Reference to the Stage

Hi!
I have this situation:
Document class:
private var controller:MyController = new MyController()
addChild(controller)
in MyController Class:
later in the code...
stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveListener);
MyController class extend Controller that extends Sprite
When mouse move e get this error
TypeError: Error #1009: Cannot access a property or method of a null object reference.
The problem is the stage reference.
But why?
thanks a lot!

It is most likely because the code executes before the object is fully setlled into its home. What you probably need to do is add an event listener for the event Event.ADDED_TO_STAGE in your MyController class and use that to trigger any code that involves targeting the stage.

Similar Messages

Get reference to the stage in a AS Class

Hello,
I've created an AIR app with the minimeze() and close()
options. Now these functions are handled in the MainApp.mxml of the
application. But I want to move them to a class, so I don't have
any AS in my MXML file.
My app works like this now:
MainApp.mxml creates a new instance the Main.as class (which
extends MainVisual.mxml) by calling <mainVisual:Main /> in
the MainApp.mxml
MainVisual.mxml extends Canvas.
There I handle all visual elements of my app, but I can't get
a reference to the stage.nativeWindow here. Does anyone knows how
to do this?
Thanks!

Every display object, including the Canvas, has a stage
property. However, this property will be null until the Canvas
object is added to the stage. You can use the ADDED_TO_STAGE event
to detect when that happens.

Reference to the stage not working there?

In my document class, I am instantiating a class like this:
cues = new CuePoints();
cues.addEventListener(CuePoints.CUE_POINTS_CLASS_ADDED, setCuePoints);
addChild(cues);
In the constructor method of cues, I am adding the following event listener:
public function CuePoints():void
addEventListener(Event.ADDED_TO_STAGE, classAdded);
classAdded dispatches an event that gets listened to by the document class, which then calls a function in cues, like this:
private function setCuePoints(e:Event):void
cues.setCues(videoPlaylist.getCues(0));
If I trace stage in setCues, I get the following:
[object Stage]
If I try to reference a MC that sits on the stage called videoPlayer_main like so:
stage.videoPlayer_main
I get the following error:
1119: Access of possibly undefined property videoPlayer_main through a reference with static type flash.display:Stage.

I'm still new to Flash but since no one has responded I'll take a stab at this:
I didn't think a child of the stage could be referenced like that (stage.childname)... might you use something like getChildByName() to get the movieclip that is on the stage?

Flex 4 Premium reference to the Stage issue! width and height seem to be switched??

So I am doing a very basic resize effect with a panel, but if I want it to fill the screen, I have to switch stage.stageWidth and stage.stageHeight. I have also traced them out and they come out as switched values. Anyone else having this issue?
protected function panel1_addedToStageHandler(event:Event):void
      trace(stage.stageWidth, " " , stage.stageHeight);

Hi,
You maybe running into some sort of layout constraint also it depends on how you are initiating the animation, if you are doing it on startup you need to wait for creationComplete to ensure all your dimensions have been calculated for the browser. You shouldn't need to use stage dimensions either. The following code resizes a panel to fill the browser. (note using top/left/bottom/right is a lot smoother than width and height).
David
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
   xmlns:s="library://ns.adobe.com/flex/spark"
   xmlns:mx="library://ns.adobe.com/flex/mx"
   creationComplete="application1_creationCompleteHandler(event)">
<fx:Script>
<![CDATA[
import mx.events.FlexEvent;
protected function application1_creationCompleteHandler(event:FlexEvent):void
pw.valueFrom=pnl.width;
ph.valueFrom=pnl.height;
fillscreen.play();
]]>
</fx:Script>
<fx:Declarations>
<s:Animate id="fillscreen" target="{pnl}" repeatCount="1" duration="1000">
<s:SimpleMotionPath id="pw" property="width" valueTo="{width}"/>
<s:SimpleMotionPath id="ph" property="height" valueTo="{height}"/>
</s:Animate>
</fx:Declarations>
<s:Panel id="pnl" width="250" height="200" horizontalCenter="0" verticalCenter="0">
</s:Panel>
</s:Application>

Adding objects to the stage & acceessing stage properties - I'm a bit confused..

