Why is eglCreateImageKHR returning EGL_NO_IMAGE_KHR (on android)?

Question

I need to create a texture in one thread and use it in another thread. I have tried using a shared context but the texture does not seem to be shared. I tried using eglCreateImageKHR using this sample (the code posted by Wiktor)

eglCreateImageKHR is returning EGL_NO_IMAGE_KHR.

Also while using the extensions I had to define #define EGL_EGLEXT_PROTOTYPES and #define GL_GLEXT_PROTOTYPES before including eglext.h and gl2ext.h to get the code to compile. Is this wrong? Should these be defined in some other header?

If it helps, here is my code for the thread that creates the texture. I think what I am doing wrong is passing the texture handle returned by OpenGL to eglCreateImageKHR and just casting it to EGLClientBuffer. (Also I do not know what reinterpret_cast does, have just copied it from the sample. But the sample is not very clear about this part.)

  GLuint framebuffer;
    GLuint depthRenderbuffer;
    GLuint texture;
    GLint texWidth = 256, texHeight = 256;



    const EGLint attribs[] = {
        EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
        EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
        EGL_RED_SIZE, 8,
        EGL_GREEN_SIZE, 8,
        EGL_BLUE_SIZE, 8,
        EGL_ALPHA_SIZE, 8,
        EGL_DEPTH_SIZE, 8,
        EGL_STENCIL_SIZE, 0,
        EGL_NONE
    };

    const EGLint pbuf_attribs[] = {
                    EGL_WIDTH, 512,
                    EGL_HEIGHT, 512,
                    EGL_NONE};

    EGLSurface psurface;
    EGLContext context;
    EGLConfig config;
    EGLint numConfigs;
    EGLDisplay display;
    const EGLint contextAttribs[] = {EGL_CONTEXT_CLIENT_VERSION,2, EGL_NONE };

    if ((display = eglGetDisplay(EGL_DEFAULT_DISPLAY)) == EGL_NO_DISPLAY) {
        LOG_ERROR("Tex eglGetDisplay() returned error %d", eglGetError());
        return false;
    }

    if (!eglChooseConfig(display, attribs, &config, 1, &numConfigs)) {
        LOG_ERROR("eglChooseConfig() returned error %d", eglGetError());
        destroy();
        return false;
    }

    if (!(context = eglCreateContext(display, config, 0, contextAttribs))) {
        LOG_ERROR("Tex eglCreateContext() returned error %d", eglGetError());
        destroy();
        return false;
    }

    if (!(psurface = eglCreatePbufferSurface(display, config, pbuf_attribs))) {
        LOG_ERROR("Tex eglCreatePbufferSurface() returned error %d", eglGetError());
        destroy();
        return false;
    }

    LOGI("About to make current. Display %p surface %p context %p",display, psurface, context);
    if (!eglMakeCurrent(display, psurface, psurface, context)) {
        LOG_ERROR("Tex eglMakeCurrent() returned error %d", eglGetError());
        destroy();
        return false;
    }
    checkGlError("make current");

    glGenFramebuffers(1, &framebuffer);
    glGenRenderbuffers(1, &depthRenderbuffer);
    glGenTextures(1, &texture);

    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texWidth, texHeight,
    0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, NULL);


    glBindTexture(GL_TEXTURE_2D, 0); //FIXME Should this be here?? Tried with and without
    EGLint imageAttributes[] = { EGL_GL_TEXTURE_LEVEL_KHR, 0,
            EGL_IMAGE_PRESERVED_KHR, EGL_FALSE, EGL_NONE };

    LOGI("Before CreateImage display %p context %p texture %d",display, context, texture);

    _eglImage = eglCreateImageKHR(display, context,
            EGL_GL_TEXTURE_2D_KHR, reinterpret_cast<EGLClientBuffer>(texture),
            0);

    if(_eglImage == EGL_NO_IMAGE_KHR){
        LOGE("eglCreateImageKHR failed");
    }