mutter/clutter/clutter-main.c

/*
 * Clutter.
 *
 * An OpenGL based 'interactive canvas' library.
 *
 * Authored By Matthew Allum  <mallum@openedhand.com>
 *
 * Copyright (C) 2006 OpenedHand
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 *
 *
 */
/**
 * SECTION:clutter-main
 * @short_description: Various 'global' clutter functions.
 *
 * Functions to retrieve various global Clutter resources and other utility
 * functions for mainloops, events and threads
 *
 * <refsect2 id="clutter-Threading-Model">
 *   <title>Threading Model</title>
 *   <para>Clutter is <emphasis>thread-aware</emphasis>: all operations
 *   performed by Clutter are assumed to be under the big Clutter lock,
 *   which is created when the threading is initialized through
 *   clutter_threads_init().</para>
 *   <example id="example-Thread-Init">
 *     <title>Thread Initialization</title>
 *     <para>The code below shows how to correctly initialize Clutter
 *     in a multi-threaded environment. These operations are mandatory for
 *     applications that wish to use threads with Clutter.</para>
 *     <programlisting>
 * int
 * main (int argc, char *argv[])
 * {
 *   /&ast; initialize GLib's threading support &ast;/
 *   g_thread_init (NULL);
 *
 *   /&ast; initialize Clutter's threading support &ast;/
 *   clutter_threads_init ();
 *
 *   /&ast; initialize Clutter &ast;/
 *   clutter_init (&amp;argc, &amp;argv);
 *
 *   /&ast; program code &ast;/
 *
 *   /&ast; acquire the main lock &ast;/
 *   clutter_threads_enter ();
 *
 *   /&ast; start the main loop &ast;/
 *   clutter_main ();
 *
 *   /&ast; release the main lock &ast;/
 *   clutter_threads_leave ();
 *
 *   /&ast; clean up &ast;/
 *   return 0;
 * }
 *     </programlisting>
 *   </example>
 *   <para>This threading model has the caveat that it is only safe to call
 *   Clutter's API when the lock has been acquired &mdash; which happens
 *   between pairs of clutter_threads_enter() and clutter_threads_leave()
 *   calls.</para>
 *   <para>The only safe and portable way to use the Clutter API in a
 *   multi-threaded environment is to never access the API from a thread that
 *   did not call clutter_init() and clutter_main().</para>
 *   <para>The common pattern for using threads with Clutter is to use worker
 *   threads to perform blocking operations and then install idle or timeour
 *   sources with the result when the thread finished.</para>
 *   <para>Clutter provides thread-aware variants of g_idle_add() and
 *   g_timeout_add() that acquire the Clutter lock before invoking the provided
 *   callback: clutter_threads_add_idle() and
 *   clutter_threads_add_timeout().</para>
 * </refsect2>
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdlib.h>
#include <glib/gi18n-lib.h>
#include <locale.h>

#include "clutter-actor.h"
#include "clutter-backend-private.h"
#include "clutter-debug.h"
#include "clutter-device-manager-private.h"
#include "clutter-event.h"
#include "clutter-feature.h"
#include "clutter-frame-source.h"
#include "clutter-main.h"
#include "clutter-master-clock.h"
#include "clutter-private.h"
#include "clutter-profile.h"
#include "clutter-stage-manager.h"
#include "clutter-stage-private.h"
#include "clutter-version.h" 	/* For flavour define */

#include <cogl/cogl.h>
#include <cogl-pango/cogl-pango.h>

#include "cally.h" /* For accessibility support */

/* main context */
static ClutterMainContext *ClutterCntx       = NULL;

/* main lock and locking/unlocking functions */
static GMutex *clutter_threads_mutex         = NULL;
static GCallback clutter_threads_lock        = NULL;
static GCallback clutter_threads_unlock      = NULL;

/* command line options */
static gboolean clutter_is_initialized       = FALSE;
static gboolean clutter_show_fps             = FALSE;
static gboolean clutter_fatal_warnings       = FALSE;
static gboolean clutter_disable_mipmap_text  = FALSE;
static gboolean clutter_use_fuzzy_picking    = FALSE;
static gboolean clutter_enable_accessibility = TRUE;

static guint clutter_default_fps             = 60;

static ClutterTextDirection clutter_text_direction = CLUTTER_TEXT_DIRECTION_LTR;

static guint clutter_main_loop_level         = 0;
static GSList *main_loops                    = NULL;

guint clutter_debug_flags = 0;  /* global clutter debug flag */
guint clutter_paint_debug_flags = 0;
guint clutter_pick_debug_flags = 0;

guint clutter_profile_flags = 0;  /* global clutter profile flag */

const guint clutter_major_version = CLUTTER_MAJOR_VERSION;
const guint clutter_minor_version = CLUTTER_MINOR_VERSION;
const guint clutter_micro_version = CLUTTER_MICRO_VERSION;

#ifdef CLUTTER_ENABLE_DEBUG
static const GDebugKey clutter_debug_keys[] = {
  { "misc", CLUTTER_DEBUG_MISC },
  { "actor", CLUTTER_DEBUG_ACTOR },
  { "texture", CLUTTER_DEBUG_TEXTURE },
  { "event", CLUTTER_DEBUG_EVENT },
  { "paint", CLUTTER_DEBUG_PAINT },
  { "pick", CLUTTER_DEBUG_PICK },
  { "gl", CLUTTER_DEBUG_GL },
  { "alpha", CLUTTER_DEBUG_ALPHA },
  { "behaviour", CLUTTER_DEBUG_BEHAVIOUR },
  { "pango", CLUTTER_DEBUG_PANGO },
  { "backend", CLUTTER_DEBUG_BACKEND },
  { "scheduler", CLUTTER_DEBUG_SCHEDULER },
  { "script", CLUTTER_DEBUG_SCRIPT },
  { "shader", CLUTTER_DEBUG_SHADER },
  { "multistage", CLUTTER_DEBUG_MULTISTAGE },
  { "animation", CLUTTER_DEBUG_ANIMATION },
  { "layout", CLUTTER_DEBUG_LAYOUT },
  { "clipping", CLUTTER_DEBUG_CLIPPING }
};
#endif /* CLUTTER_ENABLE_DEBUG */

static const GDebugKey clutter_pick_debug_keys[] = {
  { "nop-picking", CLUTTER_DEBUG_NOP_PICKING },
  { "dump-pick-buffers", CLUTTER_DEBUG_DUMP_PICK_BUFFERS }
};

static const GDebugKey clutter_paint_debug_keys[] = {
  { "disable-swap-events", CLUTTER_DEBUG_DISABLE_SWAP_EVENTS },
  { "disable-clipped-redraws", CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS },
  { "redraws", CLUTTER_DEBUG_REDRAWS },
  { "paint-volumes", CLUTTER_DEBUG_PAINT_VOLUMES },
  { "disable-culling", CLUTTER_DEBUG_DISABLE_CULLING }
};

#ifdef CLUTTER_ENABLE_PROFILE
static const GDebugKey clutter_profile_keys[] = {
  {"picking-only", CLUTTER_PROFILE_PICKING_ONLY },
  {"disable-report", CLUTTER_PROFILE_DISABLE_REPORT }
};
#endif /* CLUTTER_ENABLE_DEBUG */

/**
 * clutter_get_show_fps:
 *
 * Returns whether Clutter should print out the frames per second on the
 * console. You can enable this setting either using the
 * <literal>CLUTTER_SHOW_FPS</literal> environment variable or passing
 * the <literal>--clutter-show-fps</literal> command line argument. *
 *
 * Return value: %TRUE if Clutter should show the FPS.
 *
 * Since: 0.4
 */
gboolean
clutter_get_show_fps (void)
{
  return clutter_show_fps;
}

/**
 * clutter_get_accessibility_enabled:
 *
 * Returns whether Clutter has accessibility support enabled.  As
 * least, a value of TRUE means that there are a proper AtkUtil
 * implementation available
 *
 * Return value: %TRUE if Clutter has accessibility support enabled
 *
 * Since: 1.4
 */
gboolean
clutter_get_accessibility_enabled (void)
{
  return cally_get_cally_initialized ();
}

/**
 * clutter_redraw:
 *
 * Forces a redraw of the entire stage. Applications should never use this
 * function, but queue a redraw using clutter_actor_queue_redraw().
 *
 * This function should only be used by libraries integrating Clutter from
 * within another toolkit.
 */
void
clutter_redraw (ClutterStage *stage)
{
  g_return_if_fail (CLUTTER_IS_STAGE (stage));

  clutter_stage_ensure_redraw (stage);
}

/**
 * clutter_set_motion_events_enabled:
 * @enable: %TRUE to enable per-actor motion events
 *
 * Sets whether per-actor motion events should be enabled or not (the
 * default is to enable them).
 *
 * If @enable is %FALSE the following events will not work:
 * <itemizedlist>
 *   <listitem><para>ClutterActor::motion-event, unless on the
 *     #ClutterStage</para></listitem>
 *   <listitem><para>ClutterActor::enter-event</para></listitem>
 *   <listitem><para>ClutterActor::leave-event</para></listitem>
 * </itemizedlist>
 *
 * Since: 0.6
 */
void
clutter_set_motion_events_enabled (gboolean enable)
{
  ClutterStageManager *stage_manager;
  ClutterMainContext *context;
  const GSList *l;

  enable = !!enable;

  context = _clutter_context_get_default ();
  if (context->motion_events_per_actor == enable)
    return;

  /* store the flag for later query and for newly created stages */
  context->motion_events_per_actor = enable;

  /* propagate the change to all stages */
  stage_manager = clutter_stage_manager_get_default ();

  for (l = clutter_stage_manager_peek_stages (stage_manager);
       l != NULL;
       l = l->next)
    {
      _clutter_stage_set_motion_events_enabled (l->data, enable);
    }
}

/**
 * clutter_get_motion_events_enabled:
 *
 * Gets whether the per-actor motion events are enabled.
 *
 * Return value: %TRUE if the motion events are enabled
 *
 * Since: 0.6
 */
gboolean
clutter_get_motion_events_enabled (void)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  return context->motion_events_per_actor;
}

ClutterActor *
_clutter_get_actor_by_id (ClutterStage *stage,
                          guint32       actor_id)
{
  if (stage == NULL)
    {
      ClutterMainContext *context = _clutter_context_get_default ();

      return _clutter_id_pool_lookup (context->id_pool, actor_id);
    }

  return _clutter_stage_get_actor_by_pick_id (stage, actor_id);
}

void
_clutter_id_to_color (guint         id_,
                      ClutterColor *col)
{
  ClutterMainContext *ctx;
  gint red, green, blue;

  ctx = _clutter_context_get_default ();

  if (ctx->fb_g_mask == 0)
    {
      /* Figure out framebuffer masks used for pick */
      cogl_get_bitmasks (&ctx->fb_r_mask,
			 &ctx->fb_g_mask,
			 &ctx->fb_b_mask, NULL);

      ctx->fb_r_mask_used = ctx->fb_r_mask;
      ctx->fb_g_mask_used = ctx->fb_g_mask;
      ctx->fb_b_mask_used = ctx->fb_b_mask;

