axmol/cocos/base/CCEventListener.h

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 Copyright (c) 2013-2016 Chukong Technologies Inc.
 Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

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#ifndef __CCEVENTLISTENER_H__
#define __CCEVENTLISTENER_H__

#include <functional>
#include <string>
#include <memory>

#include "platform/CCPlatformMacros.h"
#include "base/CCRef.h"

/**
 * @addtogroup base
 * @{
 */

NS_CC_BEGIN

class Event;
class Node;

/** @class EventListener
 *  @brief The base class of event listener.
 *  If you need custom listener which with different callback, you need to inherit this class.
 *  For instance, you could refer to EventListenerAcceleration, EventListenerKeyboard, EventListenerTouchOneByOne,
 * EventListenerCustom.
 */
class CC_DLL EventListener : public Ref
{
public:
    /** Type Event type.*/
    enum class Type
    {
        UNKNOWN,
        TOUCH_ONE_BY_ONE,
        TOUCH_ALL_AT_ONCE,
        KEYBOARD,
        MOUSE,
        ACCELERATION,
        FOCUS,
        GAME_CONTROLLER,
        CUSTOM
    };

    typedef std::string ListenerID;

    CC_CONSTRUCTOR_ACCESS :
        /**
         * Constructor
         * @js ctor
         */
        EventListener();

    /**
     * Initializes event with type and callback function
     * @js NA
     */
    bool init(Type t, const ListenerID& listenerID, const std::function<void(Event*)>& callback);

public:
    /** Destructor.
     * @js NA
     */
    virtual ~EventListener();

    /** Checks whether the listener is available.
     *
     * @return True if the listener is available.
     */
    virtual bool checkAvailable() = 0;

    /** Clones the listener, its subclasses have to override this method.
     */
    virtual EventListener* clone() = 0;

    /** Enables or disables the listener.
     * @note Only listeners with `enabled` state will be able to receive events.
     *        When an listener was initialized, it's enabled by default.
     *        An event listener can receive events when it is enabled and is not paused.
     *        paused state is always false when it is a fixed priority listener.
     *
     * @param enabled True if enables the listener.
     */
    void setEnabled(bool enabled) { _isEnabled = enabled; }

    /** Checks whether the listener is enabled.
     *
     * @return True if the listener is enabled.
     */
    bool isEnabled() const { return _isEnabled; }

protected:
    /** Sets paused state for the listener
     *  The paused state is only used for scene graph priority listeners.
     *  `EventDispatcher::resumeAllEventListenersForTarget(node)` will set the paused state to `true`,
     *  while `EventDispatcher::pauseAllEventListenersForTarget(node)` will set it to `false`.
     *  @note 1) Fixed priority listeners will never get paused. If a fixed priority doesn't want to receive events,
     *           call `setEnabled(false)` instead.
     *        2) In `Node`'s onEnter and onExit, the `paused state` of the listeners which associated with that node
     * will be automatically updated.
     */
    void setPaused(bool paused) { _paused = paused; }

    /** Checks whether the listener is paused */
    bool isPaused() const { return _paused; }

    /** Marks the listener was registered by EventDispatcher */
    void setRegistered(bool registered) { _isRegistered = registered; }

    /** Checks whether the listener was registered by EventDispatcher */
    bool isRegistered() const { return _isRegistered; }

    /** Gets the type of this listener
     *  @note It's different from `EventType`, e.g. TouchEvent has two kinds of event listeners - EventListenerOneByOne,
     * EventListenerAllAtOnce
     */
    Type getType() const { return _type; }

    /** Gets the listener ID of this listener
     *  When event is being dispatched, listener ID is used as key for searching listeners according to event type.
     */
    const ListenerID& getListenerID() const { return _listenerID; }

    /** Sets the fixed priority for this listener
     *  @note This method is only used for `fixed priority listeners`, it needs to access a non-zero value.
     *  0 is reserved for scene graph priority listeners
     */
    void setFixedPriority(int fixedPriority) { _fixedPriority = fixedPriority; }

    /** Gets the fixed priority of this listener
     *  @return 0 if it's a scene graph priority listener, non-zero for fixed priority listener
     */
    int getFixedPriority() const { return _fixedPriority; }

    /** Sets the node associated with this listener */
    void setAssociatedNode(Node* node) { _node = node; }

    /** Gets the node associated with this listener
     *  @return nullptr if it's a fixed priority listener, otherwise return non-nullptr
     */
    Node* getAssociatedNode() const { return _node; }

    ///////////////
    // Properties
    //////////////
    std::function<void(Event*)> _onEvent;  /// Event callback function

    Type _type;              /// Event listener type
    ListenerID _listenerID;  /// Event listener ID
    bool _isRegistered;      /// Whether the listener has been added to dispatcher.

    int _fixedPriority;  // The higher the number, the higher the priority, 0 is for scene graph base priority.
    Node* _node;         // scene graph based priority
    bool _paused;        // Whether the listener is paused
    bool _isEnabled;     // Whether the listener is enabled
    friend class EventDispatcher;
};

NS_CC_END

// end of base group
/// @}

#endif  // __CCEVENTLISTENER_H__