How do I update an image in gui using selections?

I created a GUI with check boxes and an indexed, labelled image of foot bones and the check boxes are of the names of the bones. I want the check boxes to cause a display on the axes of all of the bones corresponding to boxes that have been selected. How would I do this since the variables are not global? This is what I have now for distal phalange 1 and I was hoping to create an image that is the sum of all of the images resulting from the check boxes.

% --- Executes on button press in dp1.
function dp1_Callback(hObject, eventdata, handles)
% hObject    handle to dp1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hint: get(hObject,'Value') returns toggle state of dp1
dp1=zeros(680,498);
if (get(hObject,'Value')==get(hObject,'Max'))
    axes(handles.axes1);
    fl=imread('foot_label.png');
    for q=1:680     
        for w=1:498
           if fl(q,w)==14
               dp1(q,w)=1;
           end
        end

          imshow(double(dp1));
          %+dp3+dp4+ mp1+mp2+mp3+mp4+mp5+ pp1pp2+pp3+pp4+pp5+ m1+m2+m3+m4+m5+mc+ 
          %lc+ic+cu+ta+ca+ti
    end 
else
    dp1=zeros(680,498);
end

Answer 1

[Joseph Cheng]

I see you've already know about the get(handles.(tag),'value') to get the state of the checkbox(s) so the question is in whatever button or checkbox update how do you access the image data or other stuff. Well you'd want to store them in the handles structure. For example in most of my GUIs i have a button called load which then goes through and reads, parses, conversions if need be, etc and stores them under handles.Raw which then in another button can be access for plotting, additional calculations, etc by referencing handles.Raw.temperature or handles.Raw.Volts.

[Joseph Cheng]

ah... after it was edited by Geoff Hayes (thank you Geoff its way too late on a friday to wade through it deeply) it might seem that you're in a push button? if you're in side a push button and you want to access the checkboxes use the get(handles.(tag),'Value') which tag is the tag assigned to the checkbox that you inserted. it probably has the default tag of checkbox1 to checkboxN unless you renamed them. by using hObject as you did there you'll only get the value from the pushbutton as that is the handle of the object passed to the callback function.

Another thing you could do to make it easier and less laborious to check each and every check box if you have lots of them. in each checkbox callback you flip a flag on a stored variable in handles. such as

 function myGUI_OpeningFcn(hObject, eventdata, handles, varargin)
    handles.output = hObject;
    handles.CheckboxChecked = zeroes(1,N) %where N is the number of checkboxes.

 %where X is the specific checkbox callback 
 function checkboxX_Callback(hObject,eventdata,handles) 
      handles.CheckBoxFlags(X)=get(handles.checkboxX,'value');

then in your dp1_callback function (which is a button?) you can then figure out which boxes are checked by the values inside handles.CheckBoxFlags.

Answer 2

[Geoff Hayes]

Nina - if you wish to have one callback access the variables created in another callback (for example, your dp1) then you can use the handles structure to manage that data along with the function guidata to store that data.

Suppose you wish to store the dp1 from the above code. In your callback you would do something like

 % --- Executes on button press in dp1.
 function dp1_Callback(hObject, eventdata, handles)

 % create dp1 as above
 dp1 = ...;

 % add dp1 to the structure
 handles.dp1 = dp1;

 % save the updated structure
 guidata(hObject,handles);

Now in another callback you can access this data directly from handles as

 handles.dp1

Is that what you would like to do?

[Nina Friedly]

so I could output an image as handles.dp1+handles.dp2+handles.dp3+handles.dp4handles.dp5 and it would show if the checkbox was checked?

[Geoff Hayes]

Nina - I may do something like the following for each of your checkboxes. Start with what you have and call another function to display the image. Something like

 function dp1_Callback(hObject, eventdata, handles)
 % hObject    handle to dp1 (see GCBO)
 % eventdata  reserved - to be defined in a future version of MATLAB
 % handles    structure with handles and user data (see GUIDATA)
 % Hint: get(hObject,'Value') returns toggle state of dp1
 dp1=zeros(680,498);
 if (get(hObject,'Value')==get(hObject,'Max'))
    axes(handles.axes1);
    fl=imread('foot_label.png');
    for q=1:680     
        for w=1:498
           if fl(q,w)==14
               dp1(q,w)=1;
           end
        end
 else
    dp1=zeros(680,498);
 end

 handles.dp1 = dp1;
 guidata(hObject,handles);

 updateImage(hObject);

So each checkbox does the above and then calls a function that will update the image. This function (which is a just one more function of your GUI and so is not in a separate file) may look something like

 function updateImage(hObject)

 handles = guidata(hObject);  % could pass handles into this function

 myImg = handles.dp1 + handles.dp2 + ... ;
 imshow(double(myImg));

Note that the above assumes that all of the fields dp1, dp2, etc. exist in handles but they won't until the user presses any of the checkboxes. So you will have to add these fields to your handles structure in the OpeningFcn of your GUI. (If you don't do this, you will observe errors such as Reference to non-existent field 'dp1'.) You could do something like

 function myGui_OpeningFcn(hObject, eventdata, handles, varargin)

 handles.output = hObject; 

 handles.dp1 = zeros(680,498);
 handles.dp2 = zeros(680,498);

 % etc.
 guidata(hObject,handles);

Try the above and see what happens!

[Nina Friedly]

I will try that. Thank you so much! You are da bomb diggity.

[Nina Friedly]

I got this error: Undefined function 'updateImage' for input arguments of type 'double'.

Error in foot_anatomy>dp2_Callback (line 162) updateImage(hObject);

[Geoff Hayes]

Nina - did you copy this function into your GUI m-file? i.e. the same file that has the dp2_Callback? The error message is telling you that the function cannot be found in the MATLAB search path.

[Nina Friedly]

Yes I did and added a button that does:

% --- Executes on button press in done.
function done_Callback(hObject, eventdata, handles)
% hObject    handle to done (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
handles = guidata(hObject); 
 myImg = handles.dp1 + handles.dp2 +  handles.dp3+ handles.dp4+ handles.dp5;
 imshow(double(myImg));

[Geoff Hayes]

Nina - you have tried to use a function called updateImage but you have never defined what it does. All you have added is the callback for the DONE button. If you want your other callbacks to reference this one, then you mush replace the calls to updateImage with

 done_Callback(handles.done,[],handles);

From this callback you can remove the line

 handles = guidata(hObject);

as it isn't needed since you handles is being passed in as the third input.

[Nina Friedly]

That fixed it. I learned a lot, it's my first time using this. Thanks again!