Callback Properties :: Laying Out GUIs and Setting Properties (Creating Graphical User Interfaces)

Creating Graphical User Interfaces

Callback Properties

A callback is a function that executes when a user performs a specific action such as clicking a push button or pressing a keyboard key, or when a component is created or deleted. Each component and menu item has properties that specify its callbacks. When you create a GUI, you must program the callbacks you need to control operation of the GUI.

The following table lists the various callback properties and briefly describes the purpose of each callback. See the components' property reference pages to find out which callbacks apply to a specific component.

Callback Property
Description

ButtonDownFcn
Executes when the user presses a mouse button while the pointer is on or within five pixels of a component.

Callback
Performs the primary work of the component. It executes, for example, when a user clicks a push button or selects a menu item. See The Tag Property for additional information.

CreateFcn
Initializes the component when it is created. It executes when the component is created, but before it becomes visible.

DeleteFcn
Performs cleanup operations just before the component is destroyed.

KeyPressFcn
Executes when the user presses a keyboard key and the callback's component has focus.

ResizeFcn
Executes when a user resizes a panel or button group whose Resize behavior is set to Other.

SelectionChangeFcn
Executes when a user selects a different radio button or toggle button in a button group component.

Callback Property	Description
`ButtonDownFcn`	Executes when the user presses a mouse button while the pointer is on or within five pixels of a component.
`Callback`	Performs the primary work of the component. It executes, for example, when a user clicks a push button or selects a menu item. See The Tag Property for additional information.
`CreateFcn`	Initializes the component when it is created. It executes when the component is created, but before it becomes visible.
`DeleteFcn`	Performs cleanup operations just before the component is destroyed.
`KeyPressFcn`	Executes when the user presses a keyboard key and the callback's component has focus.
`ResizeFcn`	Executes when a user resizes a panel or button group whose Resize behavior is set to `Other`.
`SelectionChangeFcn`	Executes when a user selects a different radio button or toggle button in a button group component.

Adding Callbacks to the M-file

If you checked Generate callback function prototypes in the GUI Options dialog, GUIDE automatically adds the most commonly used callbacks to the GUI M-file. If you want GUIDE to include other callbacks in the GUI M-file and provide names for them, you can do one of the following:

In the Property Inspector, set the value of the callback property, e.g., KeyPressFcn, to the string %automatic. GUIDE adds the callback to the M-file the next time you save the GUI.
In the View menu, select View Callbacks. Then select the desired callback, e.g., KeyPressFcn. GUIDE adds the callback to the M-file, opens the M-file if it is not already open, and scrolls to the first line of the new callback.

Setting Properties for Some Specific Components Changing Tag and Callback Properties