Sharing variables between unicontrol function and WindowScrollWheelFcn

Hello,

I wrote a little program to read dicom files and then show them by using scroll mouse function. The program works well. However I would like to open another folder with dicom images and then read it again without closing the program. And here I have a problem because I do not know how to pass variables from unicontrol function to WindowScrollWheelFcn. Below I present my program.

 function ct_scans_read

 clear all

 f = figure('Name','Image diacom file read','Position',[600 300 900 650]);
 h = axes('Parent',f,'units','pixels','Position',[50 100 512 512]);
 set(f, 'WindowScrollWheelFcn',@figScroll);

 text1=uicontrol('Parent',f,'Style','text','String','Path to directory','Position',[100 60 160 25],'BackgroundColor','white','FontSize',12,'FontWeight','bold');

 pathr= uicontrol('Parent',f,'Style', 'edit', 'String','C:\CT Images\','Position', [20 30 850 20],'BackgroundColor','white','FontSize',10,'FontWeight','bold');

 name_path = get( pathr , 'string' );
 dirOutput = dir(name_path);
 row = size(dirOutput,1);

 for i = 3:row
    nname = [name_path dirOutput(i).name];
    info = dicominfo(nname);
    dicom_images(:,:,i-2) = dicomread(info);
end

 h = imshow(dicom_images(:,:,1));

    function figScroll(src,callbackdata)

        if callbackdata.VerticalScrollCount > 0

            if i >= row-2;
                i = row-2;
            else
                i=i+1;
            end

            h = imshow(imadjust(uint16(dicom_images(:,:,i)),[1923/65535 1924/65535],[]));

        elseif callbackdata.VerticalScrollCount < 0

            if i <= 1;
                i = 1;
            else
                i=i-1;
            end

            h = imshow(imadjust(uint16(dicom_images(:,:,i)),[1923/65535 1924/65535],[]));

        end
    end
end

If I do this way I have an error: Error: File: ct_scans_read.m Line: 39 Column: 17 "i" previously appeared to be used as a function or command, conflicting with its use here as the name of a variable. A possible cause of this error is that you forgot to initialize the variable, or you have initialized it implicitly using load or eval.

 function ct_scans_read

 clear all

 f = figure('Name','Image diacom file read','Position',[600 300 900 650]);
 h = axes('Parent',f,'units','pixels','Position',[50 100 512 512]);
 set(f, 'WindowScrollWheelFcn',@figScroll);

 text1=uicontrol('Parent',f,'Style','text','String','Path to directory','Position',[100 60 160 25],'BackgroundColor','white','FontSize',12,'FontWeight','bold');

 pathr= uicontrol('Parent',f,'Style', 'edit', 'String','C:\CT Images\','Position', [20 30 850 20],'BackgroundColor','white','FontSize',10,'FontWeight','bold');

 set(pathr, 'callback', {@unicontrol,h})
    function f=unicontrol(hObject, eventdata, f)  

        name_path = get( pathr , 'string' );
        dirOutput = dir(name_path);
        row = size(dirOutput,1);

        for i = 3:row
            nname = [name_path dirOutput(i).name];
            info = dicominfo(nname);
            dicom_images(:,:,i-2) = dicomread(info);
        end

        h = imshow(dicom_images(:,:,1));
        i=row-2;

    end

    function figScroll(src,callbackdata)

        if callbackdata.VerticalScrollCount > 0

            if i >= row-2;
                i = row-2;
            else
                i=i+1;
            end

            h = imshow(imadjust(uint16(dicom_images(:,:,i)),[1923/65535 1924/65535],[]));

        elseif callbackdata.VerticalScrollCount < 0

            if i <= 1;
                i = 1;
            else
                i=i-1;
            end

            h = imshow(imadjust(uint16(dicom_images(:,:,i)),[1923/65535 1924/65535],[]));

        end
    end
end

Any help will be appreciated. Thank you.

[Stephen23]

Putting

clear all

as the first line of a function is not required. This is just a bad habit that beginners pick up when they don't realize that functions begin with an empty workspace. Avoid cargo cult programming: do not add clear all at the start of your functions.

Even better is to learn to avoid using clear (and friends) in scripts too.

[Kamil]

I will try to avoid "cargo cult programming" in my future project. Thank you for your interest.

[Gabe]

Just curious, what seemed to be the problem?

[Walter Roberson]

@Gabe

The user tried to use the variable i as a shared variable in nested functions. However, shared variables need to be defined before a nested function that uses the shared variable. The user needed to initialize i before definining function f=unicontrol(hObject, eventdata, f)

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

[Kamil]

Thank you for the link. It was much easier than I thought.