Segfault when connect cleanup OpenGL function to signal QOpenGLContext::aboutToBeDestroyed

dalishi

Hi I am using the QOpenGLWidget of Qt 5.9.2 on Ubuntu16.04. Using the following connect() to clean up OpenGL buffer objects but get segment fault when destroy buffer objects. So I ended up putting cleanup() in the destructor. I remembered this signal ::aboutToBeDestroyed is recommended to do cleanup to the destructor but why it does not work now.

Does not work:

connect(context(), &QOpenGLContext::aboutToBeDestroyed, this, &MainOpenGLWidget::cleanup);

void MainOpenGLWidget::cleanup()
{
    makeCurrent();

    if (m_program)
    {
        delete m_program;
        m_program = 0;
    }

    if (m_vboPos.isCreated())
        m_vboPos.destroy(); // Segfault here

    if (m_vboCol.isCreated())
        m_vboCol.destroy();

    if (m_vao.isCreated())
        m_vao.destroy();

    doneCurrent();
}

This works:

MainOpenGLWidget::~MainOpenGLWidget()
{
    cleanup();
}