Cocos2d-x How to save ScreenShot ？

 1void SaveScreenshot()
 2{
 3    CCSize size = CCDirector::sharedDirector()->getWinSize();
 4    CCRenderTexture* texture = CCRenderTexture::create((int)size.width, (int)size.height);    
 5    texture->setPosition(ccp(size.width/2, size.height/2));    
 6    texture->begin();
 7    CCDirector::sharedDirector()->getRunningScene()->visit();
 8    texture->end();
 9    texture->saveToFile("screenshot.png", kCCImageFormatPNG);
10}