Air - How to choose the right hardware acceleration mode?

Question

I'm building an Android note taking app with Adobe Air 3.6 that is only vector based. Which hardware acceleration mode is recommended for such an app? There are three modes to choose from:

1. None 
2. Direct 
3. GPU

Answer 1

For purely vector based (display list) app, Direct mode won't be of help, because it is intended for use with Direct3D. GPU mode will enable some graphics offloading to the GPU (mainly blitting and compositing, I believe), which could be beneficial, especially if you use cacheAsBitmap and cacheAsBitmapMatrix where appropriate.

In any case, you should do some testing before you settle on a solution. Potential benefits greatly depend on what the app is actually displaying.

Answer 2

Adobe recommends using the Direct render mode for mobile devices (see http://help.adobe.com/en_US/as3/mobile/WS5d37564e2b3bb78e5247b9e212ea639b4d7-8000.html). However, historically I've had issues rendering vector graphics using Direct mode. Additionally the documentation makes reference to using Stage3D, which I believe does not support vector graphics.

With that in mind, the best way to determine which rendering mode to use is to benchmark your application. Adobe Scout can be used to determine how fast your app is rendering, so you could create a build of your app using each of the different render modes and see which one performs the best. Additionally you may find that content that renders under None will not render properly under Direct or GPU.