Run long task on glThread without blocking UI thread on Android

Question

I have to run through a lot of initialisation before I can render anything in my GLSurfaceView

Theses must be done on the OpenGL thread.

However this hangs my main thread for the duration of the initialisation.

Here is my code:

@Override
protected void onStart() {
    super.onStart();
    FrameLayout renderingLayout = (FrameLayout) findViewById(R.id.movie_rendering_layout);
    if (renderingLayout != null && mGLView == null) {
        mGLView = new MyGLSurfaceView(getApplicationContext());
        /** [..] **/
        renderingLayout.addView(mGLView, params);
    }
}

/*--------------- OPENGL RELATED ---------------*/

protected class MyGLSurfaceView  extends GLSurfaceView {

    private final MyGLRenderer mRenderer;

    public MyGLSurfaceView(Context context) {
        super(context);
        // Create an OpenGL ES 1.0 context
        setEGLContextClientVersion(1);
        mRenderer = new MyGLRenderer();
        // Set the Renderer for drawing on the GLSurfaceView
        setRenderer(mRenderer);
    }
}


protected class MyGLRenderer implements GLSurfaceView.Renderer {
    private int mWidth, mHeight = 0;
    private boolean isFinished = false;


    public void onSurfaceCreated(GL10 unused, EGLConfig config) {
        // Set the background frame color
       GLES10.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
        init(mMovieIndex, AssetsUtils.getBinPath(getApplicationContext())); // <----- THIS takes long time

    }

    public void onDrawFrame(GL10 pGL10) {

        GLES10.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
        GLES10.glClear(GLES10.GL_COLOR_BUFFER_BIT);
        /* [...] */
    }

Answer 1

I found a solution:

The issue is that you must not block in onDrawFrame or onSurfaceCreated, since they are called synchronously by the main thread.

To disable the calls, I used in my surface constructor:

setRenderMode(RENDERMODE_WHEN_DIRTY);

This way, the calls to onDrawFrame will stop once the view is settled.

I performed the initialisation from

public void onWindowFocusChanged(boolean hasFocus) 

Be careful it can be called twice. If anyone has a better suggestion I'd gladly listen to it (taken from How to make a callback after the view is completely rendered?)

I also overrided

@Override
public boolean isDirty()
   return false;
}

And don't forget to use queueEvent to run code on the GLThread