OE-1 "Maintaining OpenCV 1.x C API" discussion

[vpisarev]

the feature request about evolution proposal OE-1

[kinchungwong]

/cc @alalek Re: #10246 (comment)

Possible solution here is FFI (https://en.wikipedia.org/wiki/Foreign_function_interface) bindings for C which should be able to emulate C++ features effectively.
To implement this we must think about emulation of C++ exceptions in C, classes/methods/objects, etc, including some "runtime library" to support this.
If you want strategic/political answer then you should ask

/cc @dkogan Re: #10246 (comment)

Can you please update the docs, and at least the front webpage to not claim there's a C API anymore?

Dear Vadim,

Please clarify whether a C-compatible FFI (foreign function interface) is within the scope of OE-1 or outside. Whether it is or not in OE-1, a C-compatible FFI needs to be on Evolution Proposals, because many open-source projects require the functionality of OpenCV. This issue also affects the relationship between OpenCV and the larger open-source community.

Some of them require OpenCV 1.x, but some of them may also require newer functionalities from 2.x or 3.x.

Also of interest is OpenVX. I wonder if C projects might benefit from using OpenVX directly, for at least some of their functionalities? Feedback from open-source projects are appreciated.

There may also be a need to either section off parts of core/cvdef.h for C compilers, or to poison off the entire file for C compilers (so that it's clear it won't build).

[alalek]

This OE is about "OpenCV 1.x API" and about using of this API in other OpenCV parts.

C-compatible FFI is not covered here. Perhaps it would be another C-like API - at least internally (but compatibility headers/wrappers may be proposed).
See: #11666

[sturkmen72]

i think functions like cvCanny can be cleaned up. i can work on this