Create a Button in a figure which activates another function

Actually I use the 'getpts' function a lot in one of my scripts since I need the user to specify some points in an image. Sometimes the image might have a big resolution, so it would be nice to zoom in before choosing the points (the original 'getpts' function doesn't allow zooming). I read on another forum about the idea to impement a button in the opened figure which starts 'getpts' upon pressing it. With this option the user can zoom into the part of the image where he/she wants to specify points. I wrote a function which does exactly what I want it to do, but there are no output arguments given by it. Can someone help me to spot my mistake and maybe give a solution to this problem.

Thanks

David

function [x,y] = getpts_zoom(pic_analyze)
% open preloaded picture
image(pic_analyze)
axis equal
% create button
button=uicontrol('style','push','Position',[20 20 100 50],'String','Get Points','Callback',@(x,y)buttonpress_getpoints);
    % subfunction getpts
    function [x,y] = buttonpress_getpoints       
        [x,y] = getpts;
    end
end

Answer 1

[Stephen23]

function [x,y] = getpts_zoom(pic_analyze)
x = []; % Must be specified in the main workspace.
y = []; % Must be specified in the main workspace.
% Show picture
image(pic_analyze)
axis equal
% Create button:
uicontrol('style','push','Position',[20 20 100 50],'String','Get Points','Callback',@mynest);
% Nested function:
    function mynest(~,~)       
        [x,y] = getpts();
    end
waitfor(gcf)
end

Read about nested functions:

https://www.mathworks.com/help/matlab/matlab_prog/nested-functions.html