static gboolean
gst_gl_context_wgl_create_context (GstGLContext * context,
    GstGLAPI gl_api, GstGLContext * other_context, GError ** error)
{
  GstGLWindow *window;
  GstGLContextWGL *context_wgl;
  HGLRC external_gl_context = NULL;
  HGLRC trampoline;
  HDC device;

  context_wgl = GST_GL_CONTEXT_WGL (context);
  window = gst_gl_context_get_window (context);
  device = (HDC) gst_gl_window_get_display (window);

  if (other_context) {
    if (gst_gl_context_get_gl_platform (other_context) != GST_GL_PLATFORM_WGL) {
      g_set_error (error, GST_GL_CONTEXT_ERROR,
          GST_GL_CONTEXT_ERROR_WRONG_CONFIG,
          "Cannot share context with a non-WGL context");
      goto failure;
    }
    external_gl_context = (HGLRC) gst_gl_context_get_gl_context (other_context);
  }

  trampoline = wglCreateContext (device);
  if (trampoline)
    GST_DEBUG ("gl context created: %" G_GUINTPTR_FORMAT,
        (guintptr) trampoline);
  else {
    g_set_error (error, GST_GL_CONTEXT_ERROR,
        GST_GL_CONTEXT_ERROR_CREATE_CONTEXT, "failed to create glcontext:0x%x",
        (unsigned int) GetLastError ());
    goto failure;
  }
  g_assert (trampoline);

  /* get extension functions */
  wglMakeCurrent (device, trampoline);

  context_wgl->priv->wglCreateContextAttribsARB =
      (PFNWGLCREATECONTEXTATTRIBSARBPROC)
      wglGetProcAddress ("wglCreateContextAttribsARB");

  wglMakeCurrent (device, 0);
  wglDeleteContext (trampoline);
  trampoline = NULL;

  if (context_wgl->priv->wglCreateContextAttribsARB != NULL
      && gl_api & GST_GL_API_OPENGL3) {
    gint i;

    for (i = 0; i < G_N_ELEMENTS (opengl_versions); i++) {
      gint profileMask = 0;
      gint contextFlags = 0;

      if ((opengl_versions[i].major > 3
              || (opengl_versions[i].major == 3
                  && opengl_versions[i].minor >= 2))) {
        profileMask |= WGL_CONTEXT_CORE_PROFILE_BIT_ARB;
        contextFlags |= WGL_CONTEXT_DEBUG_BIT_ARB;
      } else {
        break;
      }

      GST_DEBUG_OBJECT (context, "trying to create a GL %d.%d context",
          opengl_versions[i].major, opengl_versions[i].minor);

      context_wgl->wgl_context = _create_context_with_flags (context_wgl,
          device, external_gl_context, opengl_versions[i].major,
          opengl_versions[i].minor, contextFlags, profileMask);

      if (context_wgl->wgl_context) {
        context_wgl->priv->context_api = GST_GL_API_OPENGL3;
        break;
      }
    }
  }

  if (!context_wgl->wgl_context) {

    if (context_wgl->priv->wglCreateContextAttribsARB && external_gl_context) {
      context_wgl->wgl_context =
          context_wgl->priv->wglCreateContextAttribsARB (device,
          external_gl_context, 0);
    }


    if (!context_wgl->wgl_context) {

      context_wgl->wgl_context = wglCreateContext (device);

      if (!context_wgl->wgl_context) {
        g_set_error (error, GST_GL_CONTEXT_ERROR,
            GST_GL_CONTEXT_ERROR_CREATE_CONTEXT,
            "Failed to create WGL context 0x%x",
            (unsigned int) GetLastError ());
        goto failure;
      }

      if (external_gl_context) {
        if (!wglShareLists (external_gl_context, context_wgl->wgl_context)) {
          g_set_error (error, GST_GL_CONTEXT_ERROR,
              GST_GL_CONTEXT_ERROR_CREATE_CONTEXT,
              "failed to share contexts through wglShareLists 0x%x",
              (unsigned int) GetLastError ());
          goto failure;
        }
      }
    }

