How can I change the elements of a matrix when hovering over its figure with the mouse?

I am trying to write a code that does the following: the user inserts the values for the row and column numbers for a matrix with values of 0. Then, when displaying the said matrix (as a white grided figure), whenever the mouse hovers over a matrix cell, the value of that becomes 1 and the cell's background is turned black. When hovering again on that cell, it turns back to 0 and white background, respectively. I'm a rather novice in MatLab so there might be simple stuff that I still didn't get right.

Here is my main .m file:

close all; clear all; clc; format long e;

r = input('How many rows do you want? ');
c = input('How many columns do you want? ');

M = zeros(r, c);

disp('Press a key when you want to start...');
clc;

stop = 'n';

figure

while stop == 'n';
    imagesc(M); colormap('gray');
    set(gcf,'WindowButtonMotionFcn', @mouseMove);
    for i = 1: r,
        for j = 1 : c,
            if (x == i && y == j)
                M{i, j} = 1 - M{i, j};
            end
        end
    end
    stop = input('Stop? (y/n) \n');
end
hold off;
And here's my mouseMove function:

function [x, y] = mouseMove
[x, y] = get (gca, 'CurrentPoint');
Please help me understand what I did wrong.

Answer 1

[Giorgos Papakonstantinou]

Hi Bogdan! Maybe you can try this:

close all; clear all; clc; 

fig = figure;
set(fig, 'Color',[0,0.5,0.5]);
grid on;

r = input('How many rows do you want? ');
c = input('How many columns do you want? ');

M = zeros(r, c);
img = imagesc(M, [0 1]);
title('press space to stop')

colormap(gray)
set(gcf,'WindowButtonMotionFcn', @(obj, evd, x)mouseMove(obj, evd, img), ...
        'KeyPressFcn', @(obj, evd)StopButtonMotion(obj, evd));

The WindowButtonMotionFcn:

function mouseMove(obj, evd, img)
persistent previousIndex

Coord   = get (gca, 'CurrentPoint');
x       = Coord(1, 2); % rows
y       = Coord(1, 1); % cols
m       = get(img, 'CData');
s       = size(m);

% Is the mouse of over th image ?
idx1    = bsxfun(@(a, b) a>=b, [x, y], [0.5 0.5]);
idx2    = bsxfun(@(a, b) a<=b, [x, y], [s(1) s(2)] + 0.5);
flag    = all([idx1 idx2], 2);
if any(flag)
    ii = round(x);
    jj = round(y);
    index = [ii, jj];
    if ~isequal(index, previousIndex)
        m(ii, jj) = 1 - m(ii, jj);
        set(img, 'CData', m)
        previousIndex = index;
    end   

end

The KeyPressFcn:

function StopButtonMotion(obj, evd)
if strcmp(evd.Key, 'space');...
        set(gcf, 'WindowButtonMotionFcn', '');
end;