我不明白 hello world 的部分代码示例 cocos2d-x

I do not understand part of the code example of hello world cocos2d-x

我是 cocos2d-x 的新手,正在阅读 HelloWorldScene.cpp 代码文件,到目前为止,除了以下几行代码,我什么都懂:

void HelloWorld::menuCloseCallback(Ref* pSender)
{
Director::getInstance()->end();
#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
exit(0);
#endif
}

我的问题如下:变量CC_TARGET_PLATFORM、CC_PLATFORM_IOS有什么作用? , cofigo Director::getInstance()->end() 这一行是做什么的 -> end (); 做什么?在哪里调用函数 menuCloseCallback?

代码如下:

#include "HelloWorldScene.h"
//#include "MainmenuScene.h"

USING_NS_CC; 

Scene* HelloWorld::createScene()
{
// 'scene' is an autorelease object
auto scene = Scene::create();

// 'layer' is an autorelease object
auto layer = HelloWorld::create();

// 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()
{
//////////////////////////////
// 1. super init first
if ( !Layer::init() )
{
    return false;
}

Size visibleSize = Director::getInstance()->getVisibleSize();
Vec2 origin = Director::getInstance()->getVisibleOrigin();

/////////////////////////////
// 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
auto closeItem = MenuItemImage::create(
                                       "continuar.jpg",
                                       "continuar1.jpg",
                                          CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));

closeItem->setPosition(Vec2(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
                            origin.y + closeItem->getContentSize().height/2));

// create menu, it's an autorelease object
auto menu = Menu::create(closeItem, NULL);
menu->setPosition(Vec2::ZERO);
this->addChild(menu, 1);

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

// add a label shows "Hello World"
// create and initialize a label

auto label = Label::createWithTTF("Hello World", "fonts/Marker Felt.ttf", 24);

// position the label on the center of the screen
label->setPosition(Vec2(origin.x + visibleSize.width/2,
                        origin.y + visibleSize.height - label->getContentSize().height));

// add the label as a child to this layer
this->addChild(label, 1);

// add "HelloWorld" splash screen"
auto sprite = Sprite::create("HelloWorld.png");

// position the sprite on the center of the screen
sprite->setPosition(Vec2(visibleSize.width/2 + origin.x, visibleSize.height/2 + origin.y));

// add the sprite as a child to this layer
this->addChild(sprite, 0);*/

return true;
}


void HelloWorld::menuCloseCallback(Ref* pSender)
{
Director::getInstance()->end();

#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
exit(0);
#endif
}
auto closeItem = MenuItemImage::create(
                                   "continuar.jpg",
                                   "continuar1.jpg",
                                      CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));

MenuItemImage 有回调(在某些事件上调用的函数):

  • 按下按钮但没有松开手指 - MenuItemImage 显示 continuar1.jpg,在其他情况下显示 continuar.jpg.

  • 按下按钮(按下后手指向上推) - 它调用带有参数的函数 HelloWorld::menuCloseCallback。

代码块

#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
  exit(0);
#endif

检查编译的目标平台是否为iOS,如果是,则添加到 exit(0);

Director::getInstance()->end();

结束当前 运行 应用程序(关闭 - 这是关闭菜单项的作用)此函数作为菜单项创建中的回调连接。