getkey

 GETKEY - get a single keypress
   CH = GETKEY waits for a keypress and returns the ASCII code. Accepts
   all ascii characters, including backspace (8), space (32), enter (13),
   etc, that can be typed on the keyboard. Non-ascii keys (ctrl, alt, ..)
   return a NaN. CH is a double. 

   CH = GETKEY('non-ascii') uses non-documented matlab features to return
   a string describing the key pressed. In this way keys like ctrl, alt,
   tab etc. can also distinguished. CH is a string.

   This function is kind of a workaround for getch in C. It uses a modal,
   but non-visible window, which does show up in the taskbar.
   C-language keywords: KBHIT, KEYPRESS, GETKEY, GETCH

   Examples:

    fprintf('\nPress any key: ') ;
    ch = getkey ;
    fprintf('%c\n',ch) ;

    fprintf('\nPress the Ctrl-key: ') ;
    if strcmp(getkey('non-ascii'),'control'),
      fprintf('OK\n') ;
    else
      fprintf(' ... wrong key ...\n') ;
    end

  See also INPUT, UIWAIT
           GETKEYWAIT (File Exchange)

0001 function ch = getkey(m) 
0002 
0003 % GETKEY - get a single keypress
0004 %   CH = GETKEY waits for a keypress and returns the ASCII code. Accepts
0005 %   all ascii characters, including backspace (8), space (32), enter (13),
0006 %   etc, that can be typed on the keyboard. Non-ascii keys (ctrl, alt, ..)
0007 %   return a NaN. CH is a double.
0008 %
0009 %   CH = GETKEY('non-ascii') uses non-documented matlab features to return
0010 %   a string describing the key pressed. In this way keys like ctrl, alt,
0011 %   tab etc. can also distinguished. CH is a string.
0012 %
0013 %   This function is kind of a workaround for getch in C. It uses a modal,
0014 %   but non-visible window, which does show up in the taskbar.
0015 %   C-language keywords: KBHIT, KEYPRESS, GETKEY, GETCH
0016 %
0017 %   Examples:
0018 %
0019 %    fprintf('\nPress any key: ') ;
0020 %    ch = getkey ;
0021 %    fprintf('%c\n',ch) ;
0022 %
0023 %    fprintf('\nPress the Ctrl-key: ') ;
0024 %    if strcmp(getkey('non-ascii'),'control'),
0025 %      fprintf('OK\n') ;
0026 %    else
0027 %      fprintf(' ... wrong key ...\n') ;
0028 %    end
0029 %
0030 %  See also INPUT, UIWAIT
0031 %           GETKEYWAIT (File Exchange)
0032 
0033 % for Matlab 6.5 and higher
0034 % version 1.3 (jan 2012)
0035 % author : Jos van der Geest
0036 % email  : jos@jasen.nl
0037 %
0038 % History
0039 % 2005 - creation
0040 % dec 2006 - modified lay-out and help
0041 % apr 2009 - tested for more recent MatLab releases
0042 % jan 2012 - modified a few properties, included check is figure still
0043 %            exists (after comment on FEX by Andrew).
0044 
0045 % Determine the callback string to use
0046 if nargin == 1,
0047     if strcmpi(m,'non-ascii'),
0048         callstr = 'set(gcbf,''Userdata'',get(gcbf,''Currentkey'')) ; uiresume ' ;
0049     else       
0050         error('Argument should be the string ''non-ascii''') ;
0051     end
0052 else
0053     callstr = 'set(gcbf,''Userdata'',double(get(gcbf,''Currentcharacter''))) ; uiresume ' ;
0054 end
0055 
0056 % Set up the figure
0057 % May be the position property  should be individually tweaked to avoid visibility
0058 fh = figure(...
0059     'name','Press a key', ...
0060     'keypressfcn',callstr, ...
0061     'windowstyle','modal',... 
0062     'numbertitle','off', ...
0063     'position',[0 0  1 1],...
0064     'userdata','timeout') ; 
0065 try
0066     % Wait for something to happen
0067     uiwait ;
0068     ch = get(fh,'Userdata') ;
0069     if isempty(ch),
0070         ch = NaN ; 
0071     end
0072 catch
0073     % Something went wrong, return and empty matrix.
0074     ch = [] ;
0075 end
0076 
0077 if ishandle(fh)
0078     delete(fh) ;
0079 end