Building a Game with the Cocos2d-html5 Library - HTML5 Game Development Insights - page 389

Listing 24-2. Move a Sprite 50 Pixels to the Right and 10 Pixels to the Top over a Period of 2 Seconds

var animation = cc.Animation.create ( ) ;
for ( var i = 1 ; i < 15 ; i ++ ) {
var frameName = "res/Images/grossini_dance_" + ( ( i < 10 ) ? ( "0" + i ) : i ) + ".png" ;
animation.addSpriteFrameWithFile ( frameName ) ;
}
animation.setDelayPerUnit ( 2.8 / 14 ) ;
animation.setRestoreOriginalFrame ( true ) ;
var action = cc.Animate.create ( animation ) ;
sprite.runAction ( cc.Sequence.create ( action, action.reverse ( ) ) ) ;

Scheduler
The Scheduler is responsible for triggering the scheduled callbacks. There are two different types of callbacks
(selectors) in Cocos2d:

• Update Selector : The update selector will be called on every frame. You can customize its
priority: the lower the value, the earlier it is called.

• Custom Selector : A custom selector will be called on every frame, or with a customized interval
of time.

Custom selectors should be avoided whenever possible. Update selectors are faster and consume less memory.

Touch Event
Cocos2d supports two different ways of handling touch events, which are described in CCTouchDelegateProtocol.js .
There is the TargetedTouchDelegate event and the StandardTouchDelegate event.
TargetedTouchDelegate offers two benefits:

• You don't have to deal with an event set, as the dispatcher does the job of splitting them. You

get exactly one cc.Touch per call.

cc.Touch by returning true in onTouchBegan . Updates of claimed touches are
sent only to the delegate(s) that claimed them. So if you get a move/ended/cancelled update,
you can be certain that it's your touch. This frees you up from having to do numbers checks
when using multi-touch.
StandardTouchDelegate also has two benefits:

• You can claim a

cc.Touch from the • Splitting an event set is something that you must do. You can get each

event set.

cc.TouchesBegan . All of your touch callbacks will be • You don't need to state true or false in

called when you touch the screen.
The difference between TargetedTouchDelegate and StandardTouchDelegate is as follows:

TargetedTouchDelegate processes touch events one by one, while StandardTouchDelegate
processes touch events in an event set. Thus when you need to process a multi-touch, you
should choose StandardTouchDelegate .

•

TargetedTouchDelegate has a higher priority to get a touch event than
StandardTouchDelegate .

•