Preview.SurfaceProvider

See also:

• Preview.setSurfaceProvider(Executor, SurfaceProvider)

onSurfaceRequested

public abstract void onSurfaceRequested (SurfaceRequest request)

Called when a new Surface has been requested by the camera.

This is called every time a new surface is required to keep the preview running. The camera may repeatedly request surfaces throughout usage of a Preview use case, but only a single request will be active at a time.

A request is considered active until it is fulfilled, SurfaceRequest.willNotProvideSurface() marked as 'will not complete'}, or cancelled by the camera. After one of these conditions occurs, a request is considered completed.

Once a request is successfully completed, it is guaranteed that if a new request is made, the Surface used to fulfill the previous request will be detached from the camera and SurfaceRequest.provideSurface(Surface, Executor, Consumer) will be invoked with a SurfaceRequest.Result containing SurfaceRequest.Result.RESULT_SURFACE_USED_SUCCESSFULLY. Example:

 class MyGlSurfaceProvider implements Preview.SurfaceProvider {
     // This executor must have also been used with Preview.setSurfaceProvider() to
     // ensure onSurfaceRequested() is called on our GL thread.
     Executor mGlExecutor;

     @Override
     public void onSurfaceRequested(@NonNull SurfaceRequest request) {
         // If our GL thread/context is shutting down. Signal we will not fulfill
         // the request.
         if (isShuttingDown()) {
             request.willNotProvideSurface();
             return;
         }

         // Create the surface and attempt to provide it to the camera.
         Surface surface = resetGlInputSurface(request.getResolution());

         // Provide the surface and wait for the result to clean up the surface.
         request.provideSurface(surface, mGlExecutor, (result) -> {
             // In all cases (even errors), we can clean up the state. As an
             // optimization, we could also optionally check for REQUEST_CANCELLED
             // since we may be able to reuse the surface on subsequent surface requests.
             closeGlInputSurface(surface);
         });
     }
 }