cocos2d-x源码分析-----触摸事件的实现

版本:3.0Beta2 

在android上，触摸事件的原始起点在nativeactivity分发出去。

例如：

cocos2d::Director::getInstance()->getOpenGLView()->handleTouchesBegin(1, &pointerId, &x, &y);

总共有几下几种，在EGLView当中，实现了

    virtual void handleTouchesBegin(int num, int ids[], float xs[], float ys[]);
    virtual void handleTouchesMove(int num, int ids[], float xs[], float ys[]);
    virtual void handleTouchesEnd(int num, int ids[], float xs[], float ys[]);
    virtual void handleTouchesCancel(int num, int ids[], float xs[], float ys[]);

在上面几种方法中，再由EventDispatcher的dispatchEvent方法传递出去。

dispatchEvent不仅分发了触摸事件还有其它事件，比如在drawScene方法中，渲染后，update事件等。

下面主要看触摸事件的实现，

dispatchTouchEvent(static_cast<EventTouch*>(event));

 触摸事件分为两类：oneByone,allAtOnce

oneByone会将Event一个一个传递过去，而allAtOnce会一次性将Event传递过去。Event中包括坐标信息。void EventDispatcher::dispatchTouchEvent(EventTouch* event)

{

    sortEventListeners(EventListenerTouchOneByOne::LISTENER_ID);
    sortEventListeners(EventListenerTouchAllAtOnce::LISTENER_ID);
    
    auto oneByOnelisteners = getListeners(EventListenerTouchOneByOne::LISTENER_ID);
    auto allAtOncelisteners = getListeners(EventListenerTouchAllAtOnce::LISTENER_ID);
    
    // If there aren't any touch listeners, return directly.
    if (nullptr == oneByOnelisteners && nullptr == allAtOncelisteners)
        return;
    
    bool isNeedsMutableSet = (oneByOnelisteners && allAtOncelisteners);
    
    std::vector<Touch*> orignalTouches = event->getTouches();
    std::vector<Touch*> mutableTouches(orignalTouches.size());
    std::copy(orignalTouches.begin(), orignalTouches.end(), mutableTouches.begin());

    //
    // process the target handlers 1st
    //
    if (oneByOnelisteners)
    {
        auto mutableTouchesIter = mutableTouches.begin();
        auto touchesIter = orignalTouches.begin();
        
        for (; touchesIter != orignalTouches.end(); ++touchesIter)
        {
            bool isSwallowed = false;

            auto onTouchEvent = [&](EventListener* l) -> bool { // Return true to break
                EventListenerTouchOneByOne* listener = static_cast<EventListenerTouchOneByOne*>(l);
                
                // Skip if the listener was removed.
                if (!listener->_isRegistered)
                    return false;
             
                event->setCurrentTarget(listener->_node);
                
                bool isClaimed = false;
                std::vector<Touch*>::iterator removedIter;
                
                EventTouch::EventCode eventCode = event->getEventCode();
                
                if (eventCode == EventTouch::EventCode::BEGAN)
                {
                    if (listener->onTouchBegan)
                    {
                        isClaimed = listener->onTouchBegan(*touchesIter, event);
                        if (isClaimed && listener->_isRegistered)
                        {
                            listener->_claimedTouches.push_back(*touchesIter);
                        }
                    }
                }
                else if (listener->_claimedTouches.size() > 0
                         && ((removedIter = std::find(listener->_claimedTouches.begin(), listener->_claimedTouches.end(), *touchesIter)) != listener->_claimedTouches.end()))
                {
                    isClaimed = true;
                    
                    switch (eventCode)
                    {
                        case EventTouch::EventCode::MOVED:
                            if (listener->onTouchMoved)
                            {
                                listener->onTouchMoved(*touchesIter, event);
                            }
                            break;
                        case EventTouch::EventCode::ENDED:
                            if (listener->onTouchEnded)
                            {
                                listener->onTouchEnded(*touchesIter, event);
                            }
                            if (listener->_isRegistered)
                            {
                                listener->_claimedTouches.erase(removedIter);
                            }
                            break;
                        case EventTouch::EventCode::CANCELLED:
                            if (listener->onTouchCancelled)
                            {
                                listener->onTouchCancelled(*touchesIter, event);
                            }
                            if (listener->_isRegistered)
                            {
                                listener->_claimedTouches.erase(removedIter);
                            }
                            break;
                        default:
                            CCASSERT(false, "The eventcode is invalid.");
                            break;
                    }
                }
                
                // If the event was stopped, return directly.
                if (event->isStopped())
                {
                    updateListeners(event);
                    return true;
                }
                
                CCASSERT((*touchesIter)->getID() == (*mutableTouchesIter)->getID(), "");
                
                if (isClaimed && listener->_isRegistered && listener->_needSwallow)
                {
                    if (isNeedsMutableSet)
                    {
                        mutableTouchesIter = mutableTouches.erase(mutableTouchesIter);
                        isSwallowed = true;
                    }
                    return true;
                }
                
                return false;
            };
            
            //
            dispatchEventToListeners(oneByOnelisteners, onTouchEvent);
            if (event->isStopped())
            {
                return;
            }
            
            if (!isSwallowed)
                ++mutableTouchesIter;
        }
    }
    
    //
    // process standard handlers 2nd
    //
    if (allAtOncelisteners && mutableTouches.size() > 0)
    {
        
        auto onTouchesEvent = [&](EventListener* l) -> bool{
            EventListenerTouchAllAtOnce* listener = static_cast<EventListenerTouchAllAtOnce*>(l);
            // Skip if the listener was removed.
            if (!listener->_isRegistered)
                return false;
            
            event->setCurrentTarget(listener->_node);
            
            switch (event->getEventCode())
            {
                case EventTouch::EventCode::BEGAN:
                    if (listener->onTouchesBegan)
                    {
                        listener->onTouchesBegan(mutableTouches, event);
                    }
                    break;
                case EventTouch::EventCode::MOVED:
                    if (listener->onTouchesMoved)
                    {
                        listener->onTouchesMoved(mutableTouches, event);
                    }
                    break;
                case EventTouch::EventCode::ENDED:
                    if (listener->onTouchesEnded)
                    {
                        listener->onTouchesEnded(mutableTouches, event);
                    }
                    break;
                case EventTouch::EventCode::CANCELLED:
                    if (listener->onTouchesCancelled)
                    {
                        listener->onTouchesCancelled(mutableTouches, event);
                    }
                    break;
                default:
                    CCASSERT(false, "The eventcode is invalid.");
                    break;
            }
            
            // If the event was stopped, return directly.
            if (event->isStopped())
            {
                updateListeners(event);
                return true;
            }
            
            return false;
        };
        
        dispatchEventToListeners(allAtOncelisteners, onTouchesEvent);
        if (event->isStopped())
        {
            return;
        }
    }
    
    updateListeners(event);
}

sortEventListeners(EventListenerTouchOneByOne::LISTENER_ID);

sortEventListeners(EventListenerTouchAllAtOnce::LISTENER_ID);

首先根据优先级进行排序。

然后分发给各个node