1 Intro to Programming & Algorithm Design GUI Copyright 2003 by Janson Industries This...

Intro to Programming & Algorithm Design

This presentation can be viewed on line in a file named: ch11.IntrotoProg.GUI.ppt

Objectives Explain

Event driven programming

Designing a GUI

Threads

Demonstrate

GUI components

How to code a GUI

Animation

GUI What do you think of the command

line interface?

That's why there are GUI's

Instead of commands and syntax, GUI's allow users to point and click on:

Buttons

Menu items

GUI GUI's help to cut down on errors

by only allowing valid input

Instead of letting users specify a value, user given

A menu of values

Checkboxes associated with values

A drop down list of values

Events An event is when a user does something Clicks, double clicks, right clicks,

presses a key, etc.

Each GUI component is tied to an event handler (in Java a listener)

The listener "reacts" to an event Of course, the programmer codes this

"reaction" Yep, sequence, selection and loops!

This type of programming is called event-driven

GUI Components Labels: display text

Text fields: accept and display text

Button: small square that when clicked, appears to go down

List box: a text field and a small button usually with an arrow head icon Clicking the button results in the text

field being expanded and a menu being displayed inside it

Components Check box: label and a small

square text field that can display a check mark

Option buttons: label and a small round text field that can display a black dot Only one option button can be

selected Also called radio buttons or a check

box group

Components Have properties that are

controlled with setters/getters

Common properties

Location

Text Font, size, foreground color,

background color, alignment, etc.

Components Most IDEs provide a drag/drop

visual editor to define the GUI Drag and drop the GUI components

from a "tool box" The IDE generates the code

Clicking on a component will display a list of all the properties values Programmer can change the values

and the IDE will generate the code

In RAD, components dragged and

dropped from the palette

Property pane provides control

over all properties values

When component selected, resize handles allow you to

control size

Events Components react to different

events Clicking a label does nothing

Even if 2 components react to the same event they may react differently

Clicking a text field puts the cursor in the text field

Clicking a check box selects or deselects the check box

Designing a GUI It should be predictable (follow

standards) Menu bars at top of screen

Standard icons

Using unusual icons or layouts will cause confusion

Users will make mistakes

May not use application

Designing a GUI It should be pleasing to the eye

No weird color combinations

No distracting graphics

It should be easy to read

No fancy fonts or small size

Good contrast between text color and background color

Not too many components or options

Designing a GUI Customizable

Users can drag components where they want them

Change color schemes Suppress/add options or components

Forgiving No dead ends Help info Easy navigation

Application index, search

Designing a GUI GUI is only a means to an end

The GUI should make the user more productive

Enable users to specify the input and actions more efficiently

After all options specified, the real work of the application begins

Story Boards Mock ups of the screens

Shows each individual screen and all of its components.

Welcome to the Pizza Palace

What would you like to order?

Pizza Soda

Finished Exit

Story Boards In addition, create

Object dictionary

Interactivity diagram

Pizza Order

Size? Toppings Double Triple

6 inch Pepperoni12 inch Ham18 inch Mushroom

Order Exit

Object Dictionary Will list each component and

Screens it appears on Variables it can affect Any methods/modules tied to

Soda Order

Size? Flavor?

12 oz Cola20 oz Lemon/Lime46 oz Cherry

Order Exit

Order Total

The following items were ordered:

# size item: ###.### size item: ###.## # size item: ###.##

For a total of:

# soda(s) and # pizza(s)

The order amount is $#,###.##

Story Boards

Print Exit

Designing a GUI Each component is an object

Like all other objects, usually assigned to a variable

Considered the name of the GUI component

Object Screen Variables MethodsLabel welcomeLbl Welcome none noneLabel orderLbl Welcome none noneRadioButton pizzaRB Welcome none getItem()RadioButton sodaRB Welcome none getItem()Button finishedBtn Welcome sodaCtr, pizzaCtr,

orderTotalcalcTotals(orderedItems)

