在cocos2d-x 2.x版本中,相信大家都抱怨过其中的触摸机制;在3.0版本中,采用了全新的触摸事件处理机制。
在官方的文档中:点击打开链接 这篇文章有对新的事件分发机制的介绍。
下面,我将通过引擎中自带的sample来探索一下这个新的触摸事件处理机制。
注:例子来自Test cpp/NewEventDispatcherTest
一、例子1
(1)创建三个精灵
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auto sprite1 = Sprite::create("Images/CyanSquare.png");
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sprite1->setPosition(origin+Point(size.width/2, size.height/2) + Point(-80, 80));
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addChild(sprite1, 10);
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auto sprite2 = Sprite::create("Images/MagentaSquare.png");
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sprite2->setPosition(origin+Point(size.width/2, size.height/2));
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addChild(sprite2, 20);
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auto sprite3 = Sprite::create("Images/YellowSquare.png");
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sprite3->setPosition(Point(0, 0));
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sprite2->addChild(sprite3, 1);
(2)创建一个单点触摸事件监听器,处理触摸事件逻辑
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auto listener1 = EventListenerTouchOneByOne::create();
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listener1->setSwallowTouches(true);
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listener1->onTouchBegan = [](Touch* touch, Event* event){
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auto target = static_cast<Sprite*>(event->getCurrentTarget());
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Point locationInNode = target->convertToNodeSpace(touch->getLocation());
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Size s = target->getContentSize();
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Rect rect = Rect(0, 0, s.width, s.height);
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if (rect.containsPoint(locationInNode))
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{
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log("sprite began... x = %f, y = %f", locationInNode.x, locationInNode.y);
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target->setOpacity(180);
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return true;
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}
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return false;
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};
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listener1->onTouchMoved = [](Touch* touch, Event* event){
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auto target = static_cast<Sprite*>(event->getCurrentTarget());
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target->setPosition(target->getPosition() + touch->getDelta());
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};
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listener1->onTouchEnded = [=](Touch* touch, Event* event){
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auto target = static_cast<Sprite*>(event->getCurrentTarget());
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log("sprite onTouchesEnded.. ");
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target->setOpacity(255);
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if (target == sprite2)
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{
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sprite1->setZOrder(100);
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}
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else if(target == sprite1)
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{
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sprite1->setZOrder(0);
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}
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};
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_eventDispatcher->addEventListenerWithSceneGraphPriority(listener1, sprite1);
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_eventDispatcher->addEventListenerWithSceneGraphPriority(listener1->clone(), sprite2);
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_eventDispatcher->addEventListenerWithSceneGraphPriority(listener1->clone(), sprite3);
①其中的触摸监听类型为:EventListenerTouchOneByOne 表示的是单点触摸;而EventListenerTouchAllAtOnce 表示的就是多点触摸。
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class EventListenerTouchOneByOne : public EventListener
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{
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public:
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static const std::string LISTENER_ID;
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static EventListenerTouchOneByOne* create();
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virtual ~EventListenerTouchOneByOne();
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void setSwallowTouches(bool needSwallow);
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virtual EventListenerTouchOneByOne* clone() override;
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virtual bool checkAvailable() override;
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public:
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std::function<bool(Touch*, Event*)> onTouchBegan;
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std::function<void(Touch*, Event*)> onTouchMoved;
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std::function<void(Touch*, Event*)> onTouchEnded;
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std::function<void(Touch*, Event*)> onTouchCancelled;
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private:
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EventListenerTouchOneByOne();
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bool init();
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std::vector<Touch*> _claimedTouches;
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bool _needSwallow;
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friend class EventDispatcher;
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};
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class EventListenerTouchAllAtOnce : public EventListener
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{
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public:
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static const std::string LISTENER_ID;
