在Android平台中对cocos2d-x截屏，但是获取的图像为全黑

cocos2d-x C++
#1

Cocos2d-x版本为2.2.1, 使用的代码如下 :

void SaveScreenshot()
{
    CCSize size = CCDirector::sharedDirector()->getWinSize();
    CCRenderTexture* texture = CCRenderTexture::create((int)size.width, (int)size.height);    
    texture->setPosition(ccp(size.width/2, size.height/2));    
    texture->begin();
    CCDirector::sharedDirector()->getRunningScene()->visit();
    texture->end();
    texture->saveToFile("screenshot.png", kCCImageFormatPNG);
}