cocos2dx 3.1 CC_CALLBACK用std::bind替换CC_CALLBACK_N

在cocos2dx 3.0 版本中,回调函数基本上由4个CC_CALLBACK_N 函数代替,N代表回调函数的参数个数
1.先让我们来看看这些CC_CALLBACK_N怎么用

比如action的回调 ,CC_CALLBACK_0

auto animation = Animation::create();
auto animate = Animate::create(animation);
CallFunc* animateDone = CallFunc::create(CC_CALLBACK_0(PlaneLayer::removePlane,this));
auto sequence = Sequence::create(animate,animateDone,NULL);
sprite1->runAction(sequence);

void PlaneLayer::removePlane(){
	//.....
}



或者action带一个参数的回调:CC_CALLBACK_1,在这里,pSender就是动作的执行者sprite2

auto actionMove = MoveTo::create(randomDuration, Point(0, 0));
auto actionDone = CallFuncN::create(CC_CALLBACK_1(EnemyLayer::enemy1MoveFinished,this));
auto sequence = Sequence::create(actionMove,actionDone,NULL);
sprite2->runAction(sequence);

void EnemyLayer::enemy1MoveFinished(Node* pSender){
 	Sprite* sprite2 = (Sprite*)pSender;
}



或者按钮的回调函数:CC_CALLBACK_1
auto pauseNormal = Sprite::create("game_pause_nor.png");
auto pausePressed = Sprite::create("game_pause_pressed.png");
	
auto menuItem = MenuItemSprite::create(pauseNormal,pausePressed,NULL,CC_CALLBACK_1(ControlLayer::menuPauseCallback,this));
menuItem->setPosition(Point::ZERO);
auto menuPause = Menu::create(menuItem,NULL);
menuPause->setPosition(Point::ZERO);

//回调函数
void ControlLayer::menuPauseCallback(Object* pSender)
{
	//....
}



或者touch函数:CC_CALLBACK_2

//单点触摸  
    virtual bool onTouchBegan(Touch *touch, Event *unused_event);   
    virtual void onTouchMoved(Touch *touch, Event *unused_event);   
    virtual void onTouchEnded(Touch *touch, Event *unused_event);   
    virtual void onTouchCancelled(Touch *touch, Event *unused_event);

  
    auto dispatcher = Director::getInstance()->getEventDispatcher();
    auto listener = EventListenerTouchOneByOne::create();
    listener->onTouchBegan = CC_CALLBACK_2(GameLayer::onTouchBegan,this);
    listener->onTouchMoved = CC_CALLBACK_2(GameLayer::onTouchMoved,this);
    listener->onTouchEnded = CC_CALLBACK_2(GameLayer::onTouchEnded,this);
    listener->setSwallowTouches(true);//不向下传递触摸
    dispatcher->addEventListenerWithSceneGraphPriority(listener,this);




一般来说:


CallFunc用于 不带参数的
CallFuncN 用于创建 带一个Node节点参数的,Node*节点参数是动作的执行者
CCCallFuncND 比CallFuncN多了一个参数,可以是任意类型的参数  void *,用法看下面

auto animation = AnimationCache::getInstance()->animationByName("Enemy1Blowup");
auto animate = Animate::create(animation);
CCCallFuncND* animateDone = CCCallFuncND::create(this,callfuncND_selector(EnemyLayer::removeEnemy1),(void*)enemy1);
auto sequence = Sequence::create(animate, animateDone,NULL);
Sprite* m_sprite = enemy1->getSprite();
m_sprite ->runAction(sequence);


void EnemyLayer::removeEnemy1(Node* pTarget, void* data){
	Sprite* m_sprite = (Sprite*) pTarget; //node节点为动作的执行者
	Enemy* enemy1 = (Enemy*)data;         //我们传的自定义数据enemy1
	//...
}



其实上面调用带两个参数的函数的这句代码:

CCCallFuncND* animateDone = CCCallFuncND::create(this,callfuncND_selector(EnemyLayer::removeEnemy1),(void*)enemy1);



我们还可以这样子写:

//写法1
CCCallFuncN* animateDone = CCCallFuncN::create(CC_CALLBACK_1(EnemyLayer::removeEnemy1,this,enemy1));
//写法2
CCCallFunc* animateDone = CCCallFunc::create(CC_CALLBACK_0(EnemyLayer::removeEnemy1,this,enemy1->getSprite(),enemy1));
//写法3,用std::bind
CCCallFuncN* animateDone = CCCallFuncN::create(std::bind(&EnemyLayer::removeEnemy1,this,enemy1->getSprite(),enemy1));



其实上面的CC_CALLBACK_0 啊CC_CALLBACK_1 啊,都可以类似这么写,很多种写法, 原因是因为CC_CALLBACK_N有一个可变参数宏##__VA_ARGS__


