Ue4_C++委托

本文主要是介绍Ue4_C++委托，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

五种委托形式

1.单播委托

2.多播委托

3.事件

4.动态单播委托

5.动态多播委托

DelegateCombinations.h
/** Declares a delegate that can only bind to one native function at a time */
#define DECLARE_DELEGATE( DelegateName ) FUNC_DECLARE_DELEGATE( DelegateName, void )
/** Declares a broadcast delegate that can bind to multiple native functions simultaneously */
#define DECLARE_MULTICAST_DELEGATE( DelegateName ) FUNC_DECLARE_MULTICAST_DELEGATE( DelegateName, void )
#define DECLARE_EVENT( OwningType, EventName ) FUNC_DECLARE_EVENT( OwningType, EventName, void )

/** Declares a blueprint-accessible delegate that can only bind to one UFUNCTION at a time */
#define DECLARE_DYNAMIC_DELEGATE( DelegateName ) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_DELEGATE) FUNC_DECLARE_DYNAMIC_DELEGATE( FWeakObjectPtr, DelegateName, DelegateName##_DelegateWrapper, , FUNC_CONCAT( *this ), void )
/** Declares a blueprint-accessible broadcast delegate that can bind to multiple native UFUNCTIONs simultaneously */
#define DECLARE_DYNAMIC_MULTICAST_DELEGATE( DelegateName ) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_DELEGATE) FUNC_DECLARE_DYNAMIC_MULTICAST_DELEGATE( FWeakObjectPtr, DelegateName, DelegateName##_DelegateWrapper, , FUNC_CONCAT( *this ), void )

Engine\Source\Runtime\Core\Public\Delegates

单播委托绑定

通过创建函数指针

    
DelegateSignatureImpl.inl 
/**
     * Binds a UFunction-based member function delegate.
     *
     * UFunction delegates keep a weak reference to your object.
     * You can use ExecuteIfBound() to call them.
     */
    template <typename UObjectTemplate, typename... VarTypes>
    inline void BindUFunction(UObjectTemplate* InUserObject, const FName& InFunctionName, VarTypes... Vars)
    {
        *this = CreateUFunction(InUserObject, InFunctionName, Vars...);
    }

/**
     * Binds a UObject-based member function delegate.
     *
     * UObject delegates keep a weak reference to your object.
     * You can use ExecuteIfBound() to call them.
     */
    template <typename UserClass, typename... VarTypes>
    inline void BindUObject(UserClass* InUserObject, typename TMemFunPtrType<false, UserClass, RetValType (ParamTypes..., VarTypes...)>::Type InFunc, VarTypes... Vars)
    {
        static_assert(!TIsConst<UserClass>::Value, "Attempting to bind a delegate with a const object pointer and non-const member function.");

        *this = CreateUObject(InUserObject, InFunc, Vars...);
    }
    template <typename UserClass, typename... VarTypes>
    inline void BindUObject(const UserClass* InUserObject, typename TMemFunPtrType<true, UserClass, RetValType (ParamTypes..., VarTypes...)>::Type InFunc, VarTypes... Vars)
    {
        *this = CreateUObject(InUserObject, InFunc, Vars...);
    }

多播委托的绑定

/**
     * Adds a delegate instance to this multicast delegate's invocation list.
     *
     * @param Delegate The delegate to add.
     */
    FDelegateHandle Add(const FDelegate& InNewDelegate)
    {
        FDelegateHandle Result;
        if (Super::GetDelegateInstanceProtectedHelper(InNewDelegate))
        {
            Result = Super::AddDelegateInstance(CopyTemp(InNewDelegate));
        }

        return Result;
    }

/**
     * Adds a UObject-based member function delegate.
     *
     * UObject delegates keep a weak reference to your object.
     *
     * @param    InUserObject    User object to bind to
     * @param    InFunc            Class method function address
     */
    template <typename UserClass, typename... VarTypes>
    inline FDelegateHandle AddUObject(UserClass* InUserObject, typename TMemFunPtrType<false, UserClass, void (ParamTypes..., VarTypes...)>::Type InFunc, VarTypes... Vars)
    {
        static_assert(!TIsConst<UserClass>::Value, "Attempting to bind a delegate with a const object pointer and non-const member function.");

        return Add(FDelegate::CreateUObject(InUserObject, InFunc, Vars...));
    }

remove方法

/**
     * Removes a delegate instance from this multi-cast delegate's invocation list (performance is O(N)).
     *
     * Note that the order of the delegate instances may not be preserved!
     *
     * @param Handle The handle of the delegate instance to remove.
     * @return  true if the delegate was successfully removed.
     */
    bool Remove( FDelegateHandle Handle )
    {
        bool bResult = false;
        if (Handle.IsValid())
        {
            bResult = RemoveDelegateInstance(Handle);
        }
        return bResult;
    }

动态委托：

动态单播委托

动态多播委托

注：动态委托可序列化，其函数可按命名查找，但其执行速度比常规委托慢

多态委托简单使用

//动态委托可序列化，其函数可按命名查找，但其执行速度比常规委托慢
DECLARE_DYNAMIC_MULTICAST_DELEGATE(FTestDyMulDELEGATE);

DECLARE_DYNAMIC_DELEGATE(FTestDyDELEGATE);

UPROPERTY(BlueprintAssignable,BlueprintCallable)
        FTestDyMulDELEGATE TestDyMulDELEGATE;
    
        FTestDyDELEGATE TestDyDELEGATE;
    
    UFUNCTION(BlueprintCallable)
        void ExDyDELEGATE();
    UFUNCTION(BlueprintCallable)
    void LogFunc();

    UFUNCTION(BlueprintCallable)
        void CallExDyMul();
    UFUNCTION()
    void DyMul_Log();

ATraceCharacter.cpp
//绑定
TestDyDELEGATE.BindUFunction(this,TEXT("LogFunc"));
TestDyMulDELEGATE.AddDynamic(this,&ATraceCharacter::DyMul_Log);

void ATraceCharacter::LogFunc()
{
　　//单播
    UE_LOG(LogTemp,Warning,TEXT("DyDELEGATE Excute"))
}
void ATraceCharacter::ExDyDELEGATE()
{
　　//单播动态委托调用
    TestDyDELEGATE.ExecuteIfBound();
}

void ATraceCharacter::CallExDyMul()
{
    TestDyMulDELEGATE.Broadcast();
}

void ATraceCharacter::DyMul_Log()
{
    UE_LOG(LogTemp, Warning, TEXT("DyMul_Log"));
}

多态多播委托：可在蓝图中调用/c++ Broadcast 调用

单播动态委托

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