Hi,
I'm a little confused on two fronts regarding display
programming:
A. What the best way to add objects to the stage?
B. How to access stage properties.
I can do both of these when the project is an 'Action Script
Project', but I'm having trouble when it is a 'Flex Project' (e.g.
an MXML file). See the two attached files with questions included
in the comment to see exactly what I mean.
A. What the best way to add objects to the stage?
=====================================
In an action script project that extends Sprite I can just
call addChild()
In an MXML project I can add objects to the stage by first
adding them to a UIComponent, then adding that to the stage.
1. Is that the best way to do it?
In this doc:
http://livedocs.adobe.com/flex/3/html/help.html?content=05_Display_Programming_02.html
it says that
quote:
Each SWF file has an associated ActionScript class, known as
the main class of the SWF file. When Flash Player opens a SWF file
in an HTML page, Flash Player calls the constructor function for
that class and the instance that is created (which is always a type
of display object) is added as a child of the Stage object. The
main class of a SWF file always extends the Sprite class
2. why cant I just add a sprite object direct to the stage
without the UIComponent?
3. What is the 'main class', and how can i get access to it?
B. How to access stage properties.
=========================
In an action script project that extends Sprite I can just
call trace(stage.framerate)
But in an MXML file I cannot figure out how to access the
stage properties.
See the attached code for the things that I tried, but which
didnt work.
In the page:
http://www.actionscript.org/forums/showthread.php3?t=140655
It says
quote:
For stage access you have a couple of rules:
* natively, only display objects have inherent access to
stage
* display objects only have a valid reference to stage if
they're within the stage's display list (on the screen, after added
to it with addChild)
* The only display objects which immediately have access to
the stage before the use of addChild (in their constructor) are the
document/application class instance (root) and any instance from
the library placed on the timeline (not created with AS).
* Non-display object classes have to be passed or assigned a
reference to the stage from another object which already has access
to it - they cannot access it otherwise.
4. How do I access the stage properties in the MXML project?
5. I suspect this is related to the "main class", which I
dont yet understand - is it?
Sorry for the long post.
cheers
tom

"tom saffell" <[email protected]> wrote in
message
news:gd7cm9$d1v$[email protected]..
> Thanks Luigi - that helps a lot.
> I hadnt seen the Flex 3 Developer Guide before - it's
very useful.
>
> I now see that I can access properties of the
application object directly
> with
> this.<property>.
> However, the framerate property cannot be set by
actionscript, only in
> MXML (I
> can set it in the <mx:application> tag). But I
need to be able to set it
> programatically, dependent on user input.
>
> 5. Is there a way around this?
> 6. Can I set the stage's framerate to achieve the same
outcome?
>
> I still dont understand why I cannot access the stage
object. When I call
> either
this.stage or
uic.stage * then I get
quote:
Cannot access
> a
> property or method of a null object reference.
My understanding is
> that I
> can access the stage object via any display object on
the display list.
> I'm
> confused about this bit..
>
> * - uic is a UIComponent that has been added to the
display list (i think)
> by
> calling addChild(uic) from the AS3 within the
application
>
> 7. How do I access stage properties in AS3 in an MXML
project?
http://www.adobe.com/livedocs/flex/3/html/help.html?content=05_Display_Programming_10.html
It seems like possibly your real problem is that you're
having trouble
searching the Help effectively:
http://flexdiary.blogspot.com/2008/07/getting-help-in-flex-builder.html

Using the Stage and Tools panel

This question was posted in response to the following article: http://help.adobe.com/en_US/flash/cs/using/WSd60f23110762d6b883b18f10cb1fe1af6-7fb8a.html

how do I garantee the symbol editing area has the same giude references as the stage?

Possible to set the alpha of a component physically placed on the stage?

I am trying to access a button that has been added to the stage to change it's alpha value. I'm changing it from inside an object that is also on the stage. So I thought this.parent.feed_btn.alpha=0 would work but flash is saying:
1119: Access of possibly undefined property feed_btn through a reference with static type flash.display:DisplayObjectContainer.
I would actually prefer to remove it, but removeChild threw up the same error.
Can someone help please?

