Android Live wallpaper SGL, what is it?

This link, http://developer.android.com/resources/articles/live-wallpapers.html, talks about OpenG开发者_C百科L for 3D wallpapers and SGL for 2D wallpapers. Even though everyone is saying that you should still use OpenGl for 2D wallpapers, they make no mention of it on that website. My question is, is SGL just the good old drawing onto Canvas or is it something different?

Also, the screenshots of all four of those 2D wallpapers in the link are 2D wallpapers that don't make the phone run any slower. If SGL is just the canvas method of drawing, do all of these 2D wallpapers use OpenGL?

SGL should be fine, and probably easier to get running then trying to fuss with the OpenGL way. Both will work though, although 2d still looks good. Check out the Doom Wallpaper