How to use First button function codes "symbol name" in Second button function in App Designer

I have an image. In app designer , I use "axes application" to add image there. When I click first button I add image and show it in Axes area.

I added second button . In second button I want to filter that same image when I click it.

For example my image name is "imgf" and I use imshow(img) when I click first button and show it. I want to use that "imgf" in my second button. But it gives error.

Because that "imgf" belongs to in first button function codes. How will I use that "imgf" in my second button function codes.

Codes are below

% Callbacks that handle component events
    methods (Access = private)

        % Button pushed function: SelectAnImageButton
        function SelectAnImageButtonPushed(app, event)
            global imgf;
            [filename pathname]= uigetfile({'*.jpg'},"Open file");
            fullpathname= strcat(pathname,filename);
            
            imgf=imread(fullpathname);
            if(size(imgf,3)>1)
            imgf=rgb2gray(imgf);
            end
           
            imshow(imgf,'parent',app.UIAxes);
            
        end

        % Button pushed function: FilterTheImageButton
        function FilterTheImageButtonPushed(app, event)
            
            img=imgaussfilt(imgf);  % I want to use "imgf" in here to filter the image 

            imshow(img,'parent',app.UIAxes);

        end
    end

[Ali Zulfikaroglu]

I want to also use third button. In Third button I want to use roipoly command to draw a circle on image.

But I should use filtered image in second function and continue with that "img" in third button function .

mask=roipoly(img);

How will I draw a circle with using roipoly command on uıaxes ?

[Rik]

It doesn't look like roipoly allows the use of a uifigure, only a figure.

Answer 1

[Rik]

Don't use global variables. There are many other ways to share data between callbacks. You should probably store the variable in a property.

[Ali Zulfikaroglu]

I just used global for image adding. How will ı use property ? I tried property but it doesn't work or I couldn't manage to use it in proper way. Can you add your solution in my codes ?

[Rik]

You can add a property in AppDesigner (in the code browser, select 'Properties' and click the plus symbol).

properties (Access = private)
    imgf
end

[Ali Zulfikaroglu]

I realised my mistake at property .

And it should be added app.

 properties (Access = private)
        t % Using this description
        end

% Callbacks that handle component events
    methods (Access = private)
        % Button pushed function: SelectAnImageButton
        function SelectAnImageButtonPushed(app, event)
            global imgf;
            [filename pathname]= uigetfile({'*.jpg'},"Open file");
            fullpathname= strcat(pathname,filename);
            
            imgf=imread(fullpathname);
            if(size(imgf,3)>1)
            imgf=rgb2gray(imgf);
            end
           
            imshow(imgf,'parent',app.UIAxes);
            app.t=imgf % t is in here property function and it should be app.t
            
        end
        % Button pushed function: FilterTheImageButton
        function FilterTheImageButtonPushed(app, event)
            
            img=imgaussfilt(app.t);  
            imshow(img,'parent',app.UIAxes);
        end
    end

[Rik]

Yes, that is equivalent to what I suggested. Now you can remove that global imgf; line.