train method
Train WaldBoost detector.
Implementation
void train(String posSamples, String negImgs) {
final cp = posSamples.toNativeUtf8().cast<ffi.Char>();
final cn = negImgs.toNativeUtf8().cast<ffi.Char>();
cvRun(() => cffi.WBDetector_Train(ptr, cp, cn));
calloc.free(cp);
calloc.free(cn);
}