Now there is a Constructor: MyMarker(icon:DisplayObject=null) which accepts any DisplayObject, if I create a new instance of MyMarker(just new MyMarker()),it will be dsplayed with a default Icon,so how to set a Image/Icon into this Constructor? Any ideas are much appreciated!
It's kind of hard to tell from your question but, if you want to set a default icon if NO DisplayObject is passed, just check if icon is null in the MyMarker constructor, eg:
...
public function MyMarker(icon:DisplayObject=null) {
if (icon==null) {
// set default icon here...
}
}
...
As for the inheritance issue, so long as the object passed inherits from DisplayObject, you should be fine. You may run into trouble if you try to invoke methods on the object that don't appear in DisplayObject.
You should create an appropriate DisplayObject in advance and then pass the reference to this object in the constructor:
var myLittleCustomIcon:Sprite = new Sprite();
myLittleCustomIcon.graphics.beginFill(0x00FF00, 1);
myLittleCustomIcon.graphics.drawRect(0, 0, 100, 50);
myLittleCustomIcon.graphics.endFill();
var myCustomMaker:MyMarker = new MyMarker(myLittleCustomIcon);
Related
I have a MovieClip inside library, linkaged to MyObject and it contains a textField.
I don't know how I can access this textField without using the getChildByName method.
Apparently, the 3rd section works when object is on stage (without using addChild). But when using addChild I think there has to be some kind of casting; which I don't know how.
var childElement: MyObject = new MyObject();
childElement.name = "theChildElement";
container.addChild(childElement);
btn.addEventListener(MouseEvent.CLICK, changeText);
function changeText(event: MouseEvent): void
{
var targetBox:MovieClip = container.getChildByName(childElement.name) as MovieClip;
targetBox.textField.text = "hello"; // THIS WORKS
// This works too:
// MovieClip(container.getChildByName("theChildElement"))["textField"].text = "hello"; // THIS WORKS TOO.
// THIS DOESN'T WORK. why?
// container["theChildElement"]["textField"].text = "hello";
}
As confusing as it may seem, instance name, and name are not the same. From your code you should always be able to get to your MC by it's variable name. To get your last like to work you could just use this.
childElement["textField"].text = "hello";
There is a difference between Symbols created by the Flash IDE, which aggregate other DisplayObjects and programmatically created DisplayObjects.
When a DisplayObject is created in the Flash IDE, it's instance name can be used to resolve the instance as a property - which means it can be accessed via []. The [] can be used to access properties or keys of dynamic declared classes - like MovieClip. This necessary because you'll most likely down cast to MovieClip instead of using the symbol class created by Flash. That is not possible when simply using addChild, addChildAt or setChildAt from the DisplayObjectContainer API.
It is always the save way to access it via getChildByNameand check for null because otherwise your app, website or whatever is doomed for 1009 errors as soon as someone is changing the symbols.
I'd create a bunch of helper methods, like
// not tested
function getChildIn(parent:DisplayObjectContainer, names:Array):DisplayObject {
var child:DisplayObject, name:String;
while (names.length > 0) {
name = names.shift();
child = parent.getChildByName(name);
if (!child) {
// log it
return null;
}
if (names.length == 0) {
return child;
}
}
// log it
return null;
}
function getTextFieldIn(parent:DisplayObjectContainer, names:Array):TextField {
return getChildIn(parent, names) as TextField;
}
function getMovieClipIn(parent:DisplayObjectContainer, names:Array):MovieClip {
return getChildIn(parent, names) as MovieClip;
}
Your third method doesn't work because you are trying to call the ChildElement by it's name
without using getChildByName method. On the other hand, you shouldn't call your textField textField, because that's already an actionScript property.
Your should rather call it 'displayText' for example.
For a textField called 'displayText' contained in childElement :
function changeText(event:MouseEvent): void
{
childElement.displayText.text = "hello";
}
I have a movieClip I am loading from the Libary and I have properly LINKED it to export with a name of myMC. This movieclip contains another movieClip and some properties. Lets call the movieClip inside: insideMC.
Here is my code:
function loadScreen()
{
var newMC:MovieClip = new myMC();
addChild(newMC);
loadButtons();
}
function loadButtons()
{
newMC.insideMC.addEventListener(MouseEvent.CLICK, homeButtons);
}
loadScreen();
HOWEVER, when I call the function loadButtons() within the loadScreen() function then I get this error.
