Difference between SurfaceView and View?
Views are all drawn on the same GUI thread which is also used for all user interaction.
So if you need to update GUI rapidly or if the rendering takes too much time and affects user experience then use SurfaceView
.
A few things I've noted:
- SurfaceViews contain a nice rendering mechanism that allows threads to update the surface's content without using a handler (good for animation).
- Surfaceviews cannot be transparent, they can only appear behind other elements in the view hierarchy.
- I've found that they are much faster for animation than rendering onto a View.
For more information (and a great usage example) refer to the LunarLander project in the SDK 's examples section.
updated 05/09/2014
OK. We have official document now. It talked all I have mentioned, in a better way.
Read more detailed here.
Yes, the main difference is surfaceView can be updated on the background thread. However, 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 orview.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.
The main difference is that SurfaceView
can be drawn on by background theads but Views
can't.
SurfaceViews
use more resources though so you don't want to use them unless you have to.
A SurfaceView
is a custom view in Android that can be used to drawn inside it.
The main difference between a View
and a SurfaceView
is that a View is drawn in the
UI Thread
, which is used for all the user interaction.
If you want to update the UI rapidly enough and render a good amount of information in
it, a SurfaceView is a better choice.
But there are a few technical insides to the SurfaceView
:
1. They are not hardware accelerated.
2. Normal views are rendered when you call the methods invalidate
or postInvalidate()
, but this does not mean the view will be
immediately updated (A VSYNC
will be sent, and the OS decides when
it gets updated. The SurfaceView
can be immediately updated.
3. A SurfaceView has an allocated surface buffer
, so it is more costly