MATLAB: Is there an example of how to add a callback to drawcircle to get the current position

drawcircle

I need to get the curent radius and position of the circle using drawcircle() in GUIDE. Is there an example of how to add a callback? I'm not sure how to use the images.roi.CircleMovingEventData class

Thank you

Best Answer

h = drawcircle('Center', [500, 500], 'Radius', 100, 'StripeColor', 'red');   %adjust parameters as needed
L1 = addlistener(h, 'ROIMoved', @(hObject, event) disp(event.CurrentCenter))  %example callback

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MATLAB: How to display coordinates as rectangle is drawn over an image

Hello!

One way that you could do this is by using imrect instead of getrect. getrect only returns the coordinates of the rectangle when the user is done placing it, but imrect allows the user to resize the rectangle and can return the current coordinates at any time.

So, for example, using code from the imrect documentation, you could display the current coordinates of the rectangle in the title of the figure (this version is slightly simplified, the one in the doc is a bit more complex):

imshow('moon.tif')
rect = imrect;
addNewPositionCallback(rect, @(p) title(mat2str(p,3)));

It isn't the prettiest way to display the coordinates, but you could modify the callback function to display them in whatever way you want!

Hope that helps!

MATLAB: Accessing an ROI move listener in another function so to delete it

Assuming you don't want to delete the ellipse, you could instead delete the listener within your button's callback function. You can pass the listener to that function in a number of ways, one of which is to save the listener within (or as) a property of your app. Another possibility is to directly pass the listener to your button's callback property. I hope the following helps illustrate this, even though it is simply a script and not tied to an object like in appdesigner:

f = uifigure;
ax = axes(f, 'Position', [0.1, 0.6, 0.8, 0.4]);
b = uibutton(f,...
    'Position', [0.1*f.Position(3), 0.1*f.Position(4), 0.8*f.Position(3), 0.4*f.Position(4)],...
    'ButtonPushedFcn', @buttonpress);
% Draw ROI
h = images.roi.Ellipse(ax, 'Center', [0.5 0.5],...
    'Semiaxes', [0.3 0.3]);
% Listen for mouse movement of the ROI
l = addlistener(h, 'MovingROI', @allevents);
% Update button's callback, passing in the listener l
b.ButtonPushedFcn = {b.ButtonPushedFcn, l};
function allevents(~, evt)
    evname = evt.EventName;
    if strcmp(evname, 'MovingROI')
        disp(['ROI moving Current Center: ' mat2str(evt.CurrentCenter)]);
        disp(['ROI moving Current SemiAxes: ' mat2str(evt.CurrentSemiAxes)]);
    end
end
function buttonpress(src, ~, l)
    if nargin > 2 % if nargin > 3 in appdesigner, I believe
        delete(l)
        % src.ButtonPushedFcn = @buttonpress;
    end
end

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MATLAB: How to display coordinates as rectangle is drawn over an image

MATLAB: Accessing an ROI move listener in another function so to delete it

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