Button exitBtn All none windowClosing(Window Event)Label pizzaOrdLbl PizzaOrder none noneLabel pizzaSizeLbl PizzaOrder none noneLabel toppingsLbl PizzaOrder none noneRadioButton 6inRB PizzaOrder pizza noneRadioButton 12inRB PizzaOrder pizza noneRadioButton 18inRB PizzaOrder pizza noneCheckbox pepCB PizzaOrder selectedToppings noneCheckbox hamCB PizzaOrder selectedToppings noneCheckbox shroomCB PizzaOrder selectedToppings noneRadioButton dblPepRB PizzaOrder selectedToppings noneRadioButton dblHamRB PizzaOrder selectedToppings noneRadioButton dblShroomRB PizzaOrder selectedToppings noneRadioButton tplPepRB PizzaOrder selectedToppings noneRadioButton tplHamRB PizzaOrder selectedToppings noneRadioButton tplShroomRB PizzaOrder selectedToppings noneButton orderPizzaBtn PizzaOrder pizza getPizza()

Object Screen Variables MethodsLabel sodaOrdLbl SodaOrder none noneLabel sodaSizeLbl SodaOrder none noneLabel sodaFlavorsLbl SodaOrder none noneRadioButton 12ozRB SodaOrder soda noneRadioButton 20ozRB SodaOrder soda noneRadioButton 46ozRB SodaOrder soda noneRadioButton colaRB SodaOrder soda noneRadioButton lemLimeRB SodaOrder soda noneRadioButton cherryRB SodaOrder soda noneButton orderSodaBtn SodaOrder soda getSoda()Label ordTotLbl OrderTotal none noneLabel itemsLbl OrderTotal none noneLabel itemLbl1-10 OrderTotal none noneLabel itemsTotLbl OrderTotal none noneLabel itemsTotInfoLbl OrderTotal none noneLabel ordAmountLbl OrderTotal none noneButton printBtn OrderTotal soda printReceipt()

Object Dictionary

Why bother?

Besides clearly defining each component

When changing a component, can easily find affected screens

Therefore can test more easily to see affect of the change

Object Dictionary

Show which screens call other screens

PizzaApp pretty simple

Interactivity Diagram

Welcome

SodaOrder

PizzaOrder

OrderTotal

As mentioned, GUI component properties must be specified Size and location

For Java frames, must set visible property to true

For frame components, must add them to the frame

To react to actions, must define listeners and add to components

GUI Java Example

So, to get our Frame as seen here, need a class that extends Frame and imports all the component classes

GUI Java Exampleimport java.awt.Frame;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.ItemEvent;import java.awt.event.ItemListener;import java.awt.event.WindowEvent;import java.awt.event.WindowListener;import java.awt.CheckboxGroup;import java.awt.Rectangle;import java.awt.Label;import java.awt.Font;import java.awt.Checkbox;import java.awt.Dimension;import java.awt.Point;import java.awt.Button;

public class Welcome extends Frame implements ActionListener, WindowListener, ItemListener {

this.setLayout(null);this.setTitle("Frame");

this.setBounds(new Rectangle(100, 100, 700, 500));this.setVisible(true);

GUI Java Example

private Label welcomeLbl = null;private Label orderLbl = null;private Checkbox pizzaRB = null;private Checkbox sodaRB = null;private Button exitBtn = null;private Button finishedBtn = null;private CheckboxGroup itemCBG = new CheckboxGroup();

Create variables for the GUI componentsWhere did the names

come from?

