building a matlab gui - community.iisme.org

BUILDING A MATLAB GUI

Education Transfer Plan Seyyed Khandani, Ph.D.

IISME 2014

Seyyed Khandani/IISME/ETP/2014 [email protected] 2

Graphical User Interface (GUI)

A GUI is useful for presenting your final software.

It makes adjusting parameters and visualizing your

programs easier.

It allows wrapping the software in a form that could

be used by people with no knowledge of computer

programming.

It encourages design-oriented mentality which is

essential in engineering education.

MATLAB provide a tool, called guide, for creating a

GUI.

Typing guide in the command window opens the

“GUIDE Quick Start” window shown below:

>> guide

Begin by using

Blank GUI (default)

template.

3

Guide

Seyyed Khandani/IISME/ETP/2014 [email protected]

Guide window and blank GUI panel shown below

The window has 3 areas:

(1) The menu and menu

bar on the top.

(2) Buttons to select GUI

objects, or controls, on

the left.

(3) The resizable panel

with grid marks where

GUI objects will be

placed.

________________ To resize the panel grab the lower right corner with the mouse and stretch.

4

Guide Window


Guide GUI objects are instances of a MATLAB class called uicontrol (user interface control)

Push button ------ A button to activate by mouse

Radio button ----- Changes state from unselected

to selected and back

Edit textbox ------ Input data by typing text into

the box

Pop-up menu ---- A list of options to select one

Toggle button ---- Pressed down, it stays down

until it is pressed again

Axes ----------------- A surface on which to display

two and three-dimensional

graphs

Button group ---- Groups a set of radio buttons

or toggle buttons; only one at

a time is selected

Slide ---------------- Enter a real number by adjusting

the position of the slider

Checkbox --------- Changes state between select and unselected

Static text --------- Displays a text; use for label or show the result of a calculation

Listbox ------------- Display a list of options where several can be selected

Table ---------------- Display data in a tabular form

Panel --------------- Groups objects together visually

ActiveX control For insertion of an ActiveX control made by another program

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GUI Objects (controls) in Guide

Push button

Radio button

Edit textbox

Pup-up menu

Toggle button

Axes

Button group ActiveX control

Panel

Table

Listbox

Static text

Checkbox

Slide


MyGUI is an example of how to create a GUI.

First layout the basic controls for our program.

It contains Axes(axes1),

Static Text, Edit Text,

and Push Button

controls.

Use drag-and-drop to

add GUI objects, or

controls, to the panel.

Resize and move around

each object to look like

the image on the right.

6

MyGUI

Selected Object

Tag Property Mouse Pointer

Position

Selected Object

Position

Resize Box


Each GUI object has a number of properties. Double-

click on an object to open the property

inspector

Sample of properties (1) Tag – the name of the control in the code;

best to rename it to something identifiable like

“PlotButton” versus “button1”

(2) String – the text that appears on the control

(3) ForegroundColor – color of the text

(4) BackgroundColor – color of the control

(5) Value – current value (initial value is zero)

(6) Min and Max – depends on the type of control.

In slider, for example, they show the range of

the value

7

GUI Object Property Inspector


Change properties of different controls: (1) axes1

tag: PlotArea

(2) push button

tag: PlotButton

string: Plot (3) edit text tag: EquationBox

string: Equation

(4) static text

tag: EquationLabel string: y=

Save the setup as MyGUI and then run it by pressing

on the menu bar. It will look like the image show above

It looks right but it does not do anything until callbacks

are defined. 8

Running MyGUI


When MyGUI was saved, two files were created.

(1) MyGUI.fig – contains information about the GUI

layout, geometry, and its controls.

(2) MyGUI.m – contains the program that creates and

executes the GUI tool you have made.

– also contains code that defines a

callback for each of the controls in GUI.

– This m-file loads in the MATLAB editor

when MyGUI is first saved.

Generally the content of the m-file is left alone except for

some callback functions.

In the m-file, we will modify a callback function called

PlotButton_callback.

9

GUI File Formats


10

MyGUI.m File Content

MyGUI.m contains a number of functions including:

(1) function MyGUI_OpeningFcn(hObject, eventdata, handles, varargin)

- This opening function, executes just before MyGUI is made visible.

- The function has no output.

- Input argument “handles” is a structure containing handles for all GUI

controls such as handles.EquationBox, and handles.PlotArea. - This function will not be modified

(2) function PlotButton_Callback(hObject, eventdata, handles)

- This is the callback function for plot button.

- The function has no output.

- Entering an equation in the Equation box followed by a click on the

Plot button, should result in display of the plot of that function in the

plot area. Therefore this function must be modified.


11

Writing Callbacks

Since the only part to be modified is PlotButton_Callback

function. Then add the following code to the end of this

function % added code to MyGUI.m x=-10:0.1:10; % an arbitrary range for x s=get(handles.EquationBox, 'String'); % gets the equation entered y=eval(s); % eval function finds values of y h=handles.PlotArea; % records the handle of where % the plot is displayed plot(h,x,y); % plots on the PlotArea xlabel(h,'x-value'); ylabel(h,'y-value'); title(h,'Plot of y versus x');

Save MyGUI.m once


12

Running MyGUI

When the m-file code is modified, there is no need to re-

run the GUI. The new code will run as a callback

allowing a quick testing of the changes made.

To run the GUI, the only thing to do is to enter MyGUI in

the MATLAB command window:

>> MyGUI

As a result of running MyGUI.m, the corresponding GUI

opens. First enter your function in the Equation box and

then click on the Plot button to see the results.


13

Test Results for MyGUI

Inputs: y=sin(x), or y=4*x.^3+2*x-1, or y=x.*sin(x)


14

Usefull MATLAB Functions

get This function is used to get the properties of a graphic (e.g. gui) object.

<var>=get(handle, ‘PropertyName’)

where handle is a handle to the object and var represent the value of the

property listed

set This function sets the value of a property of a graphic (e.g. gui) object.

set(handle, ‘PropertyName’, property_value)

findobj Finds objects with specified property values.

handles = findobj('P1Name',P1Value,...)

returns the handles of all objects whose property values match those

passed as param-value pairs to the findobj command.


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