Tài liệu Thiết kế flash với flash cs5 part 60 pdf

A Class is a separate ActionScript file that is associated with the main Flash file and movie clips.. Create a Simple Class File Click the File menu, click New, click ActionScript 3.0, a

ActionScript 3.0 now supports the

ECMAScript, DOM3, event model syntax In

laymen’s terms, this means that you now use

the Listener object to detect when you

inter-act with your Flash movie using either a

key-board, mouse, or the new gesture interfaces

used in touching the screen directly

This is a big move from ActionScript 2.0 As

an example, the following script is

ActionScript 2.0 that instructs a Movie Clip to

jump to frame 25 of a movie:

ActionScript 3.0 uses Listeners to trigger

when an event occurs Listeners are more

complex to work with, but, give you more

flexibility There are essentially two parts to a

Listener The first is a function that describes

what is going to happen when you trigger an

event The second is the Listener that waits for

a specified event to happen, such as mouse

clicking on a button

The following steps adds an ActionScript 3.0

event that mimics the same event as the

ActionScript 2.0 example above

Use ActionScript 3.0

Click the File menu, click New, click

ActionScript 3.0, and then click OK

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Create a new layer in the Timeline with the name Actions, and then select the layer

Open the Actions panel, create the function, and then add the listener that triggers the function

The function is called gotoFunction and the parenthesis dictates that it is looking for a mouse driven event There is only one instruction in the function, the gotoAndStop function that moves the Timeline to frame 25

The first part of the Listener, myMovie, instructs ActionScript to target the movie clip object on the Stage The second part

of the Listener, addEventListener, instructs Flash that you are using the Listener object.The parenthesis has two parts that explain that the event is a mouse event and to use the function gotoFunction

The ActionScript 3.0 event model gives you flexibility to write more complex scripts and

to extend the functionality of the event model beyond traditional mouse and keyboard inter-faces To do this you use the core object class controlling events on the screen called the EventsDispatcher class Through this you can not only leverage standard events such as

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Developing Solutions Built with the DOM3 Event Model

A common design pattern in Object Oriented

programs separates design, programming

and data elements Flash CS5 adds this

func-tionality with the inclusion of Classes A Class

is a packaged document that you can use to

explain how UI components, business logic

and data elements are to interact

A Class is a separate ActionScript file that

is associated with the main Flash file and

movie clips You can use Flash CS5 as the

Class file editor or your favorite text editor

such as Eclipse, Notepad or Textedit A Class

file is only a text file It is very easy to create

entire Flash movies using just Class files and

not even add any content into a traditional

timeline

Create a Simple Class File

Click the File menu, click New, click

ActionScript 3.0, and then click OK

Click the File menu, and then click Save

to save the file with the name

helloWorld.fla

Open the Properties panel

Click the Edit Class Definition button

(pencil icon) in the Property inspector,

enter a new class with the name

helloClass, and then click OK

A new ActionScript file named

helloClass.as opens with the following

ActionScript 3.0 script

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Remove the line that says //constructor code and replace it with:

trace (“Hello, World”);

Click the File menu, and then click Save

to save the Class file

In the Flash document, click the Control menu, point to Test Movie, and then click Test to view the results

The words “Hello, World” posted to the Output panel

Classes provide you a way in which you can create public and private class elements

The difference between the two is related to how you use the data For instance, a public property can be shared throughout your whole Flash movie A private property can only be used within the class it is defined in

Add Classes to Movie Clips

You can also add separate class references directly to Movie Clips in your Library

Open the Library panel

Right-click (Win) or Control-click (Mac) a Movie Clip, and then click Properties

In the Properties dialog box, click Advanced if necessary, and then select the Export For ActionScript check box

Click OK

A class is automatically created for the sym-bol using the name of the Movie Clip You can now modify the Class file for the Movie Clip in your favorite text editor

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Working with Classes

With ActionScript 3.0, you specify a class definition, either document or object level, to work with objects using ActionScript code To create your own class, you need to follow a certain syntax First, you enter a package statement to indicate where your class will be found Then, you enter a class statement to define the name of the class At this point, you define each property in the class by using variables, and each method by using functions When you define a class element, such as a property or method, you can also specify an attribute A pri-vate attribute can be called only by code within the class, while a pub-lic attribute can be called by any code in the program After you define

a class, you can define a subclass that inherits all the properties and methods of the parent class, or superclass In the subclass, you can add methods and properties and override others from the superclass, known as polymorphism If you want to trigger actions based on events, you can use the EventDispatcher class to keep track of event listeners and notify them of events

Working with Objects

and Classes

Work with Objects and Classes

in ActionScript

Create or open a Flash document

(ActionScript 3.0)

Open the Properties panel.

Click the Stage

In the Class field, type the name of

the ActionScript file to create a

document class definition

IMPORTANT Be sure not to

include the as extension

Open the Library panel.

Right-click (Win) or A-click

(Mac) the object you want to

control in ActionScript, and then

click Properties.

Click Advanced, if available

(Button name changes to Basic.)

Enter a name for the object

Select the Export for ActionScript

check box

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Class definitions

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Click OK.

If prompted, click OK to define the

new class

Click the File menu, and then click

Save.

Click the File menu, and then click

New.

Click ActionScript File.