      /* XXX - describe what "fuzzy picking" is */
      if (clutter_use_fuzzy_picking)
	{
	  ctx->fb_r_mask_used--;
	  ctx->fb_g_mask_used--;
	  ctx->fb_b_mask_used--;
	}
    }

  /* compute the numbers we'll store in the components */
  red   = (id_ >> (ctx->fb_g_mask_used+ctx->fb_b_mask_used))
        & (0xff >> (8-ctx->fb_r_mask_used));
  green = (id_ >> ctx->fb_b_mask_used)
        & (0xff >> (8-ctx->fb_g_mask_used));
  blue  = (id_)
        & (0xff >> (8-ctx->fb_b_mask_used));

  /* shift left bits a bit and add one, this circumvents
   * at least some potential rounding errors in GL/GLES
   * driver / hw implementation.
   */
  if (ctx->fb_r_mask_used != ctx->fb_r_mask)
    red = red * 2;
  if (ctx->fb_g_mask_used != ctx->fb_g_mask)
    green = green * 2;
  if (ctx->fb_b_mask_used != ctx->fb_b_mask)
    blue  = blue  * 2;

  /* shift up to be full 8bit values */
  red   = (red   << (8 - ctx->fb_r_mask)) | (0x7f >> (ctx->fb_r_mask_used));
  green = (green << (8 - ctx->fb_g_mask)) | (0x7f >> (ctx->fb_g_mask_used));
  blue  = (blue  << (8 - ctx->fb_b_mask)) | (0x7f >> (ctx->fb_b_mask_used));

  col->red   = red;
  col->green = green;
  col->blue  = blue;
  col->alpha = 0xff;

  /* XXX: We rotate the nibbles of the colors here so that there is a
   * visible variation between colors of sequential actor identifiers;
   * otherwise pick buffers dumped to an image will pretty much just look
   * black.
   */
  if (G_UNLIKELY (clutter_pick_debug_flags & CLUTTER_DEBUG_DUMP_PICK_BUFFERS))
    {
      col->red   = (col->red << 4)   | (col->red >> 4);
      col->green = (col->green << 4) | (col->green >> 4);
      col->blue  = (col->blue << 4)  | (col->blue >> 4);
    }
}

guint
_clutter_pixel_to_id (guchar pixel[4])
{
  ClutterMainContext *ctx;
  gint red, green, blue;
  guint retval;

  ctx = _clutter_context_get_default ();

  /* reduce the pixel components to the number of bits actually used of the
   * 8bits.
   */
  if (G_UNLIKELY (clutter_pick_debug_flags & CLUTTER_DEBUG_DUMP_PICK_BUFFERS))
    {
      guchar tmp;

      /* XXX: In _clutter_id_to_color we rotated the nibbles of the colors so
       * that there is a visible variation between colors of sequential actor
       * identifiers (otherwise pick buffers dumped to an image will pretty
       * much just look black.) Here we reverse that rotation.
       */
      tmp = ((pixel[0] << 4) | (pixel[0] >> 4));
      red = tmp >> (8 - ctx->fb_r_mask);
      tmp = ((pixel[1] << 4) | (pixel[1] >> 4));
      green = tmp >> (8 - ctx->fb_g_mask);
      tmp = ((pixel[2] << 4) | (pixel[2] >> 4));
      blue = tmp >> (8 - ctx->fb_b_mask);
    }
  else
    {
      red   = pixel[0] >> (8 - ctx->fb_r_mask);
      green = pixel[1] >> (8 - ctx->fb_g_mask);
      blue  = pixel[2] >> (8 - ctx->fb_b_mask);
    }

  /* divide potentially by two if 'fuzzy' */
  red   = red   >> (ctx->fb_r_mask - ctx->fb_r_mask_used);
  green = green >> (ctx->fb_g_mask - ctx->fb_g_mask_used);
  blue  = blue  >> (ctx->fb_b_mask - ctx->fb_b_mask_used);

  /* combine the correct per component values into the final id */
  retval = blue
         + (green <<  ctx->fb_b_mask_used)
         + (red << (ctx->fb_b_mask_used + ctx->fb_g_mask_used));

  return retval;
}

static CoglPangoFontMap *
clutter_context_get_pango_fontmap (void)
{
  ClutterMainContext *self;
  CoglPangoFontMap *font_map;
  gdouble resolution;
  gboolean use_mipmapping;

  self = _clutter_context_get_default ();
  if (G_LIKELY (self->font_map != NULL))
    return self->font_map;

  font_map = COGL_PANGO_FONT_MAP (cogl_pango_font_map_new ());

  resolution = clutter_backend_get_resolution (self->backend);
  cogl_pango_font_map_set_resolution (font_map, resolution);

  use_mipmapping = !clutter_disable_mipmap_text;
  cogl_pango_font_map_set_use_mipmapping (font_map, use_mipmapping);

  self->font_map = font_map;

  return self->font_map;
}

static ClutterTextDirection
clutter_get_text_direction (void)
{
  PangoDirection dir = PANGO_DIRECTION_LTR;
  const gchar *direction;

  direction = g_getenv ("CLUTTER_TEXT_DIRECTION");
  if (direction && *direction != '\0')
    {
      if (strcmp (direction, "rtl") == 0)
        dir = CLUTTER_TEXT_DIRECTION_RTL;
      else if (strcmp (direction, "ltr") == 0)
        dir = CLUTTER_TEXT_DIRECTION_LTR;
    }
  else
    {
      /* Translate to default:RTL if you want your widgets
       * to be RTL, otherwise translate to default:LTR.
       *
       * Do *not* translate it to "predefinito:LTR": if it
       * it isn't default:LTR or default:RTL it will not work
       */
      char *e = _("default:LTR");

      if (strcmp (e, "default:RTL") == 0)
        dir = CLUTTER_TEXT_DIRECTION_RTL;
      else if (strcmp (e, "default:LTR") == 0)
        dir = CLUTTER_TEXT_DIRECTION_LTR;
      else
        g_warning ("Whoever translated default:LTR did so wrongly.");
    }

  return dir;
}

static void
update_pango_context (ClutterBackend *backend,
                      PangoContext   *context)
{
  ClutterSettings *settings;
  PangoFontDescription *font_desc;
  const cairo_font_options_t *font_options;
  gchar *font_name;
  PangoDirection pango_dir;
  gdouble resolution;

  settings = clutter_settings_get_default ();

  /* update the text direction */
  if (clutter_text_direction == CLUTTER_TEXT_DIRECTION_RTL)
    pango_dir = PANGO_DIRECTION_RTL;
  else
    pango_dir = PANGO_DIRECTION_LTR;

  pango_context_set_base_dir (context, pango_dir);

  g_object_get (settings, "font-name", &font_name, NULL);

  /* get the configuration for the PangoContext from the backend */
  font_options = clutter_backend_get_font_options (backend);
  resolution = clutter_backend_get_resolution (backend);

  font_desc = pango_font_description_from_string (font_name);

  if (resolution < 0)
    resolution = 96.0; /* fall back */

  pango_context_set_font_description (context, font_desc);
  pango_cairo_context_set_font_options (context, font_options);
  pango_cairo_context_set_resolution (context, resolution);

  pango_font_description_free (font_desc);
  g_free (font_name);
}

PangoContext *
_clutter_context_get_pango_context (void)
{
  ClutterMainContext *self = _clutter_context_get_default ();

  if (G_UNLIKELY (self->pango_context == NULL))
    {
      PangoContext *context;

      context = _clutter_context_create_pango_context ();
      self->pango_context = context;

      g_signal_connect (self->backend, "resolution-changed",
                        G_CALLBACK (update_pango_context),
                        self->pango_context);
      g_signal_connect (self->backend, "font-changed",
                        G_CALLBACK (update_pango_context),
                        self->pango_context);
    }
  else
    update_pango_context (self->backend, self->pango_context);

  return self->pango_context;
}

PangoContext *
_clutter_context_create_pango_context (void)
{
  CoglPangoFontMap *font_map;
  PangoContext *context;

  font_map = clutter_context_get_pango_fontmap ();

  context = cogl_pango_font_map_create_context (font_map);
  update_pango_context (clutter_get_default_backend (), context);
  pango_context_set_language (context, pango_language_get_default ());

  return context;
}

/**
 * clutter_main_quit:
 *
 * Terminates the Clutter mainloop.
 */
void
clutter_main_quit (void)
{
  g_return_if_fail (main_loops != NULL);

  g_main_loop_quit (main_loops->data);
}

/**
 * clutter_main_level:
 *
 * Retrieves the depth of the Clutter mainloop.
 *
 * Return value: The level of the mainloop.
 */
gint
clutter_main_level (void)
{
  return clutter_main_loop_level;
}

#ifdef CLUTTER_ENABLE_PROFILE
static gint (*prev_poll) (GPollFD *ufds, guint nfsd, gint timeout_) = NULL;

static gint
timed_poll (GPollFD *ufds,
            guint nfsd,
            gint timeout_)
{
  gint ret;
  CLUTTER_STATIC_TIMER (poll_timer,
                        "Mainloop", /* parent */
                        "Mainloop Idle",
                        "The time spent idle in poll()",
                        0 /* no application private data */);

  CLUTTER_TIMER_START (uprof_get_mainloop_context (), poll_timer);
  ret = prev_poll (ufds, nfsd, timeout_);
  CLUTTER_TIMER_STOP (uprof_get_mainloop_context (), poll_timer);
  return ret;
}
#endif

/**
 * clutter_main:
 *
 * Starts the Clutter mainloop.
 */
void
clutter_main (void)
{
  GMainLoop *loop;
  CLUTTER_STATIC_TIMER (mainloop_timer,
                        NULL, /* no parent */
                        "Mainloop",
                        "The time spent in the clutter mainloop",
                        0 /* no application private data */);

  if (clutter_main_loop_level == 0)
    CLUTTER_TIMER_START (uprof_get_mainloop_context (), mainloop_timer);

  if (!_clutter_context_is_initialized ())
    {
      g_warning ("Called clutter_main() but Clutter wasn't initialised. "
		 "You must call clutter_init() first.");
      return;
    }

  CLUTTER_MARK ();

  clutter_main_loop_level++;

#ifdef CLUTTER_ENABLE_PROFILE
  if (!prev_poll)
    {
      prev_poll = g_main_context_get_poll_func (NULL);
      g_main_context_set_poll_func (NULL, timed_poll);
    }
#endif

  loop = g_main_loop_new (NULL, TRUE);
  main_loops = g_slist_prepend (main_loops, loop);

  if (g_main_loop_is_running (main_loops->data))
    {
      clutter_threads_leave ();
      g_main_loop_run (loop);
      clutter_threads_enter ();
    }

  main_loops = g_slist_remove (main_loops, loop);

  g_main_loop_unref (loop);

  clutter_main_loop_level--;

  CLUTTER_MARK ();

  if (clutter_main_loop_level == 0)
    CLUTTER_TIMER_STOP (uprof_get_mainloop_context (), mainloop_timer);
}

static void
clutter_threads_impl_lock (void)
{
  if (G_LIKELY (clutter_threads_mutex != NULL))
    g_mutex_lock (clutter_threads_mutex);
}

static void
clutter_threads_impl_unlock (void)
{
  if (G_LIKELY (clutter_threads_mutex != NULL))
    g_mutex_unlock (clutter_threads_mutex);
}

