Cocos2d-x CC_CALLBACK_0, Callback functions

Cocos2d-x has callback functions like

CC_CALLBACK_0
CC_CALLBACK_1
CC_CALLBACK_2
CC_CALLBACK_3

these functions are defined functions.

// 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__)

CC_CALLBACK_(N) function N means, the number of callback function pass parameters.

CC_CALLBACK_0 function: pass no parameter.
CC_CALLBACK_1 function: pass one parameter.
CC_CALLBACK_2 function: pass two parameter.

example code)
https://gist.github.com/pineoc/ca43124d321acb21486d

	bool HelloWorld::init()
	{
	/*has some code*/
	//CC_CALLBACK_0 function
	auto sprite1 = Sprite::create("CloseNormal.png");
	auto callback = CCCallFunc::create(CC_CALLBACK_0(HelloWorld::myFunction1, this));
	sprite1->runAction(callback);
	this->addChild(sprite1);
	auto sprite2 = Sprite::create("CloseNormal.png");
	auto callback = CCCallFunc::create(CC_CALLBACK_1(HelloWorld::myFunction2, this));
	sprite2->runAction(callback);
	this->addChild(sprite2);
	auto btn = Button::create("CloseNormal.png","CloseNormal.png");
	btn->addTouchEventListener(CC_CALLBACK_2(HelloWorld::myFunction3, this));
	this->addChild(btn);
	}
	void HelloWorld::myFunction1()
	{// no passed param
	CCLOG("myFunction1");
	}
	void HelloWorld::myFunction2(Ref* pSender)
	{//one passed param
	CCLOG("myFunction2");
	}
	void HelloWorld::myFunction3(Ref* pSender, Widget::TouchEvent e)
	{//two passed param
	//Button event listener
	CCLOG("myFunction3");
	}

view raw CC_CALLBACK_functions.cpp hosted with ❤ by GitHub

CC_CALLBACK_3 function: pass three parameter.
example code)
http://www.cocos2d-x.org/wiki/Game_Controller

	void HelloWorld::registerControllerListener()
	{
	//create an evnetListenerController
	_listener = EventListenerController::create();
	//bind onConneected event call function
	_listener->onConnected = CC_CALLBACK_2(HelloWorld::onConnectController,this);
	//bind disconnect event call function
	_listener->onDisconnected = CC_CALLBACK_2(HelloWorld::onDisconnectedController,this);
	//bind onKeyDown event call function
	_listener->onKeyDown = CC_CALLBACK_3(HelloWorld::onKeyDown, this);
	//bind onKeyUp event call function
	_listener->onKeyUp = CC_CALLBACK_3(HelloWorld::onKeyUp, this);
	//bind onAxis event call function, onAxis will be called when analog stick is changed
	_listener->onAxisEvent = CC_CALLBACK_3(HelloWorld::onAxisEvent, this);
	//Activate the listener into the event dispatcher
	_eventDispatcher->addEventListenerWithSceneGraphPriority(_listener, this);
	//This function should be called for iOS platform
	Controller::startDiscoveryController();
	}
	//Controller is the obejects of the Controller，keyCode means the keycode of the controller you click down
	void HelloWorld::onKeyDown(cocos2d::Controller *controller, int keyCode, cocos2d::Event *event)
	{
	CCLOG("KeyDown:%d", keyCode);
	}
	void HelloWorld::onKeyUp(cocos2d::Controller *controller, int keyCode, cocos2d::Event *event)
	{
	//You can get the controller by tag, deviceId or devicename if there are multiple controllers
	CCLOG("tag:%d DeviceId:%d DeviceName:%s", controller->getTag(), controller->getDeviceId(), controller->getDeviceName().c_str());
	CCLOG("KeyUp:%d", keyCode);
	}
	//The axis includes X-axis and Y-axis and its range is from -1 to 1. X-axis is start from left to right and Y-axis is bottom to top.
	void HelloWorld::onAxisEvent(cocos2d::Controller* controller, int keyCode, cocos2d::Event* event)
	{
	const auto& keyStatus = controller->getKeyStatus(keyCode);
	CCLOG("Axis KeyCode:%d Axis Value:%f", keyCode, keyStatus.value);
	}
	void HelloWorld::onConnectController(Controller* controller, Event* event)
	{
	CCLOG("Game controller connected");
	}
	void HelloWorld::onDisconnectedController(Controller* controller, Event* event)
	{
	CCLOG("Game controller disconnected");
	}
	bool HelloWorld::init()
	{
	//////////////////////////////
	// 1. super init first
	if ( !Layer::init() )
	{
	return false;
	}
	......
	......
	registerControllerListener();
	return true;
	}

view raw CC_CALLBACK_functions2.cpp hosted with ❤ by GitHub