MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Manuale Utente Scaricare il pdf (Pagina 62)

3 Creating a GUI Programmatically

3-14

Programming the GUI

You use callbacks to program the GUI components. Callbacks are the functions

that execute in response to user-generated events such as a mouse click.

This topic shows you how to write callbacks for the simple GUI, then shows you

how to associate each callback with its component.

• “Programming the Pop-Up Menu” on page 3-14

• “Programming the Push Buttons” on page 3-15

• “Associating Callbacks with Their Components” on page 3-15

Programming the Pop-Up Menu

The pop-up menu enables users to select the data to plot. When a GUI user

selects one of the three data sets, MATLAB sets the pop-up menu

Value

property to the index of the selected string. The pop-up menu callback reads

the pop-up menu

Value property to determine which item is currently

displayed and sets

current_data accordingly.

Add the following callback to your file following the initialization code and

before the final

end statement.

% Pop-up menu callback. Read the pop-up menu Value property

% to determine which item is currently displayed and make it

% the current data. This callback automatically has access to

% current_data because this function is nested at a lower level.

function popup_menu_Callback(source,eventdata)

% Determine the selected data set.

str = get(source, 'String');

val = get(source,'Value');

% Set current data to the selected data set.

switch str{val};

case 'Peaks' % User selects Peaks

current_data = peaks_data;

case 'Membrane' % User selects Membrane

current_data = membrane_data;

case 'Sinc' % User selects Sinc

current_data = sinc_data;

end

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MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Manuale Utente Pagina 62