Cocos2d-x实例：设置背景音乐与音效-设置场景实现

设置场景（Setting），Setting.h文件代码例如以下：

#ifndef __Setting_SCENE_H__
#define __Setting_SCENE_H__

#include "cocos2d.h"
#include "SimpleAudioEngine.h"

class Setting : public cocos2d::Layer
{
bool isEffect;														①
public:
static cocos2d::Scene* createScene();
virtual bool init();
virtual void onEnter();
virtual void onEnterTransitionDidFinish();
virtual void onExit();
virtual void onExitTransitionDidStart();
virtual void cleanup();

void menuSoundToggleCallback(cocos2d::Ref* pSender);
void menuMusicToggleCallback(cocos2d::Ref* pSender);
void menuOkCallback(cocos2d::Ref* pSender);

CREATE_FUNC(Setting);
};

#endif // __Setting_SCENE_H__

#define __HELLOWORLD_SCENE_H__

上述代码第①是定义布尔类型成员变量isEffect，它用来保存如今是否同意音效，其实是否同意音效和背景音乐播放状态应该持久化到文件里，因为我们还没有介绍数据持久化，所以我们採用isEffect变量记录状态。当我们在后面的章节学习完毕数据持久化后，再保存它们状态。其他的代码与HelloWorld场景代码很类似，这里不再赘述。

Setting.cpp文件代码例如以下：

#include "SettingScene.h"

USING_NS_CC;
using namespace CocosDenshion;

… …
bool Setting::init()
{
if ( !Layer::init() )
{
return false;
}

log("Setting init");

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

Sprite *bg = Sprite::create("setting-back.png");

bg->setPosition(Point(origin.x + visibleSize.width/2,
origin.y + visibleSize.height /2));
this->addChild(bg);

//音效
auto soundOnMenuItem = MenuItemImage::create(
"on.png",
"on.png");
auto soundOffMenuItem = MenuItemImage::create(
"off.png",
"off.png");

auto soundToggleMenuItem = MenuItemToggle::createWithCallback(
CC_CALLBACK_1(Setting::menuSoundToggleCallback, this),
soundOffMenuItem,
soundOnMenuItem,
NULL);
soundToggleMenuItem->setPosition(Director::getInstance()->convertToGL(Point(818, 220)));

//背景音乐
auto musicOnMenuItem  = MenuItemImage::create(
"on.png",
"on.png");
auto musicOffMenuItem  = MenuItemImage::create(
"off.png",
"off.png");
auto musicToggleMenuItem = MenuItemToggle::createWithCallback(
CC_CALLBACK_1(Setting::menuMusicToggleCallback, this),
musicOffMenuItem,
musicOnMenuItem,
NULL );
musicToggleMenuItem->setPosition(Director::getInstance()->convertToGL(Point(818, 362)));

//Okbutton
auto okMenuItem  = MenuItemImage::create(
"ok-down.png",
"ok-up.png",
CC_CALLBACK_1(Setting::menuOkCallback, this));

okMenuItem->setPosition(Director::getInstance()->convertToGL(Point(600, 510)));

Menu* mn = Menu::create(soundToggleMenuItem, musicToggleMenuItem,okMenuItem, NULL);
mn->setPosition(Point::ZERO);
this->addChild(mn);

return true;
}

void Setting::menuOkCallback(Ref* pSender)
{
Director::getInstance()->popScene();
if (isEffect) {
SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");					①
}
}

void Setting::menuSoundToggleCallback(Ref* pSender)							②
{
auto soundToggleMenuItem = (MenuItemToggle*)pSender;
log("soundToggleMenuItem %d", soundToggleMenuItem->getSelectedIndex());

if (isEffect) {
SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");					③
}

if (soundToggleMenuItem->getSelectedIndex() == 1) {//选中状态Off -> On				④
isEffect = false;
} else {
isEffect = true;
SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");					⑤
}
}

void Setting::menuMusicToggleCallback(Ref* pSender)							⑥
{
auto musicToggleMenuItem = (MenuItemToggle*)pSender;
log("musicToggleMenuItem %d", musicToggleMenuItem->getSelectedIndex());

if (musicToggleMenuItem->getSelectedIndex() == 1) {//选中状态Off -> On				⑦
SimpleAudioEngine::getInstance()->stopBackgroundMusic("sound/Synth.mp3");
} else {
SimpleAudioEngine::getInstance()->playBackgroundMusic("sound/Synth.mp3");
}
if (isEffect) {
SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");					⑧
}
}

void Setting::onEnter()
{
Layer::onEnter();
log("Setting onEnter");
}

void Setting::onEnterTransitionDidFinish()
{
Layer::onEnterTransitionDidFinish();
log("Setting onEnterTransitionDidFinish");
isEffect = true;
//播放
SimpleAudioEngine::getInstance()->playBackgroundMusic("sound/Synth.mp3", true);		⑨
}

void Setting::onExit()
{
Layer::onExit();
log("Setting onExit");
}

void Setting::onExitTransitionDidStart()
{
Layer::onExitTransitionDidStart();
log("Setting onExitTransitionDidStart");
}

void Setting::cleanup()
{
Layer::cleanup();
log("Setting cleanup");
//停止
SimpleAudioEngine::getInstance()->stopBackgroundMusic("sound/Synth.mp3");			⑩
}

上述代码第①、③、⑧行是在推断isEffect为true（音效播放开关打开）情况下播放音效。
代码第②行menuSoundToggleCallback是用户点击音效开发button时候回调函数，当中第④行代码是推断是否button状态从Off -> On，假设是则将开关变量isEffect 设置为false，否则为true。并且通过第⑤行代码SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav")播放一次音效。
代码第⑥行menuMusicToggleCallback是用户点击背景音乐button时候回调函数，当中第⑦行代码是推断是否button状态从Off -> On，假设是则停止播放背景音乐。否则为開始播放。
第⑧行代码是onEnterTransitionDidFinish()函数中播放背景音乐。第⑨行代码是cleanup()函数中停止播放背景音乐。

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