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at iRosary_fla::MainTimeline/loadButtons()[iRosary_fla.MainTimeline::frame1:83]
at iRosary_fla::MainTimeline/loadScreen()[iRosary_fla.MainTimeline::frame1:110]
at iRosary_fla::MainTimeline/frame1()[iRosary_fla.MainTimeline::frame1:103]
It is not seeing the insideMC. Perhaps because it's calling to fast or not loaded yet. It is calling and loading the newMC tho. Just the function loadButtons() is not working because it is not seeing the insideMC movieClip. I am sure this is an easy fix but I can't find it anywhere. Thanks
newMC is a local variable in your loadScreen() method, therefore it has no scope in your loadButtons() method.
Declare newMC as a class member variable and it will have scope in loadButtons()
for example :
// in class declarations
public var newMC:MovieClip;
function loadScreen()
{
newMC = new myMC();
addChild(newMC);
loadButtons();
}
It's important to understand that :
var newMC:MovieClip = new myMC();
Creates a local variable. From your comments, it sounds like you did have newMC as a class variable. So you assumed that the above line was assigning the new instance to your class member newMC, and not the local variable you created.
Not completely sure this is your problem. But to access a movie clip within a movie clip you have to give that "insideMC" an instance name within the first movie clip. Otherwise you'll reference an object that you haven't added to the stage - a null object.
Tutorial on instance names here
I am new to AS3 and am trying to lean its OOP ways. What I am having problems with is understanding how to access the stage with separate classes.
Here is an example of what I am trying to do:
package game{
import flash.display.*;
public class Main extends MovieClip{
function Main(){
var player = new Player();
var playerBullets = new playerBullet();
addChild(player.players);
}
}
package game{
import flash.display.*;
public class Bullet extends Main // also tried with MovieClip and Sprite{
function Bullet(){
// empty
}
function blah(){
var someSprite = new someSprite();
Main.addChild(someSprite);
stage.addChild(someSprite);
root.addChild(someSprite);
}
}
}
I have Omitted another class which calls the blah method as I feel it is not relevant.
Basically what I want to know is how to add things to the stage in classes as it lookes like I am missing something crucial.
*EDIT TO INCLUDE ERROR*
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at game::Bullet/blah()
at game::Player/fire()
You shouldn't necessarily be extending main to create something like a bullet class, this can be it's own class that extends Sprite or MovieClip. The stage object is considered a global object, as it is a singleton (except in the case of Adobe AIR where you can have one stage per NativeWindow that you spawn). So any object that extends DisplayObject or has DisplayObject in it's inheritance chain will by default have a reference to the stage via a getter, which is populated automatically when a displayObject is added to the display list. This can happen by either adding a clip directly to the root stage object or by adding a clip as a child of another clip, that eventually connects to the stage. For example:
var clip1:MovieClip = new MovieClip();
stage.addChild(clip1); //Clip 1 can now access the stage reference internally.
ver clip2:MovieClip = new MovieClip(); //Right now, clip2 cannot access the stage reference interally.
clip1.addChild(clip2); //Now clip2 can access the internal stage reference because it has been connected to the display list through clip1.
The other mistake people make is accessing stage within a DisplayObject typed class (such as your Main class) without first ensuring that the object itself has been added to the stage. You do this by listening for the Event.ADDED_TO_STAGE event within the constructor of the class, like so:
public class Main extends MovieClip{
function Main(){
if(stage){
//The stage reference is present, so we're already added to the stage
init();
}else{
addEventListener(Event.ADDED_TO_STAGE, init);
}
var player = new Player();
var playerBullets = new playerBullet();
addChild(player.players);
}
private function init(e:Event = null)
{
trace("Added to stage, the stage reference is now populated and stage can be accessed");
}
}
This could be the problem you're having, but it's hard to say since you have not specified any errors. However, this is likely an issue or will be for you, since it's quite common. Inside the init() method you can then set a flag so that when external classes call your Main.blah() method, you can ensure that the stage reference exists before attempting to add something to the stage. Take note however that within your Main class when you simply say:
addChild(someChild);
or
this.addChild(someChild);
you're not adding that child to the stage, but rather to the Main object, which is a MovieClip or Sprite based object that is itself attached to the stage automatically when you set it as the Document class. Hope this info helps.
