Question

I have a simple, sort of GUI code shown below.
This “test_keypress” function creates a figure, and it responses to the keypress (space).

Now, I want to add a constraint so that Matlab accepts only one keypress for a certain period of time (say, 1 second).
In other words, I want to reject a keypress if it happens within 1 sec after the previous keypress occurred.

How can I do that?

function test_keypress

f = figure;
set(f,'KeyPressFcn',@figInput);
imshow(ones(200,200,3));

end


function figInput(src,evnt)

if strcmp(evnt.Key,'space')
    imshow(rand(200,200,3));
end

end

Answer 1

You can store the current time, and only evaluate the imshow command if the key-press occurs at least 100 seconds after the last one.

function test_keypress

f = figure;
set(f,'KeyPressFcn',@figInput);
imshow(ones(200,200,3));

%# initialize time to "now"
set(f,'userData',clock);

end


function figInput(src,evnt)

currentTime = clock;
%# get last time
lastTime = get(src,'UserData');

%# show new figure if the right key has been pressed and at least
%# 100 seconds have elapsed
if strcmp(evnt.Key,'space') && etime(lastTime,currentTime) > 100
    imshow(rand(200,200,3));
    %# also update time
    set(src,'UserData',currentTime)
end

end