How to use KeyPressFCN in matlab with a function already create? - matlab

Question

i'm in seek of information.
Me and a other students like me have to create sound in Matlab. We create them, and we have to create also an interactif interface to play those sound.
So we create a piano, and when we click on a key, it's play the sound ( that is the function. )
We also wanted that we can push a key on the Keyboard that call the function. We heard about KeyPressFCN, but we don't know how to use it, because when we search every tutorial, they didn't give enough information about it.
So, when we rightclick on the element we want, and them we call KeyPressFCN, what is the next step ? What did we have to do to "put" the function on this KeyPressFCN.
For example, to make one of the sound, we have :
% --- Execution lors d'un appui sur le bouton Do (première blanche)
function pushbutton1_Callback(hObject, eventdata, handles)
octave = str2double(get(handles.zone1,'String'));
frequence = 2093; %--- Fréquence initialement Do6
frequence2 = frequence./ octave;
son = sin(2*pi*frequence2*(0:0.000125:0.2));
sound(son);

Answer 1

Actually I am just quoting Matlab docs and help.
If you are using GUIDE right click on your figure (not on any object) >> View Callbacks >> KeyPressFcn, then it will auto-generate the following function:
function figure1_KeyPressFcn(hObject, eventdata, handles)
% hObject handle to figure1 (see GCBO)
% eventdata structure with the following fields (see FIGURE)
% Key: name of the key that was pressed, in lower case
% Character: character interpretation of the key(s) that was pressed
% Modifier: name(s) of the modifier key(s) (i.e., control, shift) pressed
% handles structure with handles and user data (see GUIDATA)
% add this part as an experiment and see what happens!
eventdata % Let's see the KeyPress event data
disp(eventdata.Key) % Let's display the key, for fun!
Play around with your keyboard and see the eventdata. Obviously the figure must be active when you are typing.
If you are using the uicontrol (and not GUIDE) which is the programmatic way of making gui
(using Inline function)
fig_h = figure; % Open the figure and put the figure handle in fig_h
set(fig_h,'KeyPressFcn',#(fig_obj,eventDat) disp(['You just pressed: ' eventDat.Key]));
% or again use the whole eventDat.Character or eventDat.Modifier if you want.
Or if you do not want to use inline function:
fig_h = figure;
set(fig_h,'KeyPressFcn', #key_pressed_fcn);
and then define your key_pressed_fcn like: (create a new mfile with name: key_pressed_fcn.m, of course you could use whatever name you want but the same as KeyPressFcn name above)
function key_pressed_fcn(fig_obj,eventDat)
get(fig_obj, 'CurrentKey')
get(fig_obj, 'CurrentCharacter')
get(fig_obj, 'CurrentModifier')
% or
disp(eventDat)
OR! use a script as your KeyPressFcn callback function
fig_h = figure;
set(fig_h,'KeyPressFcn', 'key_pressed');
and then write key_pressed script:
get(fig_h, 'CurrentKey')
get(fig_h, 'CurrentCharacter')
get(fig_h, 'CurrentModifier')
For Matlab help refer to "KeyPressFcn Event Structure" in:
http://www.mathworks.com/help/matlab/ref/figure_props.html