Question

EDIT: See also next question on Stackoverflow:
Flash builder Mobile AS3 project: Screen DPI, Application DPI, image DPI, center image

It has something to do with DPI settings…….

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I want to center a DisplayObject to the center of the screen. This is an image dynamically created from a resource. I use the the following code to center the object after it is created:

public function showProgress(bValue : Boolean = true):void
{
  this.imgProgress.visible = bValue;
  if( bValue )
  {
    this.imgProgress.x = (this.stage.stageWidth - this.imgProgress.width) * 0.5;
  }
}

Looks quite simple to me but the object is still not in the center. For example:

this.stage.stageWidth == 500;
this.imgProgress.width == 480;
Result is: 10px; (this.imgProgress.x) /* 10px is correct */

I tried several things, also with localToGlobal and GlobalToLocal but getting unpredictable results, still not centered.

I think it has something to do with the screen dpi or something? But the Capabilities.screenDPI returns strange results. For example, running as iPhone 3GS it returns 163dpi.

How do i calculate the correct center position?

EDIT:
Some extra info:

public class Main extends Sprite
{
// setup stage
this.stage.color = 0;
this.stage.align = StageAlign.TOP_LEFT;
this.stage.scaleMode = StageScaleMode.NO_SCALE;

imgProgress is a child of this.stage

Answer 1

It has something to with the aspect ratio (when calculated you are able to center it correcly)

See also:
Set ApplicationDPI in AS3 Mobile application