/**
 * clutter_threads_init:
 *
 * Initialises the Clutter threading mechanism, so that Clutter API can be
 * called by multiple threads, using clutter_threads_enter() and
 * clutter_threads_leave() to mark the critical sections.
 *
 * You must call g_thread_init() before this function.
 *
 * This function must be called before clutter_init().
 *
 * It is safe to call this function multiple times.
 *
 * Since: 0.4
 */
void
clutter_threads_init (void)
{
  if (!g_thread_supported ())
    g_error ("g_thread_init() must be called before clutter_threads_init()");

  if (clutter_threads_mutex != NULL)
    return;

  clutter_threads_mutex = g_mutex_new ();

  if (!clutter_threads_lock)
    clutter_threads_lock = clutter_threads_impl_lock;

  if (!clutter_threads_unlock)
    clutter_threads_unlock = clutter_threads_impl_unlock;
}

/**
 * clutter_threads_set_lock_functions: (skip)
 * @enter_fn: function called when aquiring the Clutter main lock
 * @leave_fn: function called when releasing the Clutter main lock
 *
 * Allows the application to replace the standard method that
 * Clutter uses to protect its data structures. Normally, Clutter
 * creates a single #GMutex that is locked by clutter_threads_enter(),
 * and released by clutter_threads_leave(); using this function an
 * application provides, instead, a function @enter_fn that is
 * called by clutter_threads_enter() and a function @leave_fn that is
 * called by clutter_threads_leave().
 *
 * The functions must provide at least same locking functionality
 * as the default implementation, but can also do extra application
 * specific processing.
 *
 * As an example, consider an application that has its own recursive
 * lock that when held, holds the Clutter lock as well. When Clutter
 * unlocks the Clutter lock when entering a recursive main loop, the
 * application must temporarily release its lock as well.
 *
 * Most threaded Clutter apps won't need to use this method.
 *
 * This method must be called before clutter_threads_init(), and cannot
 * be called multiple times.
 *
 * Since: 0.4
 */
void
clutter_threads_set_lock_functions (GCallback enter_fn,
                                    GCallback leave_fn)
{
  g_return_if_fail (clutter_threads_lock == NULL &&
                    clutter_threads_unlock == NULL);

  clutter_threads_lock = enter_fn;
  clutter_threads_unlock = leave_fn;
}

gboolean
_clutter_threads_dispatch (gpointer data)
{
  ClutterThreadsDispatch *dispatch = data;
  gboolean ret = FALSE;

  clutter_threads_enter ();

  if (!g_source_is_destroyed (g_main_current_source ()))
    ret = dispatch->func (dispatch->data);

  clutter_threads_leave ();

  return ret;
}

void
_clutter_threads_dispatch_free (gpointer data)
{
  ClutterThreadsDispatch *dispatch = data;

  /* XXX - we cannot hold the thread lock here because the main loop
   * might destroy a source while still in the dispatcher function; so
   * knowing whether the lock is being held or not is not known a priori.
   *
   * see bug: http://bugzilla.gnome.org/show_bug.cgi?id=459555
   */
  if (dispatch->notify)
    dispatch->notify (dispatch->data);

  g_slice_free (ClutterThreadsDispatch, dispatch);
}

/**
 * clutter_threads_add_idle_full:
 * @priority: the priority of the timeout source. Typically this will be in the
 *    range between #G_PRIORITY_DEFAULT_IDLE and #G_PRIORITY_HIGH_IDLE
 * @func: function to call
 * @data: data to pass to the function
 * @notify: functio to call when the idle source is removed
 *
 * Adds a function to be called whenever there are no higher priority
 * events pending. If the function returns %FALSE it is automatically
 * removed from the list of event sources and will not be called again.
 *
 * This function can be considered a thread-safe variant of g_idle_add_full():
 * it will call @function while holding the Clutter lock. It is logically
 * equivalent to the following implementation:
 *
 * |[
 * static gboolean
 * idle_safe_callback (gpointer data)
 * {
 *    SafeClosure *closure = data;
 *    gboolean res = FALSE;
 *
 *    /&ast; mark the critical section &ast;/
 *
 *    clutter_threads_enter();
 *
 *    /&ast; the callback does not need to acquire the Clutter
 *     &ast; lock itself, as it is held by the this proxy handler
 *     &ast;/
 *    res = closure->callback (closure->data);
 *
 *    clutter_threads_leave();
 *
 *    return res;
 * }
 * static gulong
 * add_safe_idle (GSourceFunc callback,
 *                gpointer    data)
 * {
 *   SafeClosure *closure = g_new0 (SafeClosure, 1);
 *
 *   closure-&gt;callback = callback;
 *   closure-&gt;data = data;
 *
 *   return g_add_idle_full (G_PRIORITY_DEFAULT_IDLE,
 *                           idle_safe_callback,
 *                           closure,
 *                           g_free)
 * }
 *]|
 *
 * This function should be used by threaded applications to make sure
 * that @func is emitted under the Clutter threads lock and invoked
 * from the same thread that started the Clutter main loop. For instance,
 * it can be used to update the UI using the results from a worker
 * thread:
 *
 * |[
 * static gboolean
 * update_ui (gpointer data)
 * {
 *   SomeClosure *closure = data;
 *
 *   /&ast; it is safe to call Clutter API from this function because
 *    &ast; it is invoked from the same thread that started the main
 *    &ast; loop and under the Clutter thread lock
 *    &ast;/
 *   clutter_label_set_text (CLUTTER_LABEL (closure-&gt;label),
 *                           closure-&gt;text);
 *
 *   g_object_unref (closure-&gt;label);
 *   g_free (closure);
 *
 *   return FALSE;
 * }
 *
 *   /&ast; within another thread &ast;/
 *   closure = g_new0 (SomeClosure, 1);
 *   /&ast; always take a reference on GObject instances &ast;/
 *   closure-&gt;label = g_object_ref (my_application-&gt;label);
 *   closure-&gt;text = g_strdup (processed_text_to_update_the_label);
 *
 *   clutter_threads_add_idle_full (G_PRIORITY_HIGH_IDLE,
 *                                  update_ui,
 *                                  closure,
 *                                  NULL);
 * ]|
 *
 * Rename to: clutter_threads_add_idle
 *
 * Return value: the ID (greater than 0) of the event source.
 *
 * Since: 0.4
 */
guint
clutter_threads_add_idle_full (gint           priority,
                               GSourceFunc    func,
                               gpointer       data,
                               GDestroyNotify notify)
{
  ClutterThreadsDispatch *dispatch;

  g_return_val_if_fail (func != NULL, 0);

  dispatch = g_slice_new (ClutterThreadsDispatch);
  dispatch->func = func;
  dispatch->data = data;
  dispatch->notify = notify;

  return g_idle_add_full (priority,
                          _clutter_threads_dispatch, dispatch,
                          _clutter_threads_dispatch_free);
}

/**
 * clutter_threads_add_idle: (skip)
 * @func: function to call
 * @data: data to pass to the function
 *
 * Simple wrapper around clutter_threads_add_idle_full() using the
 * default priority.
 *
 * Return value: the ID (greater than 0) of the event source.
 *
 * Since: 0.4
 */
guint
clutter_threads_add_idle (GSourceFunc func,
                          gpointer    data)
{
  g_return_val_if_fail (func != NULL, 0);

  return clutter_threads_add_idle_full (G_PRIORITY_DEFAULT_IDLE,
                                        func, data,
                                        NULL);
}

/**
 * clutter_threads_add_timeout_full:
 * @priority: the priority of the timeout source. Typically this will be in the
 *            range between #G_PRIORITY_DEFAULT and #G_PRIORITY_HIGH.
 * @interval: the time between calls to the function, in milliseconds
 * @func: function to call
 * @data: data to pass to the function
 * @notify: function to call when the timeout source is removed
 *
 * Sets a function to be called at regular intervals holding the Clutter
 * threads lock, with the given priority. The function is called repeatedly
 * until it returns %FALSE, at which point the timeout is automatically
 * removed and the function will not be called again. The @notify function
 * is called when the timeout is removed.
 *
 * The first call to the function will be at the end of the first @interval.
 *
 * It is important to note that, due to how the Clutter main loop is
 * implemented, the timing will not be accurate and it will not try to
 * "keep up" with the interval. A more reliable source is available
 * using clutter_threads_add_frame_source_full(), which is also internally
 * used by #ClutterTimeline.
 *
 * See also clutter_threads_add_idle_full().
 *
 * Rename to: clutter_threads_add_timeout
 *
 * Return value: the ID (greater than 0) of the event source.
 *
 * Since: 0.4
 */
guint
clutter_threads_add_timeout_full (gint           priority,
                                  guint          interval,
                                  GSourceFunc    func,
                                  gpointer       data,
                                  GDestroyNotify notify)
{
  ClutterThreadsDispatch *dispatch;

  g_return_val_if_fail (func != NULL, 0);

  dispatch = g_slice_new (ClutterThreadsDispatch);
  dispatch->func = func;
  dispatch->data = data;
  dispatch->notify = notify;

  return g_timeout_add_full (priority,
                             interval,
                             _clutter_threads_dispatch, dispatch,
                             _clutter_threads_dispatch_free);
}

/**
 * clutter_threads_add_timeout: (skip)
 * @interval: the time between calls to the function, in milliseconds
 * @func: function to call
 * @data: data to pass to the function
 *
 * Simple wrapper around clutter_threads_add_timeout_full().
 *
 * Return value: the ID (greater than 0) of the event source.
 *
 * Since: 0.4
 */
guint
clutter_threads_add_timeout (guint       interval,
                             GSourceFunc func,
                             gpointer    data)
{
  g_return_val_if_fail (func != NULL, 0);

  return clutter_threads_add_timeout_full (G_PRIORITY_DEFAULT,
                                           interval,
                                           func, data,
                                           NULL);
}

/**
 * clutter_threads_enter:
 *
 * Locks the Clutter thread lock.
 *
 * Since: 0.4
 */
void
clutter_threads_enter (void)
{
  if (clutter_threads_lock)
    (* clutter_threads_lock) ();
}

/**
 * clutter_threads_leave:
 *
 * Unlocks the Clutter thread lock.
 *
 * Since: 0.4
 */
void
clutter_threads_leave (void)
{
  if (clutter_threads_unlock)
    (* clutter_threads_unlock) ();
}


/**
 * clutter_get_debug_enabled:
 *
 * Check if clutter has debugging turned on.
 *
 * Return value: TRUE if debugging is turned on, FALSE otherwise.
 */
gboolean
clutter_get_debug_enabled (void)
{
#ifdef CLUTTER_ENABLE_DEBUG
  return clutter_debug_flags != 0;
#else
  return FALSE;
#endif
}

gboolean
_clutter_context_is_initialized (void)
{
  if (ClutterCntx == NULL)
    return FALSE;

  return ClutterCntx->is_initialized;
}

ClutterMainContext *
_clutter_context_get_default (void)
{
  if (G_UNLIKELY (ClutterCntx == NULL))
    {
      ClutterMainContext *ctx;

