MATLAB Programming/Psychtoolbox/GetMouse AllowMultipleHack

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A simple hack I made to get around the limitation on the number of mice. It gets around the problem by ignoring that there are multiple mice.

This is useful if you have a trackpad on a laptop and need to use an external mouse.

function [x,y,buttons] = GetMouse_AllowMultipleHack(windowPtrOrScreenNumber)
% [x,y,buttons] = GetMouse([windowPtrOrScreenNumber])
% Returns the current (x,y) position of the cursor and the up/down state
% of the mouse buttons. "buttons" is a 1xN matrix where N is the number of
% mouse buttons. Each element of the matrix represents one mouse button.
% The element is true (1) if the corresponding mouse button is pressed and
% false (0) otherwise. 
% % Test if any mouse button is pressed. 
% if any(buttons)
%   fprintf('Someone''s pressing a button.\n');
% end
% % Test if the first mouse button is pressed.
% if buttons(1)
%   fprintf('Someone''s pressing the first button!\n');
% end
% % Test if the second mouse button is pressed.
% if length(buttons)>=2 & buttons(2)
%   fprintf('Someone''s pressing the second button!\n');
% end
% length(buttons) tells you how many buttons there are on your mouse.
% The cursor position (x,y) is "local", i.e. relative to the origin of
% the window or screen, if supplied. Otherwise it's "global", i.e. relative
% to the origin of the main screen (the one with the menu bar).
% NOTE: If you use GetMouse to wait for clicks, don't forget to wait
% for the user to release the mouse button, ending the current click, before
% you begin waiting for the next mouse press.
% fprintf('Please click the mouse now.\n');
% [x,y,buttons] = GetMouse;
% while any(buttons) % if already down, wait for release
%       [x,y,buttons] = GetMouse;
% end
% while ~any(buttons) % wait for press
%       [x,y,buttons] = GetMouse;
% end
% while any(buttons) % wait for release
%       [x,y,buttons] = GetMouse;
% end
% fprintf('You clicked! Thanks.\n');
% NOTE: GetMouse no longer supports this obsolete usage:
% xy = GetMouse([windowPtrOrScreenNumber])
% where xy is a 1x2 vector containing the x, y coordinates.
% OS X: ___________________________________________________________________
% Even if your mouse has more than three buttons, GetMouse will return as
% many values as your mouse has buttons, 
% GetMouse can not cope if your computer has more than one mouse connected. 
% It exits with an error.  
% _________________________________________________________________________
% See also: GetClicks, SetMouse

% 4/27/96  dhb  Wrote this help file.
% 5/12/96  dgp  Removed confusing comment about columns.
%               Added query about coordinates.
% 5/16/96  dhb  Modified MEX file to conform to above usage, answered
%               query about coordinates.
% 5/29/96  dhb  Flushing mouse button events added by dgp.
% 8/23/96  dhb  Added support for windowInfo argument.
% 2/24/97  dgp  Updated.
% 2/24/97  dgp  Updated comments about flushing mouse button events.
% 3/10/97  dgp  windowPtrOrScreenNumber
% 3/23/97  dgp  deleted obsolete comment about flushing mouse button events.
% 5/9/00   dgp  Added note about waiting for release before waiting for next click.
% 8/5/01   awi  Added examples and modified to document new size of returned button matrix
%                               on windows.  
% 8/6/01   awi  Added See also line for GetClicks and note about prior Windows version.
% 4/13/02  dgp  Cosmetic.
% 5/16/02  awi  Changed Win GetMouse to return variable number of button values and updated 
%               help accordingly.  
% 5/20/02  dgp  Cosmetic.
% 5/22/02  dgp  Note that obsolete usage is no longer supported.
% 6/10/01  awi  Added SetMouse to see also.
% 7/12/04  awi  ****** OS X-specific fork from the OS 9 version *******
%               Added note that this is not supported in OS X.  When the
%               new OS X mouse functions are in place this will have to be updated.
%               Check to see if the OS 9 GetMouse source would work in
%               Carbon on OS X so that we could still support this.
% 11/18/04 awi  Added support for OS X
% 04/25/05 robkohr  A simple hack I made to get around the limitation on
%               the number of mice. It gets around the problem by 
%               ignoring that there are
%               multiple mice.

% Exit with an error if we don't find the a mex file on Windows or OS 9.    
AssertMex('MAC2', 'PCWIN');

% On OS X we execute this sript, otherwise either MATLAB found the mex file
% file and exuted this, or else this  file was exucuted and exited with
% error on the AssertMex command above.  

%get the number of mouse buttons from PsychHID
numMice = length(mousedices);

%changed to avoid multiple mouse problem
mousedices = mousedices(1);
% if numMice > 1
%     error('GetMouse detected more than one mouse connected to your computer and got confused');
% elseif numMice == 0
%     error('GetMouse could not find any mice connected to your computer');
% end   

if numMice == 0
    error('GetMouse could not find any mice connected to your computer');

%%End Change


%read the mouse position and  buttons
[globalX, globalY, rawButtons]=Screen('GetMouseHelper', numMouseButtons);

%renormalize to screen coordinates from display space