OpenCV 4.0中如何用cvCreateMat创建cv::Mat共享指针？兼容求助

Hey there! Let's work through this compatibility hiccup you're hitting after upgrading to OpenCV 4.0. The core issue here is that OpenCV 4.x has largely phased out the old C API functions (like cvCreateMat) in favor of the modern, safer C++ API—so your original 3.4 code won't play nicely anymore.

Why Your Original Code Breaks #

Your 3.4 code uses cvCreateMat (a C API tool) to make a CvMat object, then wraps it in a cv::Ptr<CvMat> smart pointer. In OpenCV 4.0, CvMat and most C API utilities are either deprecated or fully removed, so this approach is no longer supported.

The Recommended C++ API Fix #

Instead of leaning on the outdated C API, use OpenCV's native C++ cv::Mat class paired with cv::makePtr to create your smart pointer. Here's the direct equivalent for OpenCV 4.0:

cv::Ptr<cv::Mat> _pts = cv::makePtr<cv::Mat>(4, 4, CV_32FC2);

A couple of quick notes to clarify:

• cv::makePtr is the official, preferred way to generate smart pointers for OpenCV objects in 4.x—it handles memory management cleanly, just like your original code intended.
• If you don't strictly need a smart pointer, you can simplify even further: cv::Mat already uses reference counting to manage its own memory, so this works perfectly too:

  cv::Mat _pts(4, 4, CV_32FC2);
  

Why This Is Better #

The C++ cv::Mat class is the backbone of OpenCV's modern ecosystem. It offers stronger type safety, more built-in functionality, and integrates smoothly with other C++ features. Ditching the C API also ensures your code stays compatible with future OpenCV updates.

内容的提问来源于stack exchange，提问作者user11715878