I would create a function in the parent timeline for removing the event listener, since all of the parts likely live there, and just call that function.
When you are commending this in the child...
parent_mc.dogTimer.removeEventListener(TimerEvent.TIMER,updateApplication);
Isn't the updateApplication function in the parent timeline?

How to dynamically duplicate an item on the stage

Hello,
I have a box (lets call it 'xBox') on the stage that contains
a couple comboboxes and buttons.
One of the buttons (labelled 'add new search feature') when
clicked will duplicate the whole box 'xbox' and give it a new
unique name that can be referenced. So, now there would be two
boxes on the stage that look exactly the same.
You can click the 'add new search feature' button repeatedly
and each time a new 'xbox' will appear at the bottom below the
previously created 'xbox's....
I have played with states some, but am unsure how that would
apply to an infinite amount of new 'xbox's being created.
Is this possible? Any help is greatly appreciated.
here is the code:
<mx:Box direction="horizontal" borderStyle="solid"
paddingTop="10" paddingBottom="10" paddingLeft="10"
paddingRight="10">
<mx:ComboBox id="xField" width="100%">

<mx:Array>
<mx:Object data="0" label="Yards gained" />
<mx:Object data="1" label="Shotgun" />
<mx:Object data="2" label="TD" />
<mx:Object data="3" label="Down" />
<mx:Object data="4" label="Leading" />
<mx:Object data="5" label="Quarter" />
<mx:Object data="6" label="Turf/grass" />
<mx:Object data="7" label="Stadium type" />
<mx:Object data="8" label="Home" />
<mx:Object data="9" label="Opponent" />
<mx:Object data="10" label="Month" />
<mx:Object data="11" label="Season" />
</mx:Array>
</mx:ComboBox>
<mx:ComboBox id="argument" width="100%">

<mx:Array>
<mx:Object data="0" label="Equals" />
<mx:Object data="1" label="is greater" />
<mx:Object data="2" label="is less" />
<mx:Object data="3" label="is not" />
</mx:Array>
</mx:ComboBox>
<mx:TextInput id="enter_data"/>
<mx:Button label="Search"/>
<mx:Button label="Add new Search Feature"/>
</mx:Box>

Okay, what you want to do is, make a custom component out of
the xBox. Then in your main application you wan to make an array of
objects. Every time the button (to add xBoxes) is clicked add one
to the array, then also add it to the main app's list of children.
You want to add it to the array so that you can still reference it.
Try something like this:
import xBox;
import mx.collections.ArrayCollection;
private var xBoxArray : ArrayCollection = new
ArrayCollection();
private var location : int = 1;
private function buttonClickHandler() : void
var temp : xBox = new xBox ();
xBoxArray.addItemAt ( location, temp );
whereYouWantTheXBoxesToGo.addChildAt ( location,
xBoxArray.getItemAt ( location ) );
<mx:Button click="buttonClickHandler()"
label="More xBoxes" id="360" />
<mx:Box id="whereYouWantTheXBoxesToGo"/>

This is just a rough guide of what to try. But something like
this should work.

Controlling properties on items added to the stage in a loop

Hi there,
I have a loop that adds xml elements to the stage (10). Once added, I need to control the items (checkbox = do something).
Here is where I add them to the stage.
          private function createLayout():void {
               container = new VBox();
               for(var i:int=0; i<10; i++) {
                    vBox = new VBox();
                    hBox = new HBox();
                    titleText = new LinkButton();
                    itemInfo = new Text();
                    abstract = new Text();
                    archive = new CheckBox();
                    rateItem = new ComboBox();
                    category = new ComboBox();
                    var categoryLabels:Array = new Array("Food & Ag","News","Health","People","General","What's Coming","Biofuel","Environment");
                    var rateLabels:Array = new Array("Excellent","Good","Bad","Neutral","Controversial");
                    titleText.label = listCollection.getItemAt(i).title;
                    titleText.width = 400;
                    itemInfo.text = listCollection.getItemAt(i).source + " | " + listCollection.getItemAt(i).date;
                    abstract.text = listCollection.getItemAt(i).abstract;
                    abstract.width = 400;
                    archive.label = "Archive";
                    category.prompt = "Category";
                    category.dataProvider = categoryLabels;
                    category.rowCount = categoryLabels.length;
                    rateItem.prompt = "Rate";
                    rateItem.dataProvider = rateLabels;
                    vBox.addChild(titleText);
                    vBox.addChild(itemInfo);
                    vBox.addChild(abstract);
                    vBox.addChild(hBox);
                    hBox.addChild(archive);
                    hBox.percentWidth = 80;
                    hBox.percentHeight = 80;
                    archive.addEventListener(Event.CHANGE, toggleArchive);
                    container.addChild(vBox);
               addChild(container);
I listen for a checkbox (change event) and when clicked, call a function that adds two comboboxes to the stage.
archive.addEventListener(Event.CHANGE, toggleArchive);
I then call the function that will handle the event.
          public function toggleArchive(e:Event):void {
               if(archive.selected == true){
                    hBox.addChild(category);
                    hBox.addChild(rateItem);
               else {
                    hBox.removeChild(category);
                    hBox.removeChild(rateItem);
When I have one item it works fine.
for(var i:int=0; i<1; i++) {
When I add 10 nothing happens. I feel like i should be doing something to identify what item I'm referring to. Any thoughts/reccomendations would br great!