    context_wgl->priv->context_api = GST_GL_API_OPENGL;
  }

  GST_LOG ("gl context id: %" G_GUINTPTR_FORMAT,
      (guintptr) context_wgl->wgl_context);

  gst_object_unref (window);

  return TRUE;

failure:
  gst_object_unref (window);

  return FALSE;
}
static gboolean
gst_gl_context_egl_create_context (GstGLContext * context,
    GstGLAPI gl_api, GstGLContext * other_context, GError ** error)
{
  GstGLContextEGL *egl;
  GstGLWindow *window = NULL;
  EGLNativeWindowType window_handle = (EGLNativeWindowType) 0;
  EGLint egl_major;
  EGLint egl_minor;
  gboolean need_surface = TRUE;
  guintptr external_gl_context = 0;
  guintptr egl_display;

  egl = GST_GL_CONTEXT_EGL (context);
  window = gst_gl_context_get_window (context);

  GST_DEBUG_OBJECT (context, "Creating EGL context");

  if (other_context) {
    if (gst_gl_context_get_gl_platform (other_context) != GST_GL_PLATFORM_EGL) {
      g_set_error (error, GST_GL_CONTEXT_ERROR,
          GST_GL_CONTEXT_ERROR_WRONG_CONFIG,
          "Cannot share context with non-EGL context");
      goto failure;
    }
    external_gl_context = gst_gl_context_get_gl_context (other_context);
  }

  if ((gl_api & (GST_GL_API_OPENGL | GST_GL_API_OPENGL3 | GST_GL_API_GLES2)) ==
      GST_GL_API_NONE) {
    g_set_error (error, GST_GL_CONTEXT_ERROR, GST_GL_CONTEXT_ERROR_WRONG_API,
        "EGL supports opengl or gles2");
    goto failure;
  }

  if (!egl->display_egl) {
    GstGLDisplay *display = gst_gl_context_get_display (context);

    egl->display_egl = gst_gl_display_egl_from_gl_display (display);
    if (!egl->display_egl) {
      g_set_error (error, GST_GL_CONTEXT_ERROR,
          GST_GL_CONTEXT_ERROR_RESOURCE_UNAVAILABLE,
          "Failed to create EGLDisplay from native display");
      goto failure;
    }

    gst_object_unref (display);
  }

  egl_display = gst_gl_display_get_handle (GST_GL_DISPLAY (egl->display_egl));
  egl->egl_display = (EGLDisplay) egl_display;

  if (eglInitialize (egl->egl_display, &egl_major, &egl_minor)) {
    GST_INFO ("egl initialized, version: %d.%d", egl_major, egl_minor);
  } else {
    g_set_error (error, GST_GL_CONTEXT_ERROR,
        GST_GL_CONTEXT_ERROR_RESOURCE_UNAVAILABLE,
        "Failed to initialize egl: %s",
        gst_egl_get_error_string (eglGetError ()));
    goto failure;
  }

  egl->egl_exts = eglQueryString (egl->egl_display, EGL_EXTENSIONS);

  if (gl_api & (GST_GL_API_OPENGL | GST_GL_API_OPENGL3)) {
    GstGLAPI chosen_gl_api = 0;
    gint i;

    /* egl + opengl only available with EGL 1.4+ */
    if (egl_major == 1 && egl_minor <= 3) {
      if ((gl_api & ~GST_GL_API_OPENGL) == GST_GL_API_NONE) {
        g_set_error (error, GST_GL_CONTEXT_ERROR, GST_GL_CONTEXT_ERROR_OLD_LIBS,
            "EGL version (%i.%i) too old for OpenGL support, (needed at least 1.4)",
            egl_major, egl_minor);
        goto failure;
      } else {
        GST_WARNING
            ("EGL version (%i.%i) too old for OpenGL support, (needed at least 1.4)",
            egl_major, egl_minor);
        if (gl_api & GST_GL_API_GLES2) {
          goto try_gles2;
        } else {
          g_set_error (error, GST_GL_CONTEXT_ERROR,
              GST_GL_CONTEXT_ERROR_WRONG_CONFIG,
              "Failed to choose a suitable OpenGL API");
          goto failure;
        }
      }
    }

    if (!eglBindAPI (EGL_OPENGL_API)) {
      g_set_error (error, GST_GL_CONTEXT_ERROR, GST_GL_CONTEXT_ERROR_FAILED,
          "Failed to bind OpenGL API: %s",
          gst_egl_get_error_string (eglGetError ()));
      goto failure;
    }

