%% Use the built-in function: getrect

figure; imshow(A); %

rect = getrect; % current figure by default; not applicable for subplot image

% rect is a four-element vector [xmin, ymin, width, height];

% actual region selected by mouse is [xmin:xmin+width-1, ymin:ymini+height-1];

rect = round(rect); % conversion to integer

rs = rect(2); %starting row

re = rect(2) + rect(4) -1; %ending row

cs = rect(1); %starting column

ce = rect(1) + rect(3) -1;

figure; imshow(A(rs:re,cs:ce));

%% use figure's WindowButtonDownFcn property

%define a call-back function
% main
function test_mouse_track()
figure;
axis([-10,10,0,5]);
set(gcf,'WindowButtonDownFcn',@ButttonDownFcn);

%% Otherwise, use get function

k = waitforbuttonpress;             
point1 = get(gca,'CurrentPoint');   
finalRect = rbbox;                
point2 = get(gca,'CurrentPoint');  
point1 = point1(1,1:2);           
point2 = point2(1,1:2);

p1 = min(floor(point1),floor(point2));             % calculate position
p2 = max(floor(point1),floor(point2));
offset = abs(floor(point1)-floor(point2));         % offset(1): width，offset(2): height

x = [p1(1) p1(1)+offset(1) p1(1)+offset(1) p1(1) p1(1)];
y = [p1(2) p1(2) p1(2)+offset(2) p1(2)+offset(2) p1(2)];