Set ApplicationDPI in AS3 Mobile application

Question

I developing an application in Flash Builder with AS3 only (no flex stuff). In flex it is possible to set the application's dpi by the following code:

<s:ViewNavigatorApplication xmlns:fx="http://ns.adobe.com/mxml/2009" 
   xmlns:s="library://ns.adobe.com/flex/spark" applicationDPI="320">

But I using only AS3. I have read that it is not possible to change the application's DPI in run-time (with AS3), but how can I set this in project settings, compiler settings or is there another way to do it?

Also, what is the default application's DPI setting?

Ask it here because can't find it on the net (only flex based solutions).

Answer 1

The DPI on mobile is set by the hardware, it is entirely dependent on the phone and screen. When you set the applicationDPI in a Flex mobile you're telling Flex to automatically scale your assets.

Automatic scaling. Developers can choose to specify a target DPI for their application by setting the applicationDPI property on the application. When this is explicitly set, developers should set up their skins and layout as if they were running on a device of the given DPI. At runtime, if the device has a different DPI from the specified target DPI, Flex will automatically scale the entire application to preserve the approximate physical size of the application and its controls. For example, if an application is targeted at 160 DPI, it will automatically scale by 1.5x on a 240 DPI device. If you choose not to use this feature, you'll need to make sure your custom skins and view layouts adapt properly to different pixel densities at runtime. Source

In an AS3 mobile project you're going to need to handle this yourself.

You can get the current DPI using Capabilities.screenDPI but I think what you may be after is a ratio to scale your assets by. One way to do this would be to start with the original game width.

 private static const WIDTH:Number = 1024;

You can then get a ratio using

 var ratio:Number = stage.fullScreenWidth / WIDTH;

And apply this to your assets

myBitmap.scaleX = myBitmap.scaleY = ratio;

Now this isn't going to take the rotation of the device into account, so fullScreenWidth/Height may be flipped. To check for that you're going to need to do something like this

if (stage.fullScreenWidth > stage.fullScreenHeight){
  //portrait 
} else {
  //landscape
}

Hopefully this helps