Action Sci Rpt 1 Handle

8/8/2019 Action Sci Rpt 1 Handle

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Getting a handle on ActionScript

A basic primer for non-programmers


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Intermediate Flash with ActionScript 2

ActionScript

Similar to JavaScript

Reusable pieces of code

Action panel automates process Somewhat accessible for non-programmers

Flash MX 2004 Utilizes ActionScript 2.0

syntax


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Variables

Containers for data types

Comparison in Flash MX 2004

Symbols are containers for different objects you create

Variables are containers you create with ActionScript

They store the values of the different objects you create

They can change dynamically

You can see the value in Flash my using the trace function

Example trace (VariableName); Trace also used as a debugging tool


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Objects and Classes

Classes are the blueprint to define how

objects behave.

Example: Dog is a member of the animal class.

Dog is the object, Animal is the class.

All objects are members of a Class and are

instances of that Class.

Objects are data types such as sound,graphics, text, numeric values


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Properties

Each class has a pre-defined set of

properties.

Each object of a class can have its ownvalues set to its properties.

Example; Movie Clip properties include:

_height, _width, _rotation

You can define and change the properties ofeach object (instance) of a Class through

ActionScript.


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Methods

The things objects can do

Example; Sound class has a setVolume method

When an object does something using amethod we say the method is called or that

the object calls the method

You can add your own methods


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Objects requiring construction

To use certain objects within a Class you

must create an instance of the Class by

giving it a name (instantiating)myColor = new Color();

myDate = new Date ();

mySound = new Sound();


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Calling a method

The next step involves calling an objects

methods or evaluating and assigning new

properties. You can call a method by entering

an expression using dot syntax

Example:

// construct the object

myDate = new Date ();// call the method of the constructed object

myDisplay = myDate.getdate();


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Dot Syntax

Statements use dot syntax to put together

objects, properties, and methods

Example; movieclip1._rotation = 45 OBJECT PROPERTY VALUE

We use multiple dots to maintain object hierarchy


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Dot Syntax

Methods are called in the same way

Example; mouse. gotoAndPlay (scene1, 20)

The parenthesis after gotoAndPlay signifies amethod rather than a property

The statement inside the parenthesis is an

argument or a parameter


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More punctuation

Semicolon functions as a period does in asentence Example:

stopAllSounds();play();

Curly braces group together related blocks ofActionScript statements

on (release) {stopAllSounds();

play();

}


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Actions Panel

Type as in a text-editing application

When you use ActionScript 2.0 syntax you

get Strict Typing


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Flash MX 2004

ActionScript Categories


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ActionScript 2.0

More like other programming languages

Strict Typing

Optional Good for troubleshooting code

Opens up code hinting window

Example:

var myVar:Number Tells Flash content of variable is a particular data type

Using var is not required but tells Flash you are declaring a

variable


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Santa Rosa Junior College

I

ntermediate Flash with ActionScriptJeffrey Diamond C IS 75.31A

Functions


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Characteristics of Functions

Functions hold other actions

Allows you to control when functions are

executed when you call the function


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Advantages of Functions

Flexible

Convenient

Reusable

Centralized

Created in one place but executed fromanywhere in the movie.

Ex.- three buttons in three MCs with the samepurpose. We can put one copy in a function onthe main timeline and invoke it from each buttonas needed.


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Functions Fundamentals

Declaration- creating them

Invocation- calling the function

Arguments and parameters- providing thedata to manipulate

Termination- ending the execution

Scope- determining the availability and

lifespan


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Creating the function

We need a function name and a block of

statement to perform

function functionName () {

Statement one;

Statement two;

Statement three;

}

Creating the function does NOT execute the

function


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Running or invoking the function

Simply proclaim the functions name

(invocation)

on (release) {

functionName ();

}


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Function Availability

Directly accessible for invocation from:

Code or button attached to timeline of movie clip

that bears the function declaration

Indirectly accessible using dot syntax

Ex.- myClip.myOtherClip.myfunction();


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Passing information to functions

Statements

function moveBall(){

ball._x +=10;

ball._y +=10;

}


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Creating functions with parameters

Parameters are the variables that can be usedwithin the function

We provide a list of identifiers between the

parenthesis of the function declarationfunction moveClip (theClip, xDist, yDist) {theClip._x += xDist;

theClip._y +=yDist;

}

We replace hard-coded values = more flexibility Allows you to modify how all the actions within that function

behave


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Invoking functions with parameters

To pass multiple parameters we separate

them with commas

Each of the parameters is assigned as the

value of the corresponding parameter named

in the function declaration

Example:

on (release){moveClip (clip1, 100, 200)

}


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Terminating a function

Done with a return statement

ActionScript does it by default at the end of a

function invocation if no return statement is

there

Otherwise you can use return to prematurely

end a function (usually done in the context of

an if then statement)


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Returning values from functions

Return terminates a function but it can also

send a value back to the script that invoked

the function

return expression


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Function Lifespan

A function defined on a movie clip timeline is

lost when that clip is removed from the stage.

Defining a function on the MTL is the best

way to insure the functions permanence

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Action Sci Rpt 1 Handle