Callback Problem

Question

Pietro Rossi 2011-4-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/5669-callback-problem

Hi everyone! I built a simple GUI with GUIDE and edited Callback function. The program is very simple: you can choose from popup-menù if copy A to B or B to A. The first time, it works correctly, (i.e A to B or B to A), but if you want to use it again, there is an error, but I don't know why. This is a short part of the program (if you want, i can send you .m and .figure files, my e-mail is pietropp11@gmail.com):

 [...]
 function edit1_Callback(hObject, eventdata, handles)
 val = str2double(get(hObject, 'String'));
 if isnan(val)
    set(hObject, 'String', 0);
    errordlg('Devi inserire un numero','Errore');
 end
 handles.edit1 = val;
 guidata(hObject,handles)
 [...]
 function edit2_Callback(hObject, eventdata, handles)
 val = str2double(get(hObject, 'String'));
 if isnan(val)
    set(hObject, 'String', 0);
    errordlg('Devi inserire un numero','Errore');
 end
 handles.edit2 = val;
 guidata(hObject,handles)
 [...]
 function pulsante_Callback(hObject, eventdata, handles)
 popup = get(handles.popupmenu1, 'Value');
 switch popup
    case 1
        cambio= handles.edit1;
        set(handles.edit2, 'String', num2str(cambio));
    case 2
        cambio= handles.edit2;
        set(handles.edit1, 'String', num2str(cambio));
 end
 [...]

I'm sorry if my English in not very well. Best Regards

Pietro Rossi

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Answer 1

Pietro Rossi 2011-4-18

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https://ww2.mathworks.cn/matlabcentral/answers/5669-callback-problem#answer_7946

Thank you for your answer, but I don't know the solution. What should I do for a simple GUI, i.e., does sum between three numbers? I would two 3 boxes (a,b,c) for number input and 1 text box (d) for the sum, but the first and the second edit (a and b) have to be the same: so if you set a, b==a, and if you set b, a==b. The number you see in the box have to change too. (d==a+b+c)

Thanks a lot for your answer Best Regards

Pietro Rosi

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Jarrod Rivituso 2011-4-19

You can definitely do this. Lets say the handles are such that

handles.edit1 - corresponds to the "a" edit box

handles.edit2 - corresponds to the "b" edit box

handles.edit3 - corresponds to the "c" edit box

handles.edit4 - corresponds to the "d" edit box

So, for the callback of edit boxes 1-3, you would need to recalculate d and set its value

>> a = get(handles.edit1,'Value');

>> b = get(handles.edit2,'Value');

>> c = get(handles.edit3,'Value');

>> set(handles.edit4,'Value',str2num(a+b+c))

Additionally, for the callbacks of edit boxes 1 and 2, you need to ensure that a and b remain the same. You could do this by analyzing hObject (the first callback parameter) to see which uicontrol was clicked

if (hObject == handles.edit1)

%We know the first edit box has changed, so change b

set(handles.edit2,'Value',get(handles.edit1,'Value'));

end

if (hObject == handles.edit2)

%We know the first edit box has changed, so change b

set(handles.edit1,'Value',get(handles.edit2,'Value'));

end

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Answer 2

Jarrod Rivituso 2011-4-17

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https://ww2.mathworks.cn/matlabcentral/answers/5669-callback-problem#answer_7926

在 MATLAB Online 中打开

It is strange for me to see code such as

handles.edit1 = val;

in your callback, considering that val is a number you determined seemingly based on user input.

GUIDE starts you off with a handles structure that contains "handles" to each of the uicontrol objects in your GUI. These handles are just unique numbers that are used to identify which uicontrol you are referring to.

When you change the values of these, then the number can no longer be used as an identifier to the uicontrol.