Tài liệu Thiết kế flash với flash cs5 part 57 doc

You can attach onClipEvent handlers to the same movie clip instance.. The first would exe-cute when the movie clip first loads or appears on the Stage; the second executes when the movie

on(press) { trace("The button has been pressed.");

} You can specify two or more events for each on() handler, separated by commas The ActionScript in a handler executes when one

of the events specified by the handler occurs

For example, the following on() handler attached to a button will execute whenever the mouse rolls over or out of the button

on(rollOver, rollOut) { trace("mouse rolled in or out");

}

If you want different scripts to run when different events occur, you have the option to attach more than one handler to an object

You can attach onClipEvent() handlers to the same movie clip instance The first would exe-cute when the movie clip first loads (or appears on the Stage); the second executes when the movie clip is unloaded from the Stage

onClipEvent(load) { trace("loaded");

} onClipEvent (unload) { trace("unloaded");

If you’re working with ActionScript 2.0 (not

supported in ActionScript 3.0), you can attach

clip events to movie clips, which triggers an

action specified in the onClipEvent handler

Event handlers, also known as event

listen-ers, control when events in Flash occur When

you create a script, some event will be

invoked to trigger that particular action You

might want a specific movie clip to stop

play-ing when another movie clip loads on the

Stage, or when the user clicks or moves their

mouse

The Clip Event is one of a series of event

handlers that Flash uses to create actions

within a Flash movie You can attach event

handlers directly to a button or movie clip

instance by using the onClipEvent() or the

on() handlers The onClipEvent() handles

movie clip events, and on() handles button

events To use an on() or onClipEvent()

han-dler, attach it directly to an instance of a

but-ton or movie clip on the Stage, and then

specify the event you want to handle for that

instance For example, the following on()

event handler executes whenever the user

clicks the button the handler is attached to

Working with Clip Events

For ActionScript 2.0, you can only attach an onClipEvent() to a movie clip instance that has been placed on the Stage You can't attach an onClipEvent() to a movie clip instance that is created at runtime; for example, using the attachMovie() method However, you can still attach multiple event handlers Using different event handlers within the same Flash document do not conflict with each other You could have a but-ton with an on(press) handler that tells the SWF file to play, and the same button can have an onPress method, for which you define a func-tion that tells an object on the Stage to rotate When the button is clicked, the SWF file plays, and the object will rotate Being able to consolidate different event handlers with a single instance gives you greater control, as well as less Stage clutter

Attaching a Clip Event

to a Movie Clip

Attach an onClipEvent

to a Movie Clip

Create or open a Flash document

(ActionScript 2.0), place a movie

clip on the Stage, and then select

the movie clip

Give the movie clip a unique

instance name in the Properties

panel

Move down the Timeline and add a

keyframe at frame 80

Click the Insert menu, point to

Timeline, and then click Keyframe.

Add a second movie clip to the

Stage, and then select the second

movie clip

Enter the script as shown in the

illustration

Click the Control menu, point to

Test Movie, and then click Test.

When the playhead hits frame 80 it

loads the second movie clip The

loading of the movie will trigger

the onClipEvent handler, and stop

the playing of the movie clip with

the unique instance name of

movie2

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Working with Loops

Loops allow Flash to perform an action

repeatedly You can use a loop to create a

dynamic drop-down menu, validate data,

search for text, duplicate movie clips, and

even detect collisions in games that have

pro-jectiles and objects Conditional statements

let you execute an action based on a specific

condition You can have a specific action

con-tinue to loop until a certain condition is met

For example, continue to search for a specific

text string until it is found or the end of the

text document is reached Loops come in two

forms—While loops and For loops While

loops wait for a specific condition to start or

stop the loop That may sound similar to the

For loop, with one exception: The For loop is

self-contained, and the While loop works with

an external condition, or one outside the

scope of the loop

◆ While Loops While loops continue to

execute while a certain condition exists

(keep looping or searching) until a

specific value is reached

i = 4;

while (var i > 0) {

my_mc.duplicateMovieClip("newMC" + i, i );

i ;

