Key press in MATLAB

I have a main script in MATLAB in which I am calling four different functions each has been defined in a separate script.

function[] = main()
  [par_1] =function_1(inp_1);
  [par_2] = function_2(inp_2);
  [par_3] = function_3(inp_3);
end

Now I want to define here that while for example function_1 is being called and is running, by pressing a key, for example 'esc', function_1 stops and return and function_2 starts running and so on. I don't know how to do this in MATLAB.

Answer 1

[Walter Roberson]

In MATLAB, you can only do that with the cooperation of the function itself. You would define a callback such as a figure WindowKeyPressFcn callback, that would set a "key was pressed!" flag in a common space, and the functions being run would have to periodically check whether the flag was set and voluntarily exit if it found the flag set.

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.28s.29.3F

[Nick Matin]

Thanks for your answer. I am trying to do this but since the event listener is undocumented in matlab, I am having some problem. First of all should I use the event class as follows?

event.addlistener (Hsourse, 'KeyPressFcn',@CallbackFunction)

If yes, how should I define Hsource? Also how should I define the 'CallbackFunction' ? If you could refer me to an example in this regard, I appreciate that.

[Walter Roberson]

It is not an event listener, it is a Figure property. The ability to listen to keypresses is associated with figures in MATLAB.

set(gcf, 'Windowkeypressfcn', @(src, event) set(src, 'UserData' true) )

Then when the cooperating routine starts, it should

set(gcf, 'UserData', false);     %reset key-has-been-pressed

And assuming it is in a loop, from time to time it should

   drawnow();    %give the graphics queue a chance to process the callback
   if get(gcf, 'UserData')   %was key pressed?
     %the user pressed a key. Gracefully exit the loop
     break;
   end

[Nick Matin]

thank you so much.

[Thomas]

Need a comma after that first line's 'UserData'

[Walter Roberson]

You are correct, Thomas, it should have been

set(gcf, 'Windowkeypressfcn', @(src, event) set(src, 'UserData', true) )