Stop execution of function using a specific key press

Hello,

I am trying to write a program where the user has to click several times on a video that is being played. After the user has clicked on the video as many times as he/she wanted, he/she has to end his/her 'clicking session' by pressing a specific key (e.g. when pressing 'g'). I'm thinking of using 'waitforbuttonpress', but is there any way to specify that a specific key has to be pressed before the script continues?

So far, I've been using the 'imrect' and 'wait' command to achieve this. So after the user has clicked as many times as he/she wanted, he/she has to draw a rectangle to terminate his/her clicking session. But now I am looking for a more convenient way to stop the execution by pressing a specific key.

Here is my code:

vid = VideoReader('test1.mp4'); %make VideoReader object
curr_axes = axes;
hfig = figure(1);
set(hfig,'WindowButtonDownFcn',@countclicks) %use callback (user clicking on video)

framecount = 0;
while vid.hasFrame() %play video
temp = vid.readFrame();
framecount = framecount + 1;
curr_time(framecount) = vid.CurrentTime;
image(temp,'Parent',curr_axes);
curr_axes.Visible = 'off';
pause(0.05/vid.FrameRate); 
if framecount == 78 || framecount == 78*2 || framecount == 78*3 %after every 3 seconds, the user has to draw a rectangle before proceeding
    p1 = imrect; %draw a rectangle to proceed to the next 3 seconds of the video
    wait(p1)
end
end

function countclicks(gcbo,eventdata,handles)
disp(get(gcf,'SelectionType'))
disp(get(gcf,'CurrentPoint'))
end

Answer 1

[Ameer Hamza]

See WindowKeyPressFcn callback(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/matlab.ui.figure-properties.html#buiwuyk-1-WindowKeyPressFcn. This callback also passes the key-pressed by the user, so you can make different decisions based the keypress.

[Sam]

Thank you very much! How would this be implemented?

[Ameer Hamza]

It is just like a regular callback function. For example, run the following code

fig = figure('WindowKeyPressFcn', @keyPressFcn)

function keyPressFcn(obj, eve)
    disp(eve);
end

and press the keys while the figure window is focused.

[Sam]

Thank you. But now the video doesn't pause every 3 seconds anymore

[Ameer Hamza]

This just shows an example of how the callback works. You need to modify it according to your program logic.