What is wrong with this uibutton and callback function?

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Stelios Fanourakis 2019-2-9

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评论： Stelios Fanourakis 2019-2-11

Hi

I want to have two radio buttons pick one image at a time for further processing. I use this code.

bg = uibuttongroup('Visible','off',...
                  'Position',[0 0 .2 1],...
                  'SelectionChangeFcn',@Do_plot);
              
r1 = uicontrol(bg,'Style',...
                  'radiobutton',...
                  'String','Option 1',...
                  'Position',[10 350 100 30],...
                  'HandleVisibility','off');
              
r2 = uicontrol(bg,'Style','radiobutton',...
                  'String','Option 2',...
                  'Position',[10 250 100 30],...
                  'HandleVisibility','off');
              % Make the uibuttongroup visible after creating child objects. 
bg.Visible = 'on';
Img = bg; %%% This is the image I need to define whether Option1 = croppedImage, or Option2 = J; CroppedImage and J are two different images.

And the callback function at the end of the script.

function Do_plot(hObject, event, varargin)
   bg = findobj(gcf, 'Tag', 'BG1');
   sel = bg.SelectedObject;
   if isempty(sel)
       return;  %no buttons selected
   end
   sel_string = sel.String;
   switch sel_string
       case 'Option 1'
           bg.Value = croppedImage;
       case 'Option 2'
           bg.Value = J;
   end
   bg= double(bg);
end

I cannot make it run.

Is there any incongruency?

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Jan 2019-2-9

编辑：Jan 2019-2-9

在 MATLAB Online 中打开

Please mention the details. "Cannot make it run" does not explain, what you observe.

By the way, why using an expensive search, when the handle is stored already:

function Do_plot(hObject, event, handles)  % instead of: varargin
   bg = handles.BG1;  % or how itr is called  findobj(gcf, 'Tag', 'BG1');

This is strange:

Img = bg; %%% This is the image I need to define

No, bg is the handle of the button group, not an image.

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Answer 1

Jan 2019-2-9

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https://ww2.mathworks.cn/matlabcentral/answers/444066-what-is-wrong-with-this-uibutton-and-callback-function#answer_360295

在 MATLAB Online 中打开

I guess, that the object with the tag 'BG1' is not found. Then store it explicitly:

bg = uibuttongroup('Visible','off',...
                  'Position',[0 0 .2 1],...
                  'SelectionChangeFcn',@Do_plot, ...
                  'Tag', 'BG1');
handles.BG1 = bg;
guidata(hObject, handles);
...

But the rest is not clear: What do you want to achieve? Radiobuttons are mutual exclusive, usually. Have you implemented this already?

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Walter Roberson 2019-2-10

You have given us no information as to what phi is at that point.

Jan 2019-2-11

编辑：Jan 2019-2-11

@Stelios: Without knowing the code of the function ruller, I cannot guess, how to avoid the error message about the undefined variable hObject. I do not see the relation between the original question and a black image.

Again: "What is wrong with this uibutton and callback function?" does not contain any information about why you assume, that there is a problem. The comments you have given do not clarify this also. So what exactly is teh problem you want to solve?

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Answer 2

Walter Roberson 2019-2-9

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编辑：Walter Roberson 2019-2-9

在 MATLAB Online 中打开

bg= double(bg);

At that point in the code, bg is the handle of a uibuttongroup . When you apply double() to the handle of a graphics object, the result you get back is the old numeric style handle for the object:

>> bg = uibuttongroup('Visible','off',...
                  'Position',[0 0 .2 1],...
                  'SelectionChangeFcn',@Do_plot);
>> double(bg)
ans =
           0.0003662109375
>> handle(ans)
ans = 
  ButtonGroup with properties:
                  Title: ''
        BackgroundColor: [0.9400 0.9400 0.9400]
         SelectedObject: [0×0 GraphicsPlaceholder]
    SelectionChangedFcn: @Do_plot
               Position: [0 0 0.2000 1]
                  Units: 'normalized'
  Show all properties

This has nothing to do with any setting chosen by way of the button group. It is like a street address of where the button group "lives".

So you are replacing bg with the numeric handle to the button group . That is valid to do, but not recommended.

After you replace bg with the numeric handle to the button group, your callback returns without having stored any information permanently. You might as well not have run the code, if you are not going to store anything. You should be reading Share about how to store results that survive the callback.

But before that you have a problem: bg.Value = croppedImage; and bg.Value = J are not valid because uibuttongroups do not have any property named Value that can be assigned into.

... But I have explained all of this to you several times before. Graphics callbacks are not subroutines, and graphics objects do not return values.

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Stelios Fanourakis 2019-2-10

在 MATLAB Online 中打开

@Walter.

For instance. This one:

function [] = GUI_6()
% Demonstrate how to update one uicontrol with data from others.
% Creates two radiobuttons and a pushbutton.  The pushbutton, when clicked
% shows which radio button (or both or none) is currently selected.  See
% GUI_8 for similar radiobuttongroup GUI.
%
%
% Author:  Matt Fig
% Date:  7/15/2009
S.fh = figure('units','pixels',...
              'position',[400 400 120 100],...
              'menubar','none',...
              'name','GUI_6',...
              'numbertitle','off',...
              'resize','off');
S.pb = uicontrol('style','push',...
                 'unit','pix',...
                 'position',[10 10 100 20],...
                 'string','None Selected',...
                 'tooltip','Push to find out which radio button is selected');
S.rd(1) = uicontrol('style','rad',...
                    'unit','pix',...
                    'position',[10 40 100 20],...
                    'string','  Button A');
S.rd(2) = uicontrol('style','rad',...
                    'unit','pix',...
                    'position',[10 70 100 20],...
                    'string','  Button B');
set(S.pb,'callback',{@pb_call,S}); % Set the callback, pass hands.
function [] = pb_call(varargin)
% Callback for pushbutton.
S = varargin{3};  % Get structure.
R = [get(S.rd(1),'val'), get(S.rd(2),'val')];  % Get state of radios.
str = 'Both selected';  % Default string.
if R(1)==1 && R(2)==0
    str = 'A selected';
elseif R(1)==0 && R(2)==1
    str = 'B selected';
elseif ~any(R)
    str = 'None selected';
end
set(S.pb,'string',str)

Where is my output? What do I assign as Img, so Img take the value of one of two images and saves it for further processing?

I don't understand the output variable in this code I attached from "41 Complete GUI Examples"

Can you help?

Jan 2019-2-11

在 MATLAB Online 中打开

which menu.m

Stelios Fanourakis 2019-2-11

在 MATLAB Online 中打开

@Jan

May you know why I cannot access the path

/Applications/MATLAB_R2018b.app/toolbox/matlab/uitools/menu.m

Using Matlab from my Macbook??

It's just that when I click to choose the folder, from where Matlab should read the functions, all the path from Applications and onwards is just faded with no ability to chose.

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What is wrong with this uibutton and callback function?

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What is wrong with this uibutton and callback function?

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