    GST_INFO ("Bound OpenGL");

    /* api, version only matters for gles */
    if (!gst_gl_context_egl_choose_config (egl, GST_GL_API_OPENGL, 0, error)) {
      g_assert (error == NULL || *error != NULL);
      goto failure;
    }

    for (i = 0; i < G_N_ELEMENTS (opengl_versions); i++) {
      gint profileMask = 0;
      gint contextFlags = 0;

      if (GST_GL_CHECK_GL_VERSION (opengl_versions[i].major,
              opengl_versions[i].minor, 3, 2)) {
        /* skip gl3 contexts if requested */
        if ((gl_api & GST_GL_API_OPENGL3) == 0)
          continue;

        chosen_gl_api = GST_GL_API_OPENGL3;
#if defined(EGL_KHR_create_context)
        profileMask |= EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR;
        contextFlags |= EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR;
#endif
      } else if (opengl_versions[i].major == 3 && opengl_versions[i].minor == 1) {
        /* skip 3.1, the implementation is free to give us either a core or a
         * compatibility context (we have no say) */
        continue;
      } else {
        /* skip legacy contexts if requested */
        if ((gl_api & GST_GL_API_OPENGL) == 0)
          continue;

        chosen_gl_api = GST_GL_API_OPENGL;
      }

      egl->egl_context =
          _create_context_with_flags (egl, (EGLContext) external_gl_context,
          chosen_gl_api, opengl_versions[i].major,
          opengl_versions[i].minor, contextFlags, profileMask);

      if (egl->egl_context)
        break;

#if defined(EGL_KHR_create_context)
      profileMask &= ~EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR;

      egl->egl_context =
          _create_context_with_flags (egl, (EGLContext) external_gl_context,
          chosen_gl_api, opengl_versions[i].major,
          opengl_versions[i].minor, contextFlags, profileMask);

      if (egl->egl_context)
        break;
#endif
    }

    egl->gl_api = chosen_gl_api;
  } else if (gl_api & GST_GL_API_GLES2) {
    gint i;

  try_gles2:
    if (!eglBindAPI (EGL_OPENGL_ES_API)) {
      g_set_error (error, GST_GL_CONTEXT_ERROR, GST_GL_CONTEXT_ERROR_FAILED,
          "Failed to bind OpenGL|ES API: %s",
          gst_egl_get_error_string (eglGetError ()));
      goto failure;
    }

    GST_INFO ("Bound OpenGL|ES");

    for (i = 0; i < G_N_ELEMENTS (gles2_versions); i++) {
      gint profileMask = 0;
      gint contextFlags = 0;

      if (!gst_gl_context_egl_choose_config (egl, GST_GL_API_GLES2,
              gles2_versions[i].major, error)) {
        continue;
      }
#if defined(EGL_KHR_create_context)
      /* try a debug context */
      contextFlags |= EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR;

      egl->egl_context =
          _create_context_with_flags (egl, (EGLContext) external_gl_context,
          GST_GL_API_GLES2, gles2_versions[i].major,
          gles2_versions[i].minor, contextFlags, profileMask);

      if (egl->egl_context)
        break;