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static EventListenerTouchAllAtOnce* create();
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virtual ~EventListenerTouchAllAtOnce();
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virtual EventListenerTouchAllAtOnce* clone() override;
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virtual bool checkAvailable() override;
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public:
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std::function<void(const std::vector<Touch*>&, Event*)> onTouchesBegan;
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std::function<void(const std::vector<Touch*>&, Event*)> onTouchesMoved;
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std::function<void(const std::vector<Touch*>&, Event*)> onTouchesEnded;
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std::function<void(const std::vector<Touch*>&, Event*)> onTouchesCancelled;
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private:
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EventListenerTouchAllAtOnce();
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bool init();
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private:
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friend class EventDispatcher;
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};
看起来很是熟悉吧,和cocos2dx 2.x 版本中的 target touch 和 standard touch 差不多吧!只是使用的形式不太一样罢了。还有在3.0版本中,不需要注册触摸事件代理delegate了。
② _eventDispatcher
事件监听器包含以下几种:
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触摸事件 (EventListenerTouch)
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键盘响应事件 (EventListenerKeyboard)
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加速记录事件 (EventListenerAcceleration)
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鼠标响应事件 (EventListenerMouse)
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自定义事件 (EventListenerCustom)
以上事件监听器统一由 _eventDispatcher
来进行管理。
_eventDispatcher 是 Node 的属性,通过它管理当前节点(如
场景 、层、精灵等 )的所有事件分发情况。但是它本身是一个单例模式值的引用,在 Node 构造函数中,通过 "Director::getInstance()->getEventDispatcher();" 获取,有了这个属性,我们能更为方便的调用。
有两种方式将 事件监听器 listener1 添加到 事件调度器_eventDispatcher 中:
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void EventDispatcher::addEventListenerWithSceneGraphPriority(EventListener* listener, Node* node)
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void EventDispatcher::addEventListenerWithFixedPriority(EventListener* listener, int fixedPriority)
看看这两种方式的实现代码:
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void EventDispatcher::addEventListenerWithSceneGraphPriority(EventListener* listener, Node* node)
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{
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CCASSERT(listener && node, "Invalid parameters.");
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CCASSERT(!listener->isRegistered(), "The listener has been registered.");
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if (!listener->checkAvailable())
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return;
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listener->setSceneGraphPriority(node);
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listener->setFixedPriority(0);
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listener->setRegistered(true);
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addEventListener(listener);
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}
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void EventDispatcher::addEventListenerWithFixedPriority(EventListener* listener, int fixedPriority)
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{
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CCASSERT(listener, "Invalid parameters.");
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CCASSERT(!listener->isRegistered(), "The listener has been registered.");
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CCASSERT(fixedPriority != 0, "0 priority is forbidden for fixed priority since it's used for scene graph based priority.");
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if (!listener->checkAvailable())
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return;
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listener->setSceneGraphPriority(nullptr);
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listener->setFixedPriority(fixedPriority);
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listener->setRegistered(true);
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listener->setPaused(false);
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addEventListener(listener);
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}
从中我们可以知道: 其中的 addEventListenerWithSceneGraphPriority 的事件监听器优先级是 0 ;而且在 addEventListenerWithFixedPriority 中的事件监听器的优先级不可以设置为 0,因为这个是保留给 SceneGraphPriority
使用的。
注意:(1) 这里当我们再次使用 listener1 的时候,需要使用 clone()
方法创建一个新的克隆,因为在使用 addEventListenerWithSceneGraphPriority
或者 addEventListenerWithFixedPriority
方法时,会对当前使用的事件监听器添加一个已注册的标记,这使得它不能够被添加多次。
看看clone()方法的代码:
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EventListenerTouchOneByOne* EventListenerTouchOneByOne::clone()
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{
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auto ret = new EventListenerTouchOneByOne();
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if (ret && ret->init())
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{
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ret->autorelease();
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ret->onTouchBegan = onTouchBegan;
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ret->onTouchMoved = onTouchMoved;
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ret->onTouchEnded = onTouchEnded;
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ret->onTouchCancelled = onTouchCancelled;
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ret->_claimedTouches = _claimedTouches;
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ret->_needSwallow = _needSwallow;
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}
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else
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{
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CC_SAFE_DELETE(ret);
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}
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return ret;
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}
