MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Manual do Utilizador descarregar pdf (Página 223)

Sharing Data Among a GUI’s Callbacks

9-11

% Retrieve and increment the error count.

slider_data = getappdata(handles.figure1,'slider');

slider_data.number_errors = slider_data.number_errors+1;

% Save the changes.

setappdata(handles.figure1,'slider',slider_data);

% Display new total.

set(hObject,'String',...

['You have entered an invalid entry ',...

num2str(slider_data.number_errors),' times.']);

end

UserData Property

Every GUI component, and the figure itself, has a UserData property that you

can use to store application defined data. To access

UserData, a callback must

know the handle of the component with which it is associated.

Use the

get function to retrieve UserData, and the set function to set it.

UserData Property Example: Passing Data Between a Slider and an Edit

Text Box

A previous topic, “GUI Data Example: Passing Data Between a Slider and an

Edit Text Box” on page 9-7, used GUI data to initialize and maintain an error

counter. This example shows you how to do the same thing using the

UserData

property of the edit text box to store the error count. Refer to the GUI data

example for details of the example.

1 Initialize the edit text UserData property in the opening function. Add the

following code to the opening function. This code initializes the data in a

structure to allow for other data that may be needed.

number_errors = 0;

set(handles.edit1,'UserData',number_errors)

Note Alternatively, you could add a CreateFcn callback for the edit text to

the M-file, and initialize the error counter there.

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MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Manual do Utilizador Página 223