ROI deleted event listener

Is there a listener event for when an ROI has been deleted from an axes? For example, like so:

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

But this doesn't seem to work.

If not, how could I check when a ROI shape has been deleted by the user through GUIDE?

Many thanks.

[Németh Gergely]

I would be also very interested in that! I digged through the whole matlab documentation regarding roi-s but could not find it! I would appreciate some help!

[Brian Derstine]

These callbacks should all be defined and listed in the Polyline Properties webpage, but for unexplained reasons they are not:

MovingROI

ROIMoved

ROIClicked

AddingVertex

VertexAdded

DeletingVertex

VertexDeleted

DeletingROI

(presumably there's another ROIDeleted or similar undocumented or private callback but I cannot determine what it is)

[Adam Danz]

@Brian Derstine

https://www.mathworks.com/help/images/ref/images.roi.polygon.html#mw_daae5b86-cb2c-4cfe-bb6b-fc17ddd4da51

[Brian Derstine]

Thanks for the reply @Adam Danz That's a rather sneaky place to hide the events. Unfortunately, when a web user tries to search that page for any of those event names it turns up 0 results because that content is hidden until a user manually clicks on that "Events" div to uncollapse it. Very non-user-friendly. Also, that location on the page is not where Matlab's callbacks documentation states that callbacks can be found: "For a list of callbacks associated with a specific graphics object, see the properties of that object. For example, for a list of Figurecallbacks, see Figure Properties." (https://www.mathworks.com/help/matlab/creating_plots/create-callbacks-for-graphics-objects.html)

The Figure Properties page nicely lists a bunch of searchable callbacks under the normal Properties section under sub-headings like "Common Callbacks", "Keyboard Callbacks", etc. The images.roi... objects should all follow the same style.

[Adam Danz]

I know what you mean @Brian Derstine about the collapsed sections. Whenever I text search a doc page, I expand all components first to make sure I don't miss something. This option is at the top, right of doc pages that contain expansion fields.

About the callbacks, note that these are not callback function. They are events.

[Brian Derstine]

ah that's a helpful tip. thanks

Answer 1

[Matthew Siefring]

As an alternative to Adam's answer, you can use 'DeletingROI' as the event name parameter for the addListener function.

addlistener(h,'DeletingROI',@allEvents);

This way, the allEvents function will only be triggered when the user deletes the ROI interactively, instead of whenever a cleanup is triggered on the ROI object.

[Adam Danz]

+1 good call

More info on ROI events

Answer 2

[Adam Danz]

Use onCleanup to define a function that is evoked when the ROI is deleted. Store the onCleanup handle within the object.

Demo: Displays "ROI deleted" when the ROI object is deleted.

I = imread('baby.jpg');
figure
imshow(I)
h = images.roi.Circle(gca,'Center',[1000 1000],'Radius',500);
h.UserData.OnCleanup = onCleanup(@()allevents);

% Show figure, pause
drawnow; 
pause(1)

% delete ROI obj
delete(h)

function allevents
fprintf('ROI deleted\n')
end

[Németh Gergely]

Wow, thank you very much for the fast answer. It works absolutely fine. Now I don't have to use a clear button in my app for removing the additional markers when I delete the ROI line object!

[Adam Danz]

Glad I could help!

[Brian Derstine]

Is there an undocumented "ROIDeleted" function that gets called after "DeletingROI"? I am able to run code during the DeletingROI event but no matter what I do, the polyline always gets deleted after that function finishes. I want to prevent the polyline from being deleted all at once but allow individual vertices to be deleted. One way I tried to do this was by setting the "Deletable" property to 0/false, but after doing that I can no longer delete vertices on the polyline. I can add and move vertices no problem. Do I need to override the default context menu options and manually remove the Delete Polyline option somehow?