MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Bedienungsanleitung PDF herunterladen (Seite 215)

Mechanisms for Managing Data

9-3

GUI data provides application developers with a convenient interface to a

figure’s application data:

• You do not need to create and maintain a hard-coded name for the data

throughout your source code.

• You can access the data from within a callback routine using the component’s

handle, without having to find the figure handle. For GUIDE users, the

object handle is automatically passed to each callback as

hObject.

GUI Data in GUIDE

GUIDE automatically uses guidata to create and maintain the handles

structure. This structure is automatically passed as an argument to every

callback. The

handles structure contains the handles of all components in the

GUI.

In a GUI created using GUIDE, you cannot use

guidata to manage any

variable other than the

handles structure. If you do, you may overwrite the

handles structure and your GUI will not work. If you want to use GUI data to

share application-defined data among callbacks, you must save the data in

fields that you add to the

handles structure.

Note that the GUIDE templates use the

handles structure to store

application-defined data. See “Selecting a GUI Template” on page 6-5 for

information about the templates.

Note For more information, see “The Handles Structure” on page 8-13.

Adding Fields to the handles Structure

To add a field to the handles structure, which is passed as an argument to

every callback in GUIDE.

1 Assign a value to the new field. This adds the field to the structure. For

example

handles.number_errors = 0;

adds the field number_errors to the structure handles and sets it to 0.

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MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Bedienungsanleitung Seite 215