EDIT: A C-API is now available as a "technology preview" under wrappers/c (see #553).

Hi all,

I recently had to use ZXing in Go (which only officially supports C external libraries through CGo) and the process wasn't the most straightforward possible. After a long time of confusion, ZXing is actually extremely easy and simple to use! But I had to cut a lot of corners I would prefer not to have cut... :/

So, because of that, I would like to suggest/ask for your opinion on an "official" C API.

Basically I envision a single .h wrapper file that exports C names for ZXing functions, plus an accompanying .cpp with the wrapper function bodies (or maybe a single-header-library à la stb &c would also work). Something like this:

// zxing.h

#ifdef __cplusplus
extern "C" {
#endif

  zxing_ImageView * zxing_ImageView_new (void * data, int width, int height, zxing_ImageFormat fmt);
  zxing_Result * zxing_ReadBarcode (zxing_ImageView * iv, zxing_DecodeHints * hints);
  // ...

#ifdef __cplusplus
}
#endif

This would make the life of other people trying to use ZXing in C (or languages that only support C) much easier and more straightforward.

One difficulty is some C++ features that are "C-unfriendly", such as the Type enum of the Error type. I'm not very familiar with C++, so maybe it's possible, but I don't see how to define the equivalent enum in a plain C header file. This is the best I know.

enum zxing_Error_Type {
  // This is not valid C so it can't be used in plain C...
  None = ZXing::Error::Type::None,
  Format = ZXing::Error::Type::Format,
  // ...
}

If there's project support, I would be interested in working on it (maybe under wrappers/c/?).