(2)另外,有一点非常重要,FixedPriority listener添加完之后需要手动remove,而SceneGraphPriority listener是跟node绑定的,在node的析构函数中会被移除。
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_eventDispatcher->cleanTarget(this);
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CC_SAFE_RELEASE(_eventDispatcher);
二、例子2
在上面的例子中,使用的是 addEventListenerWithSceneGraphPriority 添加触摸监听器,也就是单点触摸。其结点的触摸优先级都是相同的 0 。那么上层的结点 是比 下层的结点 先处理触摸事件的。
下面看看如何使用 addEventListenerWithFixedPriority 自定义结点的触摸优先级。
(1)首先自定义精灵,其中可以设置精灵接受触摸的优先级。
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class TouchableSpriteWithFixedPriority : public Sprite
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{
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public:
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CREATE_FUNC(TouchableSpriteWithFixedPriority);
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TouchableSpriteWithFixedPriority()
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: _listener(nullptr)
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, _fixedPriority(0)
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, _useNodePriority(false)
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{
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}
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void setPriority(int fixedPriority) { _fixedPriority = fixedPriority; _useNodePriority = false; };
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void setPriorityWithThis(bool useNodePriority) { _useNodePriority = useNodePriority; _fixedPriority = true; }
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void onEnter() override
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{
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Sprite::onEnter();
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auto listener = EventListenerTouchOneByOne::create();
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listener->setSwallowTouches(true);
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listener->onTouchBegan = [=](Touch* touch, Event* event){
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Point locationInNode = this->convertToNodeSpace(touch->getLocation());
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Size s = this->getContentSize();
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Rect rect = Rect(0, 0, s.width, s.height);
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if (rect.containsPoint(locationInNode))
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{
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this->setColor(Color3B::RED);
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return true;
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}
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return false;
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};
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listener->onTouchMoved = [=](Touch* touch, Event* event){
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};
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listener->onTouchEnded = [=](Touch* touch, Event* event){
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this->setColor(Color3B::WHITE);
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};
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if (_useNodePriority)
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{
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_eventDispatcher->addEventListenerWithSceneGraphPriority(listener, this);
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}
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else
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{
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_eventDispatcher->addEventListenerWithFixedPriority(listener, _fixedPriority);
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}
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_listener = listener;
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}
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void onExit() override
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{
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_eventDispatcher->removeEventListener(_listener);
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Sprite::onExit();
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}
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private:
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EventListener* _listener;
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int _fixedPriority;
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bool _useNodePriority;
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};
(2)分别创建三个精灵,可以自定义设置每一个精灵的触摸优先级。注意:优先级值小的,接受触摸优先。
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auto sprite1 = TouchableSpriteWithFixedPriority::create();
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sprite1->setTexture("Images/CyanSquare.png");
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sprite1->setPriority(30);
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sprite1->setPosition(origin+Point(size.width/2, size.height/2) + Point(-80, 40));
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addChild(sprite1, 10);
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auto sprite2 = TouchableSpriteWithFixedPriority::create();
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sprite2->setTexture("Images/MagentaSquare.png");
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sprite2->setPriority(20);
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sprite2->setPosition(origin+Point(size.width/2, size.height/2));
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addChild(sprite2, 20);
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auto sprite3 = TouchableSpriteWithFixedPriority::create();
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sprite3->setTexture("Images/YellowSquare.png");
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sprite3->setPriority(10);
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sprite3->setPosition(Point(0, 0));
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sprite2->addChild(sprite3, 1);
三、删除触摸监听器的方法:
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void removeEventListener(EventListener* listener);
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void removeEventListeners(EventListener::Type listenerType);
前者只是删除某一个事件监听器,而后者是删除某一类事件监听器(使用了 clone 克隆)