Update
To explain the display list a little more:
Think of all your movieclips as dishes, and the stage as the table. You can only access the table from the dish, if the dish is placed directly on the table, or if a dish is stacked on top of another dish that touches the table. If you have 10 plates stacked on top of each other, they all touch the table eventually, via their connection to each other. This is essentially a visualization of the flash display list. The way you put dishes on the table is by using addChild(dish). If you have not placed an object somewhere on the table, and try to access the table from that object, you're going to fail. You're getting the "access to undefined" error because you're calling the "blah()" method, which accesses the stage (table) before the bullet (dish) has been added to the stage (table). So you must first either directly add the bullet to the stage, or add it to another object that has already been added to the stage. Change your code like so:
var myBullet:Bullet = new Bullet();
stage.addChild(myBullet);
//Or, if this class, assuming it's the player class, has already been added to the stage, just do this:
this.addChild(myBullet);
myBullet.blah();
Even so, you should still have some error checking within your "blah" method to ensure that the stage is available:
function blah(){
var someSprite = new someSprite();
if(stage){
Main.addChild(someSprite);
stage.addChild(someSprite);
root.addChild(someSprite);
}else{
trace("error, stage not present");
}
}
However you should also note that by adding this child to Main, then stage, then root all in sequence, this does not duplicate the someSprite object. When you add a display object to a new parent object, the object is automatically pulled from it's current parent and moved to the new one. So all this code will do is eventually add someSprite to root, which I believe will fail because root is not a display object, but rather a global reference mainly used to access global objects such as the stage and the Loader object used to load the SWF.
You shouldn't ever be calling stage.addChild. There should be only one child of the Stage, and that's the document class.
You make a MovieClip display on the screen by adding it to the stage's display list.
Stage
+ Main Timeline
+Anything
+Else
+You
+Want
So assuming that Main is your document class for the main timeline...
// inside of Main's constructor...
public function Main(){
var anything:MovieClip = new MovieClip();
var Else:TextField = new TextField();
var you:SimpleButton = new SimpleButton();
var want:Sprite = new Sprite();
this.addChild(anything);
this.addChild(Else);
this.addChild(you);
this.addChild(want);
}
Then in order to add children even lower, for example if you want something to be a child of "Anything" such that you have....
Stage
+ Main Timeline
+Anything
+And
+Everything
+Else
+You
+Want
public function Main(){
var anything:MovieClip = new MovieClip();
var Else:TextField = new TextField();
var you:SimpleButton = new SimpleButton();
var want:Sprite = new Sprite();
this.addChild(anything);
this.addChild(Else);
this.addChild(you);
this.addChild(want);
var And:Sprite = new Sprite();
var everything:Sprite = new Sprite();
anything.addChild(And);
anything.addChild(everything);
}
EDIT: Ascension Systems asks why you should never add any display object directly as a child of the stage. The simplest answer is that you can't ever guarantee that what you believe you're creating as a document class, or as a main timeline in fact actually is going to be used as such. Your use of the stage may later preclude your swf from being loaded as a child of a larger application depending on what it is you've done, exactly. Relying directly on the stage can mean that you're making some assumptions about the nature of the display list that may not hold in the future. That's the way in which it breaks modularity (which is not the same as breaking oop).
Why add to the stage when you could just create your entire application as a MovieClip that is completely self-contained with no reliance on the concept of a "stage" beyond that which is required for learning world coordinates? That way you can be much more modular in your design and you sacrifice nothing.
In some people's work this may be considered an edge case. In my work this has happened both to me when I've created applications that I thought at the time were purely stand-alone that ended up being repurposed later to be a module, and also to swfs that other people created that were intended to be strictly stand-alone, but that I was then to integrate as a module into a larger application. In all cases there were some nasty side effects to contend with. That's where I learned not to rely too closely on the stage for much beyond world coordinates.
Every display object has a property called stage, which is null until that object is added to the display tree.
When you are unsure if an object has been added to the stage, there is a listener you can employ for that purpose:
public class Main extends MovieClip
{
import flash.events.Event;
public function Main():void
{
if(stage) {
init();
} else {
this.addEventListener(Event.ADDED_TO_STAGE,init);
}
}
private function init(evt:Event = null):void
{
this.removeEventListener(Event.ADDED_TO_STAGE,init);
//object is now definitely on the display tree
}
}
I'm gonna take a wild stab in the dark here.
stage is a property implemented something like so:
public function get stage():Stage {
var s:DisplayObject = this;
while(s.parent) s = s.parent;
return s as Stage;
}
root is very similar but stops a level below stage (root is a child of stage).