}

◆ For Loops For loops are

self-contained counters For example, loop

then stop

x = x;

for (x=0; x<=10, ++x) {

myClip.duplicateMovieClip ("myClip" + x, x);

myClip._rotation =45 + x * 10;

}

When you create a Looping action, you can further control the loop by using the fol-lowing loop exceptions:

◆ Continue The continue exception lets you stop the current loop from performing its actions and jump directly to the next cycle of the loop

◆ Break The break exception is used to exit a loop, even if the original condition that is driving the loop is still true

For example, if you create a While loop using the following script:

total = 0;

i = 0:

while (++i <=20) {

if (i == 10) { continue;

} total +=i;

} The results would be a script that executes and adds 1 to total; unless the value of i equaled 10 This would create a sequence of numbers 1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17

18 19 20 If you had used the break exception

in place of continue, the values would read:

1 2 3 4 5 6 7 8 9 Therefore, it loops whether For or While are controlled by internal or external conditions, and using a break or con-tinue exception gives you further control over the loop

The For loop works with an increasing or decreasing numeric value For example, you could use a For loop to create several copies of a movie clip on the Stage Letting the For loop control movie clips to the Stage

is far more efficient than having to move them one at a time In addi-tion, the visitor can control when the items appear on the Stage using a button

Using For Loops

Use For Loops

Drag a movie clip from the Library

to the Stage, and then select the

movie clip

Enter a unique instance name for

the movie clip in the Properties

panel

Place a button on the Stage, and

then select the button

Enter the script (ActionScript 2.0)

as shown in the illustration

◆ ActionScript 3.0 example files

are available on the Web at

www.perspection.com

When you play the movie, clicking

on the button causes the action to

loop 10 times Each time it loops, it

duplicates the original movie clip

and rotate it by 45 degrees plus

the current value of x times 10

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You can use a For Loop to pause a

Flash movie Select a value, instruct

the loop to increment by 1, and then

loop until the value is reached Use a

loop timer for such items as a Flash

slide show, where you want the slides

to display on the stage for a given

number of seconds before moving to

the next slide

Behaviors are time-savers because they give

you sections of ActionScript 2.0 code (not

supported in ActionScript 3.0; see Code

Snippets in the next Chapter) for common

Flash tasks Behaviors are a great way to

introduce yourself to the wonderful world of

ActionScripting without having to write all the

code For example, if you want to add a Play

ActionScript to a button, you can do it using

the Add button in the Behaviors panel, or you

can write out the code on your own; see the

example code below Using Behaviors, as

opposed to writing the code by hand, is not

better, it’s simply faster The more time you

save doing common Action-Scripting tasks

using Behaviors, the more time you will have

for the creative process

Using the Behaviors Panel

You use the Behaviors panel to apply the

behavior to a triggering object, such as a

but-ton You specify the event that triggers the

behavior, such as releasing the mouse Next

select a target object, such as the movie clip

instance, and then select settings for behavior

parameters, such as a frame number or label,

or a relative or absolute path Flash comes

with built-in behaviors, such as Load Graphic,

Duplicate Movieclip, and GotoAndPlay At

Frame Or Label To add and configure a

behavior, select a trigger object, and then step through the following general instructions (steps may vary depending on the behavior):

Click the Window menu, and then click Behaviors

Click the Add (+) button, and then select a behavior from the menu

If necessary, select settings for the behavior parameters, and then click OK

Under Event, click On Release (the default event), and then select a mouse event from the menu

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Example Play ActionScript 2.0 code

on (release) {

if(this.video_1._parent._currentframe == this.video_1.parent._totalframes){

this.video_1parent.gotoAndPlay(1);

} else { this.video_1._parent.play();

Working with ActionScript Behaviors

Add button Click to select a mouse event.

Behavior parameters