Move Line on an Image with Up and Down Arrow

Hi Everyone

I have a series of pictures which i want to process with Matlab. I should be able to open the first image, then move a line up and downwards with the up and down arrow and finally change to next picture with return.

I was able to define a callback function which registers the keyboard actions.

If I press the uparrow it adds 1 to a variable s.

If I press the downarrow it subtracts 1 from a variable s.

If I press return it adds 1 to a variable k.

    function y = KeyPressCb(~,evnt)
        fprintf('%s\n',evnt.Key);
        global s
        global k
        if strcmp(evnt.Key,'uparrow')==1
        s=s+1;
        elseif strcmp(evnt.Key, 'downarrow')==1
        s=s-1;
        elseif strcmp(evnt.Key, 'return')==1
        k = k + 1;
        end
    end

Now I want to return this values to the main program, so that i can use this two variables (k and s) to change the line coordinates and the image array counter. How do i do that?

Is there an other, easier way to do it?

Greetings

[Walter Roberson]

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[Jan]

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Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.28s.29.3F

[Enea Baumann]

I have difficulties to understand this, since i'm working with callback functions for the first time. May you give me an example: For instance a program that simply changes a value x when pressing space?

Thank you in advanced!

[Walter Roberson]

 function driver
    y = 0;     %shared variable
    ax = gca;
    fig = ancestor(ax, 'figure');
    plot( ax, randn(1,50) * 10 );
    XL = get(ax, 'XLim');
    hold(ax, 'on')
    h = plot(ax, XL, [y y]);
    hold(ax, 'off');
    set(fig, 'WindowKeyPressFcn', @KeyPressCb);

    function KeyPressCb(~,evnt)
        if strcmp(evnt.Key,'uparrow')
          fprintf('up!\n');
          y = y + 1;
          set(h, 'YData', [y y]);
        elseif strcmp(evnt.Key, 'downarrow')
          fprintf('down!\n');
          y = y - 1;
          set(h, 'YData', [y y]);
        end
    end
  end

[Enea Baumann]

Wow! Thank you so much!!!!!