When is it necessary, or better to use a SurfaceView instead of a View?

Views are all drawn on the same GUI thread which is also used for all user interaction. The main difference is that SurfaceView can be drawn on by background theads but Views can’t. SurfaceViews contain a nice rendering mechanism that allows threads to update the surface’s content without using a handler (good for animation).

There are more you might care.

• surfaceView has dedicate surface buffer while all the view shares one surface buffer that is allocated by ViewRoot. In another word, surfaceView cost more resources.
• surfaceView cannot be hardware accelerated (as of JB4.2) while 95% operations on normal View are HW accelerated using openGL ES.
• More work should be done to create your customized surfaceView. You need to listener to the surfaceCreated/Destroy Event, create an render thread, more importantly, synchronized the render thread and main thread. However, to customize the View, all you need to do is override onDraw method.
• The timing to update is different. Normal view update mechanism is constraint or controlled by the framework:You call view.invalidate in the UI thread or view.postInvalid in other thread to indicate to the framework that the view should be updated. However, the view won’t be updated immediately but wait until next VSYNC event arrived. The easy approach to understand VSYNC is to consider it is as a timer that fire up every 16ms for a 60fps screen. In Android, all the normal view update (and display actually but I won’t talk it today), is synchronized with VSYNC to achieve better smoothness. Now,back to the surfaceView, you can render it anytime as you wish. However, I can hardly tell if it is an advantage, since the display is also synchronized with VSYNC, as stated previously.