My apologies, but I am somewhat confused. Thanks for taking the time to help me (first off)!
I changed the createLayout function to add name, visible, and includeInLayout propertiesfor each comboBox. I then changes the scope of "i" so that I can reference it from the function called upon the Event.CHANGE event.
          private var i:Number;
          private function createLayout():void {
               container = new VBox();
               for(var i=0; i<listCollection.length; i++) {
                    vBox = new VBox();
                    hBox = new HBox();
                    titleText = new LinkButton();
                    itemInfo = new Text();
                    abstract = new Text();
                    archive = new CheckBox();
                    rateItem = new ComboBox();
                    category = new ComboBox();
                    var categoryLabels:Array = new Array("Food & Ag","News","Health","People","General","What's Coming","Biofuel","Environment");
                    var rateLabels:Array = new Array("Excellent","Good","Bad","Neutral","Controversial");
                    titleText.label = listCollection.getItemAt(i).title;
                    titleText.width = 400;
                    itemInfo.text = listCollection.getItemAt(i).source + " | " + listCollection.getItemAt(i).date;
                    abstract.text = listCollection.getItemAt(i).abstract;
                    abstract.width = 400;
                    archive.label = "Archive";
                    category.prompt = "Category";
                    category.name = "category";
                    category.dataProvider = categoryLabels;
                    category.rowCount = categoryLabels.length;
                    category.visible = false;
                    category.includeInLayout = false;
                    rateItem.prompt = "Rate";
                    rateItem.name = "rateItem";
                    rateItem.dataProvider = rateLabels;
                    rateItem.visible = false;
                    rateItem.includeInLayout = false;
                    vBox.addChild(titleText);
                    vBox.addChild(itemInfo);
                    vBox.addChild(abstract);
                    vBox.addChild(hBox);
                    hBox.addChild(archive);
                    hBox.addChild(category);
                    hBox.addChild(rateItem);
                    hBox.percentWidth = 80;
                    hBox.percentHeight = 80;
                    archive.addEventListener(Event.CHANGE, toggleArchive);
                    container.addChild(vBox);
               addChild(container);
now I have to modify these items by name from the toggleArchive method.
          public function toggleArchive(e:Event):void {
               if(archive.selected == true){
                    var cb:ComboBox = hBox.getChildAt(i).getChildByName(category);
                    cb.visible = true;
                    cb.includeInLayout = true;
               else {
Two things, 1) i get an error saying...
Severity and Description    Path    Resource    Location    Creation Time    Id
1061: Call to a possibly undefined method getChildByName through a reference with static type flash.display:DisplayObject.    mediaTrap/src/components    listItems.mxml    line 132    1242667335601    643
2) shouldnt it be something like this
          public function toggleArchive(e:Event):void {
               if(hBox.getChildAt(i).archive.selected == true){
                    var cb:ComboBox = hBox.getChildAt(i).getChildByName(category);
                    cb.visible = true;
                    cb.includeInLayout = true;
               else {

How do I refer to the stage from a class?

