Tài liệu Flash: ActionScript Language Reference- P4 ppt

The following table shows the values you can specify for the command and parameters parameters of the fscommand function to control a SWF file playing in Flash Player, including projecto

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init An expression to evaluate before beginning the looping sequence; usually an assignment

expression A var statement is also permitted for this parameter

condition An expression that evaluates to true or false The condition is evaluated before

each loop iteration; the loop exits when the condition evaluates to false

next An expression to evaluate after each loop iteration; usually an assignment expression using

the increment (++) or decrement ( ) operators

statement(s) An instruction or instructions to execute within the body of the loop

Description

Statement; evaluates the init (initialize) expression once and then starts a looping sequence The

looping sequence begins by evaluating the condition expression If the condition expression

evaluates to true, statement is executed and the next expression is evaluated The looping

sequence then begins again with the evaluation of the condition expression

The curly braces ({}) used to enclose the block of statements to be executed by the for statement

are not necessary if only one statement will execute

Example

The following example uses for to add the elements in an array:

var my_array:Array = new Array();

for (var i:Number = 0; i<10; i++) {

my_array[i] = (i+5)*10;

//trace(my_array[i]);

}

trace(my_array); // output: 50,60,70,80,90,100,110,120,130,140

The following example uses for to perform the same action repeatedly In the code, the for loop

adds the numbers from 1 to 100

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The following example shows that curly braces ({}) are not necessary if only one statement will execute:

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variableIterant The name of a variable to act as the iterant, referencing each property of an

object or element in an array

object The name of an object to be iterated

statement(s) An instruction to execute for each iteration

Returns

Nothing

Description

Statement; iterates over the properties of an object or elements in an array and executes the

statement for each property or element Methods of an object are not enumerated by the

for in action

Some properties cannot be enumerated by the for in action For example, movie clip

properties, such as _x and _y, are not enumerated In external class files, static members are not

enumerable, unlike instance members

The for in statement iterates over properties of objects in the iterated object’s prototype chain

Properties of the object are enumerated first, then properties of its immediate prototype, then

properties of the prototype’s prototype, and so on The for in statement does not enumerate

the same property name twice If the object child has prototype parent and both contain the

property prop, the for in statement called on child enumerates prop from child but ignores

the one in parent

The curly braces ({}) used to enclose the block of statements to be executed by the for in

statement are not necessary if only one statement will execute

If you write a for in loop in a class file (an external AS file), then instance members are not

available for the loop, but static members are However, if you write a for in loop in a FLA file

for an instance of the class, then instance members are available but static ones are not

Examples

The following example shows using for in to iterate over the properties of an object:

var myObject:Object = {name:"Tara", age:27, city:"San Francisco"};

for (var name in myObject) {

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myObject.name = Tara

myObject.age = 27

myObject.city = San Francisco

The following example shows using for in to iterate over the elements of an array:

var myArray:Array = new Array("one", "two", "three");

for (var index in myArray)

for (var name in this) {

if (typeof (this[name]) == "movieclip") {

trace("I have a movie clip child named "+name);

}

Note: If you have several movie clips, the output consists of the instance names of those clips.

The following example enumerates the children of a movie clip and sends each to Frame 2 in their respective Timelines The RadioButtonGroup movie clip is a parent with several children,

_RedRadioButton_, _GreenRadioButton_, and _BlueRadioButton

for (var name in RadioButtonGroup) {

RadioButtonGroup[name].gotoAndStop(2);

}

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Function; lets the SWF file communicate with either Flash Player or the program hosting Flash

Player, such as a web browser You can also use the fscommand() function to pass messages to

Macromedia Director, or to Visual Basic, Visual C++, and other programs that can host

ActiveX controls

Usage 1: To send a message to Flash Player, you must use predefined commands and parameters

The following table shows the values you can specify for the command and parameters

parameters of the fscommand() function to control a SWF file playing in Flash Player,

including projectors

fullscreen true or false Specifying true sets Flash Player to full-screen mode

Specifying false returns the player to normal menu view.

allowscale true or false Specifying false sets the player so that the SWF file is always

drawn at its original size and never scaled Specifying true

forces the SWF file to scale to 100% of the player.

showmenu true or false Specifying true enables the full set of context menu items

Specifying false dims all the context menu items except About Flash Player.

application

Executes an application from within the projector.

trapallkeys true or false Specifying true sends all key events, including accelerator keys,

to the onClipEvent(keyDown/keyUp) handler in Flash Player

CHAPTER 2

ActionScript Language Reference

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The exec command can contain only the characters A–Z, a–z, 0–9, period (.), and underscore (_) The exec command runs in the subdirectory fscommand only In other words, if you use the

fscommand exec command to call an application, the application must reside in a subdirectory named fscommand

Usage 2: To use the fscommand() function to send a message to a scripting language such as JavaScript in a web browser, you can pass any two parameters in the command and parameters

parameters These parameters can be strings or expressions and are used in a JavaScript function

that handles, or catches, the fscommand() function

In a web browser, the fscommand() function calls the JavaScript function

moviename_DoFScommand in the HTML page containing the SWF file The moviename is the name of the Flash Player as assigned by the NAME attribute of the EMBED tag or the ID property of the OBJECT tag If you assign the Flash Player the name myDocument, the JavaScript function called is myDocument_DoFScommand