Set some frame properties

GUI Java Example

orderLbl = new Label();orderLbl.setFont(new Font("Verdana", Font.PLAIN, 28));orderLbl.setSize(new Dimension(377, 39));orderLbl.setLocation(new Point(161, 148));orderLbl.setText("What would you like to order?");

welcomeLbl = new Label();welcomeLbl.setBounds(new Rectangle(5, 56, 689, 39));welcomeLbl.setFont(new Font("Verdana", Font.PLAIN, 36));welcomeLbl.setAlignment(Label.CENTER);welcomeLbl.setText("Welcome to the Pizza Palace");

Create the label objects and set their

properties

GUI Java Exampleprivate Checkbox getPizzaRB() {

if (pizzaRB == null) { pizzaRB = new Checkbox(); pizzaRB.setBounds(new Rectangle(295, 240, 89,

23)); pizzaRB.setFont(new Font("Verdana", Font.PLAIN,

24)); pizzaRB.setLabel(" Pizza"); pizzaRB.setCheckboxGroup(itemCBG);}return pizzaRB;

}private Checkbox getSodaRB() {

if (sodaRB == null) { sodaRB = new Checkbox(); sodaRB.setLabel(" Soda"); sodaRB.setSize(new Dimension(89, 23)); sodaRB.setLocation(new Point(295, 282)); sodaRB.setFont(new Font("Verdana", Font.PLAIN,

24)); sodaRB.setCheckboxGroup(itemCBG);}return sodaRB;

For more complicated objects, create a separate method

GUI Java Exampleprivate Button getExitBtn() {

if (exitBtn == null) { exitBtn = new Button(); exitBtn.setBounds(new Rectangle(601, 457, 58,

23)); exitBtn.setLabel("Exit");}return exitBtn;

private Button getFinishedBtn() {if (finishedBtn == null) { finishedBtn = new Button(); finishedBtn.setBounds(new Rectangle(510, 457, 58,

23)); finishedBtn.setLabel("Finished");}return finishedBtn;

GUI Java Example

this.add(welcomeLbl, null);this.add(orderLbl, null);this.add(getPizzaRB(), null);this.add(getSodaRB(), null);this.add(getExitBtn(), null);this.add(getFinishedBtn(), null);

Must add all the components to the

Frame will look good but only problem is that it doesn't do anything

You can click all you want but none of the components are "enabled"

Need listeners!

Lots of different types WindowListener ItemListener ActionListener

Can create a separate class and define it as a listener

Or simply have the frame implement the listener interface That's what we did

Java Listeners

public class Welcome extends Frame implements ActionListener, WindowListener, ItemListener {

Each listener requires at least one method be coded in the "implementing class" When an event occurs the

associated method will be called

ActionListener requires actionPerformed method

Java Listeners

public void actionPerformed(ActionEvent e) {

System.exit(0);}

Must tie listener to a component

WindowListener requires seven methods to be coded

Java Listeners

private Button getExitBtn() {if (exitBtn == null) {

exitBtn = new Button();exitBtn.setBounds(new Rectangle(601, 457, 58,

23));exitBtn.setLabel("Exit");exitBtn.addActionListener(this);

}return exitBtn;

Of course, they all don't have to do something

Java Listeners

public void windowActivated(WindowEvent e) { }

public void windowClosed(WindowEvent e) { }

public void windowClosing(WindowEvent e) { this.dispose();

public void windowDeactivated(WindowEvent e) { }

public void windowDeiconified(WindowEvent e) { }

public void windowIconified(WindowEvent e) { }

public void windowOpened(WindowEvent e) { }

The ItemListener poses a special problem Going to be tied to 2 components

When itemStateChanged (the associated method) invoked Needs to figure out which radio

button was clicked

Easiest way: check each radio buttons state

Java Listeners

public void itemStateChanged(ItemEvent e) {

if (pizzaRB.getState()) {new PizzaOrder();

}else if (sodaRB.getState()) {

new SodaOrder(); }

First have to add listener to the radio buttons

Then code itemStateChanged

Java Listeners

pizzaRB.addItemListener(this);

sodaRB.addItemListener(this);

Java Listeners Must compile PizzaOrder and

SodaOrder before Welcome

When Welcome displayed, Close Window and Exit button should work

Clicking Pizza Radio Button...

