MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Guide de l'utilisateur télécharger pdf (Page 633)

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101

Ways to Manage Data in a Programmatic GUI

See “Share Data with Nested Functions” on page 13-11 for a complete

example.

UserData Property

All GUI components, including menus and the figure itse lf have a UserData

property. Y ou can assign any valid MATLAB workspace value as the

UserData property’s value, but only one value can exist at a time. To retrieve

the data, a callback must know the handle of the component in which the

data is stored. You access

UserData using get and se t w ith the appropriate

object’s handle. T he following example illustrates this pattern:

1 An edit text component stores the user-entered string in its UserData

property.

function editte xt1_ callback(hObject,eventd ata)

mystring = get(hObject,'String' );

set(hObject,'UserData',mystring);

2 A push button retrieves the string from the edit text component UserD ata

property.

function pushbu tton 1_callback(hObject,even tdata)

string = get(edittexthandle,'Us erData');

For example, if the menu item is Undo, its code could reset the String

of edittext1 back to the value stored in its UserData . To facilita te undo

operations, the

UserData can be a cell array o f strings , managed as a stack

or circular buffer.

Specify

UserData as a structure if you want to store multiple variables. Each

field you define can hold a different variable.

Note To use hObject (the calling object’s handle), you must specify a

component’s callback properties as function handles rather than as strings

or function names. When you do, the component handle is automatically

passed to e ach callback as

hObject. See “Specify Callbacks in Function Calls”

on page 12-11 for mo re information.

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MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Guide de l'utilisateur Page 633

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