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3332e39baa
Returned string should be freed Fixes #319
586 lines
16 KiB
C
586 lines
16 KiB
C
/* GStreamer
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* Copyright (C) 2005 Stefan Kost <ensonic@users.sf.net>
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*
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* gstchildproxy.c: interface for multi child elements
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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/**
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* SECTION:gstchildproxy
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* @title: GstChildProxy
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* @short_description: Interface for multi child elements.
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* @see_also: #GstBin
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*
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* This interface abstracts handling of property sets for elements with
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* children. Imagine elements such as mixers or polyphonic generators. They all
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* have multiple #GstPad or some kind of voice objects. Another use case are
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* container elements like #GstBin.
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* The element implementing the interface acts as a parent for those child
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* objects.
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*
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* By implementing this interface the child properties can be accessed from the
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* parent element by using gst_child_proxy_get() and gst_child_proxy_set().
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*
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* Property names are written as "child-name::property-name". The whole naming
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* scheme is recursive. Thus "child1::child2::property" is valid too, if
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* "child1" and "child2" implement the #GstChildProxy interface.
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*/
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#include "gst_private.h"
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#include "gstchildproxy.h"
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#include <gobject/gvaluecollector.h>
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/* signals */
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enum
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{
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CHILD_ADDED,
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CHILD_REMOVED,
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LAST_SIGNAL
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};
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static guint signals[LAST_SIGNAL] = { 0 };
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static GObject *
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gst_child_proxy_default_get_child_by_name (GstChildProxy * parent,
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const gchar * name)
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{
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guint count, i;
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GObject *object, *result;
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gchar *object_name;
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g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), NULL);
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g_return_val_if_fail (name != NULL, NULL);
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result = NULL;
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count = gst_child_proxy_get_children_count (parent);
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for (i = 0; i < count; i++) {
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gboolean eq;
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if (!(object = gst_child_proxy_get_child_by_index (parent, i)))
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continue;
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if (!GST_IS_OBJECT (object)) {
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goto next;
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}
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object_name = gst_object_get_name (GST_OBJECT_CAST (object));
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if (object_name == NULL) {
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g_warning ("child %u of parent %s has no name", i,
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GST_OBJECT_NAME (parent));
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goto next;
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}
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eq = g_str_equal (object_name, name);
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g_free (object_name);
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if (eq) {
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result = object;
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break;
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}
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next:
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g_object_unref (object);
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}
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return result;
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}
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/**
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* gst_child_proxy_get_child_by_name:
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* @parent: the parent object to get the child from
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* @name: the child's name
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*
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* Looks up a child element by the given name.
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*
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* This virtual method has a default implementation that uses #GstObject
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* together with gst_object_get_name(). If the interface is to be used with
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* #GObjects, this methods needs to be overridden.
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*
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* Returns: (transfer full) (nullable): the child object or %NULL if
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* not found. Unref after usage.
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*
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* MT safe.
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*/
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GObject *
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gst_child_proxy_get_child_by_name (GstChildProxy * parent, const gchar * name)
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{
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GstChildProxyInterface *iface;
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g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), 0);
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iface = GST_CHILD_PROXY_GET_INTERFACE (parent);
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if (iface->get_child_by_name != NULL)
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return iface->get_child_by_name (parent, name);
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return NULL;
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}
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/**
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* gst_child_proxy_get_child_by_index:
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* @parent: the parent object to get the child from
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* @index: the child's position in the child list
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*
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* Fetches a child by its number.
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*
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* Returns: (transfer full) (nullable): the child object or %NULL if
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* not found (index too high). Unref after usage.
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*
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* MT safe.
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*/
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GObject *
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gst_child_proxy_get_child_by_index (GstChildProxy * parent, guint index)
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{
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GstChildProxyInterface *iface;
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g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), NULL);
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iface = GST_CHILD_PROXY_GET_INTERFACE (parent);
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if (iface->get_child_by_index != NULL)
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return iface->get_child_by_index (parent, index);
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return NULL;
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}
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/**
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* gst_child_proxy_get_children_count:
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* @parent: the parent object
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*
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* Gets the number of child objects this parent contains.
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*
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* Returns: the number of child objects
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*
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* MT safe.