Usage 3: The fscommand() function can send messages to Macromedia Director that are interpreted by Lingo (Director’s scripting language) as strings, events, or executable Lingo code If the message is a string or an event, you must write the Lingo code to receive the message from the

fscommand() function and carry out an action in Director For more information, see the Director Support Center at www.macromedia.com/support/director

Usage 4: In Visual Basic, Visual C++, and other programs that can host ActiveX controls, the

fscommand() function sends a VB event with two strings that can be handled in

the environment’s programming language For more information, use the keywords Flash method

to search the Flash Support Center at www.macromedia.com/support/flash

You must add a function to the HTML page that contains the SWF file This function,

myDocument_DoFSCommand, sits in the HTML page and waits for an fscommand() function in Flash When an fscommand is triggered in Flash (for example, when a user presses the button), the

command and parameter strings are passed to the myDocument_DoFSCommand function You can use the passed strings in your JavaScript or VBScript code in any way you like In this example, the function contains a conditional if statement that checks to see if the command string is

"messagebox" If it is, a JavaScript alert box (or “message box”) opens and displays the contents

of the parameters string

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In the Flash document, add the fscommand() function to a button:

fscommand("messagebox", "This is a message box called from within Flash.")

You can also use expressions for the fscommand() function and parameters, as in the

following example:

fscommand("messagebox", "Hello, " + name + ", welcome to our website!")

To test the SWF file, select File > Publish Preview > HTML

Note: If you publish your SWF file using the Flash with FSCommand template in the HTML tab of the

Publish Settings dialog box, the myDocument_DoFSCommand function is inserted automatically The SWF file’s NAME and ID attributes will be the filename For example, for the file myDocument.fla, the attributes would be set to myDocument

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functionname The name of the new function This parameter is optional.

parameter An identifier that represents a parameter to pass to the function This parameter is

Statement; comprises a set of statements that you define to perform a certain task You can define

a function in one location and invoke, or call, it from different scripts in a SWF file When you

define a function, you can also specify parameters for the function Parameters are placeholders

for values on which the function operates You can pass different parameters to a function each

time you call it so you can reuse a function in different situations

Use the return statement in a function’s statement(s) to cause a function to generate, or return,

a value

You can use this statement to define a function with the specified functionname, parameters,

and statement(s) When a script calls a function, the statements in the function’s definition are

executed Forward referencing is permitted; within the same script, a function may be declared

after it is called A function definition replaces any prior definition of the same function You can

use this syntax wherever a statement is permitted

You can also use this statement to create an anonymous function and return a reference to it This

syntax is used in expressions and is particularly useful for installing methods in objects

For additional functionality, you can use the arguments object in your function definition

Some common uses of the arguments object are creating a function that accepts a variable

number of parameters and creating a recursive anonymous function

CHAPTER 2

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function 309

Example

The following example defines the function sqr, which accepts one parameter and returns the

Math.pow(x, 2) of the parameter:

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Function class

Availability

Flash Player 6

Description

Both user-defined and built-in functions in ActionScript are represented by Function objects,

which are instances of the Function class

Method summary for the Function class

Function.apply() Invokes the function represented by a Function object, with parameters

passed in through an array.

Function.call() Invokes the function represented by a Function object

CHAPTER 2

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thisObject The object to which myFunction is applied.

argumentsArray An array whose elements are passed to myFunction as parameters

as a comma-delimited list This is often useful when the number of parameters to be passed is not known until the script actually executes

// create a new array to pass as a parameter to apply()

var firstArray:Array = new Array(1,2,3);

theFunction.apply(null,firstArray);

// outputs: 1,2,3

// create a second array to pass as a parameter to apply()

var secondArray:Array = new Array("a", "b", "c");

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trace("this == myObj? " + (this == myObj));

trace("arguments: " + arguments);

}

// instantiate an object

var myObj:Object = new Object();

// create arrays to pass as a parameter to apply()

var firstArray:Array = new Array(1,2,3);

var secondArray:Array = new Array("a", "b", "c");

// use apply() to set the value of this to be myObj and send firstArray theFunction.apply(myObj,firstArray);

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thisObject An object that specifies the value of this within the function body

parameter1 A parameter to be passed to the myFunction You can specify zero or

if a function is invoked as a method of an object, within the body of the function, this is set to

myObject, as shown in the following example:

myObject.myMethod(1, 2, 3);

In some situations, you might want this to point somewhere else; for example, if a function must

be invoked as a method of an object, but is not actually stored as a method of that object:

myObject.myMethod.call(myOtherObject, 1, 2, 3);

You can pass the value null for the thisObject parameter to invoke a function as a regular function and not as a method of an object For example, the following function invocations are equivalent:

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var obj:Object = new myObject(); myMethod.call(obj, obj);

The trace() statement displays:

this == obj? true

Tiêu đề	ActionScript Language Reference
Trường học	University of Information Technology
Chuyên ngành	Computer Science
Thể loại	thesis
Thành phố	Ho Chi Minh City

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