      ClutterCntx = ctx = g_new0 (ClutterMainContext, 1);

      /* create the default backend */
      ctx->backend = g_object_new (_clutter_backend_impl_get_type (), NULL);

      ctx->is_initialized = FALSE;
      ctx->motion_events_per_actor = TRUE;

#ifdef CLUTTER_ENABLE_DEBUG
      ctx->timer = g_timer_new ();
      g_timer_start (ctx->timer);
#endif
    }

  return ClutterCntx;
}

/**
 * clutter_get_timestamp:
 *
 * Returns the approximate number of microseconds passed since clutter was
 * intialised.
 *
 * Return value: Number of microseconds since clutter_init() was called.
 */
gulong
clutter_get_timestamp (void)
{
#ifdef CLUTTER_ENABLE_DEBUG
  ClutterMainContext *ctx;
  gdouble seconds;

  ctx = _clutter_context_get_default ();

  /* FIXME: may need a custom timer for embedded setups */
  seconds = g_timer_elapsed (ctx->timer, NULL);

  return (gulong)(seconds / 1.0e-6);
#else
  return 0;
#endif
}

static gboolean
clutter_arg_direction_cb (const char *key,
                          const char *value,
                          gpointer    user_data)
{
  clutter_text_direction =
    (strcmp (value, "rtl") == 0) ? CLUTTER_TEXT_DIRECTION_RTL
                                 : CLUTTER_TEXT_DIRECTION_LTR;

  return TRUE;
}

#ifdef CLUTTER_ENABLE_DEBUG
static gboolean
clutter_arg_debug_cb (const char *key,
                      const char *value,
                      gpointer    user_data)
{
  clutter_debug_flags |=
    g_parse_debug_string (value,
                          clutter_debug_keys,
                          G_N_ELEMENTS (clutter_debug_keys));
  return TRUE;
}

static gboolean
clutter_arg_no_debug_cb (const char *key,
                         const char *value,
                         gpointer    user_data)
{
  clutter_debug_flags &=
    ~g_parse_debug_string (value,
                           clutter_debug_keys,
                           G_N_ELEMENTS (clutter_debug_keys));
  return TRUE;
}
#endif /* CLUTTER_ENABLE_DEBUG */

#ifdef CLUTTER_ENABLE_PROFILE
static gboolean
clutter_arg_profile_cb (const char *key,
                        const char *value,
                        gpointer    user_data)
{
  clutter_profile_flags |=
    g_parse_debug_string (value,
                          clutter_profile_keys,
                          G_N_ELEMENTS (clutter_profile_keys));
  return TRUE;
}

static gboolean
clutter_arg_no_profile_cb (const char *key,
                           const char *value,
                           gpointer    user_data)
{
  clutter_profile_flags &=
    ~g_parse_debug_string (value,
                           clutter_profile_keys,
                           G_N_ELEMENTS (clutter_profile_keys));
  return TRUE;
}
#endif /* CLUTTER_ENABLE_PROFILE */

GQuark
clutter_init_error_quark (void)
{
  return g_quark_from_static_string ("clutter-init-error-quark");
}

static ClutterInitError
clutter_init_real (GError **error)
{
  ClutterMainContext *ctx;
  ClutterBackend *backend;

  /* Note, creates backend if not already existing, though parse args will
   * have likely created it
   */
  ctx = _clutter_context_get_default ();
  backend = ctx->backend;

  if (!ctx->options_parsed)
    {
      if (error)
        g_set_error (error, CLUTTER_INIT_ERROR,
                     CLUTTER_INIT_ERROR_INTERNAL,
                     "When using clutter_get_option_group_without_init() "
		     "you must parse options before calling clutter_init()");
      else
        g_critical ("When using clutter_get_option_group_without_init() "
		    "you must parse options before calling clutter_init()");

      return CLUTTER_INIT_ERROR_INTERNAL;
    }

  /*
   * Call backend post parse hooks.
   */
  if (!_clutter_backend_post_parse (backend, error))
    return CLUTTER_INIT_ERROR_BACKEND;

  /* If we are displaying the regions that would get redrawn with clipped
   * redraws enabled we actually have to disable the clipped redrawing
   * because otherwise we end up with nasty trails of rectangles everywhere.
   */
  if (clutter_paint_debug_flags & CLUTTER_DEBUG_REDRAWS)
    clutter_paint_debug_flags |= CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS;

  /* The same is true when drawing the outlines of paint volumes... */
  if (clutter_paint_debug_flags & CLUTTER_DEBUG_PAINT_VOLUMES)
    clutter_paint_debug_flags |= CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS;

  /* this will take care of initializing Cogl's state and
   * query the GL machinery for features
   */
  if (!_clutter_feature_init (error))
    return CLUTTER_INIT_ERROR_BACKEND;

#ifdef CLUTTER_ENABLE_PROFILE
  /* We need to be absolutely sure that uprof has been initialized
   * before calling _clutter_uprof_init. uprof_init (NULL, NULL)
   * will be a NOP if it has been initialized but it will also
   * mean subsequent parsing of the UProf GOptionGroup will have no
   * affect.
   *
   * Sadly GOptionGroup based library initialization is extremly
   * fragile by design because GOptionGroups have no notion of
   * dependencies and our post_parse_hook may be called before
   * the cogl or uprof groups get parsed.
   */
  uprof_init (NULL, NULL);
  _clutter_uprof_init ();

  if (clutter_profile_flags & CLUTTER_PROFILE_PICKING_ONLY)
    _clutter_profile_suspend ();
#endif

  clutter_text_direction = clutter_get_text_direction ();

  /* Initiate event collection */
  _clutter_backend_init_events (ctx->backend);

  clutter_is_initialized = TRUE;
  ctx->is_initialized = TRUE;

  /* Initialize a11y */
  if (clutter_enable_accessibility)
    cally_accessibility_init ();

  return CLUTTER_INIT_SUCCESS;
}

static GOptionEntry clutter_args[] = {
  { "clutter-show-fps", 0, 0, G_OPTION_ARG_NONE, &clutter_show_fps,
    N_("Show frames per second"), NULL },
  { "clutter-default-fps", 0, 0, G_OPTION_ARG_INT, &clutter_default_fps,
    N_("Default frame rate"), "FPS" },
  { "g-fatal-warnings", 0, 0, G_OPTION_ARG_NONE, &clutter_fatal_warnings,
    N_("Make all warnings fatal"), NULL },
  { "clutter-text-direction", 0, 0, G_OPTION_ARG_CALLBACK,
    clutter_arg_direction_cb,
    N_("Direction for the text"), "DIRECTION" },
  { "clutter-disable-mipmapped-text", 0, 0, G_OPTION_ARG_NONE,
    &clutter_disable_mipmap_text,
    N_("Disable mipmapping on text"), NULL },
  { "clutter-use-fuzzy-picking", 0, 0, G_OPTION_ARG_NONE,
    &clutter_use_fuzzy_picking,
    N_("Use 'fuzzy' picking"), NULL },
#ifdef CLUTTER_ENABLE_DEBUG
  { "clutter-debug", 0, 0, G_OPTION_ARG_CALLBACK, clutter_arg_debug_cb,
    N_("Clutter debugging flags to set"), "FLAGS" },
  { "clutter-no-debug", 0, 0, G_OPTION_ARG_CALLBACK, clutter_arg_no_debug_cb,
    N_("Clutter debugging flags to unset"), "FLAGS" },
#endif /* CLUTTER_ENABLE_DEBUG */
#ifdef CLUTTER_ENABLE_PROFILE
  { "clutter-profile", 0, 0, G_OPTION_ARG_CALLBACK, clutter_arg_profile_cb,
    N_("Clutter profiling flags to set"), "FLAGS" },
  { "clutter-no-profile", 0, 0, G_OPTION_ARG_CALLBACK, clutter_arg_no_profile_cb,
    N_("Clutter profiling flags to unset"), "FLAGS" },
#endif /* CLUTTER_ENABLE_PROFILE */
  { "clutter-enable-accessibility", 0, 0, G_OPTION_ARG_NONE, &clutter_enable_accessibility,
    N_("Enable accessibility"), NULL },
  { NULL, },
};

/* pre_parse_hook: initialise variables depending on environment
 * variables; these variables might be overridden by the command
 * line arguments that are going to be parsed after.
 */
static gboolean
pre_parse_hook (GOptionContext  *context,
                GOptionGroup    *group,
                gpointer         data,
                GError         **error)
{
  ClutterMainContext *clutter_context;
  ClutterBackend *backend;
  const char *env_string;

  if (clutter_is_initialized)
    return TRUE;

  if (setlocale (LC_ALL, "") == NULL)
    g_warning ("Locale not supported by C library.\n"
               "Using the fallback 'C' locale.");

  clutter_context = _clutter_context_get_default ();

  clutter_context->id_pool = _clutter_id_pool_new (256);

  backend = clutter_context->backend;
  g_assert (CLUTTER_IS_BACKEND (backend));

#ifdef CLUTTER_ENABLE_DEBUG
  env_string = g_getenv ("CLUTTER_DEBUG");
  if (env_string != NULL)
    {
      clutter_debug_flags =
        g_parse_debug_string (env_string,
                              clutter_debug_keys,
                              G_N_ELEMENTS (clutter_debug_keys));
      env_string = NULL;
    }
#endif /* CLUTTER_ENABLE_DEBUG */

#ifdef CLUTTER_ENABLE_PROFILE
  env_string = g_getenv ("CLUTTER_PROFILE");
  if (env_string != NULL)
    {
      clutter_profile_flags =
        g_parse_debug_string (env_string,
                              clutter_profile_keys,
                              G_N_ELEMENTS (clutter_profile_keys));
      env_string = NULL;
    }
#endif /* CLUTTER_ENABLE_PROFILE */

  env_string = g_getenv ("CLUTTER_PICK");
  if (env_string != NULL)
    {
      clutter_pick_debug_flags =
        g_parse_debug_string (env_string,
                              clutter_pick_debug_keys,
                              G_N_ELEMENTS (clutter_pick_debug_keys));
      env_string = NULL;
    }

  env_string = g_getenv ("CLUTTER_PAINT");
  if (env_string != NULL)
    {
      clutter_paint_debug_flags =
        g_parse_debug_string (env_string,
                              clutter_paint_debug_keys,
                              G_N_ELEMENTS (clutter_paint_debug_keys));
      env_string = NULL;
    }

  env_string = g_getenv ("CLUTTER_SHOW_FPS");
  if (env_string)
    clutter_show_fps = TRUE;

  env_string = g_getenv ("CLUTTER_DEFAULT_FPS");
  if (env_string)
    {
      gint default_fps = g_ascii_strtoll (env_string, NULL, 10);

      clutter_default_fps = CLAMP (default_fps, 1, 1000);
    }

  env_string = g_getenv ("CLUTTER_DISABLE_MIPMAPPED_TEXT");
  if (env_string)
    clutter_disable_mipmap_text = TRUE;

  env_string = g_getenv ("CLUTTER_FUZZY_PICK");
  if (env_string)
    clutter_use_fuzzy_picking = TRUE;

  return _clutter_backend_pre_parse (backend, error);
}

/* post_parse_hook: initialise the context and data structures
 * and opens the X display
 */
static gboolean
post_parse_hook (GOptionContext  *context,
                 GOptionGroup    *group,
                 gpointer         data,
                 GError         **error)
{
  ClutterMainContext *clutter_context;
  ClutterBackend *backend;

  if (clutter_is_initialized)
    return TRUE;

  clutter_context = _clutter_context_get_default ();
  backend = clutter_context->backend;
  g_assert (CLUTTER_IS_BACKEND (backend));

  if (clutter_fatal_warnings)
    {
      GLogLevelFlags fatal_mask;

      fatal_mask = g_log_set_always_fatal (G_LOG_FATAL_MASK);
      fatal_mask |= G_LOG_LEVEL_WARNING | G_LOG_LEVEL_CRITICAL;
      g_log_set_always_fatal (fatal_mask);
    }

  clutter_context->frame_rate = clutter_default_fps;
  clutter_context->options_parsed = TRUE;

