Cropping a Mat

[Dirleye]

How would you go about cropping a Mat from a Rect?

The simplest way I can think of currently is by creating a whole new Mat and moving it back over (I haven't actually tested this and could be completely misunderstanding what assign_to_def() does):

let region: Rect = get_regeion_from_somewhere();
let mut target_mat: Mat = get_mat_from_somewhere();

let mut cropped: Mat = Mat::default();
target_mat.roi(region).unwrap().assign_to_def(&mut cropped).unwrap();
target_mat = cropped;

But that feels like too much work for something this simple. Am I missing something really obvious?

Thanks for any help.

[twistedfall]

If you need an independent Mat then something like this should work:

let cropped = target_mat.roi(region)?.try_clone()?;
let target_mat = cropped;

[Dirleye]

Ah so cloning into a new Mat is definitely needed. That is simpler though so thank you.

[twistedfall]

Yeah, I don't think that OpenCV supports in-place crop at all, so one or the other form of copying is required.