ActionScript classes reference - actionscript-3

Question

I have a class Square and a class Circle.
This my class Circle:
public class Circle extends MovieClip
{
var growthRate:Number = 2;
public function Circle()
{
addEventListener(Event.ENTER_FRAME, grow);
}
function grow(e :Event):void
{
e.target.width +=growthRate;
e.target.height +=growthRate;
}
}
I need to stop growing the circle inside a function from Shape.
public function Square() {
buttonMode = true;
addEventListener(MouseEvent.MOUSE_DOWN, down);
}
protected function down ( event: MouseEvent):void
{
//here i need to stop the circle
}
I don't know how to make a relation with the Circle class in order to stop the circle growing.
Thank you in advance.

Answer 1

I don't know how to make a relation with the Circle class in order to stop the circle growing.
That's because you cannot with the code you have right now. There's nothing in your class that's accessible from outside (public), that stops the growth. But there's not even something private in your class that does this. The functionality simply is not there.
So first of all, create the desired functionality. and make it available to public.
Here's how your Circle class could look like:
public class Circle extends Sprite
{
private var growthRate:Number = 2;
public function Circle()
{
// nothing here
// this is just to create a circle graphic, if you have artwork in your library symbol, you do not need this
graphics.beginFill(0xffffff * Math.random());
graphics.drawCircle(0, 0, 10 + 30 * Math.random());
graphics.endFill();
}
public function startGrowing(rate:Number = 0):void
{
if(rate != 0)
{
growthRate = rate;
}
addEventListener(Event.ENTER_FRAME, grow);
}
public function stopGrowing():void
{
removeEventListener(Event.ENTER_FRAME, grow);
}
private function grow(e:Event):void
{
width += growthRate;
height += growthRate;
}
}
Pay attention to
the constructor: I create a circle graphic there with code. As the comment says, if Circle is a class associated to a library symbol, you do not need this, because you already created the artwork in the symbol.
the super class: It's Sprite. This should be your default superclass. The only real reason to use MovieClip is if you have a timeline animation. It doesn't look like you have any of that from what you posted, so I recommend Sprite.
the two new public methods: startGrowing and stopGrowing, which do exactly what their names imply. startGrowing has an optional parameter to to start growing at a different growth rate.
the lack of e.target: which is unnecessary here.
A simple demo of that code looks like this:
var circle:Circle = new Circle();
circle.x = 200;
circle.y = 200;
addChild(circle);
circle.startGrowing();
//circle.startGrowing(1); // grow slowly
//circle.startGrowing(5); // grow fast
To stop the growth, stop listening for the ENTER_FRAME Event.
So far so good, now to your actual question:
how to make a relation with the Circle class
protected function down ( event: MouseEvent):void
{
//here i need to stop the circle
}
You think that you should make this connection in your Square class, but you are wrong about that. It's very bad practice to connect two classes this way. You want the classes to be as individual as possible.
Think about it like phones. Does your phone have a direct way to a specific other phone? No. It has the ability to connect to any phone, which makes it a lot more universally useful than a phone hard wired to another phone.
You make the connection outside both classes with events. That's like your phone making a call to the network with a number it wants to call. The network then figures out how to find the other phone with that number and how to establish the connection.
As a short interlude and so that we are on the same page about it, here's the Square class that I'm using:
public class Square extends Sprite
{
public function Square()
{
// nothing here
// this is just to create a circle graphic, if you have artwork in your library symbol, you do not need this
graphics.beginFill(0xffffff * Math.random());
graphics.drawRect(0, 0, 100, 100);
graphics.endFill();
}
}
As you can see, it only has a constructor in which I programmatically draw a rectangle. Again, if you have the desired artwork in your library symbol, there's no need for this. In that case, the constructor would be empty and in turn the entire class file would be empty. In this case, you do not even need a class file. Just associate the library symbol with the name. The Square is only a graphic asset without any code attached to it.
Here's a full fledged document class using both classes:
package
{
import flash.display.Sprite;
import flash.events.MouseEvent;
public class Main extends Sprite
{
private var circle:Circle;
public function Main()
{
circle = new Circle();
circle.x = 200;
circle.y = 200;
addChild(circle);
circle.startGrowing(1);
var square:Square = new Square();
addChild(square);
square.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDown);
}
private function onMouseDown(e:MouseEvent):void
{
circle.stopGrowing();
}
}
}
As you can see, the event listener is added in the document class and also the function that is executed when the event occurs is in Main.
Here's a variation of that without the square. This time you have to click on the circle to stop it growing:
package
{
import flash.display.Sprite;
import flash.events.MouseEvent;
public class Main extends Sprite
{
private var circle:Circle;
public function Main()
{
circle = new Circle();
circle.x = 200;
circle.y = 200;
addChild(circle);
circle.startGrowing(1);
circle.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDown);
}
private function onMouseDown(e:MouseEvent):void
{
circle.stopGrowing();
}
}
}
As you can see, making the connection outside both classes with events gives you a lot of flexibility to wire things up in a different way. Just like having a phone that connects to a network instead of another phone directly.