cocos2dx.3.x之重要类分析(4)——Layer

Layer

继承自Node

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Layer类是Node类的一个子类，它实现了触屏事件代理（TouchEventsDelegate）协议。

它可以实现Node类的所有功能,并且它还添加了以下这些新功能：

• 它可以接收iPhone触屏事件
• 它可以接收加速度传感器输入

class CC_DLL Layer : public Node
{
public:    
    /** creates a fullscreen black layer */
    static Layer *create();

    virtual bool onTouchBegan(Touch *touch, Event *unused_event);
    virtual void onTouchMoved(Touch *touch, Event *unused_event);
    virtual void onTouchEnded(Touch *touch, Event *unused_event);
    virtual void onTouchCancelled(Touch *touch, Event *unused_event);

    virtual void onTouchesBegan(const std::vector& touches, Event *unused_event);
    virtual void onTouchesMoved(const std::vector& touches, Event *unused_event);
    virtual void onTouchesEnded(const std::vector& touches, Event *unused_event);
    virtual void onTouchesCancelled(const std::vector&touches, Event *unused_event);
  
    virtual void onAcceleration(Acceleration* acc, Event* unused_event);

  
    void Layer::registerWithTouchDispatcher()
    {
    TouchDispatcher::sharedDispatcher()->addTargetedDelegate(this,INT_MIN+1,true);
    }
   
  
    CC_DEPRECATED_ATTRIBUTE bool isTouchEnabled() const;
    CC_DEPRECATED_ATTRIBUTE void setTouchEnabled(bool value);
    
    CC_DEPRECATED_ATTRIBUTE virtual void setTouchMode(Touch::DispatchMode mode);
    CC_DEPRECATED_ATTRIBUTE virtual Touch::DispatchMode getTouchMode() const;

    /** swallowsTouches of the touch events. Default is true */
    CC_DEPRECATED_ATTRIBUTE virtual void setSwallowsTouches(bool swallowsTouches);
    CC_DEPRECATED_ATTRIBUTE virtual bool isSwallowsTouches() const;

    /** whether or not it will receive Accelerometer events
    You can enable / disable accelerometer events with this property.
    @since v0.8.1
    */
    CC_DEPRECATED_ATTRIBUTE virtual bool isAccelerometerEnabled() const;
    CC_DEPRECATED_ATTRIBUTE virtual void setAccelerometerEnabled(bool value);
    CC_DEPRECATED_ATTRIBUTE virtual void setAccelerometerInterval(double interval);

    /** whether or not it will receive keyboard or keypad events
    You can enable / disable accelerometer events with this property.
    it's new in cocos2d-x
    */

    CC_DEPRECATED_ATTRIBUTE virtual bool isKeyboardEnabled() const;
    CC_DEPRECATED_ATTRIBUTE virtual void setKeyboardEnabled(bool value);

    /** Please use onKeyPressed instead. */
    CC_DEPRECATED_ATTRIBUTE virtual void keyPressed(int keyCode) final {};
    
    /** Please use onKeyReleased instead. */
    CC_DEPRECATED_ATTRIBUTE virtual void keyReleased(int keyCode) final {};

    /* Callback function should not be deprecated, it will generate lots of warnings.
    Since 'setKeyboardEnabled' was deprecated, it will make warnings if developer overrides onKeyXXX and invokes setKeyboardEnabled(true) instead of using EventDispatcher::addEventListenerWithXXX.
    */
    virtual void onKeyPressed(EventKeyboard::KeyCode keyCode, Event* event);
    virtual void onKeyReleased(EventKeyboard::KeyCode keyCode, Event* event);

    CC_DEPRECATED_ATTRIBUTE virtual bool isKeypadEnabled() const final { return _keyboardEnabled; }
    CC_DEPRECATED_ATTRIBUTE virtual void setKeypadEnabled(bool value);

    /** @deprecated Please override onKeyReleased and check the keycode of KeyboardEvent::KeyCode::Menu(KEY_BACKSPACE) instead. */
    CC_DEPRECATED_ATTRIBUTE virtual void keyBackClicked() final {};
    CC_DEPRECATED_ATTRIBUTE virtual void keyMenuClicked() final {};

    // Overrides
    virtual std::string getDescription() const override;

CC_CONSTRUCTOR_ACCESS:
    Layer();
    virtual ~Layer();

    virtual bool init() override;

protected:
    //add the api for avoid use deprecated api
    CC_DEPRECATED_ATTRIBUTE void _addTouchListener() {}

    CC_DEPRECATED_ATTRIBUTE void addTouchListener() {}
    CC_DEPRECATED_ATTRIBUTE int executeScriptTouchHandler(EventTouch::EventCode eventType, Touch* touch, Event* event);
    CC_DEPRECATED_ATTRIBUTE int executeScriptTouchesHandler(EventTouch::EventCode eventType, const std::vector& touches, Event* event);

    bool _touchEnabled;
    bool _accelerometerEnabled;
    bool _keyboardEnabled;
    EventListener* _touchListener;
    EventListenerKeyboard* _keyboardListener;
    EventListenerAcceleration* _accelerationListener;

    Touch::DispatchMode _touchMode;
    bool _swallowsTouches;

private:
    CC_DISALLOW_COPY_AND_ASSIGN(Layer);

};

查看以上代码可以发现 Layer层的一个主要功能 就是人和界面交互的相关设置 单点触摸监听 多点触摸监听 加速器 重力感应等等

灵活的运用layer可以用于制作很多东西 如弹出菜单 提示等