How to have an application to automatically scale when launched? - actionscript-3

Question

I want my application to automatically scale its size depending on the screen size. I want my application to fit any screen size automatically. I am making my application for mobile devices, how can I do this? I am fairly new at flash so please make it a bit simple!

Answer 1

Yes, there is no simple answer but the basics is:
stage.addEventListener(Event.RESIZE,onStageResize);
function onStageResize(e:Event):void {
// Use stage size for placing elements to their position..
// Position to left top
element1.x = 10;
element1.y = 10;
// Position to right top
element2.x = stage.stageWidth - element2.width - 10;
element2.y = 10;
// Position element to center and make it's width to scale with stage..
element3.width = stage.stageWidth - 20;
element3.x = 10;
element3.y = stage.stageHeight / 2 - element3.height / 2;
}
To scale elements place them inside on Sprite or MovieClip and scale that element like:
element.scaleX = 1.6; // scale 1 = 100% 2 = 200% etc
element.scaleY = element.scaleX;
I usually create public function "resizeElements(e:Event = null):void" for visual subclasses/components and call that from the main thread. In that function the object can resize it self.

Answer 2

In addition to #hardy's answer it's important to set the following variables on the stage:
// disables default 100% scaling of entire swf
stage.scaleMode = StageScaleMode.NO_SCALE;
// disables default align center
stage.align = StageAlign.TOP_LEFT;
Also, since the original question was regarding resize on launch, and this is mobile deployment it's important to call onStageResize(); once manually because the RESIZE event may not be fired initially. This would require changing:
function onStageResize(e:Event):void { ... }
to
function onStageResize(e:Event = null):void { ... }

Answer 3

Saying "automatically scale to screen" is too generic. The requirements this statement imposes is totally different between apps depending on what they need to do. There is no simple answer.
If your app has a main content canvas area, do you want to zoom to the content to fit the area? Do you want to keep the content the same size and show more of it? Maybe both - you could want to show more to a point, and then scale if there is still more room.
What do you want your UI to do? Dialogs could shrink/grow and remain central. Maybe you want to reflow them completely?
Do you have a slick UI? Maybe a menu with a set of buttons. Do the buttons need to be sized proportionally to the screen? What about the gaps between them? What if the screen ratio is different so if you scale them to fit they no longer work?
The point is, there isn't a simple answer. For basic layout there are UI frameworks that can assist you in placement and scaling, but you still need to decide how you want your app to behave. That totally depends on the app and what your intended design is.