CCTextureCache的多线程加载原理和使用

做引擎的时候,遇到一个texture的异步加载,这里将具体的原理和使用方法贴出来,后面根据浏览器的特性做修改移植。 

voidCCTextureCache::addImageAsync(constchar *path, CCObject *target, SEL_CallFuncO selector)

{

CCAssert(path != NULL, "TextureCache: fileimage MUST not be NULL");


CCTexture2D *texture = NULL;


// optimization


std::string pathKey = path;

CCFileUtils::ccRemoveHDSuffixFromFile(pathKey);


pathKey = CCFileUtils::fullPathFromRelativePath(pathKey.c_str());

texture = m_pTextures->objectForKey(pathKey);     //根据pathkey查看是否纹理已经加载过,如果已经有了,则不重复加载


std::string fullpath = pathKey;

if (texture != NULL)

{

if (target && selector)

{

(target->*selector)(texture);

}

return;

}

       if (target)

{

target->retain();

}


// lazy init

static bool firstRun = true;

if (firstRun)

{      

        s_pAsyncStructQueue = new queue<AsyncStruct*>();

    s_pImageQueue = new queue<ImageInfo*>();


pthread_mutex_init(&s_asyncStructQueueMutex, NULL);

sem_init(&s_sem, 0, 0);

pthread_mutex_init(&s_ImageInfoMutex, NULL);

pthread_create(&s_loadingThread, NULL, loadImage, NULL);  //创建新的线程,用于后台加载图片

 

                //创建调度队列,用来根据已加载的图片进行纹理转换

CCScheduler::sharedScheduler()->scheduleSelector(schedule_selector(CCTextureCache::addImageAsyncCallBack), this, 0, false);

need_quit = false;

firstRun = false;

}


// generate async struct

AsyncStruct *data = new AsyncStruct();

data->filename = fullpath.c_str();

data->target = target;

data->selector = selector;


// add async struct into queue

pthread_mutex_lock(&s_asyncStructQueueMutex);

s_pAsyncStructQueue->push(data);           //将需要加载的图片放入队列中

pthread_mutex_unlock(&s_asyncStructQueueMutex);


sem_post(&s_sem);

}

 从上述代码分析可以看出其过程:

1.创建线程,用于后台加载

2. 将对于需要加载的图片放入队列中

3. callback函数设定,用于将加载完成的图片转为纹理,等待使用其调用是由CCTimer::update调用的。

4. addImageAsyncCallBack函数在处理完纹理转换,还会调用addImageAsync传入的SEL_CallFuncO selector,实现用户加载图片纹理之后的具体处理。

使用例子:

CCTextureCache::sharedTextureCache()->addImageAsync("Images/blocks.png", this, callfuncO_selector(TextureCacheTest::loadingCallBack)); 

 loadingCallBack函数就是使用异步加载完之后的用户可以自处理结果,比如初始化一个sprite,用这个纹理贴出来。

关键词:cocos2d-html5,cocos2d-x,游戏引擎

posted on 2012-03-15 15:44  SeanLin  阅读(7509)  评论(0编辑  收藏  举报

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