How can we select multiple pixels,multiple times from a Figure object in GUI (developed using GUIDE) ?

I am writing a code which takes in a volume of MR image, displays the volume in 2D (squeezing 1 dimension). After selecting suitable anatomical plane, I select some pixels using ginput(), store the coordinates (3D) in an array, and then repeat the same process for a user defined number of times (multiple groups of pixels). I have the following problems:

1) While in callback routine for "Selecting Pixels", I found no way to update a check for button press ( where button press is to Squeeze Dimensions). Upon debugging, I observed the variable value is not being updated using guidata since the function is being called by value. 2) When the selectpixels routine executes a second time, the GUI created vanishes, and a blank figure appears.

I am unable to understand how to ensure the same GUI remains active, as I select multiple pixels. I have included my code here. Any help will be sincerely appreciated, thank you.

% --- Executes on button press in squeeze_1.
function squeeze_1_Callback(hObject, eventdata, handles)
              % hObject    handle to squeeze_1 (see GCBO)
              % eventdata  reserved - to be defined in a future version of MATLAB
              % handles    structure with handles and user data (see GUIDATA)

      I = handles.vol;
      pos = round(get(handles.volume_traverse,'Value'));
      handles.bpress = 1;
      % save the changes to the structure
      guidata(hObject,handles)
      I = squeeze(I(pos,:,:));
      imshow(I,[]);

    % --- Executes on button press in squeeze_2.
    function squeeze_2_Callback(hObject, eventdata, handles)
                      % hObject    handle to squeeze_2 (see GCBO)
                      % eventdata  reserved - to be defined in a future version of MATLAB
                      % handles    structure with handles and user data (see GUIDATA)

      I = handles.vol;
      pos = round(get(handles.volume_traverse,'Value'));
      handles.bpress = 2;
      I = squeeze(I(:,pos,:));
      imshow(I,[]);
      % save the changes to the structure
      guidata(hObject,handles)

    % --- Executes on button press in squeeze_3.
    function squeeze_3_Callback(hObject, eventdata, handles)
                          % hObject    handle to squeeze_3 (see GCBO)
                          % eventdata  reserved - to be defined in a future version of MATLAB
                          % handles    structure with handles and user data (see GUIDATA)
      I = handles.vol;
      pos = round(get(handles.volume_traverse,'Value'));
      handles.bpress = 3;
      I = squeeze(I(:,:,pos));
      imshow(I,[]);
      % save the changes to the structure
      guidata(hObject,handles)

    % --- Executes on button press in pixelselect.
    function pixelselect_Callback(hObject, eventdata, handles)
    % hObject    handle to pixelselect (see GCBO)
    % eventdata  reserved - to be defined in a future version of MATLAB
    % handles    structure with handles and user data (see GUIDATA)
    % loopcheck = handles.num_groups;
    % for i = 1:loopcheck

   %Disabling unnecessary handles

   set(handles.squeeze_1,'Enable','off')

    if true
      % code
    endset(handles.squeeze_2,'Enable','off')
  set(handles.squeeze_3,'Enable','off')
  set(handles.pixelselect,'Enable','off')
  count = 1;
  n = handles.pixel_count;
  while(count<handles.num_groups)
  f_vt = @volume_traverse_Callback; %Handle for slider function to allow sliding while pixel select
  [c1,c2] = getpixels(n,f_vt); %Get 2D coordinates
  switch handles.bpress
      case 1
          pos = handles.pos.*ones(length(c1),1); %Create coordinates
          M = zeros(length(pos),3);
          M(:,1) = pos;
          M(:,2) = c1;
          M(:,3) = c2;
          disp(M)
          %Update structure with label here
      case 2
          pos = handles.pos.*ones(length(c1),1); %Create coordinates
          M = zeros(length(pos),3);
          M(:,1) = c1;
          M(:,2) = pos;
          M(:,3) = c2;
          disp(M)
          %Update structure with label here
      case 3
          pos = handles.pos.*ones(length(c1),1); %Create coordinates
          M = zeros(length(pos),3);
          M(:,1) = c1;
          M(:,2) = c2;
          M(:,3) = pos;
          disp(M)
          %Update structure with label here
  end
  count = count + 1;
  end
  set(handles.exportdata,'Enable','on')

Answer 1

[Samarth Singh]

Note: I have solved the problem on GUI closing down completely. There was a rogue close all in the ginput() routine. Calling by value and handles from other callbacks not updating during a specific nested callback routine still is a problem.

[Image Analyst]

Glad it's solved. In the future, people could help you if you attach BOTH the m file AND the .fig file.

[Samarth Singh]

Sorry about that @Image Analyst - I shall keep that in mind. Please note I have still not been able to solve the callback nested routine issue. My handles do not update as I wish them , since they are called by value. Also, I have attached the m file as well as the .fig file, as advised. Both are WIP.