Working with setInterval in classes
Working with setInterval in classes
zareh boghozian
I was born in 1978 I live in Yerevan I do flash designing/programming for three years I am studing at American University of Yerevan for my master degree.
View all articles by zareh boghozianWorking with setInterval in classes
As you know flash doesn’t have threads. So if you want to have some commands that execute in time intervals you must use set Interval. But there is a problem. SetInterval a acts independently. It means it doesn’t see it’s global variables. Lets try:
Make a new action script file (File -> New -> Action Script File) copy and paste the following into it:
class Test {
var t1 = 10;
var interval;
function Test() {
trace(t1);
interval = setInterval(increase, 10);
}
function increase() {
t1++;
_root.t1 = t1;
if (t1 == 100) {
clearInterval(interval);
}
}
}
Analyze:
The class has two properties. T1 that we assign it to 3 and interval. The class constructor trace(t1) then call incease function in 10ms intervals and assign the setInterval id to interval property.
The increase function add t1 by 1 and set the t1 variable of root to it.Also it checks if t1 is equal to 100 then clearInterval.For testing our script we must make a new fla file and create a dynamic text field with variable t1.Also copy this in the action of 1st frame:
var t:Test=new Test()
So what did happen???
Setinterval can’t see the property of its class. What to do? There are several solutions for it. For example you can send the t to increase. But what if you add other properties to your class then you must add them to setInterval params section.
The Solution
For this purpose I suggest to send you object to the function then set this variable of function. That’s it. Then if you want to add 100 other properties there is no need to change the function prototype
Change the code as this:
class Test {
var t1 = 10;
var interval;
function Test() {
trace(t1);
interval = setInterval(increase, 10,this);
}
function increase(_this) {
this=_this
t1++;
_root.t1 = t1;
if (t1 == 100) {
clearInterval(interval);
}
}
}
As you see everything works fine. The function increase the t starting 10 and clearInterval on t=100.Hope it would be useful.
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2 Responses to "Working with setInterval in classes"
|
said this on 18 Jun 2007 7:59:29 AM CDT
You're currently sending the constructing object along as a parameter for the function to catch (i.e. function( _this: Object ) ). An easier, often overlooked notation to keep scopes intact is the following:
var interval: Number = setInterval( this, "methodName", 100 ); function methodName(): Void { trace( this ) // will output the actual 'this', i.e. the object/movieclip that contains both the interval and this function. } |
Author/Admin)|
said this on 13 Nov 2007 9:41:39 PM CDT
Regarding scoping using setInterval or onEnterFrame... lets go crazy!
Imagine this, being able to call a piece of code in any movieclip sitting in a certain movieclip scope, crazy? not! set it like this: var tID:Number; var mcArray:Array = [mc_1, mc_2, mc_3] // the movieclips with the code pieces tID = setInterval(this, "act", 100, mcArray); function act(arr:Array){ for(var i=0; i<arr.length; i++){ arr[i].callMe(); } } And in each of the movieclip, declare: function callMe(){ trace(this._name + "is doing something interesting"); } Want more flexibility? I'll write a tutorial soon ;) |
