/* GDK - The GIMP Drawing Kit
 *
 * gdkglcontext-x11.c: X11 specific OpenGL wrappers
 *
 * Copyright © 2014  Emmanuele Bassi
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include "gdkglcontext-x11.h"
#include "gdkdisplay-x11.h"
#include "gdkprivate-x11.h"
#include "gdkscreen-x11.h"

#include "gdkx11display.h"
#include "gdkx11glcontext.h"
#include "gdkx11screen.h"
#include "gdkx11surface.h"
#include "gdkx11property.h"
#include <X11/Xatom.h>

#include "gdkinternals.h"

#include "gdkintl.h"

#include <cairo-xlib.h>

#include <epoxy/glx.h>

G_DEFINE_ABSTRACT_TYPE (GdkX11GLContext, gdk_x11_gl_context, GDK_TYPE_GL_CONTEXT)

static void
gdk_x11_gl_context_class_init (GdkX11GLContextClass *klass)
{
}

static void
gdk_x11_gl_context_init (GdkX11GLContext *self)
{
}

gboolean
gdk_x11_display_init_gl_backend (GdkX11Display  *self,
                                 Visual        **out_visual,
                                 int            *out_depth,
                                 GError        **error)
{
  GdkDisplay *display G_GNUC_UNUSED = GDK_DISPLAY (self);

  if (GDK_DISPLAY_DEBUG_CHECK (display, GL_DISABLE))
    {
      g_set_error_literal (error, GDK_GL_ERROR,
                           GDK_GL_ERROR_NOT_AVAILABLE,
                           _("GL support disabled via GDK_DEBUG=gl-disable"));
      return FALSE;
    }

  if (GDK_DISPLAY_DEBUG_CHECK (display, GL_EGL))
    return gdk_x11_display_init_egl (self, TRUE, out_visual, out_depth, error);
  if (GDK_DISPLAY_DEBUG_CHECK (display, GL_GLX))
    return gdk_x11_display_init_glx (self, out_visual, out_depth, error);

  /* No env vars set, do the regular GL initialization.
   * 
   * We try EGL first, but are very picky about what we accept.
   * If that fails, we try to go with GLX instead.
   * And if that also fails, we try EGL again, but this time accept anything.
   *
   * The idea here is that EGL is the preferred method going forward, but GLX is
   * the tried and tested method that we know works. So if we detect issues with
   * EGL, we want to avoid using it in favor of GLX.
   */

  if (gdk_x11_display_init_egl (self, FALSE, out_visual, out_depth, error))
    return TRUE;
  g_clear_error (error);

  if (gdk_x11_display_init_glx (self, out_visual, out_depth, error))
    return TRUE;
  g_clear_error (error);

  return gdk_x11_display_init_egl (self, TRUE, out_visual, out_depth, error);
}