RotatedRect constructor
Implementation
factory RotatedRect(Point2f center, (double, double) size, double angle) {
final sz = calloc<cvg.Size2f>()
..ref.width = size.$1
..ref.height = size.$2;
final ptr = calloc<cvg.RotatedRect>()
..ref.center = center.ref
..ref.size = sz.ref
..ref.angle = angle;
final rect = RotatedRect._(ptr);
calloc.free(sz);
return rect;
}