Update the ROI with drawrectangle change

Hi,

I'm trying to draw a shape (rectangle, circle etc.) to determine region of interest (ROI) in an image. When I use the drawrectangle function, I can get the corners of the first instance that the rectangle is drawn, however when I edit the rectangle on the figure (change size/position), it does not update the roi variable. How can I update the roi variable when the rectangle is altered in a script?

Code I use is below and I use R20109a;

temp = snapshot(cam1);

imshow(temp);

rect = drawrectangle;

roi = rect.Position;

[xi]

After you change the size/position , run 'roi=rect.Position' again. Should see the difference, at least on my computer

[Mert Karakaya]

Dear Xi,

I understand your solution, and I know it works, however I am looking for a solution in a script. I don't know how to implement a refresh on that line, when the rectangle is changed. I should have clarified that.

Thanks.

[Dheeraj Singh]

You can try running the code in the loop for the required functionality

while true
    %when you receive an update
    x=input()
    rect = drawrectangle;
    %update roi
    roi = rect.Position;
end

OR you can use Callbacks using App Designer.

[Mert Karakaya]

Thanks for your answer Mr. Singh,

Unfortunately, I couldn't get it to work. However, I have found a way that might be possible.

imshow(snapshot(camL)); %Show image

rect = drawrectangle; %Start draw rectangle

roi = rect.Position; %Get inital position

addlistener(rect,'ROIMoved',@roiChange); %Update if there is a change to the rectangle

function roi = roiChange(src,evt)

evname = evt.EventName;

if isequal(evname,'ROIMoved')

roi = evt.CurrentPosition; %Update roi

end

end

My only problem is that, I cannot get the roi output with the addlistener. I have searched the documentation for a few hours now, and I cannot figure out. How can I get the output with the addlistener?

Thanks.

Answer 1

[Mert Karakaya]

For anyone who is wondering how to solve this issue; here is my solution that works;

This is the main code

imshow(snapshot(camL));

rect = drawrectangle;

roiL = rect.Position;

addlistener(rect,'ROIMoved',@(src, evt) roiChange(src,evt,'roiL'));

And the function

function roi = roiChange(src,evt,roi)

assignin('base',roi,evt.CurrentPosition);

end

Thanks for all the help.