referencing objects in different functions as3 - actionscript-3

I have an object in my mouse event functions that I want to reference in my time function.
Example, I basically created tiles and have mouse events:
var cell:MovieClip = new Tile();
cell.gotoAndStop(floor1[i][u]);
cell.x = ((u-i)*tileh)+365;
cell.y = ((u+i)*tileh/2)+70;
addChild(cell);
cell.addEventListener(MouseEvent.ROLL_OVER, mouseover);
cell.addEventListener(MouseEvent.ROLL_OUT, mouseout);
cell.addEventListener(MouseEvent.CLICK, mouseclick);
enemyMoveTimer.addEventListener(TimerEvent.TIMER, timerListener);
In the mouse events, I have something called event.currentTarget. Since I have tiles lined up with each other, I wanted to differentiate each individual tile. Thus creating that event.currentTarget. I wanted to use this in my time event, but it isn't recognizing event.currentTarget as an object, rather it's own timer. Is there any way to have the time function recognize the event.currentTarget from the mouse events?

Event.currentTarget is the last object to dispatch that specific event (and Event.target is the original object to dispatch the event). It can be absolutely anything that extends EventDispatcher.
The only way to do what you want is like this:
var currentTile:Tile;
cell.addEventListener(MouseEvent.ROLL_OVER, mouseEventsHandler);
cell.addEventListener(MouseEvent.ROLL_OUT, mouseEventsHandler);
cell.addEventListener(MouseEvent.CLICK, mouseEventsHandler);
enemyMoveTimer.addEventListener(TimerEvent.TIMER, timerListener);
function mouseEventsHandler( e:MouseEvent ):void {
this.currentTile = e.currentTarget as Tile;
}
function timeListener( e:TimerEvent ):void {
this.currentTile.blah.blah();
}
Basically you save the tile that most recently was interacted with into currentTile and then that is what you access in your timeListener.
You should really look through the LiveDocs to get a basic understanding of how events work and possibly look into how scope works as well.

Some explanation:
Your Event-Listener receives an Event-Object. Always. What kind of Event-Object it is depends on the Event. In your MouseListener you receive a MouseEvent, in you TimerListener a TimerEvent and so on.
EVERY Event-Object has two specific attributes.
event.currentTarget
is the Object, which binds the event listener (in your case "cell")
event.target
is the object, which "caused" the Event. If e.g. in you "cell"-MovieClip is another MovieClip called "nucleus" and you click on the the it, event.currentTarget would be "cell", but even.target would be "nucleus".
Since the event-object is a passed as a function parameter, it is destroyed, once the function is finished. If you wand to use parts of it in another function, you need to do it like this
var myCell:MovieClip;
function mouseClick(event:MouseEvent):void{
myCell = event.currentTarget as MovieClip;
}
function timeListener(event:TimerEvent):void{
if(myCell){
///what ever you want to do with it
myCell = null;
}
}
I hope I explained it clearly.

Here's one way you could do this :
enemyMoveTimer.addEventListener(TimerEvent.TIMER, timerListener(cell));
enemyMoveTimer.start();
public function timerListener(cell:MovieClip):Function
{
var doStuffToCell:Function = new Function(e:TimerEvent)
{
trace (cell.x + " : " + cell.y);
// do whatever you want with cell
}
return doStuffToCell;
}
I should note that I don't think it's a good idea to call your handler timerListener, as it's a handler.
Listeners do just that, they listen for an event. A handler, handles an event. The second parameter in the addEventListener method specifies a function to handle the event. Naming your handler timerListener is not a good idea in my opinion, as it's really not that.

Related

ActionScript3, moving objects of type movieclip

Here i am trying to create a new movieclip type object, which is moved when function mvBall is called. When i run the code i get this err: implicit coercion of a value with static type object to a possibly unrelated type flash.display:MovieClip. Later on i want to be able to make the ball bounce back when it colides with another object. I'm new to action script and don't really know how things work so any help would be appreciated. Here's the code:
private function frame(x:Event):void {
var ball:MovieClip = new MovieClip();
ball.addEventListener(Event.ENTER_FRAME, animate);
ball.graphics.beginFill(0xff0000);
ball.graphics.drawCircle(100, 100, 15);
ball.graphics.endFill();
stage.addChild(ball);
}
private function animate(ev:Event):void {
mvBall(ev.target);
}
private function mvBall(mc:MovieClip) {
mc.x += 10;
}
You need to cast the target to MovieClip
private function animate(ev:Event):void {
mvBall(ev.target as MovieClip);
}
With that said it is better to just have one ENTER_FRAME handler and animate your objects in there.
stage.addEventListener(Event.ENTER_FRAME, animate);
private function animate(ev:Event):void
{
mvBall(myBall);
//other object animations
}
You are getting this error because the target property of the Event class is of type object.
In order to not throw the error, you need to cast it as a MovieClip:
mvBall(ev.target as MovieClip);
or
myBall(MovieClip(ev.target));
Something else to consider, is the difference between an Events target and currentTarget properties. If you ball had multiple layers/object inside it (sprites or other movieClips), the target would be whichever one of those sub-elements had the mouse over it during the click. currentTarget refers to the object that you've attached the listener to. In your case they may be the same (if your ball doesn't have any movie clips inside it), but your code could have unexpected results if you have sub-movieClips inside your ball.

how to call function on movie load in actionscript instead using event listener?