Clicking Soda Radio Button...

How could the PizzaApp GUI be improved?

More efficient?

More functions? Let user specify total number of

pizzas and sodas on welcome screen Display shopping cart of items Allow editing of items from shopping

cart and order total screen

GUI Improvements

Sunflower Floral Designs customers can order Floral arrangement ($25) Cut flowers ($15) Corsage ($10)

Choose flower type: Roses (extra $5) Daisies Chrysanthemums Irises

GUI Exercise

Customer clicks Order Now button and the price of the order is displayed

Create: Story Board Interactivity program Object dictionary

Given the solutions the pseudocode would be….

GUI Exercise

Answer1

Answer2

Answer3

Class Screen1

Public Module Screen1()setSizePosition(600, 330, 100, 100)

Declare Label labelSunflower = New Label()labelSunflower.setPositionSize(150, 40, 300, 23)

labelSunflower.setText("Sunflower Floral Designs") labelSunflower.setFont(Verdana", 24)

Declare Label labelDesign = New Label() labelDesign. setPositionSize(31, 85, 85, 23) labelDesign.setText("Design") labelDesign.setFont(new Font ("Verdana", 24)

Declare Label labelFlower = New Label() labelFlower.setPositionSize(332, 85, 85, 23) labelFlower.setText("Flower") labelFlower.setFont("Verdana", 24)

PseudocodeModule main() Declare Screen1 screen = New Screen1() screen.display()End Module Pgm that

gets the app rolling

Define the component properties

PseudocodeDeclare RadioButton radioButtonFloral = New RadioButton()radioButtonFloral.setPositionSize(31, 136, 232, 23)radioButtonFloral.setText ("Floral Arrangement")radioButtonFloral.setFont("Verdana", 24)

Declare RadioButton radioButtonCut = New RadioButton()radioButtonCut.setPositionSize(31, 172, 232, 23)radioButtonCut.setText (“Cut Flowers")radioButtonCut.setFont("Verdana", 24)

Declare RadioButton radioButtonCorsage = New RadioButton()radioButtonCorsage.setPositionSize(31, 208, 232, 23)radioButtonCorsage.setText ("Corsage")radioButtonCorsage.setFont("Verdana", 24)

Declare RadioButton radioButtonRoses = New RadioButton()radioButtonRoses.setPositionSize(332, 136, 202, 23)radioButtonRoses.setText ("Roses")radioButtonRoses.setFont("Verdana", 24)

Declare RadioButton radioButtonDaisies = New RadioButton()radioButtonDaisies.setPositionSize(332, 172, 202, 23)radioButtonDaisies.setText ("Daisies")radioButtonDaisies.setFont("Verdana", 24)

Declare RadioButton radioChrisanthemums = New RadioButton()radioButtonChrisanthemums.setPositionSize(332, 208, 202, 23)radioButtonChrisanthemums.setText ("Chrisanthemums")radioButtonChrisanthemums.setFont("Verdana", 24)

Declare RadioButton radioButtonIrises = New RadioButton()radioButtonIrises.setPositionSize (332, 244, 202, 23)radioButtonIrises.setText ("Irises")radioButtonIrises.setFont("Verdana", 24)

Declare Button orderButton = New Button()orderButton.setPositionSize(504, 293, 80, 23)orderButton.setText("Order Now")orderButton.registerListener(orderRoutine())

add(labelSunflower)add(labelDesign)add(radioButtonFloral)add(radioButtonCut)add(radioButtonCorsage)add(labelFlower)add(radioButtonRoses)add(radioButtonDaises)add(radioButtonChrisanthemums)add(radioButtonIrises)add(orderButton)

End Module

PseudoCode

Tie the listener to a component and

specify the module to execute

PseudoCodePublic Module orderRoutine()

Declare Integer FLORAL_AMT = 25, CUT_AMT = 15, CORSAGE_AMT = 10, ROSE_AMT = 5, totalPrice