Click OK.

Click the File menu, and then click

Save As.

Navigate to the folder with the

Flash document, and then name

the file (same as the one in

Step 4)

Click Save.

In the Actions panel, enter the

script as shown in the illustration

IMPORTANT ActionScript 3.0 is

case-sensitive, so upper- and

lower-case make a difference

Click the File menu, click Save,

and then close the ActionScript

file

Click the Control menu, point to

Test Movie, and then click Test.

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Common Syntax in ActionScript 3.0

Command Description

Dot syntax Access the properties and methods of an object

myDotEx.method ();

Slash syntax Not supported in ActionScript 3.0.

Literals A value that appears directly in your code

“text”, true, false, 10 Semicolon (;) Terminates (ends) a statement var a:int = 2;

Parentheses Indicates order of operation, evaluates a series of

expressions, or pass parameters.

Comments Documents code Single-line comments begin with //,

while multi-line comment begin with /* and ends with */.

Keywords Reserved words you cannot use as identifiers as, class,

const, if, var, true, in Constants A fixed value const MINIMUM:int = 0; ActionScript

defines constants with all CAPS with words separated

by an underscore const MOUSE_DOWN:String

= “mouseDown”;

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Public attribute

Function ActionScript file

Change property

Variable

Package statement Class statement

Did You Know?

You can define accessor methods For

advanced ActionScripting, you can

also define accessors methods, which

are a cross between a method and

property (defined like a method, yet

creates an instance like a property)

Namespaces are ways in which you can

define the visibility of properties you are

cre-ating This is commonly used in XML when

you are importing documents using a URI

indicator

You can also use the NameSpace as a way

to overload your objects The principle in

overloading is to create several methods that

have the same name but differ in the types of

input and output they generate

The following example is built using a

Class called NamespaceExample The role of

this class is to pull in an XML document and

step through the formatting of the code

Using Namespaces you can instruct Flash

where to find a definition of the document

type you are using, in this case an RSS

for-matted document type

Click the File menu, click New, click

ActionScript 3.0, and then click OK

Open the Properties panel

Click the Edit Class Definition button

(small pencil icon) in the Properties

inspector, enter a new class with the

name NamespacesExample, and then

click OK

A new ActionScript file named

NamespacesExample.as opens

Create a simple RSS formatted XML

document You can use the following

formatted RSS document:

<rdf:RDF

xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"

xmlns="http://purl.org/rss/1.0/"

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<channelrdf:about="http://www.xml.com/cs/

xml/query/q/19">

<title>This is an RSS feed</title>

<link>http://www.bbc.co.uk/</link>

<description>This is a test RSS document.</description>

<language>en-us</language>

<items>

<rdf:Seq>

<rdf:li rdf:resource="http://www.bbc.co.uk/"/>

</rdf:Seq>

</items>

</channel>

<item rdf:about="http://news.bbc.co.uk/">

<title>BBC News Center</title>

<link>http://news.bbc.co.uk</link>

<description>Welcome to the BBC News Center</description>

<dc:creator>BBC</dc:creator>

<dc:date>2010-02-12</dc:date>

</item>

<item rdf:about="http://www.bbc.co.uk/radio">

<title>BBC Radio Center</title>

<link>http://www.bbc.co.uk/radio</link>

<description>Welcome to the BBC Radio Center</description>

<dc:creator>BBC</dc:creator>

<dc:date>2010-02-12</dc:date>

Using Namespaces in your Projects

Open the NamespacesExample Class,

and then define the package with a

public class named NamespacesExample

that will extend the functionality of the

Sprite object

package

{

import flash.display.Sprite;

public class NamespaceExample extends

Sprite

Insert the Namespace reference that

describes how to use RSS XML

{

private var rss:Namespace = new

Namespace("http://purl.org/rss/1.0/");

private var rdf:Namespace = new

Namespace("http://www.w3.org/1999/02/22-rdf-syntax-ns#");

private var dc:Namespace = new

Namespace("http://purl.org/dc/elements/1.1/

");

public function NamespaceExample()

RSS has several standard XML types

You are going to extract the following:

title, creator, date, link and description

Each of these items will be formatted in

accordance to the namespace called

RSS You will see in the third line of the

ActionScript that you reference the RSS

namespace

private function parseRSS(rssXML:XML):Array

{

default xml namespace = rss;

var items:XMLList = rssXML.item;

var arr:Array = new Array();

var len:uint = items.length();

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{ arr.push({title:items[i].title, creator:items[i].dc::creator, date:items[i].dc::date, link:items[i].link, description:items[i].description});

} return arr;

} Add a Public function that will use the RSS namespace and send the content to the Output panel:

public function NamespaceExample() {

var myXML:XML = getRSS();

var rssItems:Array = parseRSS(myXML);

var len:uint = rssItems.length;

for (var i:uint; i < len; i++) {

trace(rssItems[i].title);

trace(rssItems[i].creator);

trace(rssItems[i].date);

trace(rssItems[i].link);

trace(rssItems[i].description);

} }

Click the Control menu, point to Test Movie, and then click Test to see the RSS feed results sent to your Output panel

Namespaces are an effective way to man-age your control over XML data As with all core classes in Flash, you can extend the Namespace to use it in conjunction with other objects and data types

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