc(int32 Param1, FString Param2);//有一个int32参数和一个FString参数的委托函数int32 RetValDelegateFunc();//有返回值的委托函数};

MyDelegateActor.cpp


#include "MyDelegateActor.h"// Sets default values
AMyDelegateActor::AMyDelegateActor()
{// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.PrimaryActorTick.bCanEverTick = true;NoParamDelegate.BindUObject(this, &AMyDelegateActor::NoParamDelegateFunc);	   // 绑定无参委托函数OneParamDelegate.BindUObject(this, &AMyDelegateActor::OneParamDelegateFunc);   // 绑定有一个int32参数的委托函数TwoParamsDelegate.BindUObject(this, &AMyDelegateActor::TwoParamsDelegateFunc); // 绑定有一个int32参数和一个FString参数的委托函数RetValDelegate.BindUObject(this, &AMyDelegateActor::RetValDelegateFunc);	   // 绑定有返回值的委托函数
}// Called when the game starts or when spawned
void AMyDelegateActor::BeginPlay()
{Super::BeginPlay();NoParamDelegate.Execute(); // 执行无参委托函数OneParamDelegate.Execute(1); // 执行有一个int32参数的委托函数TwoParamsDelegate.Execute(1, TEXT("TwoParamsDelegate")); // 执行有一个int32参数和一个FString参数的委托函数int32 RetVal = RetValDelegate.Execute(); // 执行有返回值的委托函数UE_LOG(LogTemp, Warning, TEXT("RetVal:%d"), RetVal);}// Called every frame
void AMyDelegateActor::Tick(float DeltaTime)
{Super::Tick(DeltaTime);
}
void AMyDelegateActor::NoParamDelegateFunc()
{UE_LOG(LogTemp, Warning, TEXT("NoParamDelegateFunc"));
}
void AMyDelegateActor::OneParamDelegateFunc(int32 Param)
{UE_LOG(LogTemp, Warning, TEXT("OneParamDelegateFunc Param:%d"), Param);
}
void AMyDelegateActor::TwoParamsDelegateFunc(int32 Param1, FString Param2)
{UE_LOG(LogTemp, Warning, TEXT("TwoParamsDelegateFunc Param1:%d Param2:%s"), Param1, *Param2);
}
int32 AMyDelegateActor::RetValDelegateFunc()
{UE_LOG(LogTemp, Warning, TEXT("RetValDelegateFunc"));return 1;
}

然后把C++类 MyDelegateActor 拖到场景中，运行
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多播委托

多播委托（代理）可以绑定绑定多个函数

创建一个C++类 MyDelegateActor

MyDelegateActor.h

// Fill out your copyright notice in the Description page of Project Settings.#pragma once#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "MyDelegateActor.generated.h"// 多播委托代理
DECLARE_MULTICAST_DELEGATE(NoParamMulticastDelegate);							  // 声明一个无参多播委托
DECLARE_MULTICAST_DELEGATE_OneParam(OneParamMulticastDelegate, int32);			  // 声明一个有一个int32参数的多播委托
DECLARE_MULTICAST_DELEGATE_TwoParams(TwoParamsMulticastDelegate, int32, FString); // 声明一个有一个int32参数和一个FString参数的多播委托UCLASS()
class DEMO_API AMyDelegateActor : public AActor
{GENERATED_BODY()public:// Sets default values for this actor's propertiesAMyDelegateActor();protected:// Called when the game starts or when spawnedvirtual void BeginPlay() override;public:// Called every framevirtual void Tick(float DeltaTime) override;/*****     多播委托代理         ******/NoParamMulticastDelegate NoParamMulticastDelegate;	 // 声明一个无参多播委托OneParamMulticastDelegate OneParamMulticastDelegate;	 // 声明一个有一个int32参数的多播委托TwoParamsMulticastDelegate TwoParamsMulticastDelegate; // 声明一个有一个int32参数和一个FString参数的多播委托void NoParamMulticastDelegateFunc();					 // 无参多播委托函数void NoParamMulticastDelegateFunc2();void OneParamMulticastDelegateFunc(int32 Param);		 // 有一个int32参数的多播委托函数void OneParamMulticastDelegateFunc2(int32 Param);void TwoParamsMulticastDelegateFunc(int32 Param1, FString Param2); // 有一个int32参数和一个FString参数的多播委托函数void TwoParamsMulticastDelegateFunc2(int32 Param1, FString Param2); };

