在Qt中線程間connect收不到signal的問題。

例如使用QObject::connect( video_frame_process, SIGNAL(ImageReady(cv::Mat )),this, SLOT(ShowImage(cv::Mat)));

編譯沒問題，但啟動並執行時候發現收不到ImageReady的signal，沒有觸發ShowImage，查看debug的output會看到

Make sure 'cv::Mat' is registered using qRegisterMetaType()

 

修改的做法參考：

http://stackoverflow.com/questions/9646110/how-to-send-a-qt-signal-containing-a-cvmat

“You need to call
qRegisterMetaType in addition to the macro (or instead of it, depending on your needs). This is necessary for the signals to be able to marshal your data across threads. However, it might be a wiser idea to pass by reference or smart pointer, or raw pointer
if you are using the QObject hierarchy to manage the object lifetime.”

 

也就是說要麼註冊cv::Mat 類型，要麼使用已經可以識別的類型，如可以改成使用指標傳遞參數：

QObject::connect( video_frame_process, SIGNAL(ImageReady(cv::Mat  *)),this, SLOT(ShowImage(cv::Mat *)));