Mat.create constructor
Implementation
factory Mat.create({int rows = 0, int cols = 0, int r = 0, int g = 0, int b = 0, MatType? type}) {
type = type ?? MatType.CV_8UC3;
final scalar = Scalar(b.toDouble(), g.toDouble(), r.toDouble(), 0);
final p = calloc<cvg.Mat>();
cvRun(() => cffi.Mat_NewFromScalar(scalar.ref, rows, cols, type!.value, p));
final mat = Mat._(p);
return mat;
}