Converting pixel data from JavaScript to OpenCV's Mat

[Adam Pash]

A followup to https://groups.google.com/forum/#!topic/native-client-discuss/zBJ_iFQJrzE:

Passing my image data from JS to my NaCl module this way worked great, so thanks again. Now a new issue:

I'd like to convert this buffer array to an OpenCV Mat type. 

Currently the image data looks like this: 

    pp::VarArrayBuffer array_buffer(dictionary.Get("data"));

In the example, that's cast to uint32_t

    uint32_t* pixels = static_cast<uint32_t*>(array_buffer.Map());

Now I need to figure out a way to read that into OpenCV's Mat type for processing. Any suggestions? 

[Adam Pash]

An update: I *think* I've figured this one out. This code appears to be doing the trick for me:

              uint32_t* pixels = static_cast<uint32_t*>(array_buffer.Map());

              cv::Mat img(cv::Size(width, height), CV_8UC4);

              memcpy(img.ptr(), (void*) pixels, height * width * 4);

              array_buffer.Unmap();

Ideally I'll try writing this file to disk at some point so I can verify, but I've been able to manipulate the Mat inside my code without it crashing, which feels like a good sign.