Android Surfacing example

This example shows how to initialize CPU rendering (ANativeWindow_lock) or OpenGL (eglCreateWindowSurface) with SurfaceTexture from TextureView and how to properly deinitialize it so that you can switch from OpenGL to CPU rendering and vice versa on the same SurfaceTexture and in the same TextureView.

Rationale

If deinitialization is not properly done, you can spend several days or even weeks debugging cryptic errors in Logcat, such as:

connect: already connected (cur=2, req=1)

Unfortunately, there is very little documentation, no examples and you may get the impression that switching from CPU rendering to OpenGL is for some reason not supported (eventhough it is). To spare you from the headache of going through Buffer Queue sources, I prepared this simple and easy-to-follow example of how to do it properly on any Android that supports TextureView and OpenGL ES2.

Threading

In the example here, all drawing is done on the main (UI) thread. This is fine for the simple one-color drawing we do here but you may want to move the drawing to another thread. Synchronization on surface events (onSurface…) will than be necessary. Generally, you don't need to create OpenGL context on the same thread that will use it but I strongly recommend keeping one context on the same thread. But if you have multiple TextureViews, feel free to use one thread for each.