Here is the code to call function using event listener:
var listListener:Object = new Object();
listListener.change = function() { changeImage(); }
thelist.addEventListener("change", listListener);
Is there a way to call the function simply when the frame is loaded using the same function as above?
Thanks
agus
So long as you're calling this from within an instance of a Class that extends EventDispatcher (i.e. MovieClip, Sprite, etc.)...
Use this to dispatch an event of that type (i.e. "change").
dispatchEvent(new Event("change"));

Anonymous functions as event handlers in Action Script - good or bad?

I came to AS3 from JS world, and I should confess that anonymous functions are my weakness. I tend to use them everywhere. Now, coming to AS3 I've heard and read in lots of places, that AS and Flash are enormously bad at handling garbage collection, that one should empty, dispose and remove all event handlers and objects manually to avoid weird and unexplainable memory leaks and crashes. Not sure what part of this is true, but I would like to follow best practices right from the beginning.
So my question would be - how bad is idea of using anonymous functions as event handlers? Consider for example a code like this:
addEventListener(Event.ENTER_FRAME, function() : void {
controls.elapsed = stream.time;
});
contorls.elapsed is the setter, which apart from setting current play time for video player, updates the whole UI, and stream is NetStream object, which streams the actual video.
There are lot's of other places where anonymous function may make code cleaner and more intuitive. Check the following code for simple fade-in effect for the control bar:
public function showControls() : void
{
var self:Controls = this;
if (!visible) {
visible = true;
fadeTimer = new Timer(30, 10);
fadeTimer.addEventListener(TimerEvent.TIMER, function() : void {
self.alpha += 0.1;
});
fadeTimer.addEventListener(TimerEvent.TIMER_COMPLETE, function() : void {
self.alpha = 1;
});
fadeTimer.start();
}
}
I totally like how it looks and fits into the code, but I'm concerned about leaks. While Event.ENTER_FRAME handler probably would never become harmful in this form, what about timer listeners. Should I remove those listeners manually, or they will be removed automatically, as soon as I set fadeTimer = null ? Is it possible to remove listeners with anonymous functions properly at all?
Just noticed this post -- there are a couple things that might be of use to you. One is arguments.callee (which is a reference to the current function you're in). This is useful for removing references in anonymous functions. Also, it could be noted that you could use weak references in your addEventListener code -- however, this won't work for variables that are anonymous, as they'd get GC'd pretty much immediately. For simplicity sake I rewrote your code like this: (should work -- haven't tested)
private function showControls() : void {
if (visible) {
return;
}
var self:DisplayObject = this;
var fadeTimer= new Timer(30,10);
var handler = function(e:Event) {
switch (e.type) {
// timer complete
case TimerEvent.TIMER_COMPLETE:
// remove references to this anonymous function -- for garbage collection
fadeTimer.removeEventListener(TimerEvent.TIMER_COMPLETE, arguments.callee);
fadeTimer.removeEventListener(TimerEvent.TIMER, arguments.callee);
// break out
return self.alpha = 1;
// timer
case TimerEvent.TIMER:
return self.alpha += 0.1;
}
}
fadeTimer.addEventListener(TimerEvent.TIMER, handler);
fadeTimer.addEventListener(TimerEvent.TIMER_COMPLETE, handler);
fadeTimer.start();
}
I would do it something like this. And, be sure to use dispose() when you want to make sure to clear the timer if interrupting.
private function showControls() : void
{
if(_isVisible)
return;
// start you control here
_fadeTimer = new Timer(30, 10);
_fadeTimer.removeEventListener(TimerEvent.TIMER, updateFade);
_fadeTimer.removeEventListener(TimerEvent.TIMER_COMPLETE, updateFadeComplete);
_fadeTimer.start();
}
private function updateFade(event : TimerEvent) : void
{
// update fade here
}
private function updateFadeComplete(event : TimerEvent) : void
{
dispose();
}
private function dispose() : void
{
if(_fadeTimer)
{
_fadeTimer.stop();
_fadeTimer.removeEventListener(TimerEvent.TIMER, updateFade);
_fadeTimer.removeEventListener(TimerEvent.TIMER_COMPLETE, updateFadeComplete);
_fadeTimer = null;
}
}
There's nothing wrong with using function methods where it works. As far as memory leaks go, you need to track the object to the stage to see if it can be removed.
Adding an ENTER_FRAME event handler to the control ensures that the control has a reference to the anonymous function. As the code is part of the control (or so it appears), this is fine as the anonymous function will be removed when the control is.
Adding an event handler to the timer ensures that the timer has a reference to the anonymous function. If the timer is running, it will keep the anonymous function reference alive and, by association, the enture control. Once the timer has stopped, however, both it and the function should be collected.
If all else fails, use the profiler and see! ;)

