/* GStreamer

 *

 * Copyright (C) 2007 Sebastian Dröge <slomo@circular-chaos.org>

 *

 * gstcontrolsource.c: Interface declaration for control sources

 *

 * 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, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

/**

 * SECTION:gstcontrolsource

 * @short_description: base class for control source sources

 *

 * The #GstControlSource is a base class for control value sources that could

 * be used by #GstController to get timestamp-value pairs.

 *

 * A #GstControlSource is used by first getting an instance, binding it to a

 * #GParamSpec (for example by using gst_controller_set_control_source()) and

 * then by having it used by the #GstController or calling

 * gst_control_source_get_value() or gst_control_source_get_value_array().

 *

 * For implementing a new #GstControlSource one has to implement a

 * #GstControlSourceBind method, which will depending on the #GParamSpec set up

 * the control source for use and sets the #GstControlSourceGetValue and

 * #GstControlSourceGetValueArray functions. These are then used by

 * gst_control_source_get_value() or gst_control_source_get_value_array()

 * to get values for specific timestamps.

 *

 */

#include <glib-object.h>

#include <gst/gst.h>

#define GST_CAT_DEFAULT controller_debug

GST_DEBUG_CATEGORY_EXTERN (GST_CAT_DEFAULT);

static void gst_control_source_class_init (GstControlSourceClass * klass);

static void gst_control_source_init (GstControlSource * self);

G_DEFINE_ABSTRACT_TYPE (GstControlSource, gst_control_source, G_TYPE_OBJECT);

static GObjectClass *parent_class = NULL;

static void

gst_control_source_class_init (GstControlSourceClass * klass)

{

  //GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  parent_class = g_type_class_peek_parent (klass);

  /* Has to be implemented by children */

  klass->bind = NULL;

}

static void

gst_control_source_init (GstControlSource * self)

{

  /* Set default handlers that print a warning */

  self->get_value = NULL;

  self->get_value_array = NULL;

  self->bound = FALSE;

}

/**

 * gst_control_source_get_value:

 * @self: the #GstControlSource object

 * @timestamp: the time for which the value should be returned

 * @value: the value

 *

 * Gets the value for this #GstControlSource at a given timestamp.

 *

 * Returns: FALSE if the value couldn't be returned, TRUE otherwise.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

gboolean

gst_control_source_get_value (GstControlSource * self, GstClockTime timestamp,

    GValue * value)

{

  g_return_val_if_fail (GST_IS_CONTROL_SOURCE (self), FALSE);

  if (G_LIKELY (self->get_value)) {

    return self->get_value (self, timestamp, value);

  } else {

    GST_ERROR ("Not bound to a specific property yet!");

    return FALSE;

  }

}

/**

 * gst_control_source_get_value_array:

 * @self: the #GstControlSource object

 * @timestamp: the time that should be processed

 * @value_array: array to put control-values in

 *

 * Gets an array of values for one element property.

 *

 * All fields of @value_array must be filled correctly. Especially the

 * @value_array->values array must be big enough to keep the requested amount

 * of values.

 *

 * The type of the values in the array is the same as the property's type.

 *

 * Returns: %TRUE if the given array could be filled, %FALSE otherwise

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

gboolean

gst_control_source_get_value_array (GstControlSource * self,

    GstClockTime timestamp, GstValueArray * value_array)

{

  g_return_val_if_fail (GST_IS_CONTROL_SOURCE (self), FALSE);

  if (G_LIKELY (self->get_value_array)) {

    return self->get_value_array (self, timestamp, value_array);

  } else {

    GST_ERROR ("Not bound to a specific property yet!");

    return FALSE;

  }

}

/**

 * gst_control_source_bind:

 * @self: the #GstControlSource object

 * @pspec: #GParamSpec for the property for which this #GstControlSource should generate values.

 *

 * Binds a #GstControlSource to a specific property. This must be called only once for a

 * #GstControlSource.

 *

 * Returns: %TRUE if the #GstControlSource was bound correctly, %FALSE otherwise.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

gboolean

gst_control_source_bind (GstControlSource * self, GParamSpec * pspec)

{

  gboolean ret = FALSE;

  g_return_val_if_fail (GST_IS_CONTROL_SOURCE (self), FALSE);

  g_return_val_if_fail (GST_CONTROL_SOURCE_GET_CLASS (self)->bind, FALSE);

  g_return_val_if_fail (!self->bound, FALSE);

  ret = GST_CONTROL_SOURCE_GET_CLASS (self)->bind (self, pspec);

  if (ret)

    self->bound = TRUE;

  return ret;

}