刚开始做卡牌的时候没有想到要做loading，因为小游戏资源不多。
但是后来不断的加图片，直到在真机上发现卡顿的问题，我才知道该需要加loading了......
首先，我们先定义类：
class Loading : public Layer
{
public:
bool init();
CREATE_FUNC( Loading);
static Scene* CreateScene();
int total_pic_num;//需加载图片数
int total_sound_num;//需加载声音数
int all_num;//总共需要加载的数量
int load_num;//已加载数量
std::vector<:string> plist_name;//plist名
int load_plist_num;//加载了几个plist
void load_sound(int num);
void load_pic(Object* pSender);
void load_plist(Object* pSender);
};
在cpp中先初始化一些参数：
total_pic_num=BACKGROUND_NUM+CARD_HERO_NUM+CARD_EQUIP_NUM+CARD_BACK_NUM+BUTTON_ACTION_NUM+TOUCH_ACTION_NUM+CARD_SKILL_NUM;
total_sound_num=BGM_NUM+EFFECT_NUM;
all_num=total_pic_num+total_sound_num;
load_num=0;
load_plist_num=0;
//plist名
plist_name.push_back(UI/button_action/button_action);
plist_name.push_back(UI/touch_action/touch_act_three);
plist_name.push_back(skill/atk/flame);
plist_name.push_back(skill/atk/freeze);
plist_name.push_back(skill/atk/lightning);
plist_name.push_back(skill/atk/wind);
然后开始加载资源吧：
//-------------------------------------------------------------预加载背景音乐
CocosDenshion::SimpleAudioEngine::getInstance()->preloadBackgroundMusic(sound/bgm/bgm_start.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadBackgroundMusic(sound/bgm/bgm_game.mp3);
load_sound(BGM_NUM);
//-------------------------------------------------------------预加载音效
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/button_1.mp3);
//攻击音效
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/button_out.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/flame_shoot.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/freeze_shoot.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/lightning_shoot.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/wind_shoot.mp3);
//控制音效
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/open_card.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/card_out.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/equip_out.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/no.mp3);
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect(sound/effect/card_die.mp3);
load_sound(EFFECT_NUM);
//-------------------------------------------------------------背景
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/background_start.jpg, CC_CALLBACK_1(Loading::load_pic, this));
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/background_help.jpg,CC_CALLBACK_1(Loading::load_pic, this));
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/background_about.jpg,CC_CALLBACK_1(Loading::load_pic, this));
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/help_word.jpg,CC_CALLBACK_1(Loading::load_pic, this));
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/background_game.jpg,CC_CALLBACK_1(Loading::load_pic, this));
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/setting_back.png,CC_CALLBACK_1(Loading::load_pic, this));
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/setting_face.png,CC_CALLBACK_1(Loading::load_pic, this));
CCTextureCache::sharedTextureCache()->addImageAsync(UI/background/title.png,CC_CALLBACK_1(Loading::load_pic, this));
//-------------------------------------------------------------卡牌
//back
char file_name_c[100];
for(int i=0;i<=CARD_BACK_NUM;i++)
{
sprintf(file_name_c,card/back/card_need_magic_%d.jpg,i);
std::string file_name(file_name_c);
CCTextureCache::sharedTextureCache()->addImageAsync(file_name, CC_CALLBACK_1(Loading::load_pic, this));
}
//equip
for(int i=0;i<=CARD_EQUIP_NUM;i++)
{
sprintf(file_name_c,card/equip/card_equip_%d.jpg,i);
std::string file_name(file_name_c);
CCTextureCache::sharedTextureCache()->addImageAsync(file_name, CC_CALLBACK_1(Loading::load_pic, this));
}
//hero
for(int i=0;i<=CARD_HERO_NUM;i++)
{
sprintf(file_name_c,card/people/card_hero_%d.jpg,i);
std::string file_name(file_name_c);
CCTextureCache::sharedTextureCache()->addImageAsync(file_name, CC_CALLBACK_1(Loading::load_pic, this));
}
//-------------------------------------------------------------加载精灵表
for(std::string a : plist_name)
{
CCTextureCache::sharedTextureCache()->addImageAsync(a+.png, CC_CALLBACK_1(Loading::load_plist, this));
//load_plist_num++;
}
注意加载图片和精灵表的回调函数是不一样的，因为加载这两种资源需要不同的方式
以下为一个自定义函数和两个回调函数（用于动态显示加载进度和加载）：
void Loading::load_sound(int num)//这个函数可以忽略不看
{
load_num+=num;
int percent=((float)load_num/(float)all_num)*100;
auto loading_font = (Label*)getChildByTag(1);
loading_font->setString(String::createWithFormat(Loading......%d%%,percent)->_string);
}
void Loading::load_pic(Object* pSender)//加载图片的回调函数
{
load_num+=1;
int percent=((float)load_num/(float)all_num)*100;
this->runAction(DelayTime::create(15));//休息
auto loading_font = (Label*)getChildByTag(1);
loading_font->setString(String::createWithFormat(Loading......%d%%,percent)->_string);
if(percent>=100)
{
Director::getInstance()->replaceScene(Start::CreateScene());//如果加载完成跳转
}
}
void Loading::load_plist(Object* pSender)//加载精灵表的回调函数
{
SpriteFrameCache::getInstance()->addSpriteFramesWithFile(plist_name.at(load_plist_num)+.plist,plist_name.at(load_plist_num)+.png);//图片已经加载过貌似会直接从缓存中读取，目的是把图片和plist一起加载
load_plist_num++;
this->runAction(DelayTime::create(15));
load_num+=1;
int percent=((float)load_num/(float)all_num)*100;
this->runAction(DelayTime::create(15));
auto loading_font = (Label*)getChildByTag(1);
loading_font->setString(String::createWithFormat(Loading......%d%%,percent)->_string);
if(percent>=100)
{
Director::getInstance()->replaceScene(Start::CreateScene());
}
}
如上就是异步加载的方法，现在我们需要知道如何从缓存中获取：
获取图片：
Sprite *BK=Sprite::createWithTexture(TextureCache::sharedTextureCache()->textureForKey(UI/background/background_start.jpg));
获取精灵表：
CCSpriteFrameCache *frameCache=CCSpriteFrameCache::sharedSpriteFrameCache();
frameCache->getSpriteFrameByName(UI/touch_action/touch_act_three.plist);
这样就能从缓存中获取资源了，我测试了下真的快很多
