cocos2d-x学习笔记——EventDispatcher事件分发机制

Eventdispatcher 事件分发机制先创建事件，注册到事件管理中心 _eventdispatcher，通过发布事件得到响应进行回调，完成事件流。_eventdispatcher是Node的属性，通过它管理当前节点（场景、层、精灵等）的所有事件的分发。但它本身是一个单例模式值的引用，在Node的构造函数中，通过Director::getInstance()->getEventdispatcher(); 获取，有了这个属性，就能方便的处理事件。

有五种不同的事件机制：

1. EventListenerTouch 响应触控事件
2. EventListenerKeyboard 响应键盘事件
3. EventListeneracceleration 响应加速器事件
4. EventListenMouse 响应鼠标事件
5. EventListenerCustom 响应自定义的事件

优先级：

1. addEventListenerWithFixedPriority(EventListener* listener,int fixedPriority) 中 fixedPriority 的值越低，则优先级越高。

2. 若优先级相同。Layer 的z顺序高的（绘制于顶部的）层将优于z顺序低的层。这将保证了诸如触碰事件的自顶向下传播

3. 注意：如果是固定优先值的监听器添加到一个节点(addEventListenerWithFixedPriority)，那当这个节点被移除时必须同时手动移除这个监听器，但是添加场景图优先监听器到节点(addEventListenerWithSceneGraPHPriority)就不用这么麻烦，监听器和节点是绑定好的，一旦节点的析构函数被调用，监听器也会同时被移除。

触摸事件：

void EventdispatcherTest::funEventTouch(Sprite* sprite)
{
    this->_eventdispatcher->removeAllEventListeners();

    auto listener = EventListenerTouchOneByOne::create();
    listener->onTouchBegan = CC_CALLBACK_2(EventdispatcherTest::onTouchBeganss,this);
    listener->onTouchMoved = CC_CALLBACK_2(EventdispatcherTest::onTouchMovedss,this);
    listener->onTouchEnded = CC_CALLBACK_2(EventdispatcherTest::onTouchEndedss,this);
    listener->onTouchCancelled = CC_CALLBACK_2(EventdispatcherTest::onTouchCancelledss,this);

    listener->setSwallowtouches(true);//是否向下传递

    this->_eventdispatcher->addEventListenerWithSceneGraPHPriority(listener,sprite);
}

bool EventdispatcherTest::onTouchBeganss(Touch* touch,Event* ev)
{
    auto target = static_cast<Sprite*>(ev->getCurrentTarget());

    Vec2 locationInNode = target->convertToNodeSpace(touch->getLocation());
    Size s = target->getContentSize();
    Rect rect = Rect(0,0,s.width,s.height);
　　//判断触摸区域是否在目标上
    if (rect.containsPoint(locationInNode))
    {
        label->setString("onTouchBegan......");
        target->setopacity(180);
        return true;
    }
    return false;
}
void EventdispatcherTest::onTouchMovedss(Touch* touch,Event* ev)
{
    auto target = static_cast<Sprite*>(ev->getCurrentTarget());
    target->setPosition(target->getPosition() + touch->getDelta());
    label->setString("onTouchMoved......");
}
void EventdispatcherTest::onTouchEndedss(Touch* touch,Event* ev)
{
    auto target = static_cast<Sprite*>(ev->getCurrentTarget());
    target->setopacity(255);
    label->setString("onTouchEnded......");
}
void EventdispatcherTest::onTouchCancelledss(Touch* touch,Event* ev)
{
    label->setString("onTouchCancelled......");
}

键盘事件：

void EventdispatcherTest::funEventKeyboard()
{
    this->_eventdispatcher->removeAllEventListeners();

    auto listener = EventListenerKeyboard::create();
    listener->onKeypressed = CC_CALLBACK_2(EventdispatcherTest::onKeypressedss,this);
    listener->onkeyreleased = CC_CALLBACK_2(EventdispatcherTest::onkeyreleasedss,this);
    this->_eventdispatcher->addEventListenerWithSceneGraPHPriority(listener,this);
}

void EventdispatcherTest::onKeypressedss(EventKeyboard::KeyCode keycode,Event* ev)
{
    char txt[100] = {}; sprintf_s(txt,"key %d is pressed!",(int)keycode); label->setString(txt); } void EventdispatcherTest::onkeyreleasedss(EventKeyboard::KeyCode keycode,Event* ev) { label->setString("key is Released!"); }

鼠标事件：

void EventdispatcherTest::funEventMouse(Sprite* sprite)
{
    this->_eventdispatcher->removeAllEventListeners();

    auto listener = EventListenerMouse::create();
    listener->onMouseDown = CC_CALLBACK_1(EventdispatcherTest::onMouseDownss,this);
    listener->onMouseMove = CC_CALLBACK_1(EventdispatcherTest::onMouseMovess,this);
    listener->onmouseup = CC_CALLBACK_1(EventdispatcherTest::onmouseupss,this);
    listener->onMouseScroll = CC_CALLBACK_1(EventdispatcherTest::onMouseScrollss,sprite);
}

void EventdispatcherTest::onMouseDownss(Event* ev)
{
    label->setString("onMouseDown!");
}
void EventdispatcherTest::onMouseMovess(Event* ev)
{
    label->setString("onMouseMove!");
}
void EventdispatcherTest::onmouseupss(Event* ev)
{
    label->setString("onmouseup!");
}
void EventdispatcherTest::onMouseScrollss(Event* ev)
{
    label->setString("onMouseScroll!");
}

自定义事件：

//自定义事件
funEventCustom();
//2秒发派一次自定义事件，测试
scheduleOnce(schedule_selector(EventdispatcherTest::dispatcherCustomEvents),2.0f);

void EventdispatcherTest::funEventCustom()
{
    auto listener = EventListenerCustom::create("custom_event_1",CC_CALLBACK_1(EventdispatcherTest::onEventCustom,this));
    this->_eventdispatcher->addEventListenerWithFixedPriority(listener,1);//添加到事件分發器
}

void EventdispatcherTest::dispatcherCustomEvents(float at)
{
    //派發事件custom_event_1 事件內容為字符串custom event test!
    this->_eventdispatcher->dispatchCustomEvent("custom_event_1","custom event test!");
}

void EventdispatcherTest::onEventCustom(EventCustom* event)
{
    auto data = static_cast<char*>(event->getUserData());
    label->setString(data);
}

加速器事件：

　除了触摸，移动设备上一个很重要的输入源是设备的方向，因此大多数设备都配备了加速计，用于测量设备静止或匀速运动时所受到的重力方向。

重力感应来自移动设备的加速计，通常支持X,Y和Z三个方向的加速度感应，所以又称为三向加速计。在实际应用中，可以根据3个方向的力度大小来计算手机倾斜的角度或方向。

加速计监听器EventListeneracceleration，其静态create方法中有个acceleration的参数。acceleration是一个类，包含了加速计获得的3个方向的加速度。

void EventdispatcherTest::funEventacceleration()
{
    //启动硬件设备
    Device::setAccelerometerEnabled(true); 

    auto listener = EventListeneracceleration::create(CC_CALLBACK_2(EventdispatcherTest::onacceleration,this));
    this->_eventdispatcher->addEventListenerWithSceneGraPHPriority(listener,this);
}

void EventdispatcherTest::onacceleration(acceleration* acc,Event* event)
{
    char str[100]={};
    sprintf_s(str,"x:%2d,y:%2d,z:%2d,timestamp:%2d",acc->x,acc->y,acc->z,acc->timestamp);
    log(str);
}