如何使用imagemagick Magick ++将图像作为gif写入blob

Question

  vector<Magick::Image> frames;
int delay = 20;
for(auto iter=taskList.begin(); iter != taskList.end(); ++iter){
/* hide some codes here*/
  frames.push_back(*img);
}
// write images to file, works fine
Magick::writeImages(frames.begin(), frames.end(), "xxx.gif");
Magick::Blob tmpBlob;
// write images to blob, I then decode the data in blob,  
// and write this blob to yyy.gif. The gif file only contains the first frame image.
Magick::writeImages(frames.begin(), frames.end(), &tmpBlob, true);
// the length is far too small 
LOG_DEBUG("blob data length: %d", tmpBlob.length());
// read from the blob into a imagelist, and print the size of the list
// the size is 1 
vector<Magick::Image> image_list;
Magick::readImages(&image_list, tmpBlob);
LOG_DEBUG("new frames length: %d", image_list.size());

嗨，当我尝试使用ImageMagick（版本7.0.3）Magick ++ STL.h writeImages函数编写Image to Blob列表时出现问题。它没有正常工作，似乎只有一帧被写入blob。但是使用相同的图像列表，将它们写入gif文件就可以了。有人可以帮帮我吗？