MATLAB: How to initiate the double-click callback function once ROI is moved by user

addlistenercustomwaitimage processingregion of interestroi

I would like to add an ROI (line) to an image frame. I would like to specify the size of that line but allow a user to move it within the frame. I am able to generate the line of specified length with the following code but I am unsure how to indicate that once the user moves the ROI and double clicks, the new location is accepted and the script proceeds.

Thanks in advance for any assistance.

Display image and line:

imshow(frame);

h = images.roi.Line(gca,'Position',[600 600;600 650])

addlistener(h,'MovingROI',@allevents);

addlistener(h,'ROIMoved',@allevents);

customWait function:

function pos = customWait(hROI)

l = addlistener(hROI, 'ROIMoved', @allevents)

uiwait;

delete(l)

pos = hROI.Position;

end

Best Answer

You could refer to the following link to refer the double-click workflow for ROI using wait function and modify it according to your use case. You can disable the mouse event listeners in your double-click listener function so that you can restrict the user from modifying the ROI after double-clicking.

https://www.mathworks.com/help/images/use-wait-function-after-drawing-roi-example.html

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MATLAB: DrawingFinished event No response

drawassisted is a simple wrapper around the image.roi.AssistedFreehand object. The function drawassisted really only constructs the ROI object and calls the draw method on the object so the user can begin drawing immediately. The problem with using drawassisted is that you can't set up listeners for the ROI object until after the object has already been drawn. For most events this isn't an issue but, as you observed, you can't set up DrawingStarted and DrawingFinished because the draw interaction will occur before you get the chance.

My suggestion would be to use the formal interface images.roi.AssistedFreehand directly:

https://www.mathworks.com/help/images/ref/images.roi.assistedfreehand.html

Step 1: Construct the ROI object and parent it to the axes

I = imread('peppers.png');
imshow(I);
ax = gca;
drawroi = images.roi.AssistedFreehand('Parent',ax);

Step 2: Set up the listeners

addlistener(drawroi,'DrawingStarted',@(~,~) disp('Drawing Has Started'));
addlistener(drawroi,'DrawingFinished',@(~,~) disp('Drawing Has Finished'));

Step 3: Call draw method to begin interactively drawing the ROI

draw(drawroi);

MATLAB: ROI listener in appdesigner not working

OK, got it to work, have include app:

el=event.listener(h,'ROIMoved',@app.allevents)

and

function allevents(app,src,evt)

Best Answer

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MATLAB: DrawingFinished event No response

MATLAB: ROI listener in appdesigner not working

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