How to realize the Floating snow effect in a page of app?

view story

http://stackoverflow.com – How to add the Floating snow effect in an activity which has done? I use Canvas and 2D to make the Floating snow effect. But I use main.xml in my home page. I use http://ask.csdn.net/questions/1246 But I check online the code is PetalView pv = new PetalView(this); setContentView(pv); How to mix the two views together? How to make the effect on the top and do not affect the operation of this activity page? (HowTos)