MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Bedienungsanleitung PDF herunterladen (Seite 220)

9 Managing Application-Defined Data

9-8

The GUI behavior is as follows:

• When a user moves the slider, the text box displays the slider’s current value.

• When a user types a value into the text box, the slider updates to this value.

• If a user enters a value in the text box that is out of range for the slider —

that is, a value that is not between 0 an 1 — the application returns a

message in the edit text box indicating how many times the user has entered

an erroneous value.

The commands given in the following steps initialize the error counter and

implement the interchange between the slider and the edit text box.

1 Define the error counter in the opening function. The GUI records the

number of times a user enters an erroneous value in the text box and stores

this number in a field of the

handles structure. Start by defining this field,

called

number_errors, in the opening function as follows:

handles.number_errors = 0;

Type this statement before the following line, which GUIDE automatically

inserts into the opening function.

guidata(hObject,handles); % Save the updated handles structure

The guidata command saves the handles structure so that it can be

retrieved in the GUI’s callbacks.

2 Set the edit text value from the slider Callback callback. The following

command in the slider

Callback updates the value displayed in the edit text

when a user moves the slider and releases the mouse button.

set(handles.edit1,'String',...

num2str(get(handles.slider1,'Value')));

The code combines three commands:

- The

get command obtains the current value of the slider.

- The

num2str command converts the value to a string.

- The

set command sets the String property of the edit text to the updated

value.

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MATLAB SIMULINK 7 - GRAPHICAL USER INTERFACE Bedienungsanleitung Seite 220