      /* try without a debug context */
      contextFlags &= ~EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR;
#endif

      egl->egl_context =
          _create_context_with_flags (egl, (EGLContext) external_gl_context,
          GST_GL_API_GLES2, gles2_versions[i].major,
          gles2_versions[i].minor, contextFlags, profileMask);

      if (egl->egl_context)
        break;
    }
    egl->gl_api = GST_GL_API_GLES2;
  }

  if (egl->egl_context != EGL_NO_CONTEXT) {
    GST_INFO ("gl context created: %" G_GUINTPTR_FORMAT,
        (guintptr) egl->egl_context);
  } else {
    g_set_error (error, GST_GL_CONTEXT_ERROR,
        GST_GL_CONTEXT_ERROR_CREATE_CONTEXT,
        "Failed to create a OpenGL context: %s",
        gst_egl_get_error_string (eglGetError ()));
    goto failure;
  }
  /* FIXME do we want a window vfunc ? */
#if GST_GL_HAVE_WINDOW_X11
  if (GST_IS_GL_WINDOW_X11 (context->window)) {
    gst_gl_window_x11_create_window ((GstGLWindowX11 *) context->window);
  }
#endif

  if (other_context == NULL) {
    /* FIXME: fails to show two outputs at all.  We need a property/option for
     * glimagesink to say its a visible context */
#if GST_GL_HAVE_WINDOW_WAYLAND
    if (GST_IS_GL_WINDOW_WAYLAND_EGL (context->window)) {
      gst_gl_window_wayland_egl_create_window ((GstGLWindowWaylandEGL *)
          context->window);
    }
#endif
#if GST_GL_HAVE_WINDOW_WIN32
    if (GST_IS_GL_WINDOW_WIN32 (context->window)) {
      gst_gl_window_win32_create_window ((GstGLWindowWin32 *) context->window);
    }
#endif
#if GST_GL_HAVE_WINDOW_DISPMANX
    if (GST_IS_GL_WINDOW_DISPMANX_EGL (context->window)) {
      gst_gl_window_dispmanx_egl_create_window ((GstGLWindowDispmanxEGL *)
          context->window);
    }
#endif
  }

  if (window)
    window_handle =
        (EGLNativeWindowType) gst_gl_window_get_window_handle (window);

  if (window_handle) {
    GST_DEBUG ("Creating EGLSurface from window_handle %p",
        (void *) window_handle);
    egl->egl_surface =
        eglCreateWindowSurface (egl->egl_display, egl->egl_config,
        window_handle, NULL);
    /* Store window handle for later comparision */
    egl->window_handle = window_handle;
  } else if (!gst_gl_check_extension ("EGL_KHR_surfaceless_context",
          egl->egl_exts)) {
    EGLint surface_attrib[7];
    gint j = 0;

    GST_DEBUG ("Surfaceless context, creating PBufferSurface");
    /* FIXME: Width/height doesn't seem to matter but we can't leave them
     * at 0, otherwise X11 complains about BadValue */
    surface_attrib[j++] = EGL_WIDTH;
    surface_attrib[j++] = 1;
    surface_attrib[j++] = EGL_HEIGHT;
    surface_attrib[j++] = 1;
    surface_attrib[j++] = EGL_LARGEST_PBUFFER;
    surface_attrib[j++] = EGL_TRUE;
    surface_attrib[j++] = EGL_NONE;

    egl->egl_surface =
        eglCreatePbufferSurface (egl->egl_display, egl->egl_config,
        surface_attrib);
  } else {
    GST_DEBUG ("No surface/handle !");
    egl->egl_surface = EGL_NO_SURFACE;
    need_surface = FALSE;
  }

  if (need_surface) {
    if (egl->egl_surface != EGL_NO_SURFACE) {
      GST_INFO ("surface created");
    } else {
      g_set_error (error, GST_GL_CONTEXT_ERROR, GST_GL_CONTEXT_ERROR_FAILED,
          "Failed to create window surface: %s",
          gst_egl_get_error_string (eglGetError ()));
      goto failure;
    }
  }
  egl->egl_major = egl_major;
  egl->egl_minor = egl_minor;

  if (window)
    gst_object_unref (window);

  return TRUE;

failure:
  if (window)
    gst_object_unref (window);

