Store a variable from a GUI action

Hello. I'm designing a GUI for an image processing application. On pushing a button, I need an action to be executed and also a variable to be stored. The exectuted action is uigetfile to obtain the path to a file. The variable is the path to the file so my program accesses that file later. I suppose it is a string(?). I tried getting that variable like I would in a regular function:

function [file_path]=pushbutton1_Callback(hObject, eventdata, handles)

but I suppose that's not the way to do it. I found I should specify the value of a variable when using assignin as:

assignin(WS, name, value)

but how do I specify this if it's not numerical? Thank you

Answer 1

[Walter Roberson]

uicontrol callbacks cannot return a value.

See though

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

[Fer]

I didn't mean a value, what i meant is: the action triggered by pushing the button will obtain the path to a file. I successfully used assign in to save this path to the workspace, but these variables do not seem accessible for other functions in the GUI. My code:

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
%%Open a dialog box requesting the image file
    [img_name, img_path]=uigetfile('*.nii', 'Select the image');
    %Concatenate path and name for future reference
    img_path_name=[img_path, img_name];
   assignin('base', 't1_path', img_path_name);

obtains the variable 't1_path'. Which I would then want to be available as an input for a function called by another button:

% --- Executes on button press in pushbutton5.
function pushbutton5_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton5 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
t1_path=evalin('base', t1_path);
displayDecreaseFA(t1_path);

but running the program says t1_path is undefined.

[Walter Roberson]

t1_path = evalin('base', 't1_path');

But Don't Do That.

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
%%Open a dialog box requesting the image file
    [img_name, img_path] = uigetfile('*.nii', 'Select the image');
    %Concatenate path and name for future reference
    img_path_name = fullfile(img_path, img_name);
    handles.t1_path = img_path_name;
    guidata(hObject, handles);

and

% --- Executes on button press in pushbutton5.
function pushbutton5_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton5 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
t1_path = handles.t1_path;
displayDecreaseFA(t1_path);