Question

I’m trying to write a QScreen driver for Qt for Embedded Linux to be able to integrate OpenGL capabilities over the framebuffer. I have both QWS windows together with EGL surfaces on the screen with my driver for the moment. I use the default implementations of the methods exposeRegion, blit and solidFill. Unfortunately, I noticed that if I try to place a QWS window over a EGL surface, I get that the EGL surface is always over the QWS window.

Is it possible to somehow allow QWS windows to go over the EGL surface when the EGL surface is not the top level window? How can I do this?

I know that OpenGL draws directly to the screen, but I supposed that interrupting the refresh procedure should have allowed the QScreen driver to draw the window over it, but this is not happening it seems.

Thanks!

Answer 1

Just in case anyone else is interested, it is possible to do this. I couldn’t just because some other functions needed to be overridden. In my case this was missing:

bool CompositeGLScreen::chooseContext(QGLContext *context, const QGLContext *shareContext)
{
    Q_UNUSED(context);
    Q_UNUSED(shareContext);
    return false;
}

The reference implementation by Qt for the PowerVR does it this way.