Programming Callbacks for gui Components

This section explains how to program the callbacks for some specific GUI components. Callback Properties describes the different kinds of callbacks.

See a component's property reference page to determine which callbacks apply for that component. Setting Component Properties -- The Property Inspector provides links to the property reference pages.

This section provides information on the following topics:

• Toggle Button Callback

• Radio Buttons

• Check Boxes

• Edit Text

• Sliders

• List Boxes

• Pop-Up Menus

• Panels

• Button Groups

• Axes

• ActiveX Controls

• Figures

Toggle Button Callback

The callback for a toggle button needs to query the toggle button to determine what state it is in. MATLAB sets the Value property equal to the Max property when the toggle button is depressed (Max is 1 by default) and equal to the Min property when the toggle button is not depressed (Min is 0 by default).

From the GUI M-file

The following code illustrates how to program the callback in the GUI M-file.

function togglebutton1_Callback(hObject, eventdata, handles)

button_state = get(hObject,'Value');

if button_state == get(hObject,'Max')

% toggle button is pressed

elseif button_state == get(hObject,'Min')

% toggle button is not pressed

end

Note If you have toggle buttons that are managed by a button group component, you must include the code to control them in the button group's SelectionChangeFcn callback function, not in the individual toggle button Callback functions. A button group overwrites the Callback properties of radio buttons and toggle buttons that it manages. See Button Groups for more information.

Adding an Image to a Push Button or Toggle Button

Assign the CData property an m-by-n-by-3 array of RGB values that define a truecolor image. For example, the array a defines 16-by-128 truecolor image using random values between 0 and 1 (generated by rand).

a(:,:,1) = rand(16,128);

a(:,:,2) = rand(16,128);

a(:,:,3) = rand(16,128);

set(hObject,'CData',a)

See ind2rgb for information on converting an (X, MAP) image to an RGB image.

Radio Buttons

You can determine the current state of a radio button from within its callback by querying the state of its Value property, as illustrated in the following example:

if (get(hObject,'Value') == get(hObject,'Max'))

% then rsdio button is selected-take approriate action

else

% radio button is not selected-take approriate action

end

Note If you have radio buttons that are managed by a button group component, you must include the code to control them in the button group's SelectionChangeFcn callback function, not in the individual radio button Callback functions. A button group overwrites the Callback properties of radio buttons and toggle buttons that it manages. See Button Groups for more information

.

Check Boxes

You can determine the current state of a check box from within its callback by querying the state of its Value property, as illustrated in the following example:

function checkbox1_Callback(hObject, eventdata, handles)

if (get(hObject,'Value') == get(hObject,'Max'))

% then checkbox is checked-take approriate action

else

% checkbox is not checked-take approriate action

end