  /*
   * If not asked to defer display setup, call clutter_init_real(),
   * which in turn calls the backend post parse hooks.
   */
  if (!clutter_context->defer_display_setup)
    return clutter_init_real (error) == CLUTTER_INIT_SUCCESS;

  return TRUE;
}

/**
 * clutter_get_option_group: (skip)
 *
 * Returns a #GOptionGroup for the command line arguments recognized
 * by Clutter. You should add this group to your #GOptionContext with
 * g_option_context_add_group(), if you are using g_option_context_parse()
 * to parse your commandline arguments.
 *
 * Calling g_option_context_parse() with Clutter's #GOptionGroup will result
 * in Clutter's initialization. That is, the following code:
 *
 * |[
 *   g_option_context_set_main_group (context, clutter_get_option_group ());
 *   res = g_option_context_parse (context, &amp;argc, &amp;argc, NULL);
 * ]|
 *
 * is functionally equivalent to:
 *
 * |[
 *   clutter_init (&amp;argc, &amp;argv);
 * ]|
 *
 * After g_option_context_parse() on a #GOptionContext containing the
 * Clutter #GOptionGroup has returned %TRUE, Clutter is guaranteed to be
 * initialized.
 *
 * Return value: (transfer full): a #GOptionGroup for the commandline arguments
 *   recognized by Clutter
 *
 * Since: 0.2
 */
GOptionGroup *
clutter_get_option_group (void)
{
  ClutterMainContext *context;
  GOptionGroup *group;

  clutter_base_init ();

  context = _clutter_context_get_default ();

  group = g_option_group_new ("clutter",
                              _("Clutter Options"),
                              _("Show Clutter Options"),
                              NULL,
                              NULL);

  g_option_group_set_parse_hooks (group, pre_parse_hook, post_parse_hook);
  g_option_group_add_entries (group, clutter_args);
  g_option_group_set_translation_domain (group, GETTEXT_PACKAGE);

  /* add backend-specific options */
  _clutter_backend_add_options (context->backend, group);

  return group;
}

/**
 * clutter_get_option_group_without_init: (skip)
 *
 * Returns a #GOptionGroup for the command line arguments recognized
 * by Clutter. You should add this group to your #GOptionContext with
 * g_option_context_add_group(), if you are using g_option_context_parse()
 * to parse your commandline arguments.
 *
 * Unlike clutter_get_option_group(), calling g_option_context_parse() with
 * the #GOptionGroup returned by this function requires a subsequent explicit
 * call to clutter_init(); use this function when needing to set foreign
 * display connection with clutter_x11_set_display(), or with
 * <function>gtk_clutter_init()</function>.
 *
 * Return value: (transfer full): a #GOptionGroup for the commandline arguments
 *   recognized by Clutter
 *
 * Since: 0.8.2
 */
GOptionGroup *
clutter_get_option_group_without_init (void)
{
  ClutterMainContext *context;
  GOptionGroup *group;

  clutter_base_init ();

  context = _clutter_context_get_default ();
  context->defer_display_setup = TRUE;

  group = clutter_get_option_group ();

  return group;
}

/* Note that the gobject-introspection annotations for the argc/argv
 * parameters do not produce the right result; however, they do
 * allow the common case of argc=NULL, argv=NULL to work.
 */

/**
 * clutter_init_with_args:
 * @argc: (inout): a pointer to the number of command line arguments
 * @argv: (array length=argc) (inout) (allow-none): a pointer to the array
 *   of command line arguments
 * @parameter_string: (allow-none): a string which is displayed in the
 *   first line of <option>--help</option> output, after
 *   <literal><replaceable>programname</replaceable> [OPTION...]</literal>
 * @entries: (allow-none): a %NULL terminated array of #GOptionEntry<!-- -->s
 *   describing the options of your program
 * @translation_domain: (allow-none): a translation domain to use for
 *   translating the <option>--help</option> output for the options in
 *   @entries with gettext(), or %NULL
 * @error: (allow-none): a return location for a #GError
 *
 * This function does the same work as clutter_init(). Additionally,
 * it allows you to add your own command line options, and it
 * automatically generates nicely formatted <option>--help</option>
 * output. Note that your program will be terminated after writing
 * out the help output. Also note that, in case of error, the
 * error message will be placed inside @error instead of being
 * printed on the display.
 *
 * Return value: %CLUTTER_INIT_SUCCESS if Clutter has been successfully
 *   initialised, or other values or #ClutterInitError in case of
 *   error.
 *
 * Since: 0.2
 */
ClutterInitError
clutter_init_with_args (int            *argc,
                        char         ***argv,
                        const char     *parameter_string,
                        GOptionEntry   *entries,
                        const char     *translation_domain,
                        GError        **error)
{
  GOptionContext *context;
  GOptionGroup *group;
  gboolean res;
  ClutterMainContext *ctx;

  if (clutter_is_initialized)
    return CLUTTER_INIT_SUCCESS;

  clutter_base_init ();

  ctx = _clutter_context_get_default ();

  if (!ctx->defer_display_setup)
    {
#if 0
      if (argc && *argc > 0 && *argv)
	g_set_prgname ((*argv)[0]);
#endif

      context = g_option_context_new (parameter_string);

      group = clutter_get_option_group ();
      g_option_context_add_group (context, group);

      group = cogl_get_option_group ();
      g_option_context_add_group (context, group);

      /* Note: That due to the implementation details of glib's goption
       * parsing; cogl and uprof will not actually have there arguments
       * parsed before the post_parse_hook is called! */
#ifdef CLUTTER_ENABLE_PROFILE
      group = uprof_get_option_group ();
      g_option_context_add_group (context, group);
#endif

      if (entries)
	g_option_context_add_main_entries (context, entries, translation_domain);

      res = g_option_context_parse (context, argc, argv, error);
      g_option_context_free (context);

      /* if res is FALSE, the error is filled for
       * us by g_option_context_parse()
       */
      if (!res)
	{
	  /* if there has been an error in the initialization, the
	   * error id will be preserved inside the GError code
	   */
	  if (error && *error)
	    return (*error)->code;
	  else
	    return CLUTTER_INIT_ERROR_INTERNAL;
	}

      return CLUTTER_INIT_SUCCESS;
    }
  else
    return clutter_init_real (error);
}

static gboolean
clutter_parse_args (int      *argc,
                    char   ***argv,
                    GError  **error)
{
  GOptionContext *option_context;
  GOptionGroup *clutter_group, *cogl_group;
#ifdef CLUTTER_ENABLE_PROFILE
  GOptionGroup *uprof_group;
#endif
  GError *internal_error = NULL;
  gboolean ret = TRUE;

  if (clutter_is_initialized)
    return TRUE;

  option_context = g_option_context_new (NULL);
  g_option_context_set_ignore_unknown_options (option_context, TRUE);
  g_option_context_set_help_enabled (option_context, FALSE);

  /* Initiate any command line options from the backend */
  clutter_group = clutter_get_option_group ();
  g_option_context_set_main_group (option_context, clutter_group);

  cogl_group = cogl_get_option_group ();
  g_option_context_add_group (option_context, cogl_group);

#ifdef CLUTTER_ENABLE_PROFILE
  uprof_group = uprof_get_option_group ();
  g_option_context_add_group (option_context, uprof_group);
#endif

  if (!g_option_context_parse (option_context, argc, argv, &internal_error))
    {
      g_propagate_error (error, internal_error);
      ret = FALSE;
    }

  g_option_context_free (option_context);

  return ret;
}

/**
 * clutter_init:
 * @argc: (inout): The number of arguments in @argv
 * @argv: (array length=argc) (inout) (allow-none): A pointer to an array
 *   of arguments.
 *
 * Initialises everything needed to operate with Clutter and parses some
 * standard command line options; @argc and @argv are adjusted accordingly
 * so your own code will never see those standard arguments.
 *
 * It is safe to call this function multiple times.
 *
 * <note>This function will not abort in case of errors during
 * initialization; clutter_init() will print out the error message on
 * stderr, and will return an error code. It is up to the application
 * code to handle this case. If you need to display the error message
 * yourself, you can use clutter_init_with_args(), which takes a #GError
 * pointer.</note>
 *
 * Return value: a #ClutterInitError value
 */
ClutterInitError
clutter_init (int    *argc,
              char ***argv)
{
  ClutterMainContext *ctx;
  GError *error = NULL;
  ClutterInitError res;

  if (clutter_is_initialized)
    return CLUTTER_INIT_SUCCESS;

  clutter_base_init ();

  ctx = _clutter_context_get_default ();

  if (!ctx->defer_display_setup)
    {
#if 0
      if (argc && *argc > 0 && *argv)
	g_set_prgname ((*argv)[0]);
#endif

      /* parse_args will trigger backend creation and things like
       * DISPLAY connection etc.
       */
      if (!clutter_parse_args (argc, argv, &error))
	{
          g_critical ("Unable to initialize Clutter: %s", error->message);
          g_error_free (error);

          res = CLUTTER_INIT_ERROR_INTERNAL;
	}
      else
        res = CLUTTER_INIT_SUCCESS;
    }
  else
    {
      res = clutter_init_real (&error);
      if (error != NULL)
        {
          g_critical ("Unable to initialize Clutter: %s", error->message);
          g_error_free (error);
        }
    }

  return res;
}

gboolean
_clutter_boolean_handled_accumulator (GSignalInvocationHint *ihint,
                                      GValue                *return_accu,
                                      const GValue          *handler_return,
                                      gpointer               dummy)
{
  gboolean continue_emission;
  gboolean signal_handled;

  signal_handled = g_value_get_boolean (handler_return);
  g_value_set_boolean (return_accu, signal_handled);
  continue_emission = !signal_handled;

  return continue_emission;
}

static void
event_click_count_generate (ClutterEvent *event)
{
  /* multiple button click detection */
  static gint    click_count            = 0;
  static gint    previous_x             = -1;
  static gint    previous_y             = -1;
  static guint32 previous_time          = 0;
  static gint    previous_button_number = -1;

