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/* 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>
#include "gstcontrolsource.h"
#define GST_CAT_DEFAULT controller_debug
GST_DEBUG_CATEGORY_EXTERN (GST_CAT_DEFAULT);
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.
*/
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
*/
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.
*/
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;
}
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