An experimental pure-C binding to OpenCV 4. Intended to be used with libffi. Incomplete. Pre-alpha quality.

License: MIT.

1. Install OpenCV v 4.0.1 or later
2. Checkout the repositiry
3. Build libcvc.so:

$ mkdir build && cd build
$ cmake ..
$ make

4. Rename it to libcvc.so.0.1 (yes, I know, but this is not important at this point).
5. Either copy libcvc.so.0.1 to /usr/local/lib64 or export LD_LIBRARY_PATH=$(pwd):$LD_LIBRARY_PATH.

Since the OpenCV 4.0 release, the official C API had been completely stripped off the project. As a result, developers working with all those scripting languages out there lost access to OpenCV.

There is also PyPy, and IronPython, and Ruby (with its variants), Tcl, Lua, Common Lisp and many others -- none of them has access to OpenCV via the official bindings.

Because it is the only practical way of making libraries callable via libffi.

Libffi is a de-facto standard and is available in virtually all scripting languages.

These C++ extensions are invariably implementation-specific, not language-specific. One cannot just take a CPython extension and use it with IronPython, for example. The same applies to Common Lisp and many other languages. libffi closes this gap by allowing developers to do exactly that: share extension libraries between implementations.

It is very far from being complete. It might be considered somewhat usable at this point, depending on the task at hand.

However -- 100% completeness in terms of API coverage is not a goal. The reason is that OpenCV API contains numerous C++ specific artifacts that make no sense in other languages. Therefore, the goal is to achieve semantic completeness instead. For example, among all variadic OpenCV functions or methods solving the same problem, usually only the most specific one is wrapped.

There is a Common Lisp wrapper - https://github.com/mikeivanov/see

There is yet another project that includes pure C bindings to OpenCV -- GoCV. Although a couple of technical ideas were borrowed from GoCV, it is a completely separate effort with different goals.