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Cocos2d-X学习之Ref类

先看看定义该类的头文件——CCRef.h

  1 /****************************************************************************
  2 Copyright (c) 2010-2012 cocos2d-x.org
  3 Copyright (c) 2013-2014 Chukong Technologies
  4 
  5 http://www.cocos2d-x.org
  6 
  7 Permission is hereby granted, free of charge, to any person obtaining a copy
  8 of this software and associated documentation files (the "Software"), to deal
  9 in the Software without restriction, including without limitation the rights
 10 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 11 copies of the Software, and to permit persons to whom the Software is
 12 furnished to do so, subject to the following conditions:
 13 
 14 The above copyright notice and this permission notice shall be included in
 15 all copies or substantial portions of the Software.
 16 
 17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 20 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 22 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 23 THE SOFTWARE.
 24 ****************************************************************************/
 25 
 26 #ifndef __CCREF_H__
 27 #define __CCREF_H__
 28 
 29 #include "CCPlatformMacros.h"
 30 #include "ccConfig.h"
 31 
 32 NS_CC_BEGIN
 33 
 34 /**
 35  * @addtogroup base_nodes
 36  * @{
 37  */
 38 
 39 class Ref;
 40 
 41 /** Interface that defines how to clone an Ref */
 42 class CC_DLL Clonable
 43 {
 44 public:
 45     /** returns a copy of the Ref */
 46     virtual Clonable* clone() const = 0;
 47     /**
 48      * @js NA
 49      * @lua NA
 50      */
 51     virtual ~Clonable() {};
 52 
 53     /** returns a copy of the Ref.
 54      @deprecated Use clone() instead
 55      */
 56     CC_DEPRECATED_ATTRIBUTE Ref* copy() const
 57     {
 58         // use "clone" instead
 59         CC_ASSERT(false);
 60         return nullptr;
 61     }
 62 };
 63 
 64 class CC_DLL Ref
 65 {
 66 public:
 67     /**
 68      * Retains the ownership.
 69      *
 70      * This increases the Ref‘s reference count.
 71      *
 72      * @see release, autorelease
 73      * @js NA
 74      */
 75     void retain();
 76     
 77     /**
 78      * Release the ownership immediately.
 79      *
 80      * This decrements the Ref‘s reference count.
 81      *
 82      * If the reference count reaches 0 after the descrement, this Ref is
 83      * destructed.
 84      *
 85      * @see retain, autorelease
 86      * @js NA
 87      */
 88     void release();
 89 
 90     /**
 91      * Release the ownership sometime soon automatically.
 92      *
 93      * This descrements the Ref‘s reference count at the end of current
 94      * autorelease pool block.
 95      *
 96      * If the reference count reaches 0 after the descrement, this Ref is
 97      * destructed.
 98      *
 99      * @returns The Ref itself.
100      *
101      * @see AutoreleasePool, retain, release
102      * @js NA
103      * @lua NA
104      */
105     Ref* autorelease();
106 
107     /**
108      * Returns the Ref‘s current reference count.
109      *
110      * @returns The Ref‘s reference count.
111      * @js NA
112      */
113     unsigned int getReferenceCount() const;
114     
115 protected:
116     /**
117      * Constructor
118      *
119      * The Ref‘s reference count is 1 after construction.
120      * @js NA
121      */
122     Ref();
123     
124 public:
125     /**
126      * @js NA
127      * @lua NA
128      */
129     virtual ~Ref();
130     
131 protected:
132     /// count of references
133     unsigned int _referenceCount;
134     
135     friend class AutoreleasePool;
136     
137 #if CC_ENABLE_SCRIPT_BINDING
138 public:
139     /// object id, ScriptSupport need public _ID
140     unsigned int        _ID;
141     /// Lua reference id
142     int                 _luaID;
143 #endif
144 };
145 
146 class Node;
147 
148 typedef void (Ref::*SEL_CallFunc)();
149 typedef void (Ref::*SEL_CallFuncN)(Node*);
150 typedef void (Ref::*SEL_CallFuncND)(Node*, void*);
151 typedef void (Ref::*SEL_CallFuncO)(Ref*);
152 typedef void (Ref::*SEL_MenuHandler)(Ref*);
153 typedef void (Ref::*SEL_SCHEDULE)(float);
154 
155 #define callfunc_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFunc>(&_SELECTOR)
156 #define callfuncN_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFuncN>(&_SELECTOR)
157 #define callfuncND_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFuncND>(&_SELECTOR)
158 #define callfuncO_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFuncO>(&_SELECTOR)
159 #define menu_selector(_SELECTOR) static_cast<cocos2d::SEL_MenuHandler>(&_SELECTOR)
160 #define schedule_selector(_SELECTOR) static_cast<cocos2d::SEL_SCHEDULE>(&_SELECTOR)
161 
162 // end of base_nodes group
163 /// @}
164 
165 NS_CC_END
166 
167 #endif // __CCREF_H__
CCRef.h

头文件中主要有以下内容:

  1、Clonable接口的定义;

  2、Ref类的定义;

  3、六个回调函数宏定义(包括相应类型定义);

 

Clonable接口成员如下:

由接口的名称含义就可以知道,该接口的主要作用就是克隆Ref类的成员,由于该头文件之前还未有Ref类的定义,而接口函数中有使用了Ref,所以又一个Ref类的前向引用(C++好像有这么个概念)

clone()和copy()均可以完成Ref对象的克隆,不过新版本中copy()已经废弃,建议使用clone();

 

Ref类的函数成员如下:

retain();每调用一次引用次数+1;

release();每调用一次引用次数-1;

getReferenceCount();获取引用的次数;

autorelease();每调用一次autorelease pool 中的Ref引用数-1;

Ref类的数据成员中,有一个无符号整型成员 _referenceCount,用来记录引用次数的;

值得注意的是Ref类还有一个友元类AutoreleasePool

 

回调函数及相应类型定义

typedef void (Ref::*SEL_CallFunc)();                            //
typedef void (Ref::*SEL_CallFuncN)(Node*);
typedef void (Ref::*SEL_CallFuncND)(Node*, void*);
typedef void (Ref::*SEL_CallFuncO)(Ref*);
typedef void (Ref::*SEL_MenuHandler)(Ref*);
typedef void (Ref::*SEL_SCHEDULE)(float);

#define callfunc_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFunc>(&_SELECTOR)
#define callfuncN_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFuncN>(&_SELECTOR)
#define callfuncND_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFuncND>(&_SELECTOR)
#define callfuncO_selector(_SELECTOR) static_cast<cocos2d::SEL_CallFuncO>(&_SELECTOR)
#define menu_selector(_SELECTOR) static_cast<cocos2d::SEL_MenuHandler>(&_SELECTOR)
#define schedule_selector(_SELECTOR) static_cast<cocos2d::SEL_SCHEDULE>(&_SELECTOR)

关于回调函数宏定义及类型定义,下篇中会详细说明,因为引擎中涉及到太多太多,而且还不是很好理解。