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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 "gst_private.h"
#include <glib-object.h>
#include <gst/gst.h>
#include "gstcontrolsource.h"
#define GST_CAT_DEFAULT control_source_debug
GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
#define _do_init \
GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "gstcontrolsource", 0, \
"dynamic parameter control sources");
G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GstControlSource, gst_control_source,
GST_TYPE_OBJECT, _do_init);
static GObject *gst_control_source_constructor (GType type,
guint n_construct_params, GObjectConstructParam * construct_params);
static void
gst_control_source_class_init (GstControlSourceClass * klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->constructor = gst_control_source_constructor;
}
static void
gst_control_source_init (GstControlSource * self)
{
self->get_value = NULL;
self->get_value_array = NULL;
}
static GObject *
gst_control_source_constructor (GType type, guint n_construct_params,
GObjectConstructParam * construct_params)
{
GObject *self;
self =
G_OBJECT_CLASS (gst_control_source_parent_class)->constructor (type,
n_construct_params, construct_params);
gst_object_ref_sink (self);
return self;
}
/**
* 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,
gdouble * 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 first timestamp
* @interval: the time steps
* @n_values: the number of values to fetch
* @values: array to put control-values in
*
* Gets an array of values for for this #GstControlSource. Values that are
* undefined contain NANs.
*
* Returns: %TRUE if the given array could be filled, %FALSE otherwise
*/
gboolean
gst_control_source_get_value_array (GstControlSource * self,
GstClockTime timestamp, GstClockTime interval, guint n_values,
gdouble * values)
{
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, interval, n_values, values);
} else {
GST_ERROR ("Not bound to a specific property yet!");
return FALSE;
}
}
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