GUIDE: how to share variables of a local function on its .m file to another callback button?

Hello fellows. This questions is about using GUIDE.

Here's the problem: I have a function @callbackslider nested with another function (showDicom), which the input is a DICOM file to see along the slices. The function showDicom is called in a callback button.

These functions are in the showDicom.m file.

I'd like to use the slice number (from @callbackslider) information to use in another function (also with its own .m file) which is called within another callback button.

.m

function showDicom(x, handles)
acquisition = squeeze(x);
[row, col, z] = size(acquisition);
figure (1)         
imagesc(acquisition(:,:,1));
colormap jet;
title('Transverse');
sld = uicontrol('Style', 'Slider', 'SliderStep', [1/94 1], 'Value',1,...
  'Min', 1, 'Max', 95, 'Callback', @callbackslider01);

        function callbackslider01(hObject, eventdata)
        val = hObject.Value;
        figure (1);
        imagesc(acquisition(:,:,val));
        title(num2str(val));
        colormap jet;

    end
end

Now, as I said, I want to use the val variable in another callback button, which calls the function Uniformity.m:

    function test_Callback(hObject, eventdata, handles)
% hObject    handle to Uniformity (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

 f = msgbox('Look for the best slice, then press OK','test');
    drawnow
    waitfor(f);
    Uniformity(dicom(:,:,val)); %function to run the test

I've extensively tried to use handles and guidata, but it didn't work. Thanks in advance.

[Walter Roberson]

val would be a particular reading of the slider value as of the time the callbackslider01 ran. Is that particular reading required (for example for consistency with the image display), or would it be acceptable to fetch the current value of the object? Such as by saving sld into handles and then accessing sld.Value in test_Callback .

[drummer]

Walter, I'd like val to be the currently slider value which the user would choose the best slice. Then, I'd like to use val in the Uniformity test. But even using handles, how would it be available to test_callback?

Answer 1

[Image Analyst]

See the FAQ: https://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.28s.29.3F

Answer 2

[Walter Roberson]

In showDicom after assigning to sld, do

handles.sld = sld;
guidata(hObject, handles);

Then

      function test_Callback(hObject, eventdata, handles)
  % hObject    handle to Uniformity (see GCBO)
  % eventdata  reserved - to be defined in a future version of MATLAB
  % handles    structure with handles and user data (see GUIDATA)

if ~isfield(handles, 'sld')
   uiwait( msgbox('You must load data first') );
   return;
end

     f = msgbox('Look for the best slice, then press OK','test');
      drawnow
      waitfor(f);
      val = max(1, min( round( handles.sld.Value ), size(dicom,3) ) );
      Uniformity(dicom(:,:,val)); %function to run the test

This leaves open the question of how dicom got into test_Callback.

[drummer]

After doing

handles.sld = sld;
guidata(hObject, handles);

in showDicom, right bellow the function @callbackslider01, I still get the error Undefined function or variable 'hObject'.

Maybe because it is on its own .m file?

Regarding dicom, it got into test_Callback in a previous callback button to load the dicom image like:

dicom = dicomread(file);
handles.dicom = dicom
guidata(hObject, handles)

Uniformity(dicom(:,:,val)) would return 3 figures, but it's not yet.

Thanks so far Walter. Do you have any idea of the error I'm still getting?

[Walter Roberson]

hobject = gcf;

But see also https://www.mathworks.com/matlabcentral/answers/?term=tag%3A%22always+parent%22

If dicom is stored in handles, then before assignment to val, do

dicom = handles.dicom;

[drummer]

where shoulb hObject = gcf be placed?

[Walter Roberson]

Change

handles.sld = sld;
guidata(hObject, handles);

to

handles.sld = sld;
hObject = ancestor(sld, 'figure');
guidata(hObject, handles);

[drummer]

Walter, thanks for the insights. Even using ancestor, my function Uniformity has not received the value of sld in val within another callback button.

What I did was a 'brute' approach, which was telling the code, for instance, that val = 75 (75th slice) in the other callback. I also brought the Uniformity code within the callback button instead of letting it in other .m file.

It worked after all, but I still have the problem of getting val from the previous callback button. I'll maybe bring the showDicom code inside the callback button too. I'd like to keep it separate, but c'est la vie.

[Image Analyst]

You didn't read the FAQ, did you?

[drummer]

ahhhhhhhhhhhh Image Analyst! Thank you very much! Declaring as a global variable worked!!!

Walter, thanks for everything!