Re: Matlab compatibility for keypressfcn

[Julien Bect]

Le 19/04/2015 00:30, Rik a écrit :
> 4/18/15
>
> Does anyone know if the callback for keypressfcn is executed when a
> modifier key is pressed alone?  I'm debugging problems with ginput() and
> have found that Octave will execute the callback for any actual key pressed
> including the modifiers like SHIFT and CTRL.  This is rather awkward
> because generally the modifiers are part of a key sequence like <CTRL+C>
> and the there is no key in the data structure for the first part of the
> sequence when CTRL is pressed by itself.
>
> Sample code, if necessary, for testing
>
> In file mycb.m:
>
> function mycb ()
>    disp ('mycb called');
> end
>
> Then,
> figure
> set (gcf, 'keypressfcn', @mycb)
> %% Now try typing just SHIFT or just CTRL in figure window and see if 'mycb
> called' is displayed.

# Result on Matalb R2012a / Ubuntu 14.10 32 bits

# The callback gets called, but this results in an error:
Error using mycb
Too many input arguments.

Error while evaluating figure KeyPressFcn


# If I modify the callback as follows:
function mycb (varargin)
  disp ('mycb called');
  varargin{:}
end

# I get the result:
mycb called

ans =

     1


ans =

    Character: ''
     Modifier: {'control'}
          Key: 'control'

# So, the answer is yes: the callback is executed when a modifier key is 
pressed alone