Cocos2d-X學習之Ref類

先看看定義該類的頭文件——CCRef.h

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  2 Copyright (c) 2010-2012 cocos2d-x.org
  3 Copyright (c) 2013-2014 Chukong Technologies
  4 
  5 http://www.cocos2d-x.org
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  8 of this software and associated documentation files (the "Software"), to deal
  9 in the Software without restriction, including without limitation the rights
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 11 copies of the Software, and to permit persons to whom the Software is
 12 furnished to do so, subject to the following conditions:
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 14 The above copyright notice and this permission notice shall be included in
 15 all copies or substantial portions of the Software.
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 18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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 21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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 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

頭文件中主要有如下內容：

　　一、Clonable接口的定義；

　　二、Ref類的定義；

　　三、六個回調函數宏定義（包括相應類型定義）；

 

Clonable接口成員以下：

由接口的名稱含義就能夠知道，該接口的主要做用就是克隆Ref類的成員，因爲該頭文件以前還未有Ref類的定義，而接口函數中有使用了Ref，因此又一個Ref類的前向引用（C++好像有這麼個概念）

clone()和copy()都可以完成Ref對象的克隆，不過新版本中copy()已經廢棄，建議使用clone();

 

Ref類的函數成員以下：

retain()；每調用一次引用次數+1；

release()；每調用一次引用次數-1；

getReferenceCount()；獲取引用的次數；

autorelease()；每調用一次autorelease pool 中的Ref引用數-1；

Ref類的數據成員中，有一個無符號整型成員 _referenceCount，用來記錄引用次數的；

值得注意的是Ref類還有一個友元類AutoreleasePool；

 

回調函數及相應類型定義

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)

關於回調函數宏定義及類型定義，下篇中會詳細說明，由於引擎中涉及到太多太多，並且還不是很好理解。