MyDelegateActor.cpp

// Fill out your copyright notice in the Description page of Project Settings.#include "MyDelegateActor.h"// Sets default values
AMyDelegateActor::AMyDelegateActor()
{// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.PrimaryActorTick.bCanEverTick = true;/*****     多播委托代理         ******/NoParamMulticastDelegate.AddUObject(this, &AMyDelegateActor::NoParamMulticastDelegateFunc); // 绑定无参多播委托函数NoParamMulticastDelegate.AddUObject(this, &AMyDelegateActor::NoParamMulticastDelegateFunc2);OneParamMulticastDelegate.AddUObject(this, &AMyDelegateActor::OneParamMulticastDelegateFunc); // 绑定有一个int32参数的多播委托函数OneParamMulticastDelegate.AddUObject(this, &AMyDelegateActor::OneParamMulticastDelegateFunc2);TwoParamsMulticastDelegate.AddUObject(this, &AMyDelegateActor::TwoParamsMulticastDelegateFunc); // 绑定有一个int32参数和一个FString参数的多播委托函数TwoParamsMulticastDelegate.AddUObject(this, &AMyDelegateActor::TwoParamsMulticastDelegateFunc2);
}// Called when the game starts or when spawned
void AMyDelegateActor::BeginPlay()
{Super::BeginPlay();/*****     多播委托代理         ******/NoParamMulticastDelegate.Broadcast();								// 执行无参多播委托函数OneParamMulticastDelegate.Broadcast(1);								// 执行有一个int32参数的多播委托函数TwoParamsMulticastDelegate.Broadcast(1, TEXT("TwoParamsDelegate")); // 执行有一个int32参数和一个FString参数的多播委托函数
}// Called every frame
void AMyDelegateActor::Tick(float DeltaTime)
{Super::Tick(DeltaTime);
}/*****     多播委托代理         ******/
void AMyDelegateActor::NoParamMulticastDelegateFunc()
{UE_LOG(LogTemp, Warning, TEXT("NoParamMulticastDelegateFunc"));
}
void AMyDelegateActor::NoParamMulticastDelegateFunc2()
{UE_LOG(LogTemp, Warning, TEXT("NoParamMulticastDelegateFunc2"));
}
void AMyDelegateActor::OneParamMulticastDelegateFunc(int32 Param)
{UE_LOG(LogTemp, Warning, TEXT("OneParamMulticastDelegateFunc Param:%d"), Param);
}
void AMyDelegateActor::OneParamMulticastDelegateFunc2(int32 Param)
{UE_LOG(LogTemp, Warning, TEXT("OneParamMulticastDelegateFunc2 Param:%d"), Param);
}
void AMyDelegateActor::TwoParamsMulticastDelegateFunc(int32 Param1, FString Param2)
{UE_LOG(LogTemp, Warning, TEXT("TwoParamsMulticastDelegateFunc Param1:%d Param2:%s"), Param1, *Param2);
}
void AMyDelegateActor::TwoParamsMulticastDelegateFunc2(int32 Param1, FString Param2)
{UE_LOG(LogTemp, Warning, TEXT("TwoParamsMulticastDelegateFunc2 Param1:%d Param2:%s"), Param1, *Param2);
}

打印日志
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动态多播代理

动态多播委托代理区别在于可以暴露给蓝图，在蓝图中进行事件绑定, 一定要是F开头
还有就是参数和参数名一定要配合使用

创建一个C++类 MyDelegateActor

MyDelegateActor.h

// Fill out your copyright notice in the Description page of Project Settings.#pragma once#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "MyDelegateActor.generated.h"// 动态多播委托代理 区别在于可以暴露给蓝图，在蓝图中进行事件绑定, 一定要是F开头
DECLARE_DYNAMIC_MULTICAST_DELEGATE(FNoParamDynamicMulticastDelegate);												  // 声明一个无参多播委托
DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FOneParamDynamicMulticastDelegate, FString, ParamStr);					  // 声明一个有一个int32参数的多播委托
DECLARE_DYNAMIC_MULTICAST_DELEGATE_TwoParams(FTwoParamsDynamicMulticastDelegate, int32, ParamInt, FString, ParamStr); // 声明一个有一个int32参数和一个FString参数的多播委托UCLASS()
class DEMO_API AMyDelegateActor : public AActor
{GENERATED_BODY()public:// Sets default values for this actor's propertiesAMyDelegateActor();protected:// Called when the game starts or when spawnedvirtual void BeginPlay() override;public:// Called every framevirtual void Tick(float DeltaTime) override;/*****     动态多播委托代理         ******/UPROPERTY(BlueprintAssignable, Category = "MyDelegate")FNoParamDynamicMulticastDelegate NoParamDynamicMulticastDelegate; // 声明一个无参多播委托UPROPERTY(BlueprintAssignable, Category = "MyDelegate")FOneParamDynamicMulticastDelegate OneParamDynamicMulticastDelegate; // 声明一个有一个int32参数的多播委托UPROPERTY(BlueprintAssignable, Category = "MyDelegate")FTwoParamsDynamicMulticastDelegate TwoParamsDynamicMulticastDelegate; // 声明一个有一个int32参数和一个FString参数的多播委托
};

MyDelegateActor.cpp

// Fill out your copyright notice in the Description page of Project Settings.#include "MyDelegateActor.h"// Sets default values
AMyDelegateActor::AMyDelegateActor()
{// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.PrimaryActorTick.bCanEverTick = true;
}// Called when the game starts or when spawned
void AMyDelegateActor::BeginPlay()
{Super::BeginPlay();/*****     执行动态多播委托代理         ******/NoParamDynamicMulticastDelegate.Broadcast();OneParamDynamicMulticastDelegate.Broadcast(TEXT("OneParamsDelegate"));TwoParamsDynamicMulticastDelegate.Broadcast(1, TEXT("TwoParamsDelegate"));
}// Called every frame
void AMyDelegateActor::Tick(float DeltaTime)
{Super::Tick(DeltaTime);
}