  ClutterInputDevice *device = NULL;
  ClutterSettings *settings;
  guint double_click_time;
  guint double_click_distance;

  settings = clutter_settings_get_default ();

  g_object_get (settings,
                "double-click-distance", &double_click_distance,
                "double-click-time", &double_click_time,
                NULL);

  device = clutter_event_get_device (event);
  if (device != NULL)
    {
      click_count = device->click_count;
      previous_x = device->previous_x;
      previous_y = device->previous_y;
      previous_time = device->previous_time;
      previous_button_number = device->previous_button_number;

      CLUTTER_NOTE (EVENT,
                    "Restoring previous click count:%d (device:%d, time:%u)",
                    click_count,
                    clutter_input_device_get_device_id (device),
                    previous_time);
    }
  else
    {
      CLUTTER_NOTE (EVENT,
                    "Restoring previous click count:%d (time:%u)",
                    click_count,
                    previous_time);
    }

  switch (clutter_event_type (event))
    {
      case CLUTTER_BUTTON_PRESS:
        /* check if we are in time and within distance to increment an
         * existing click count
         */
        if (event->button.button == previous_button_number &&
            event->button.time < (previous_time + double_click_time) &&
            (ABS (event->button.x - previous_x) <= double_click_distance) &&
            (ABS (event->button.y - previous_y) <= double_click_distance))
          {
            CLUTTER_NOTE (EVENT, "Increase click count (button: %d, time: %u)",
                          event->button.button,
                          event->button.time);

            click_count += 1;
          }
        else /* start a new click count*/
          {
            CLUTTER_NOTE (EVENT, "Reset click count (button: %d, time: %u)",
                          event->button.button,
                          event->button.time);

            click_count = 1;
            previous_button_number = event->button.button;
          }

        previous_x = event->button.x;
        previous_y = event->button.y;
        previous_time = event->button.time;

        /* fallthrough */
      case CLUTTER_BUTTON_RELEASE:
        event->button.click_count = click_count;
        break;

      default:
        g_assert_not_reached ();
        break;
    }

  if (event->type == CLUTTER_BUTTON_PRESS && device != NULL)
    {
      CLUTTER_NOTE (EVENT, "Storing click count: %d (device:%d, time:%u)",
                    click_count,
                    clutter_input_device_get_device_id (device),
                    previous_time);

      device->click_count = click_count;
      device->previous_x = previous_x;
      device->previous_y = previous_y;
      device->previous_time = previous_time;
      device->previous_button_number = previous_button_number;
    }
}

static inline void
emit_event (ClutterEvent *event,
            gboolean      is_key_event)
{
  static gboolean      lock = FALSE;

  GPtrArray *event_tree = NULL;
  ClutterActor *actor;
  gint i = 0;

  if (event->any.source == NULL)
    {
      CLUTTER_NOTE (EVENT, "No source set, discarding event");
      return;
    }

  /* reentrancy check */
  if (lock != FALSE)
    {
      g_warning ("Tried emitting event during event delivery, bailing out.");
      return;
    }

  lock = TRUE;

  event_tree = g_ptr_array_sized_new (64);

  actor = event->any.source;

  /* Build 'tree' of emitters for the event */
  while (actor)
    {
      ClutterActor *parent;

      parent = clutter_actor_get_parent (actor);

      if (clutter_actor_get_reactive (actor) ||
          parent == NULL ||         /* stage gets all events */
          is_key_event)             /* keyboard events are always emitted */
        {
          g_ptr_array_add (event_tree, g_object_ref (actor));
        }

      actor = parent;
    }

  /* Capture */
  for (i = event_tree->len - 1; i >= 0; i--)
    if (clutter_actor_event (g_ptr_array_index (event_tree, i), event, TRUE))
      goto done;

  /* Bubble */
  for (i = 0; i < event_tree->len; i++)
    if (clutter_actor_event (g_ptr_array_index (event_tree, i), event, FALSE))
      goto done;

done:
  for (i = 0; i < event_tree->len; i++)
    g_object_unref (g_ptr_array_index (event_tree, i));

  g_ptr_array_free (event_tree, TRUE);

  lock = FALSE;
}

/*
 * Emits a pointer event after having prepared the event for delivery (setting
 * source, computing click_count, generating enter/leave etc.).
 */

static inline void
emit_pointer_event (ClutterEvent       *event,
                    ClutterInputDevice *device)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  if (context->pointer_grab_actor == NULL &&
      (device == NULL || device->pointer_grab_actor == NULL))
    {
      /* no grab, time to capture and bubble */
      emit_event (event, FALSE);
    }
  else
    {
      if (context->pointer_grab_actor != NULL)
        {
          /* global grab */
          clutter_actor_event (context->pointer_grab_actor, event, FALSE);
        }
      else if (device != NULL && device->pointer_grab_actor != NULL)
        {
          /* per device grab */
          clutter_actor_event (device->pointer_grab_actor, event, FALSE);
        }
    }
}

static inline void
emit_keyboard_event (ClutterEvent *event)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  if (context->keyboard_grab_actor == NULL)
    emit_event (event, TRUE);
  else
    clutter_actor_event (context->keyboard_grab_actor, event, FALSE);
}

static gboolean
is_off_stage (ClutterActor *stage,
              gfloat        x,
              gfloat        y)
{
  gfloat width, height;

  clutter_actor_get_size (stage, &width, &height);

  return (x < 0 ||
          y < 0 ||
          x >= width ||
          y >= height);
}

/**
 * clutter_do_event
 * @event: a #ClutterEvent.
 *
 * Processes an event.
 *
 * The @event must be a valid #ClutterEvent and have a #ClutterStage
 * associated to it.
 *
 * This function is only useful when embedding Clutter inside another
 * toolkit, and it should never be called by applications.
 *
 * Since: 0.4
 */
void
clutter_do_event (ClutterEvent *event)
{
  /* we need the stage for the event */
  if (event->any.stage == NULL)
    {
      g_warning ("%s: Event does not have a stage: discarding.", G_STRFUNC);
      return;
    }

  /* stages in destruction do not process events */
  if (CLUTTER_ACTOR_IN_DESTRUCTION (event->any.stage))
    return;

  /* Instead of processing events when received, we queue them up to
   * handle per-frame before animations, layout, and drawing.
   *
   * This gives us the chance to reliably compress motion events
   * because we've "looked ahead" and know all motion events that
   * will occur before drawing the frame.
   */
  _clutter_stage_queue_event (event->any.stage, event);
}

static void
_clutter_process_event_details (ClutterActor        *stage,
                                ClutterMainContext  *context,
                                ClutterEvent        *event)
{
  ClutterInputDevice *device = NULL;

  device = clutter_event_get_device (event);

  switch (event->type)
    {
      case CLUTTER_NOTHING:
        event->any.source = stage;
        break;

      case CLUTTER_KEY_PRESS:
      case CLUTTER_KEY_RELEASE:
        {
          ClutterActor *actor = NULL;

          /* check that we're not a synthetic event with source set */
          if (event->any.source == NULL)
            {
              actor = clutter_stage_get_key_focus (CLUTTER_STAGE (stage));
              event->any.source = actor;
              if (G_UNLIKELY (actor == NULL))
                {
                  g_warning ("No key focus set, discarding");
                  return;
                }
            }

          emit_keyboard_event (event);
        }
        break;

      case CLUTTER_ENTER:
        /* if we're entering from outside the stage we need
         * to check whether the pointer is actually on another
         * actor, and emit an additional pointer event
         */
        if (event->any.source == stage &&
            event->crossing.related == NULL)
          {
            ClutterActor *actor = NULL;

            emit_pointer_event (event, device);

            actor = _clutter_input_device_update (device, FALSE);
            if (actor != stage)
              {
                ClutterEvent *crossing;

                /* we emit the exact same event on the actor */
                crossing = clutter_event_copy (event);
                crossing->crossing.related = stage;
                crossing->crossing.source = actor;

                emit_pointer_event (crossing, device);
                clutter_event_free (crossing);
              }
          }
        else
          emit_pointer_event (event, device);
        break;

      case CLUTTER_LEAVE:
        /* same as CLUTTER_ENTER above: when leaving the stage
         * we need to also emit a CLUTTER_LEAVE event on the
         * actor currently underneath the device, unless it's the
         * stage
         */
        if (event->any.source == stage &&
            event->crossing.related == NULL &&
            device->cursor_actor != stage)
          {
            ClutterEvent *crossing;

            crossing = clutter_event_copy (event);
            crossing->crossing.related = stage;
            crossing->crossing.source = device->cursor_actor;

            emit_pointer_event (crossing, device);
            clutter_event_free (crossing);
          }
        emit_pointer_event (event, device);
        break;

      case CLUTTER_DESTROY_NOTIFY:
      case CLUTTER_DELETE:
        event->any.source = stage;
        /* the stage did not handle the event, so we just quit */
        clutter_stage_event (CLUTTER_STAGE (stage), event);
        break;

      case CLUTTER_MOTION:
        /* only the stage gets motion events if they are enabled */
        if (!_clutter_stage_get_motion_events_enabled (CLUTTER_STAGE (stage)) &&
            event->any.source == NULL)
          {
            /* Only stage gets motion events */
            event->any.source = stage;

            /* global grabs */
            if (context->pointer_grab_actor != NULL)
              {
                clutter_actor_event (context->pointer_grab_actor,
                                     event,
                                     FALSE);
                break;
              }
            else if (device != NULL && device->pointer_grab_actor != NULL)
              {
                clutter_actor_event (device->pointer_grab_actor,
                                     event,
                                     FALSE);
                break;
              }

            /* Trigger handlers on stage in both capture .. */
            if (!clutter_actor_event (stage, event, TRUE))
              {
                /* and bubbling phase */
                clutter_actor_event (stage, event, FALSE);
              }
            break;
          }

      /* fallthrough from motion */
      case CLUTTER_BUTTON_PRESS:
      case CLUTTER_BUTTON_RELEASE:
      case CLUTTER_SCROLL:
        {
          ClutterActor *actor;
          gfloat x, y;

          clutter_event_get_coords (event, &x, &y);

          /* Only do a pick to find the source if source is not already set
           * (as it could be in a synthetic event)
           */
          if (event->any.source == NULL)
            {
              /* emulate X11 the implicit soft grab; the implicit soft grab
               * keeps relaying motion events when the stage is left with a
               * pointer button pressed. since this is what happens when we
               * disable per-actor motion events we need to maintain the same
               * behaviour when the per-actor motion events are enabled as
               * well
               */
              if (is_off_stage (stage, x, y))
                {
                  if (event->type == CLUTTER_BUTTON_RELEASE)
                    {
                      CLUTTER_NOTE (EVENT,
                                    "Release off stage received at %.2f, %.2f",
                                    x, y);

                      event->button.source = stage;
                      event->button.click_count = 1;

                      emit_pointer_event (event, device);
                    }
                  else if (event->type == CLUTTER_MOTION)
                    {
                      CLUTTER_NOTE (EVENT,
                                    "Motion off stage received at %.2f, %2.f",
                                    x, y);

                      event->motion.source = stage;

                      emit_pointer_event (event, device);
                    }

                  break;
                }

              /* if the backend provides a device then we should
               * already have everything we need to update it and
               * get the actor underneath
               */
              if (device != NULL)
                actor = _clutter_input_device_update (device, TRUE);
              else
                {
                  CLUTTER_NOTE (EVENT, "No device found: picking");

                  actor = _clutter_stage_do_pick (CLUTTER_STAGE (stage),
                                                  x, y,
                                                  CLUTTER_PICK_REACTIVE);
                }

              if (actor == NULL)
                break;

              event->any.source = actor;
            }
          else
            {
              /* use the source already set in the synthetic event */
              actor = event->any.source;
            }