  return FALSE;
}
static gboolean
gst_gl_context_glx_create_context (GstGLContext * context,
    GstGLAPI gl_api, GstGLContext * other_context, GError ** error)
{
  GstGLContextGLX *context_glx;
  GstGLWindow *window;
  GstGLWindowX11 *window_x11;
  GstGLDisplay *display = NULL;
  gboolean create_context;
  const char *glx_exts;
  Display *device;
  guintptr external_gl_context = 0;

  context_glx = GST_GL_CONTEXT_GLX (context);
  window = gst_gl_context_get_window (context);

  if (!GST_IS_GL_WINDOW_X11 (window)) {
    g_set_error (error, GST_GL_CONTEXT_ERROR,
        GST_GL_CONTEXT_ERROR_WRONG_CONFIG,
        "Cannot create an GLX context from a non-X11 window");
    goto failure;
  }

  window_x11 = GST_GL_WINDOW_X11 (window);
  display = gst_gl_context_get_display (context);

  if (other_context) {
    if (gst_gl_context_get_gl_platform (other_context) != GST_GL_PLATFORM_GLX) {
      g_set_error (error, GST_GL_CONTEXT_ERROR,
          GST_GL_CONTEXT_ERROR_WRONG_CONFIG,
          "Cannot share context with non-GLX context");
      goto failure;
    }

    external_gl_context = gst_gl_context_get_gl_context (other_context);
  }

  device = (Display *) gst_gl_display_get_handle (display);
  if (!device) {
    g_set_error (error, GST_GL_CONTEXT_ERROR,
        GST_GL_CONTEXT_ERROR_RESOURCE_UNAVAILABLE, "Invalid Display handle");
    goto failure;
  }

  glx_exts = glXQueryExtensionsString (device, DefaultScreen (device));

  create_context = gst_gl_check_extension ("GLX_ARB_create_context", glx_exts);
  context_glx->priv->glXCreateContextAttribsARB =
      (gpointer) glXGetProcAddressARB ((const GLubyte *)
      "glXCreateContextAttribsARB");

  if (!context_glx->glx_context && gl_api & GST_GL_API_OPENGL3 && create_context
      && context_glx->priv->glXCreateContextAttribsARB) {
    gint i;

    for (i = 0; i < G_N_ELEMENTS (opengl_versions); i++) {
      gint profileMask = 0;
      gint contextFlags = 0;

      if ((opengl_versions[i].major > 3
              || (opengl_versions[i].major == 3
                  && opengl_versions[i].minor >= 2))) {
        profileMask |= GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
        contextFlags |= GLX_CONTEXT_DEBUG_BIT_ARB;
      } else {
        break;
      }

      GST_DEBUG_OBJECT (context, "trying to create a GL %d.%d context",
          opengl_versions[i].major, opengl_versions[i].minor);

      context_glx->glx_context = _create_context_with_flags (context_glx,
          device, context_glx->priv->fbconfigs[0],
          (GLXContext) external_gl_context, opengl_versions[i].major,
          opengl_versions[i].minor, contextFlags, profileMask);

      if (context_glx->glx_context) {
        context_glx->priv->context_api = GST_GL_API_OPENGL3;
        break;
      }
    }
  }
  if (!context_glx->glx_context && gl_api & GST_GL_API_OPENGL) {
    context_glx->glx_context =
        glXCreateContext (device, window_x11->visual_info,
        (GLXContext) external_gl_context, TRUE);
    context_glx->priv->context_api = GST_GL_API_OPENGL;
  }

  if (context_glx->priv->fbconfigs)
    XFree (context_glx->priv->fbconfigs);

  if (!context_glx->glx_context) {
    g_set_error (error, GST_GL_CONTEXT_ERROR,
        GST_GL_CONTEXT_ERROR_CREATE_CONTEXT, "Failed to create opengl context");
    goto failure;
  }

  GST_LOG ("gl context id: %ld", (gulong) context_glx->glx_context);

  gst_object_unref (window);
  gst_object_unref (display);

  return TRUE;

failure:
  if (window)
    gst_object_unref (window);
  if (display)
    gst_object_unref (display);

  return FALSE;
}