MATLAB and Simulink

Lecture 6 1

To days Outline

Graphical User Interface (GUI) Exercise on this days topics

MATLAB and Simulink

Lecture 6 2

Graphical User Interface (GUI)

Can make programs easier to use by providing them with: Pushbuttons List boxes Sliders Menus Etc

MATLAB and Simulink

Lecture 6 3

Graphical User Interface (GUI)

The GUI should behave in an understandable and predictable manner.

GUI’s are event driven A event could be a mouse click or a

key press.

MATLAB and Simulink

Lecture 6 4

Graphical User Interface (GUI)

Three principal elements required to create a MATLAB GUI:

1. Components. Each item in a GUI is a graphical component.

Controls: Pushbuttons, edit boxes, sliders etc.

Static elements: Frames and text strings

Menus Axes

MATLAB and Simulink

Lecture 6 5

Graphical User Interface (GUI)

2. Figures: The components must be within a

figure window.3. Callbacks: The GUI must perform some kind of

action if a user clicks the mouse on a button or the keyboard. (event)

The code executed in response to an event is known as a callback.

There must be a callback to each graphical component on the GUI.

MATLAB and Simulink

Lecture 6 6

Graphical User Interface (GUI)

MATLAB and Simulink

Lecture 6 7

Graphical User Interface (GUI) The basic steps to create a MATLAB GUI

1. Decide what elements are required and what function of each element. Draw a rough layout on paper.

2. Use the MATLAB tool: Graphical user interface development tool, guide. To layout all components on a figure.

3. Use a MATALB tool called: Property Inspector to set a name (a tag), color etc.

MATLAB and Simulink

Lecture 6 8

Graphical User Interface (GUI)

4. Save the figure to a file.When the figure is saved, two files will be created on the disk with the same name but with different extension. filename.fig and filename.m

The fig contains the created GUI. The m-file contains the code to load the

figure and skeleton callbacks for each GUI element.

5. Write code to implement the behavior associated with each callback function

MATLAB and Simulink

Lecture 6 9

Graphical User Interface (GUI)

GUIDE

MATLAB and Simulink

Lecture 6 10

Graphical User Interface (GUI) Property inspector

Property names and corresponding property values.

These values can be set in the property inspector.

When the program is running we can still change these values by using the set command.

…and view the values by using the get command

MATLAB and Simulink

Lecture 6 11

Graphical User Interface (GUI)

MATLAB and Simulink

Lecture 6 12

Graphical User Interface (GUI) Pushbutton

Create a GUI with one pushbutton and a text field.

The program shall count the number of times the user clicks on the button.

Display the number of clicks in the text field.

MATLAB and Simulink

Lecture 6 13

Graphical User Interface (GUI)

In the GUIDE we start by creating a pushbutton. In the property inspector:

String: ClickButtonTag: ClickButton

We must also create a text field. In the property inspector:

String: Number of clicks = 0Tag: Clicks

We save the GUI as Pbutton.fig This is our figure that we have created in the GUIDE.

MATLAB will automatically create an m-file: Pbutton.m This file contains skeleton callback functions to the

graphical objects.

MATLAB and Simulink

Lecture 6 14

Graphical User Interface (GUI)

The callback function will have the same name as the tag. function tag_Callback(hObject, eventdata,

handles)

All callback functions have handles to all graphical object as an input argument. handles is a structure with all graphical

handles. We can access all objects from a callback

function

MATLAB and Simulink

Lecture 6 15

Graphical User Interface (GUI)

Toggle buttons Every time a user clicks on it a callback is generated. Two states

On = 1 Off = 0

Val=get(handles.togglebutton,’Value’)

Radio buttons/Check boxes Every time a user clicks on it a callback is generated. Two states

On = 1 Off = 0

Val=get(handles. radiobutton,’Value’)

MATLAB and Simulink

Lecture 6 16

Graphical User Interface (GUI) Text fields

Graphical object that displays a text string Text fields do not create callbacks. Can be changed in other callback functions

by using: Set(handles.text,’String’,str)

Edit boxes Allows a user to enter a text string Generates a callback when the user presses

the Enter Key sentence=get(handles.edit,'String');

MATLAB and Simulink

Lecture 6 17

Graphical User Interface (GUI)

Example: Let a user write a

sentence in an edit box.

Rewrite the sentence backwards in a text field

MATLAB and Simulink

Lecture 6 18

Graphical User Interface (GUI) Frames

Used for drawing boxes around logically related objects

Frames do not generate callbacks

MATLAB and Simulink

Lecture 6 19

Graphical User Interface (GUI)

Popup Menus Allows a user to select one of a

mutually exclusive list of options The list of options is specified by

a cell array of strings Example:

Create a popup menu with three options.

Display the users choice in a text field

MATLAB and Simulink

Lecture 6 20

Graphical User Interface (GUI) List boxes

Functionality as popup menus

The difference between them is that a user can choose more then one line.

To enable multiple line choices set the max-min difference greater then 1 in the property editor.

MATLAB and Simulink

Lecture 6 21

Graphical User Interface (GUI) Sliders

Allows users to select values from a continues range.

Generate callbacksExample:

Construct a GUI with a slider. Display actual value in a text

field.

MATLAB and Simulink

Lecture 6 22

Graphical User Interface (GUI)

Dialog boxes A special type of figure Used to display information or to get

information from the user. Errordlg Helpdlg Inputdlg Etc

MATLAB and Simulink

Lecture 6 23

Graphical User Interface (GUI) Menus

Use the menu editor in GUIDE

Menus generate callbacks

MATLAB and Simulink

Lecture 6 24

Exercises on this days topics Create a GUI that plots the

water level in the water tanks.

We will use the differential equation from the tank process.

Create a GUI with: A start button. Axes that are plotting the

levels Check boxes so that the user

could chose which tank he/she wants to see.

Add more features if you like.

MATLAB and Simulink

Lecture 6 25

Exercises on this days topics

function xprim=TankODE(t,x)A=2734e-6;a=7e-6;km=2.7e-6;g=9.82;alfa=a/A;beta=km/A;xprim = [(beta*5-alfa*sqrt(x(1)*2*g)) alfa*sqrt(x(1)*2*g)-alfa*sqrt(x(2)*2*g)];Return

To solve the equation [time,x]=ode45(@TankODE,[0 500],[0 0]);