Actionscript3: add and remove EventListeners (with dynamic name and dynamic variables)

I am making a boardgame in flash Action Script 3. Each position on the board is a buttons like this: button_1_1, button_1_2 etc. Whenever a character is selected you want to move it so the script has to add event listeners for positions around the selected unit
// This function adds or deletes an event listener
function listentoButton (isTrue:int, position_x:int, position_y:int):void {
var myFunction:Function = new Function;
myFunction = function ():void {userClickedPosition(position_x, position_y)};
if (isTrue == 1) {
this["button_position_"+(position_x)+"_"+(position_y)].addEventListener(MouseEvent.CLICK, myFunction);
} else {
this["button_position_"+(position_x)+"_"+(position_y)].removeEventListener(MouseEvent.CLICK, myFunction);
}
}
In the rest of the code I have:
function userClickedPosition(position_x:int, position_y:int)
it selects or deselect a unit
function selectUnit(position_x:int, position_y:int):
it uses the listentoButton(1) function to add 8 listeners (the positions around the clicked unit)
function deselectUnit(position_x:int, position_y:int):
it uses the listentoButton(0) function to delete 8 listeners (the positions around the clicked unit)
My question: adding eventlisteners is no problem but removing them dont seem to work? What did I do wrong?
When you go to remove the event, you are using a new instance of myFunction, not the same one you added it with. You either need to declare the function like you would any other function, and use the event args to examine the button's position like. I Think you want the stageX and stageY properties:
http://www.adobe.com/livedocs/flex/3/langref/flash/events/MouseEvent.html
// This function adds or deletes an event listener
function listentoButton (isTrue:int, position_x:int, position_y:int):void {
if (isTrue == 1) {
this["button_position_"+(position_x)+"_"+(position_y)].addEventListener(MouseEvent.CLICK, myFunction);
} else {
this["button_position_"+(position_x)+"_"+(position_y)].removeEventListener(MouseEvent.CLICK, myFunction);
}
}
function myFunction(eventArg:MouseEvent):void {
//use MouseEvent
};
Or you can create a little MyFunctionParameters class to hold the coordinate information and create a new instance of that class, add it to a collection indexed by the x and y coordinates, and later when you go to remove the event, you would lookup the MySpaceParameters instance in the collection, based on x and y coordinates, then use that to remove function.
class MyFunctionParameters
{
public x:int;
public y:int;
function myFunction(eventArg:MouseEvent):void {
userClickedPosition(x,y);
};
}

how to capture mouseclick in actionscript 3.0

How do I capture the position of a mouseclick from the user in my Flash window using Actionscript 3.0?
Ron DeVera is close, but I wouldn't use an inline function, and the object passed to the function is not Event, but MouseEvent.
stage.addEventListener(MouseEvent.CLICK, _onStageMouseDown);
function _onStageMouseDown(e:MouseEvent):void
{
trace(e);
}
//traces
//[MouseEvent type="click" bubbles=true cancelable=false eventPhase=2 localX=96 localY=96 stageX=96 stageY=96 relatedObject=null ctrlKey=false altKey=false shiftKey=false buttonDown=false delta=0]
All of the properties in the output above are available through the object that gets passed to the Event Listener Method, _onStageMouseDown(e:MouseEvent); Hence the following
function _onStageMouseDown(e:MouseEvent):void
{
trace(e.localX);
trace(e.stageX);
//Note that the above two traces are identical as we are listening to the stage for our MouseEvent.
}
They explained it well, but here's the full code to illustrate it a little more for you:
addEventListener(MouseEvent.CLICK, clickHandler);
function clickHandler(event: MouseEvent) : void
{
// these are the x and y relative to the object
var localMouseX: Number = event.localX;
var localMouseY: Number = event.localY;
// these are the x and y relative to the whole stage
var stageMouseX: Number = event.stageX;
var stageMouseY: Number = event.stageY;
}
Location defined by what context? The whole page? One or more specific clickable controls?
You may query any DisplayObject's mouseX and mouseY whenever you like.