When I use the Zoom tools of matlab how i detect if i use mouse scroll?

Question

I developed this code to see if the user did zoom in or zoom out on a figure in matlab

function demo3

MainFig = figure;
x = sin(theta) + 0.75*rand(1,300);
y = cos(theta) + 0.75*rand(1,300);
a = 40;
hs=scatter(x,y,a,'MarkerEdgeColor',[0 .5 .5],...
'MarkerFaceColor',[0 .7 .7],...
'LineWidth',1.5);        
h = zoom;

set(MainFig, 'WindowScrollWheelFcn', @figure1_WindowScrollWheelFcn);
set(h, 'ActionPostCallback', @mypostcallback);

function mypostcallback(h, eventdata)
disp('INFO: Direction')
h2 = zoom;
get(h2,'Direction')

function figure1_WindowScrollWheelFcn(hObject, eventdata, handles)
if eventdata.VerticalScrollCount > 0
    disp ('Scrool Up ')
else
    disp ('Scrool Down ')
end

The problem is if I run the code and I use a mouse scroll the information is correct and detect if i do scroll up or down. But if I use the Zoom tools and press in zoom in the information is correct relatively to direction but if I use the mouse scroll up and down the information is the same:

INFO: Direction

ans =

in

I need a code that detects if I do a zoom in or zoom out either with the Zoom tool or with the scrool mouse.

Answer 1

Try this instead:

set(h, 'ActionPostCallback', @mypostcallback);
set(h, 'ActionPreCallback', @myprecallback);

function myprecallback(h, eventdata)
set(h, 'UserData', {eventdata.Axes.XLim, eventdata.Axes.YLim})

function mypostcallback(h, eventdata)
old_lims = get(h, 'UserData');
old_d = cellfun(@diff, old_lims);
new_d = [diff(eventdata.Axes.XLim), diff(eventdata.Axes.YLim)];
disp('INFO: Direction')
if all(old_d == new_d)
    disp('No change');
elseif  all(old_d-new_d <= 0)
    disp('Out')
elseif all(old_d-new_d >= 0)
    disp('In')
else
    disp('oops, did not expect this!')
end

This saves the axes limits just before the zoom and compares it with the limits after the zoom. If they're bigger, we zoomed out, if they're smaller, we zoomed in.