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GUI Files: An Overview

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M-Files and FIG-Files GUI M-File Structure Adding Callback Templates to an Existing GUI M-File About GUIDE-Generated Callbacks

M-Files and FIG-Files

By default, the first time you save or run a GUI, GUIDE stores the GUI in two files:

• A FIG-file, with extension .fig, that contains a complete description of the GUI layout and each GUI component, such as push buttons, axes, panels, menus, and so on. The FIG-file is a binary file and you cannot modify it except by changing the layout in GUIDE. FIG-files are specializations of MAT-files. See for more information.

• An M-file, with extension .m, that initially contains initialization code and templates for some callbacks that control GUI behavior. You generally add callbacks you write for your GUI components to this file. As the callbacks are functions, the GUI M-file can never be a MATLAB script.

  When you save your GUI the first time, GUIDE automatically opens the M-file in your default editor.

The FIG-file and the M-file must have the same name. These two files usually reside in the same folder, and correspond to the tasks of laying out and programming the GUI. When you lay out the GUI in the Layout Editor, your components and layout is stored in the FIG-file. When you program the GUI, your code is stored in the corresponding M-file.

If your GUI includes ActiveX components, GUIDE also generates a file for each ActiveX component. See ActiveX Control for more information.

For more information about naming and saving a GUI, see Saving and Running a GUIDE GUI. If you want to change the name of your GUI and its files, see Renaming GUIs and GUI Files.

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GUI M-File Structure

The GUI M-file that GUIDE generates is a function file. The name of the main function is the same as the name of the M-file. For example, if the name of the M-file is mygui.m, then the name of the main function is mygui. Each callback in the file is a subfunction of the main function.

When GUIDE generates an M-file, it automatically includes templates for the most commonly used callbacks for each component. The M-file also contains initialization code, as well as an opening function callback and an output function callback. It is your job to add code to the component callbacks for your GUI to work as you want. You can also add code to the opening function callback and the output function callback. The GUI M-file orders functions as shown in the following table.

Section	Description
Comments	Displayed at the command line in response to the help command. Edit comments as necessary for your GUI.
Initialization	GUIDE initialization tasks. Do not edit this code.
Opening function	Performs your initialization tasks before the GUI user has access to the GUI.
Output function	Returns outputs to the MATLAB command line after the opening function returns control and before control returns to the command line.
Component and figure callbacks	Control the behavior of the GUI figure and of individual components. MATLAB software calls a callback in response to a particular event for a component or for the figure itself.
Utility/helper functions	Perform miscellaneous functions not directly associated with an event for the figure or a component.

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Adding Callback Templates to an Existing GUI M-File

When you save the GUI, GUIDE automatically adds templates for some callbacks to the M-file. If you want to add other callbacks to the M-file, you can easily do so.

Within GUIDE, you can add a callback subfunction template to the GUI M-file in any of the following ways. Select the component for which you want to add the callback, and then:

• Click the right mouse button to display the Layout Editor context menu. Select the desired callback from the View callbacks submenu.

• In the View menu, select the desired callback from the View callbacks submenu.

• Double-click a component to show its properties in the Property Inspector. In the Property Inspector, click the pencil-and-paper icon next to the name of the callback you wish to install in the M-file.

• For toolbar buttons, in the Toolbar Editor, click the View button next to Clicked Callback (for Push Tool buttons) or On Callback, or Off Callback (for Toggle Tools).

When you perform any of these actions, GUIDE adds the callback template to the GUI M-file and opens the M-file for editing at the callback you just added. If you select a callback that currently exists in the GUI M-file, GUIDE adds no callback, but opens the M-file for editing at the callback you select.

For more information, see Associating Callbacks with Components.

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About GUIDE-Generated Callbacks

Callbacks created by GUIDE for GUI components are similar to callbacks created programmatically, with certain differences.

• GUIDE generates callbacks as function templates within the GUI M-file, which GUI components call via function handles.

  GUIDE names callbacks based on the callback type and the component Tag property. For example, togglebutton1_Callback is such a default callback name. If you change a component Tag, GUIDE renames all its callbacks in the M-file to contain the new tag. You can change the name of a callback, replace it with another function, or remove it entirely using the Property Inspector.

• GUIDE provides three arguments to callbacks, always named the same.

• You can append arguments to GUIDE-generated callbacks, but never alter or remove the ones that GUIDE places there.

• You can rename a GUIDE-generated callback by editing its name or by changing the component Tag.

• You can delete a callback from a component by clearing it from the Property Inspector; this action does not remove any code in the M-file.

• You can specify the same callback function for multiple components to enable them to share code.

After you delete a component in GUIDE, all callbacks it had remain in the M-file. If you are sure that no other component uses the callbacks, you can then remove the callback code manually. For details, see Deleting Callbacks from a GUI M-File. If you need a way to remove a callback without deleting its component, see .

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Callbacks: An Overview

Associating Callbacks with Components

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