          CLUTTER_NOTE (EVENT,
                        "Reactive event received at %.2f, %.2f - actor: %p",
                        x, y,
                        actor);

          /* button presses and releases need a click count */
          if (event->type == CLUTTER_BUTTON_PRESS ||
              event->type == CLUTTER_BUTTON_RELEASE)
            {
              /* Generate click count */
              event_click_count_generate (event);
            }

          emit_pointer_event (event, device);
          break;
        }

      case CLUTTER_STAGE_STATE:
        /* fullscreen / focus - forward to stage */
        event->any.source = stage;
        clutter_stage_event (CLUTTER_STAGE (stage), event);
        break;

      case CLUTTER_CLIENT_MESSAGE:
        break;
    }
}

/**
 * _clutter_process_event
 * @event: a #ClutterEvent.
 *
 * Does the actual work of processing an event that was queued earlier
 * out of clutter_do_event().
 */
void
_clutter_process_event (ClutterEvent *event)
{
  ClutterMainContext *context;
  ClutterActor *stage;

  context = _clutter_context_get_default ();

  stage = CLUTTER_ACTOR (event->any.stage);
  if (stage == NULL)
    return;

  CLUTTER_TIMESTAMP (EVENT, "Event received");

  context->last_event_time = clutter_event_get_time (event);

  context->current_event = event;
  _clutter_process_event_details (stage, context, event);
  context->current_event = NULL;
}

/**
 * clutter_get_actor_by_gid:
 * @id_: a #ClutterActor unique id.
 *
 * Retrieves the #ClutterActor with @id_.
 *
 * Return value: (transfer none): the actor with the passed id or %NULL.
 *   The returned actor does not have its reference count increased.
 *
 * Since: 0.6
 *
 * Deprecated: 1.8: The id is not used any longer.
 */
ClutterActor *
clutter_get_actor_by_gid (guint32 id_)
{
  return _clutter_get_actor_by_id (NULL, id_);
}

void
clutter_base_init (void)
{
  static gboolean initialised = FALSE;

  if (!initialised)
    {
      initialised = TRUE;

      bindtextdomain (GETTEXT_PACKAGE, CLUTTER_LOCALEDIR);
      bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");

      /* initialise GLib type system */
      g_type_init ();
    }
}

/**
 * clutter_get_default_frame_rate:
 *
 * Retrieves the default frame rate. See clutter_set_default_frame_rate().
 *
 * Return value: the default frame rate
 *
 * Since: 0.6
 */
guint
clutter_get_default_frame_rate (void)
{
  ClutterMainContext *context;

  context = _clutter_context_get_default ();

  return context->frame_rate;
}

/**
 * clutter_set_default_frame_rate:
 * @frames_per_sec: the new default frame rate
 *
 * Sets the default frame rate. This frame rate will be used to limit
 * the number of frames drawn if Clutter is not able to synchronize
 * with the vertical refresh rate of the display. When synchronization
 * is possible, this value is ignored.
 *
 * Since: 0.6
 */
void
clutter_set_default_frame_rate (guint frames_per_sec)
{
  ClutterMainContext *context;

  context = _clutter_context_get_default ();

  if (context->frame_rate != frames_per_sec)
    context->frame_rate = frames_per_sec;
}


static void
on_pointer_grab_weak_notify (gpointer data,
                             GObject *where_the_object_was)
{
  ClutterInputDevice *dev = (ClutterInputDevice *)data;
  ClutterMainContext *context;

  context = _clutter_context_get_default ();

  if (dev)
    {
      dev->pointer_grab_actor = NULL;
      clutter_ungrab_pointer_for_device (dev->id);
    }
  else
    {
      context->pointer_grab_actor = NULL;
      clutter_ungrab_pointer ();
    }
}

/**
 * clutter_grab_pointer:
 * @actor: a #ClutterActor
 *
 * Grabs pointer events, after the grab is done all pointer related events
 * (press, motion, release, enter, leave and scroll) are delivered to this
 * actor directly without passing through both capture and bubble phases of
 * the event delivery chain. The source set in the event will be the actor
 * that would have received the event if the pointer grab was not in effect.
 *
 * <note><para>Grabs completely override the entire event delivery chain
 * done by Clutter. Pointer grabs should only be used as a last resource;
 * using the #ClutterActor::captured-event signal should always be the
 * preferred way to intercept event delivery to reactive actors.</para></note>
 *
 * If you wish to grab all the pointer events for a specific input device,
 * you should use clutter_grab_pointer_for_device().
 *
 * Since: 0.6
 */
void
clutter_grab_pointer (ClutterActor *actor)
{
  ClutterMainContext *context;

  g_return_if_fail (actor == NULL || CLUTTER_IS_ACTOR (actor));

  context = _clutter_context_get_default ();

  if (context->pointer_grab_actor == actor)
    return;

  if (context->pointer_grab_actor)
    {
      g_object_weak_unref (G_OBJECT (context->pointer_grab_actor),
			   on_pointer_grab_weak_notify,
			   NULL);
      context->pointer_grab_actor = NULL;
    }

  if (actor)
    {
      context->pointer_grab_actor = actor;

      g_object_weak_ref (G_OBJECT (actor),
			 on_pointer_grab_weak_notify,
			 NULL);
    }
}

/**
 * clutter_grab_pointer_for_device:
 * @actor: a #ClutterActor
 * @id_: a device id, or -1
 *
 * Grabs all the pointer events coming from the device @id for @actor.
 *
 * If @id is -1 then this function is equivalent to clutter_grab_pointer().
 *
 * Since: 0.8
 */
void
clutter_grab_pointer_for_device (ClutterActor *actor,
                                 gint          id_)
{
  ClutterInputDevice *dev;

  g_return_if_fail (actor == NULL || CLUTTER_IS_ACTOR (actor));

  /* essentially a global grab */
  if (id_ == -1)
    {
      clutter_grab_pointer (actor);
      return;
    }

  dev = clutter_get_input_device_for_id (id_);
  if (dev == NULL)
    return;

  if (dev->pointer_grab_actor == actor)
    return;

  if (dev->pointer_grab_actor)
    {
      g_object_weak_unref (G_OBJECT (dev->pointer_grab_actor),
                           on_pointer_grab_weak_notify,
                           dev);
      dev->pointer_grab_actor = NULL;
    }

  if (actor)
    {
      dev->pointer_grab_actor = actor;

      g_object_weak_ref (G_OBJECT (actor),
                         on_pointer_grab_weak_notify,
                         dev);
    }
}


/**
 * clutter_ungrab_pointer:
 *
 * Removes an existing grab of the pointer.
 *
 * Since: 0.6
 */
void
clutter_ungrab_pointer (void)
{
  clutter_grab_pointer (NULL);
}

/**
 * clutter_ungrab_pointer_for_device:
 * @id_: a device id
 *
 * Removes an existing grab of the pointer events for device @id_.
 *
 * Since: 0.8
 */
void
clutter_ungrab_pointer_for_device (gint id_)
{
  clutter_grab_pointer_for_device (NULL, id_);
}


/**
 * clutter_get_pointer_grab:
 *
 * Queries the current pointer grab of clutter.
 *
 * Return value: (transfer none): the actor currently holding the pointer grab, or NULL if there is no grab.
 *
 * Since: 0.6
 */
ClutterActor *
clutter_get_pointer_grab (void)
{
  ClutterMainContext *context;
  context = _clutter_context_get_default ();

  return context->pointer_grab_actor;
}


static void
on_keyboard_grab_weak_notify (gpointer data,
                              GObject *where_the_object_was)
{
  ClutterMainContext *context;

  context = _clutter_context_get_default ();
  context->keyboard_grab_actor = NULL;

  clutter_ungrab_keyboard ();
}

/**
 * clutter_grab_keyboard:
 * @actor: a #ClutterActor
 *
 * Grabs keyboard events, after the grab is done keyboard
 * events (#ClutterActor::key-press-event and #ClutterActor::key-release-event)
 * are delivered to this actor directly. The source set in the event will be
 * the actor that would have received the event if the keyboard grab was not
 * in effect.
 *
 * Like pointer grabs, keyboard grabs should only be used as a last
 * resource.
 *
 * See also clutter_stage_set_key_focus() and clutter_actor_grab_key_focus()
 * to perform a "soft" key grab and assign key focus to a specific actor.
 *
 * Since: 0.6
 */
void
clutter_grab_keyboard (ClutterActor *actor)
{
  ClutterMainContext *context;

  g_return_if_fail (actor == NULL || CLUTTER_IS_ACTOR (actor));

  context = _clutter_context_get_default ();

  if (context->keyboard_grab_actor == actor)
    return;

  if (context->keyboard_grab_actor)
    {
      g_object_weak_unref (G_OBJECT (context->keyboard_grab_actor),
			   on_keyboard_grab_weak_notify,
			   NULL);
      context->keyboard_grab_actor = NULL;
    }

  if (actor)
    {
      context->keyboard_grab_actor = actor;

      g_object_weak_ref (G_OBJECT (actor),
			 on_keyboard_grab_weak_notify,
			 NULL);
    }
}

/**
 * clutter_ungrab_keyboard:
 *
 * Removes an existing grab of the keyboard.
 *
 * Since: 0.6
 */
void
clutter_ungrab_keyboard (void)
{
  clutter_grab_keyboard (NULL);
}

/**
 * clutter_get_keyboard_grab:
 *
 * Queries the current keyboard grab of clutter.
 *
 * Return value: (transfer none): the actor currently holding the keyboard grab, or NULL if there is no grab.
 *
 * Since: 0.6
 */
ClutterActor *
clutter_get_keyboard_grab (void)
{
  ClutterMainContext *context;

  context = _clutter_context_get_default ();

  return context->keyboard_grab_actor;
}

/**
 * clutter_clear_glyph_cache:
 *
 * Clears the internal cache of glyphs used by the Pango
 * renderer. This will free up some memory and GL texture
 * resources. The cache will be automatically refilled as more text is
 * drawn.
 *
 * Since: 0.8
 */
void
clutter_clear_glyph_cache (void)
{
  CoglPangoFontMap *font_map;

  font_map = clutter_context_get_pango_fontmap ();
  cogl_pango_font_map_clear_glyph_cache (font_map);
}

