MATLAB: Question regarding function using radiobutton status

guiradiobutton

Lets say I have three radio buttons. If 1 is pressed, then variables x,y,z are certain values. If 2 is pressed, then variables x,y,z are different values, etc.

How would I write a function that outputs those variables and use it within the GUI code?

Best Answer

Greg - consider placing your three radio buttons in a button group panel and assigning a SelectionChangeFcn callback to this panel. Whenever the user selects a radio button, this callback will fire and you will be able to changes the variables as you see fit based on the selected radio button

 function uipanel1_SelectionChangeFcn(hObject, eventdata, handles)
 selectedRadioBtnStr = get(hObject,'String');
 if strcmpi(selectedRadioBtnStr, 'Radio Button 1')
    handles.x = 1;
    handles.y = 2;
    handles.z = 3;
 elseif strcmpi(selectedRadioBtnStr, 'Radio Button 2')
    handles.x = 11;
    handles.y = 21;
    handles.z = 31;
 elseif strcmpi(selectedRadioBtnStr, 'Radio Button 3')
    handles.x = 111;
    handles.y = 211;
    handles.z = 311;
 end
 guidata(hObject,handles);

We then save those changes to the handles structure using guidata. See the attached for an example.

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MATLAB: Won’t the MATLAB GUI code work

Ellen - I'm guessing the error has something to do with the image_selected variable not being defined when the popup menu callback fires. This is (most likely) due to the fact that this callback is missing a global image_selected statement in the first line of the callback. So you can add in this mising line in or you can use the handles structure to manage this variable and any other that you might want to share between callbacks. Something like

% --- Executes on button press in pushbutton2.

function pushbutton2_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton2 (see GCBO)

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



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



handles.img_selected = 2
axes(handles.axes1)
imshow('policeimage2.jpg');
guidata(hObject,handles); % <---- saves the updated handles object

We call guidata so that the updated handles object is "saved" and so it's updated fields will be available to the other callbacks. In the popup menu callback, you would then do

% --- Executes on selection change in popupmenu1.

function popupmenu1_Callback(hObject, eventdata, handles)
% hObject    handle to popupmenu1 (see GCBO)

% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu1 contents as cell array

%        contents{get(hObject,'Value')} returns selected item from popupmenu1

str = get(hObject,'String')
val = get(hObject,'Value')
   switch str{val}
    case 'Sobel'
        if handles.img_selected == 1
% etc.

Note how we access this field via handles.

Or you can do something else. It looks like your code only uses img_selected to know which of the three images you have read and shown on the axes. Rather than reading the file again, you could grab the image data by saving the handle to the image object that is shown on the axes. If you make the following change to each of your three pushbutton callbacks

% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
axes(handles.axes1)
handles.hImage = imshow('policeimage2.jpg');
guidata(hObject,handles); % <---- saves the updated handles object

So now your handles structure has a handle to the image graphics object that is shown in axes1. Now in your popup menu callback, you can use this handle to get the image data:

% --- Executes on selection change in popupmenu1.
function popupmenu1_Callback(hObject, eventdata, handles)
% hObject    handle to popupmenu1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu1 contents as cell array
%        contents{get(hObject,'Value')} returns selected item from popupmenu1
str = get(hObject,'String')
val = get(hObject,'Value')
img = get(handles.hImage, 'CData');
   switch str{val}
    case 'Sobel'
        img1 = rgb2gray(img);
        img2 = edge(img1,'Sobel')
        axes(handles.axes2);
        imshow(img2);
    case 'Canny'
        img1 = rgb2gray(img);
        img2 = edge(img1,'Canny');
        axes(handles.axes2);
        imshow(img2);  
    case 'Log'
        img1 = rgb2gray(img);
        img2 = edge(img1,'log');
        axes(handles.axes2);
        imshow(img2);
     case 'Prewitt'
        img1 = rgb2gray(img);
        img2 = edge(img1,'prewitt');
        axes(handles.axes2);
        imshow(img2);     
     case 'Own Method'
        img = imread('own_edge_det_output.png');
        axes(handles.axes2);
        imshow(img);
   end

You could also remove alot of the duplicated code in the above as the only difference (with the exception of the last case) is the method used in the edge call.

MATLAB: How can i call two push buttons from the 3rd push button in GUI without disabling any pushbuttons

See attached demo where you can use the pushbutton to start or stop a process.

Best Answer

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MATLAB: Won’t the MATLAB GUI code work

MATLAB: How can i call two push buttons from the 3rd push button in GUI without disabling any pushbuttons

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