I have a class that places objects on stage with addChild(obj) it allowes me to position objects using pixels( say obj.x = 10; obj.y= 50; ) just fine but if
I try this: obj.x = stage.stageWidth / 2; I get a message that I Cannot access a property or method of a null object reference

The stage property is only available to objects that are currently on the display list. Your best bet is probably to pass a stage reference to the class when you instantiate it.

Dynamically adding multiple instances of a movie clip to the stage with one button

hello,
I was wondering if there was a way to add several instances
of the same movie clip to the stage dynamically utilizing one
button.
I can do one with the following code placed on the button...
on (release) {
attachMovie ("filledCircle", "filled1", 5);
filled1._x = 370;
filled1._y = 225;
But I want the user to be able to hit the button again and
get yet another instance of "filledCircle" on the stage.
I also want the user to be able to drag these instances
around...
Any help would be appreciated...
Thanks,
Muhl

Muhl,
> I was wondering if there was a way to add several
> instances of the same movie clip to the stage
> dynamically utilizing one button.
Sure thing.
> I can do one with the following code placed on the
> button...
>
> on (release) {
> attachMovie ("filledCircle", "filled1", 5);
> filled1._x = 370;
> filled1._y = 225;
> }
Gotcha.
> But I want the user to be able to hit the button again
> and get yet another instance of "filledCircle" on the
> stage.
You're in luck, because this isn't very hard to do. The main
thing to
keep in mind is that each instance must have A) its own
unique instance name
and B) its own unique depth. In your example, the instance
name is filled1
and the depth is 5. The next clip's instance name should be
filled2 at a
depth of 6. Then filled3, depth 7, and so on. You can use a
single
variable to handle the incrementation.
// code in a frame
var counter:Number = 1;
// code on your button
on (release) {
attachMovie ("filledCircle", "filled" + counter, counter +
4);
With me so far? The variable counter contains the numeric
value 1. The
second parameter of attachMovie() is provided with a
concatenation of
"filled" + 1, which makes "filled1". The third parameter is
provided with
the sum of counter plus 4, which makes 5. Obviously, we need
a bit more.
The button must, in addition, increment the value of counter.
The ++
operator handles this perfectly.
on (release) {
attachMovie ("filledCircle", "filled" + counter, counter +
4);
counter++;
Now, it seems you also want to position the attached movie
clip to (370,
225). Are they call supposed to go to the same place? If so,
you may use a
second variable to hold a reference to the newly attached
clip. Look up
MovieClip.attachMovie(), and you'll see that the method
returns the exact
reference you need.
// code in a frame
var counter:Number = 1;
var mc:MovieClip;
// code on your button
on (release) {
mc = attachMovie ("filledCircle", "filled" + counter,
counter + 4);
counter++;
mc._x = 370;
mc._y = 225;
Make sense?
> I also want the user to be able to drag these instances
> around...
Then you need to handle a few events. You're dealing with
movie clips
here, so your best bet is to study up on the MovieClip class,
which defines
all movie clips. (Note, also, that the TextField class
defines all input
and dynamic text fields; the Sound class defines all sounds,
etc. This is a
very handy arrangement of the ActionScript 2.0 Language
Reference.)
// code in a frame
var counter:Number = 1;
var mc:MovieClip;
// code on your button
on (release) {
mc = attachMovie ("filledCircle", "filled" + counter,
counter + 4);
counter++;
mc._x = 370;
mc._y = 225;
mc.onPress = function() {
this.startDrag();
mc.onRelease = function() {
this.stopDrag();
Easy as that. You're simply assigning a function literal to
the event
of each new MovieClip instance as you create it. Take a look
and you'll see
each of these class members available to you -- that is, to
all movie clips.
MovieClip.onPress, MovieClip.startDrag(), MovieClip._x, etc.
Wherever it shows the term MovieClip in the Language
Reference, just
replace that with the instance name of your clip -- or a
reference to that
clip (which even includes the global "this" property).
David
stiller (at) quip (dot) net
Dev essays:
http://www.quip.net/blog/
"Luck is the residue of good design."

