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Add new-position callback to ROI object

addNewPositionCallback is not recommended. Use one of the ROI classes instead, described in ROI Creation Overview.


id = addNewPositionCallback(h,fcn)



id = addNewPositionCallback(h,fcn) adds the function handle fcn to the list of new-position callback functions of the ROI object h. Whenever the ROI object changes its position, each function in the list is called with the syntax:


pos is of the form returned by the object's getPosition method. The return value, id, is used only with removeNewPositionCallback.


Display Updated Position in Title

Create a rectangle ROI object. Display the position of the rectangle in the title. The title updates when you move the rectangle.

h = imrect(gca, [10 10 100 100]);
addNewPositionCallback(h,@(p) title(mat2str(p,3)));

Now drag the rectangle using the mouse to observe the callback behavior.

Input Arguments

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ROI object, specified as an imellipse, imfreehand, imline, impoint, impoly, or imrect object.

Function handle, specified as a handle. The function must accept a numeric array as input. The array must have the same form as returned when calling getPosition on the object. For more information, see Create Function Handle (MATLAB).

Output Arguments

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Identifier of new-position callback function, returned as a struct.

Introduced in R2008a