cocos2dx 3.x 屏幕触摸事件的认识

1. 屏幕触摸事件

EventListenerTouchOneByOne ：单点触控

    std::function onTouchBegan; //触摸开始事件
    std::function onTouchMoved; //触摸移动事件
    std::function onTouchEnded; //触摸结束事件
    std::function onTouchCancelled; //触摸中断事件

 EventListenerTouchAllAtOnce：多点触控

    std::function&, Event*)> onTouchesBegan; //触摸开始事件
    std::function&, Event*)> onTouchesMoved; //触摸移动事件
    std::function&, Event*)> onTouchesEnded; //触摸结束事件
    std::function&, Event*)> onTouchesCancelled; //触摸中断事件

bool TouchTest::init()
{
    if ( !Layer::init() )
    {
        return false;
    }
	//允许接收触摸事件
	this->setTouchEnabled(true);

	EventDispatcher* eventDispatcher = Director::getInstance()->getEventDispatcher();

	auto listen = EventListenerTouchAllAtOnce::create();
	listen->onTouchesBegan = CC_CALLBACK_2(TouchTest::onTouchesBegan,this);
	listen->onTouchesMoved = CC_CALLBACK_2(TouchTest::onTouchesMoved,this);
	listen->onTouchesEnded = CC_CALLBACK_2(TouchTest::onTouchesEnded,this);
	listen->onTouchesCancelled = CC_CALLBACK_2(TouchTest::onTouchesCancelled,this);
	eventDispatcher->addEventListenerWithSceneGraphPriority(listen,this);

    return true;
}
			
//触摸事件开始，手指按下时
void TouchTest::onTouchesBegan(const std::vector& touches, cocos2d::Event  *event)
{
	for(auto &item : touches)
	{
		auto touch = item;
		auto pos1 = touch->getLocation();
		auto pos2 = touch->getLocationInView();
		auto pos3 = Director::getInstance()->convertToUI(pos2);

		log("pos1 x: %f, y: %f",pos1.x,pos1.y);
		log("pos2 x: %f, y: %f",pos2.x,pos2.y);
		log("pos2 x: %f, y: %f",pos3.x,pos3.y);
	}
}
//触摸移动事件，也就是手指在屏幕滑动的过程
void TouchTest::onTouchesMoved(const std::vector& touches, cocos2d::Event  *event)
{
	log("TouchTest onTouchesMoved");
}
//触摸事件结束，也就是手指松开时
void TouchTest::onTouchesEnded(const std::vector& touches, cocos2d::Event  *event)
{
	log("TouchTest onTouchesEnded");
}
//打断触摸事件，一般是系统层级的消息，如来电话，触摸事件就会被打断
void TouchTest::onTouchesCancelled(const std::vector& touches, cocos2d::Event  *event)
{
	log("TouchTest onTouchesCancelled");
}

setTouchEnabled(); //设置是否允许接收触摸事件

获取单击屏幕时的坐标方式：

（1）touch->getLocation(); 获得单击坐标，基于3D

（2）touch->getLocationInView(); 获取单击坐标，是屏幕坐标系的坐标

（3）Director::getInstance()->convertToUI(pos2); //将屏幕坐标系的坐标，转为cocos2dx的坐标

坐标系：cocos2d-x是基于openGLES的，所以遵循openGL的坐标系，也就是说是以屏幕的左下角为坐标原点。屏幕坐标系一般是以左下角为坐标原点。

2. 修改触控方式

//设置多点触控

this->setTouchMode(Touch::DispatchMode::ALL_AT_ONCE);

//设置单点触控

//this->setTouchMode(Touch::DispatchMode::ONE_BY_ONE);

单点触控触摸监听代码：

	this->setTouchMode(Touch::DispatchMode::ONE_BY_ONE);
	auto oneTouch = EventListenerTouchOneByOne::create();
	oneTouch->onTouchBegan = CC_CALLBACK_2(TouchTest::onTouchBegan,this);
	oneTouch->onTouchMoved = CC_CALLBACK_2(TouchTest::onTouchMoved,this);
	oneTouch->onTouchEnded = CC_CALLBACK_2(TouchTest::onTouchEnded,this);
	oneTouch->onTouchCancelled = CC_CALLBACK_2(TouchTest::onTouchCancelled,this);
	eventDispatcher->addEventListenerWithSceneGraphPriority(oneTouch,this);

多点触控的触摸监听代码：

	//设置多点触控
	this->setTouchMode(Touch::DispatchMode::ALL_AT_ONCE);
	auto listen = EventListenerTouchAllAtOnce::create();
	listen->onTouchesBegan = CC_CALLBACK_2(TouchTest::onTouchesBegan,this);
	listen->onTouchesMoved = CC_CALLBACK_2(TouchTest::onTouchesMoved,this);
	listen->onTouchesEnded = CC_CALLBACK_2(TouchTest::onTouchesEnded,this);
	listen->onTouchesCancelled = CC_CALLBACK_2(TouchTest::onTouchesCancelled,this);
	eventDispatcher->addEventListenerWithSceneGraphPriority(listen,this);

3. 屏蔽触摸向下传递

listen->setSwallowTouches(true);

setSwallowTouches用于设置是否吞没事件，也就是当某个触摸事件回调的时，截断该事件，让它不能继续传递给其他人。