/**
 * clutter_set_font_flags:
 * @flags: The new flags
 *
 * Sets the font quality options for subsequent text rendering
 * operations.
 *
 * Using mipmapped textures will improve the quality for scaled down
 * text but will use more texture memory.
 *
 * Enabling hinting improves text quality for static text but may
 * introduce some artifacts if the text is animated.
 *
 * Since: 1.0
 */
void
clutter_set_font_flags (ClutterFontFlags flags)
{
  ClutterMainContext *context = _clutter_context_get_default ();
  CoglPangoFontMap *font_map;
  ClutterFontFlags old_flags, changed_flags;
  const cairo_font_options_t *font_options;
  cairo_font_options_t *new_font_options;
  gboolean use_mipmapping;
  ClutterBackend *backend;

  backend = clutter_get_default_backend ();

  font_map = clutter_context_get_pango_fontmap ();
  use_mipmapping = (flags & CLUTTER_FONT_MIPMAPPING) != 0;
  cogl_pango_font_map_set_use_mipmapping (font_map, use_mipmapping);

  old_flags = clutter_get_font_flags ();

  font_options = clutter_backend_get_font_options (backend);
  new_font_options = cairo_font_options_copy (font_options);

  /* Only set the font options that have actually changed so we don't
     override a detailed setting from the backend */
  changed_flags = old_flags ^ flags;

  if ((changed_flags & CLUTTER_FONT_HINTING))
    cairo_font_options_set_hint_style (new_font_options,
                                       (flags & CLUTTER_FONT_HINTING)
                                       ? CAIRO_HINT_STYLE_FULL
                                       : CAIRO_HINT_STYLE_NONE);

  clutter_backend_set_font_options (backend, new_font_options);

  cairo_font_options_destroy (new_font_options);

  /* update the default pango context, if any */
  if (context->pango_context != NULL)
    update_pango_context (backend, context->pango_context);
}

/**
 * clutter_get_font_flags:
 *
 * Gets the current font flags for rendering text. See
 * clutter_set_font_flags().
 *
 * Return value: The font flags
 *
 * Since: 1.0
 */
ClutterFontFlags
clutter_get_font_flags (void)
{
  CoglPangoFontMap *font_map = NULL;
  const cairo_font_options_t *font_options;
  ClutterFontFlags flags = 0;
  cairo_hint_style_t hint_style;

  font_map = clutter_context_get_pango_fontmap ();
  if (cogl_pango_font_map_get_use_mipmapping (font_map))
    flags |= CLUTTER_FONT_MIPMAPPING;

  font_options =
    clutter_backend_get_font_options (clutter_get_default_backend ());

  hint_style = cairo_font_options_get_hint_style (font_options);
  if (hint_style != CAIRO_HINT_STYLE_DEFAULT &&
      hint_style != CAIRO_HINT_STYLE_NONE)
    flags |= CLUTTER_FONT_HINTING;

  return flags;
}

/**
 * clutter_get_input_device_for_id:
 * @id_: the unique id for a device
 *
 * Retrieves the #ClutterInputDevice from its @id_. This is a convenience
 * wrapper for clutter_device_manager_get_device() and it is functionally
 * equivalent to:
 *
 * |[
 *   ClutterDeviceManager *manager;
 *   ClutterInputDevice *device;
 *
 *   manager = clutter_device_manager_get_default ();
 *   device = clutter_device_manager_get_device (manager, id);
 * ]|
 *
 * Return value: (transfer none): a #ClutterInputDevice, or %NULL
 *
 * Since: 0.8
 */
ClutterInputDevice *
clutter_get_input_device_for_id (gint id_)
{
  ClutterDeviceManager *manager;

  manager = clutter_device_manager_get_default ();

  return clutter_device_manager_get_device (manager, id_);
}

/**
 * clutter_get_font_map:
 *
 * Retrieves the #PangoFontMap instance used by Clutter.
 * You can use the global font map object with the COGL
 * Pango API.
 *
 * Return value: (transfer none): the #PangoFontMap instance. The returned
 *   value is owned by Clutter and it should never be unreferenced.
 *
 * Since: 1.0
 */
PangoFontMap *
clutter_get_font_map (void)
{
  return PANGO_FONT_MAP (clutter_context_get_pango_fontmap ());
}

typedef struct _ClutterRepaintFunction
{
  guint id;
  GSourceFunc func;
  gpointer data;
  GDestroyNotify notify;
} ClutterRepaintFunction;

/**
 * clutter_threads_remove_repaint_func:
 * @handle_id: an unsigned integer greater than zero
 *
 * Removes the repaint function with @handle_id as its id
 *
 * Since: 1.0
 */
void
clutter_threads_remove_repaint_func (guint handle_id)
{
  ClutterRepaintFunction *repaint_func;
  ClutterMainContext *context;
  GList *l;

  g_return_if_fail (handle_id > 0);

  context = _clutter_context_get_default ();
  l = context->repaint_funcs;
  while (l != NULL)
    {
      repaint_func = l->data;

      if (repaint_func->id == handle_id)
        {
          context->repaint_funcs =
            g_list_remove_link (context->repaint_funcs, l);

          g_list_free (l);

          if (repaint_func->notify)
            repaint_func->notify (repaint_func->data);

          g_slice_free (ClutterRepaintFunction, repaint_func);

          return;
        }

      l = l->next;
    }
}

/**
 * clutter_threads_add_repaint_func:
 * @func: the function to be called within the paint cycle
 * @data: data to be passed to the function, or %NULL
 * @notify: function to be called when removing the repaint
 *    function, or %NULL
 *
 * Adds a function to be called whenever Clutter is repainting a Stage.
 * If the function returns %FALSE it is automatically removed from the
 * list of repaint functions and will not be called again.
 *
 * This function is guaranteed to be called from within the same thread
 * that called clutter_main(), and while the Clutter lock is being held.
 *
 * A repaint function is useful to ensure that an update of the scenegraph
 * is performed before the scenegraph is repainted; for instance, uploading
 * a frame from a video into a #ClutterTexture.
 *
 * When the repaint function is removed (either because it returned %FALSE
 * or because clutter_threads_remove_repaint_func() has been called) the
 * @notify function will be called, if any is set.
 *
 * Return value: the ID (greater than 0) of the repaint function. You
 *   can use the returned integer to remove the repaint function by
 *   calling clutter_threads_remove_repaint_func().
 *
 * Since: 1.0
 */
guint
clutter_threads_add_repaint_func (GSourceFunc    func,
                                  gpointer       data,
                                  GDestroyNotify notify)
{
  static guint repaint_id = 1;
  ClutterMainContext *context;
  ClutterRepaintFunction *repaint_func;

  g_return_val_if_fail (func != NULL, 0);

  context = _clutter_context_get_default ();

  /* XXX lock the context */

  repaint_func = g_slice_new (ClutterRepaintFunction);

  repaint_func->id = repaint_id++;
  repaint_func->func = func;
  repaint_func->data = data;
  repaint_func->notify = notify;

  context->repaint_funcs = g_list_prepend (context->repaint_funcs,
                                           repaint_func);

  /* XXX unlock the context */

  return repaint_func->id;
}

/*
 * _clutter_run_repaint_functions:
 *
 * Executes the repaint functions added using the
 * clutter_threads_add_repaint_func() function.
 *
 * Must be called before calling clutter_redraw() and
 * with the Clutter thread lock held.
 */
void
_clutter_run_repaint_functions (void)
{
  ClutterMainContext *context = _clutter_context_get_default ();
  ClutterRepaintFunction *repaint_func;
  GList *reinvoke_list, *l;

  if (context->repaint_funcs == NULL)
    return;

  reinvoke_list = NULL;

  /* consume the whole list while we execute the functions */
  while (context->repaint_funcs)
    {
      gboolean res = FALSE;

      repaint_func = context->repaint_funcs->data;

      l = context->repaint_funcs;
      context->repaint_funcs =
        g_list_remove_link (context->repaint_funcs, context->repaint_funcs);

      g_list_free (l);

      res = repaint_func->func (repaint_func->data);

      if (res)
        reinvoke_list = g_list_prepend (reinvoke_list, repaint_func);
      else
        {
          if (repaint_func->notify)
            repaint_func->notify (repaint_func->data);

          g_slice_free (ClutterRepaintFunction, repaint_func);
        }
    }

  if (reinvoke_list)
    context->repaint_funcs = reinvoke_list;
}

/**
 * clutter_check_version:
 * @major: major version, like 1 in 1.2.3
 * @minor: minor version, like 2 in 1.2.3
 * @micro: micro version, like 3 in 1.2.3
 *
 * Run-time version check, to check the version the Clutter library
 * that an application is currently linked against
 *
 * This is the run-time equivalent of the compile-time %CLUTTER_CHECK_VERSION
 * pre-processor macro
 *
 * Return value: %TRUE if the version of the Clutter library is
 *   greater than (@major, @minor, @micro), and %FALSE otherwise
 *
 * Since: 1.2
 */
gboolean
clutter_check_version (guint major,
                       guint minor,
                       guint micro)
{
  return (clutter_major_version > major ||
          (clutter_major_version == major &&
           clutter_minor_version > minor) ||
          (clutter_major_version == major &&
           clutter_minor_version == minor &&
           clutter_micro_version >= micro));
}

/**
 * clutter_get_default_text_direction:
 *
 * Retrieves the default direction for the text. The text direction is
 * determined by the locale and/or by the %CLUTTER_TEXT_DIRECTION environment
 * variable
 *
 * The default text direction can be overridden on a per-actor basis by using
 * clutter_actor_set_text_direction()
 *
 * Return value: the default text direction
 *
 * Since: 1.2
 */
ClutterTextDirection
clutter_get_default_text_direction (void)
{
  return clutter_text_direction;
}

/*< private >
 * clutter_clear_events_queue:
 *
 * Clears the events queue stored in the main context.
 */
void
_clutter_clear_events_queue (void)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  if (context->events_queue != NULL)
    {
      g_queue_foreach (context->events_queue,
                       (GFunc) clutter_event_free,
                       NULL);
      g_queue_free (context->events_queue);
      context->events_queue = NULL;
    }
}

guint32
_clutter_context_acquire_id (gpointer key)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  return _clutter_id_pool_add (context->id_pool, key);
}

void
_clutter_context_release_id (guint32 id_)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  return _clutter_id_pool_remove (context->id_pool, id_);
}

void
_clutter_clear_events_queue_for_stage (ClutterStage *stage)
{
  ClutterMainContext *context = _clutter_context_get_default ();
  GList *l, *next;

  if (context->events_queue == NULL)
    return;

  /* Remove any pending events for this stage from the event queue */
  for (l = context->events_queue->head; l; l = next)
    {
      ClutterEvent *event = l->data;

      next = l->next;

      if (event->any.stage == stage)
        {
          g_queue_delete_link (context->events_queue, l);
          clutter_event_free (event);
        }
    }
}

ClutterPickMode
_clutter_context_get_pick_mode (void)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  return context->pick_mode;
}

void
_clutter_context_push_shader_stack (ClutterActor *actor)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  context->shaders = g_slist_prepend (context->shaders, actor);
}

ClutterActor *
_clutter_context_peek_shader_stack (void)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  if (context->shaders != NULL)
    return context->shaders->data;

  return NULL;
}

ClutterActor *
_clutter_context_pop_shader_stack (ClutterActor *actor)
{
  ClutterMainContext *context = _clutter_context_get_default ();

  context->shaders = g_slist_remove (context->shaders, actor);

  return _clutter_context_peek_shader_stack ();
}