- (void)contentScroller{
CGRect f = _imageView.frame;
CGSize size = _scroll.frame.size;
if(f.size.width < size.width){
f.origin.x = (kScreenWidth - f.size.width)/2;
}else{
f.origin.x = 0.0f;
}
if(f.size.height < size.height){
f.origin.y = (kScreenHeight - f.size.height)/2;
}else{
f.origin.y = 0.0f;
}
_imageView.frame = f;
}