恩,是不是有点乱,记不住没关系,我也经常没记住,我们来具体看一下CC_CALLBACK_N到底是神马玩意


// new callbacks based on C++11
#define CC_CALLBACK_0(__selector__,__target__, ...) std::bind(&__selector__,__target__, ##__VA_ARGS__)
#define CC_CALLBACK_1(__selector__,__target__, ...) std::bind(&__selector__,__target__, std::placeholders::_1, ##__VA_ARGS__)
#define CC_CALLBACK_2(__selector__,__target__, ...) std::bind(&__selector__,__target__, std::placeholders::_1, std::placeholders::_2, ##__VA_ARGS__)
#define CC_CALLBACK_3(__selector__,__target__, ...) std::bind(&__selector__,__target__, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3 ##__VA_ARGS__)



是不是看到了std::bind、##__VA_ARGS__、std::placeholders::_1等等,这些都是神马玩意,


先解释一下:


##__VA_ARGS__是可变参数宏
std::placeholders::_1是参数占位符,表示第一个参数,以此类推



那std::bind是神马,不急我们先看一段代码

#include <iostream>
#include <functional>
using namespace std;

typedef std::function<void ()> fp;
void g_fun()
{
	cout<<"g_fun()"<<endl;
}
class A
{
public:
	static void A_fun_static()
	{
		cout<<"A_fun_static()"<<endl;
	}
	void A_fun()
	{
		cout<<"A_fun()"<<endl;
	}
	void A_fun_int(int i)
	{
		cout<<"A_fun_int() "<<i<<endl;
	}

	void A_fun_int_double(int i,int p)
	{
		cout<<"A_fun_int_double ()"<<i<<","<<p<<endl;
	}

	//非静态类成员,因为含有this指针,所以需要使用bind
	void init()
	{
		//绑定不带参数的函数
		fp fp1=std::bind(&A::A_fun,this);
		fp1();
	}

	void init2()
	{
		typedef std::function<void (int)> fpi;
		//绑定带一个参数的函数
		fpi f=std::bind(&A::A_fun_int,this,std::placeholders::_1);//参数要使用占位符 std::placeholders::_1表示第一个参数
		f(5);
	}

	void init3(){
		typedef std::function<void (int,double)> fpid;
		//绑定带两个参数的函数
		fpid f=std::bind(&A::A_fun_int_double,this,std::placeholders::_1,std::placeholders::_2);
		f(5,10);
	}
};
int main()
{
	//绑定到全局函数
	fp f2=fp(&g_fun);
	f2();

	//绑定到类静态成员函数
	fp f1=fp(&A::A_fun_static);
	f1();

	A().init();
	A().init2();
	A().init3();
	return 0;
}



然后看一下输出结果:
g_fun()
A_fun_static()
A_fun()
A_fun_int() 5
A_fun_int_double ()5,10



再解释一下:

std::function  --> 绑定到全局函数/类静态成员函数(类静态成员函数与全局函数没有区别)
std::bind       --> 绑定到类的非静态成员函数


到这里是不是有豁然开朗的感觉呢,哈哈,知道了bind函数怎么用,然后我们就可以使用std::bind替换CC_CALLBACK_N写法了


3.使用std:bind函数替换CC_CALLBACK_N:



比如我们要替换CC_CALLBACK_0

auto animation = Animation::create();
auto animate = Animate::create(animation);
//CallFunc* animateDone = CallFunc::create(CC_CALLBACK_0(PlaneLayer::removePlane,this));
CallFunc* animateDone = CallFunc::create(std::bind(&PlaneLayer::removePlane,this));//替换
auto sequence = Sequence::create(animate,animateDone,NULL);
sprite1->runAction(sequence);

void PlaneLayer::removePlane(){
	//.....
}



比如我们要替换带一个参数的CC_CALLBACK_1

auto actionMove = MoveTo::create(randomDuration, Point(0, 0));
//auto actionDone = CallFuncN::create(CC_CALLBACK_1(EnemyLayer::enemy1MoveFinished,this));
auto actionDone = CallFuncN::create(std::bind(&EnemyLayer::enemy1MoveFinished,this,enemy1));//替换
auto sequence = Sequence::create(actionMove,actionDone,NULL);
sprite2->runAction(sequence);

void EnemyLayer::enemy1MoveFinished(Node* pSender){
 	Sprite* sprite2 = (Sprite*)pSender;
}



再比如调用两个参数的...

auto animation = AnimationCache::getInstance()->animationByName("Enemy1Blowup");
auto animate = Animate::create(animation);
//CCCallFuncND* animateDone = CCCallFuncND::create(this,callfuncND_selector(EnemyLayer::removeEnemy1),(void*)enemy1);
CCCallFuncN* animateDone = CCCallFuncN::create(std::bind(&EnemyLayer::removeEnemy1,this,enemy1->getSprite(),enemy1));//替换
auto sequence = Sequence::create(animate, animateDone,NULL);
Sprite* m_sprite = enemy1->getSprite();
m_sprite ->runAction(sequence);


void EnemyLayer::removeEnemy1(Node* pTarget, void* data){
	Sprite* m_sprite = (Sprite*) pTarget; //node节点为动作的执行者
	Enemy* enemy1 = (Enemy*)data;         //我们传的自定义数据enemy1
	//...
}



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