基于RomainGuy的博客文章AndroidPerformanceCaseStudy在谈到overdraw时，他是这样说的:Removingthewindowbackground:thebackgrounddefinedinyourthemeisusedbythesystemtocreatepreviewwindowswhenlaunchingyourapplication.Neversetittonullunlessyourapplicationistransparent.Instead,setittothecolor/imageyouwantorgetridoffromonCre