If radioButtonFloral.getChecked() ThentotalPrice = FLORAL_AMT

ElseIf radioButtonCut.getChecked() Then

totalPrice = CUT_AMTElse

If radioButtonCorsage.getChecked() ThentotalPrice = CORSAGE_AMTEnd If

End IfEnd If

If radioButtonRoses.getChecked() ThentotalPrice = totalPrice + ROSE_AMT

End If

Declare Screen2 screen = new Screen2()screen.display(totalPrice)remove()

End Module

End Class

Class Screen2

Public Module Screen2(Integer price)setSizePosition(600, 275, 100, 100)

Declare Label labelSunflower = New Label()labelSunflower.setPositionSize(150, 40, 300, 23)

labelSunflower.setText("Sunflower Floral Designs") labelSunflower.setFont(Verdana", 24)

Declare Label labelPrice = New Label() labelPrice.setPositionSize(125, 225, 85, 23) labelPrice.setText("Price of your order:") labelPrice.setFont("Verdana", 24)

Declare Label labelPriceAmt = New Label() labelPriceAmt.setPositionSize(375, 85, 85, 23) labelPriceAmt.setText(“$“, price) labelPriceAmt.setFont("Verdana", 24)

Declare Button ExitButton = New Button()exitButton.setPositionSize(504, 239, 80, 23)exitButton.setText(“Exit")exitButton.registerListener(exitRoutine())

PseudoCode

add(RadioButtonDaises)add(RadioButtonChrisanthemums)add(RadioButtonIrises)add(exitButton)

End Module

Public Module exitRoutine()remove()

End Module

End Class

Pseudocode

Animation Used sparingly in applications

Very popular on the web, especially in ads

Really just a series of still pictures displayed rapidly Gives the illusion of motion

Like GUI components, animation must specify location as x and y coordinates of still pictures

Animation Then slightly modify the image

and redisplay

Most languages come with predefined graphics classes that make this easier

But can be done without special graphics classes Do need several new classes in

java i.e. Runnable interface

Java Animation

public void update() { if (fontSize <50) { fontSize = fontSize + 1; urgentMsgLbl.setFont(new Font("Arial", Font.PLAIN, fontSize)); } else { sleepInterval = 1000; if (showLabel) { urgentMsgLbl.setForeground(Color.RED); showLabel = false;} else { urgentMsgLbl.setForeground(Color.WHITE); showLabel = true;} }}

Assuming this is in a loop, what do you think this does?

Java Animation Download UrgentMsg.java,

compile and run to see what update does

Animation can be a resource hog Slows down the application

Multithreading can be used to help with this

Thread Set of instructions that are

executed In old days, all computers were

single-threaded First job submitted, first job executed All other jobs wait for first job to finish

Problems?• What if first job is payroll and runs for 3

hours• All other work on hold

Thread Computers nowadays will switch

between threads/tasks If first program waiting for file data,

CPU works on different program/thread

Computers are so fast, users/apps don't even notice the lack of attention

Many languages allow a programmer to define threads within a single program

Thread So animation can run and user can still click buttons

Need a Thread variable and object

Programmer can make the thread wait for a certain number of milliseconds (thousandths of a second)

Thread thread;thread = new Thread(this);thread.start();

thread.sleep(sleepInterval);

Thread Invoking the thread start() method causes the JVM to invoke the run() method

run() issues the repaint command Which runs the paint() method

paint() runs update()

update() is the method that changes the size and color

Thread and Animation To see another example of

animation and threads

Download and run BouncingBall

Points to Remember GUI's should make the user more

efficient

GUI's help to cut down on errors by only allowing valid input

Listeners are tied to GUI components and react to events

Story boards and interactivity diagrams are used to design a GUI

Points to Remember

Animation can be used to enhance a GUI

Animation is often resource intensive so it should be run in a separate thread

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