Accessing display objects via the stage var

I'm passing a stage reference to my class, but when I try to
access a movieclip on the stage I get an error.
this gives me an error:
var mc = targetStage.myMovieClip;
Thanks!

var myClass = new MyClass (this.stage);
That would be the same thing, this.stage would refer to the
Stage instance. Each .swf has one Stage instance. In a Flash
project, the stage has one child, the MainTimeline instance.
MainTimeline is basically a big MovieClip, and it contains all your
objects, scenes and timelines you create in Flash.
So, if you instantiate from the main timeline itself (either
on a frame script or Document class) you are already inside
MainTimeline, which is what you want to pass along a reference to,
so you would pass in "this" as Colin said, or "root".
Colin mentioned that MovieClip(root) would work anyway; if I
understand he is referring to the fact that every DisplayObject
(such as MovieClips and SimpleButtons created in Flash) already
have a "root" property that usually refers to the MainTimeline
instance. However, your class "MyClass" does not extend
DisplayObject so there is no root property available, which is why
you need to manually pass in a reference to the root
timeline.

Export the stage as a graphic

Hello,
I'm looking for a way, in Action Script, to take a snapshot
of the stage and
export it as a graphic. Any ideas on how to do it?
Thanks,
Brian

Yes, but my question is how are they redrawing in the
background, and how do
they generate the image for emailing, i.e. what is the Action
Script they
would use? They must be exporting something in order to be
able to send an
email with an attachment. I know in general what they are
doing, I just
don't know which Action Script code to use to accomplish it.
Thanks,
Brian
"Devendran" <[email protected]> wrote in message
news:el6gd3$jna$[email protected]..
> In your Reference Site.
> They are not Exporting any thing.
>
> They are Regenerating that image using the Datas they
have stored....
> For example After you design some thing all the data
will be stored into
> DB,
> and id will be generated.
> When u click on the url with that id, it will get the
Data from DB and
> Redraws
> the Content as per the Data....
>
> No export is here
>
>

Error when I put a component in the stage and I change any property

Hello
I'm using Flash CS4, as3 and adobe air file. I have an application with 3 scenes, first scene to login, second to set up, and third to see an video.
The problem is that, when I put a component in the second or third scene, if a change any property in the component inspector, any property it gives me error. So put the component and I change property by code in as3.
But I'm doing things with FLVPlayback component, and now before enter the scene gives me error, the solution will be to get the original properties, but I don't remember, I could install other time Flash CS4, but I can do that for any componet, better know the solution.
For example, I have an as file who is the class named p.e. MyMainclass, and in the scene3, I put FLVPlayback, who default values it's the last I used (I don't remember default after instalation), if any code in as3, it gives me this error:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at com.program::MyMainClass/__setProp___id2__scene3_myvideo1_1()[com.program.MyMainClass::__ setProp___id2__scene3_myvideo1_1:7]
I remove this component, I put another one I never used, it doesn't give me error, I change any property in the object inspector, p.e. color, it gives me error, I change to original property again, and then NO ERROR.
Thanks in advance

I would reccomend that you not use scenes for that purpose, not exactly sure why but scenes are unreliable. Try putting all of your content in one scene, one timeline and just add a few stop() 's at the end of each "scene", then in your code remove scene2 and scene3 three references, and you'll possibly need to change frame anchors/targets also if you have them.
The error indctates that you have called an object that does not exist at the time the code is run, check where you placed your code, should be frame one, scene1, and also check if you have objects entering the stage down the timeline, that do not enter in frame 1, possibly the movieClip? if so add another keyframe on your actions layer on the same frame as the object and enter the call function for it there.

Resizing the stage around its center

I have done some animation work on a stage 320px X 320px. I
find that I must present the same work on a stage 240px X 320 px.
If I use the Property Inspector window, I can enter the new stage
size. Unfortunately, the window is resized with the left hand side
of the screen as its reference point, effectively cutting off a
large part of the right side of my work. I would expect to loose a
piece of my animation at the right and the left evenly. How can I
resize the stage around its center?
Thanks

well, I'm afraid that just the thing, you really can't.
However, you can reposition everything on the Stage at the same
time. First, with all layers unlocked, right click the timeline
(anywhere but the first frame) and use 'select all frames', then
use the 'edit multiple frames' button which the little 'box' like
symbol next to the fps indicator on the bar just below the
timeline, select 'onion all', now you can drag or nudge the entire
animation at one time.

Reference to the Stage

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