解释cocos2dx的HelloWorldScene的类

转自：http://www.cnblogs.com/linux-ios/archive/2013/03/27/2985546.html

感谢原博主分享，随喜赞叹！

在之前的AppDelegate中的

//这里可以换场景de // create a scene. it's an autorelease object CCScene *pScene = HelloWorld::scene();   // run pDirector->runWithScene(pScene);

 默认导演将Hello World 这个场景展示在模拟器中

注释HelloWorldScene.h

<span style="color: #000000;">#ifndef __HELLOWORLD_SCENE_H__ #define __HELLOWORLD_SCENE_H__   #include "cocos2d.h"   class HelloWorld : public cocos2d::CCLayer { public:     // Method 'init' in cocos2d-x returns bool, instead of 'id' in cocos2d-iphone (an object pointer)     //初始化函数     virtual bool init();       // there's no 'id' in cpp, so we recommend to return the class instance pointer     //静态创建函数     static cocos2d::CCScene* scene();           // a selector callback     //menu 菜单的一个回调函数  用于响应CCMenuItemImage     void menuCloseCallback(CCObject* pSender);       // preprocessor macro for "static create()" constructor ( node() deprecated )     //备注1     CREATE_FUNC(HelloWorld); };   #endif // __HELLOWORLD_SCENE_H__ </span>

 HelloWorldScene.cpp注释

#include "HelloWorldScene.h"
#include "SimpleAudioEngine.h"

using namespace cocos2d;
using namespace CocosDenshion;

CCScene* HelloWorld::scene()
{
    //创建一个场景
    // 'scene' is an autorelease object
    CCScene *scene = CCScene::create();
    //创建一个HelloWorld的层
    // 'layer' is an autorelease object
    HelloWorld *layer = HelloWorld::create();
 //将层放到场景中去
    // add layer as a child to scene
    scene->addChild(layer);

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{//  调用父类初始化函数
    //////////////////////////////
    // 1. super init first
    if ( !CCLayer::init() )
    {
        return false;
    }

    /////////////////////////////
    // 2. add a menu item with "X" image, which is clicked to quit the program
    //    you may modify it.

    // add a "close" icon to exit the progress. it's an autorelease object
     //将一个相片创建菜单项 并调用方法menuCloseCallback
    CCMenuItemImage *pCloseItem = CCMenuItemImage::create(
                                        "CloseNormal.png",
                                        "CloseSelected.png",
                                        this,
                                        menu_selector(HelloWorld::menuCloseCallback) );
    //开关相片的位置
    pCloseItem->setPosition( ccp(CCDirector::sharedDirector()->getWinSize().width - 20, 20) );

    //将一个已经创建好的菜单项加入菜单中 并声称一个菜单对象的实例
    // create menu, it's an autorelease object
    CCMenu* pMenu = CCMenu::create(pCloseItem, NULL);
     // 设置菜单的位置
    pMenu->setPosition( CCPointZero );
    // 将菜单加入当前的layer里  并设置z轴为1
    this->addChild(pMenu, 1);

    /////////////////////////////
    // 3. add your codes below...

    // add a label shows "Hello World"
    // create and initialize a label
    //创建一个文本对象 并设置字体和大小
    CCLabelTTF* pLabel = CCLabelTTF::create("Hello World", "Thonburi", 34);

//    获取当前设备的尺寸
    // ask director the window size
    CCSize size = CCDirector::sharedDirector()->getWinSize();
//设置文本的位置
    // position the label on the center of the screen
    pLabel->setPosition( ccp(size.width / 2, size.height - 20) );

    // add the label as a child to this layer
//    将文本放大layer层中  和menu的设置轴是一样的  就是同一层
    this->addChild(pLabel, 1);

    // add "HelloWorld" splash screen"
//    设置一个精灵  并且放入图片
    CCSprite* pSprite = CCSprite::create("HelloWorld.png");
//精灵的位置
    // position the sprite on the center of the screen
    pSprite->setPosition( ccp(size.width/2, size.height/2) );
//把精灵放到layer中去   但是在底层
    // add the sprite as a child to this layer
    this->addChild(pSprite, 0);
    
    return true;
}

void HelloWorld::menuCloseCallback(CCObject* pSender)
{
//    程序退出
    CCDirector::sharedDirector()->end();
//判定是否为ios设备
#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
    exit(0);
#endif
}