getBlobChannelAsync function
Implementation
Future<Mat> getBlobChannelAsync(Mat blob, int imgidx, int chnidx) async {
final rval = cvRunAsync<Mat>(
(callback) => cffi.Net_GetBlobChannel_Async(blob.ref, imgidx, chnidx, callback),
(c, result) => c.complete(Mat.fromPointer(result.cast<cvg.Mat>())),
);
return rval;
}