How to overcome the error in the listener function while getting the final positions of an interactive ROI?

I am trying to draw an interactive elliptical ROI in an image. I have used the drawellipse function. I have also added a listener to give me the final position of the ellliptical ROI. Here is my code:

imshow(frameraw1);
roi = drawellipse('Color','r');
ell_lis = addlistener(roi,'MovingROI',@allevents_ellipse);
ell_lis = addlistener(roi,'ROIMoved',@allevents_ellipse);

The @allevents_ellipse function is as follows:

function allevents_ellipse(src,evt)
    evname = evt.EventName;
    switch(evname)
        case{'MovingROI'}
            disp(['ROI moving previous position: ' mat2str(evt.PreviousPosition)]);
            disp(['ROI moving current position: ' mat2str(evt.CurrentPosition)]);
        case{'ROIMoved'}
            disp(['ROI moved previous position: ' mat2str(evt.PreviousPosition)]);
            disp(['ROI moved current position: ' mat2str(evt.CurrentPosition)]);
    end
end

However, I am getting the following error:

Error in allevents_ellipse (line 5)

disp(['ROI moving previous position: ' mat2str(evt.PreviousPosition)]);

Error in images.roi.internal.ROI/dragROI

Error in images.roi.internal.ROI

> In images.roi.internal/ROI/dragROI

In images.roi.internal.ROI

Warning: Error occurred while executing the listener callback for event ROIMoved defined for class

images.roi.Ellipse:

Unrecognized method, property, or field 'PreviousPosition' for class

'images.roi.EllipseMovingEventData'.

Error in allevents_ellipse (line 8)

disp(['ROI moved previous position: ' mat2str(evt.PreviousPosition)]);

Error in images.roi.internal.ROI/stopDrag

Error in images.roi.internal.ROI

> In images.roi.internal/ROI/stopDrag

In images.roi.internal.ROI

Could someone please help me overcome this error?

If there are any other methods by which I can get the final position of the ellipse, those would also be appreciated.

Thank you in advance.

[Omika Wadhwa]

@Image Analyst

Answer 1

[Yazan]

If you just need to get the position of the ROI, then you do not need necessary to create a listener. Just access the feature Vertices in the ROI object.

roi.Vertices