These properties only work when the object you're calling them on is on the stage somewhere. Doesn't matter where, because the while loop will walk up the hierarchy to get to the stage node at the top. But if it's not on the stage, then parent will be null.
So if your movieclip is not on the stage, then its reference to stage will be null. Same goes for root.
I'm guessing that you're calling blah before the bullets are added to the stage? In which case your call stage.addChild(someSprite) will be a Null Reference error (stage is null).
So you either need to add the bullets to stage first, or you need to pass stage in as a parameter:
function blah(s:Stage){
var someSprite = new someSprite();
s.addChild(someSprite);
}
I'm making a game in AS3. When I add an enemy to the game screen, later on I have to remove it when it dies. But I keep getting this:
[Fault] exception, information=ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller.
But I clearly add the enemy to the gamescreen. Could this be from passing the enemy through a bunch of functions or something?
This means that you try to remove the MovieClip (or Sprite or so) from a DisplayObjectContainer that is not its parent.
You have to be sure to call the removeChild() Method on the right DisplayObjectContainer.
For instance:
var myChild:MovieClip = new MovieClip();
var holder:MovieClip = new MovieClip();
holder.addChild(myChild);
so when you want to remove the child you have to call the removeChild Method on the holder.
holder.removeChild(myChild);
If you call removeChild() on for instance the stage you will get an error because the stage does not hold myChild as a child of itself.
So double check if you call removeChild on the right container.
PS: Sample code is always easier to debug
When dealing with the timeline, it's difficult sometimes to keep track of an object's scope , in which case you can always call the method from the object's parent property.
child.parent.removeChild( child );
if you're coding in FlashDevelop & for some reason , don't wish to or can't keep track of the parent , you could implement a couple of methods to add and remove your object from the display list, practically delegating adding & removing to the object...
in your object class , you could do the following...
private var container:DisplayObjectContainer;
public function addToDisplayList( container:DisplayObjectContainer ):void
{
this.container = container;
container.addChild( this );
}
public function remove():void
{
if( container != null )
container.removeChild( this );
}
Then you can simply do this:
var child:MovieClip = new MyObject();
child.addToDisplayList( whatever );
//later...
child.remove();
how can i call public functions or vars of a sprite class from another class (or frame script)? i keep getting 1061: Call to a possibly undefined method getSide through a reference with static type flash.display:Sprite.
//Framescript
var a:Sprite = new customRect();
addChild(a);
a.getSide();
//.as file
package
{
import flash.display.Sprite;
public class customRect extends Sprite
{
public var side:Number;
private function customRect()
{
var box:Sprite = new Sprite();
box.graphics.beginFill();
box.graphics.drawRect(0, 0, 200, 200);
box.graphics.endFill();
side = box.width;
}
public function getSide():void
{
trace(side);
}
}
}
You'll need to type the other class as whatever type of class it is. Sprite doesn't, by default, have whatever property you're trying to access, so you can't just do mysprite.myRandomVariableName. However, if you happen to know mysprite is really of type MyClass then you can do MyClass(mysprite).myRandomVariableName or (mysprite as MyClass).myRandomVariableName. When using the as keyword, note that the typed mysprite will evaluate to null if mysprite is not really of type MyClass. Trying to type mySprite to MyClass using the prior method will throw an error if mysprite is not of type MyClass.
Alternatively, I believe you can use square brackets to access a sprite's dynamic properties (i.e. mysprite['myRandomVariableName'], however it's really better practice to strongly type your objects.
//edit, since you posted a code sample:
All you need here is:
var a:CustomRect = new CustomRect();//note that since CustomRect is a class name, it should be captialized.
Are you trying to call actual methods of the Sprite class or ones that you've added to a subclass of Sprite? My guess is that you need to cast the variable to the actual class that you are using. So instead of:
someReference.yourFunction();
you could try:
YourClass(someReference).yourFunction();
... this is only needed if you do not control the typing of someReference - if you do you can simply define it using var someReference:YourClass to make it known to the compiler that is is a var of YourClass type, and not of Sprite.
UPDATE after your code example was added, change:
var a:Sprite = new customRect();
to
var a:customRect = new customRect();
so the compiler knows it is a customRect and not a 'general' Sprite.
as an aside: it is custom to start classnames with an uppercase letter: so use CustomRect instead of customRect.