How do i use the edit text box in a GUI to change variables in a function that i run with the gui???

Hello i am not good at matlab at all and i am trying to make a GUI work like i want it too. I want to be able to change values in my function from the GUI before I run the GUI. This is code i want to run in the GUI and the Ss and SR are the variables i want to be able to control from the GUI.

function AutofocusGUI(Ss , SR)
    Ss=.01;
    SR=5;
    Fvar=[];
    h.MoveAbsoluteEx (0,0,1,0); % home
    pause(3)
    for z = 0:Ss:SR % Step size and Sweep range
    h.MoveAbsoluteEx (0,z,1,0);
    pause(.75)
    frame = getsnapshot(vid);
    frame=frame(160:320, 240:400);
    Fvar=[Fvar std2(im2double(frame))];
    end
    pause(2)
    figure(3)
    z = 0:Ss:SR
    plot(z,Fvar) % graph of step and variance
    xlabel('z')
    ylabel('variance')
    pause(2)
    maxFvar=max(Fvar);
    [mmaxFvar , ind] = max(Fvar);
    maxX= z(ind);
    h.MoveAbsoluteEx (0,maxX,1,0);
end

I was able to get the GUI to run AutofocusGUI(Ss, SR) code with the variables Ss and SR defined in the code and it worked great but i was not able to control Ss and SR. This is what i did.

% --- Executes on button press in StartAutofocus.

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

      AutofocusGUI(Ss,SR);
end

What should i do now to be able to control the values of Ss and SR from my edit text box in the GUI before I press the StartAutofocus button to start the function.

Answer 1

[Geoff Hayes]

If we assume that your GUI has two edit text boxes, one for Ss and one for SR, then, in the above button callback, you can get the data from those two edit text boxes and pass them to the AutofocusGUI function

 function StartAutofocus_Callback(hObject, eventdata, handles)

     Ss = str2num(char(get(handles.editSs,'String')));
     SR = str2num(char(get(handles.editSR,'String')));

In the above, the text edit boxes are named editSs and editSR. We convert the contents of each to a string, and then to a number. But we have to be aware of the user entering in non-numeric data - if either Ss or SR is empty, then we cannot proceed with the calculation

     if ~isempty(Ss) && ~isempty(SR)
         AutofocusGUI(Ss,SR);
     end

(If one or both are empty, you may want to default either value to something that can be used.) And that should be it - just remember that your AutofocusGUI function is setting Ss and SR to 0.1 and 5 respectively so this code should be removed. Hope this helps!

Answer 2

[Richard]

Hello THANKS for the fast response I will give this a shot tomorrow in the lab i cant run the code with out the hardware :/ . This is what i tried earlier after i took the defined Ss and SR out of the AutofocusGUI function.

% --- Executes on button press in StartAutofocus.

function StartAutofocus_Callback(hObject, eventdata, handles)

% hObject handle to StartAutofocus (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB

% handles structure with handles and user data (see GUIDATA)

InpStr = get(handles.Ss,'String');

Ss = str2double(InpStr);

InpStr = get(handles.SR,'String');

SR = str2double(I);

AutofocusGUI(Ss,SR);

end

When i pushed the Start Autofocus Button in the GUI i got back a error message that said:

"Attempt to reference field of non-structure arry"

Error in libsGui>StartAutofocus_Callback

InpStr = get(handles.Ss,'String');

Why do i get this error? Thanks A TON!!!!!

[Geoff Hayes]

Hi Richard - the Attempt to reference field of non-structure array error message is thrown when the code treats a variable as if it were a structure and tries to access some element of it. In this case, the line of code is handles.Ss. I think that handles may be empty (not set) because if it wasn't then either this line of code would work or throw the Reference to non-existent field 'Ss' message.

You may need to put a breakpoint at this line and then re-start the GUI and press the button. If handles is empty, then something has not been set quite right earlier in the code.

Also, look at the code for initialization for your GUI (initial block) and that for the __OpeningFcn too. There may have been an unexpected change to one or both of these functions that could result in this type of problem.

[Richard]

This worked great Thanks!!!!!!!!!!

But what is the char doing to the handles to make this work?

Thanks again Rich

[Geoff Hayes]

Awesome!

As for the char, I needed that in my version (2014a) because the result of the get(handles.editSs,'String') was a cell..so I needed to convert it to a string/char array. I haven't seen anyone else do that (in other pieces of code) so maybe it isn't necessary for you and is just something specific to the way I set something up.