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*/
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guint
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gst_child_proxy_get_children_count (GstChildProxy * parent)
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{
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GstChildProxyInterface *iface;
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g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), 0);
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iface = GST_CHILD_PROXY_GET_INTERFACE (parent);
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if (iface->get_children_count != NULL)
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return iface->get_children_count (parent);
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return 0;
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}
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/**
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* gst_child_proxy_lookup:
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* @object: child proxy object to lookup the property in
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* @name: name of the property to look up
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* @target: (out) (allow-none) (transfer full): pointer to a #GObject that
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* takes the real object to set property on
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* @pspec: (out) (allow-none) (transfer none): pointer to take the #GParamSpec
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* describing the property
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*
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* Looks up which object and #GParamSpec would be effected by the given @name.
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*
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* MT safe.
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*
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* Returns: %TRUE if @target and @pspec could be found. %FALSE otherwise. In that
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* case the values for @pspec and @target are not modified. Unref @target after
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* usage. For plain GObjects @target is the same as @object.
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*/
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gboolean
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gst_child_proxy_lookup (GstChildProxy * object, const gchar * name,
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GObject ** target, GParamSpec ** pspec)
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{
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GObject *obj;
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gboolean res = FALSE;
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gchar **names, **current;
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g_return_val_if_fail (GST_IS_CHILD_PROXY (object), FALSE);
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g_return_val_if_fail (name != NULL, FALSE);
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obj = G_OBJECT (g_object_ref (object));
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current = names = g_strsplit (name, "::", -1);
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/* find the owner of the property */
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while (current[1]) {
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GObject *next;
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if (!GST_IS_CHILD_PROXY (obj)) {
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GST_INFO
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("object %s is not a parent, so you cannot request a child by name %s",
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(GST_IS_OBJECT (obj) ? GST_OBJECT_NAME (obj) : ""), current[0]);
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break;
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}
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next = gst_child_proxy_get_child_by_name (GST_CHILD_PROXY (obj),
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current[0]);
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if (!next) {
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GST_INFO ("no such object %s", current[0]);
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break;
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}
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g_object_unref (obj);
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obj = next;
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current++;
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}
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/* look for psec */
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if (current[1] == NULL) {
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GParamSpec *spec =
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g_object_class_find_property (G_OBJECT_GET_CLASS (obj), current[0]);
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if (spec == NULL) {
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GST_INFO ("no param spec named %s", current[0]);
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} else {
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if (pspec)
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*pspec = spec;
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if (target) {
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g_object_ref (obj);
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*target = obj;
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}
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res = TRUE;
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}
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}
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g_object_unref (obj);
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g_strfreev (names);
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return res;
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}
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/**
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* gst_child_proxy_get_property:
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* @object: object to query
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* @name: name of the property
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* @value: (out caller-allocates): a #GValue that should take the result.
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*
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* Gets a single property using the GstChildProxy mechanism.
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* You are responsible for freeing it by calling g_value_unset()
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*/
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void
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gst_child_proxy_get_property (GstChildProxy * object, const gchar * name,
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GValue * value)
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{
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GParamSpec *pspec;
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GObject *target;
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g_return_if_fail (GST_IS_CHILD_PROXY (object));
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g_return_if_fail (name != NULL);
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g_return_if_fail (G_IS_VALUE (value));
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if (!gst_child_proxy_lookup (object, name, &target, &pspec))
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goto not_found;
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g_object_get_property (target, pspec->name, value);
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g_object_unref (target);
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return;
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not_found:
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{
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g_warning ("no property %s in object %s", name,
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(GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
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return;
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}
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}
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/**
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* gst_child_proxy_get_valist:
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* @object: the object to query
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* @first_property_name: name of the first property to get
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* @var_args: return location for the first property, followed optionally by more name/return location pairs, followed by %NULL
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*
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* Gets properties of the parent object and its children.
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*/
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void
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gst_child_proxy_get_valist (GstChildProxy * object,
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const gchar * first_property_name, va_list var_args)
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{
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const gchar *name;
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gchar *error = NULL;
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GValue value = { 0, };
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GParamSpec *pspec;
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GObject *target;
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g_return_if_fail (GST_IS_CHILD_PROXY (object));
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name = first_property_name;
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/* iterate over pairs */
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while (name) {
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if (!gst_child_proxy_lookup (object, name, &target, &pspec))
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goto not_found;
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g_value_init (&value, pspec->value_type);
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g_object_get_property (target, pspec->name, &value);
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g_object_unref (target);
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G_VALUE_LCOPY (&value, var_args, 0, &error);
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if (error)
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goto cant_copy;
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g_value_unset (&value);
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name = va_arg (var_args, gchar *);
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}
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return;
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not_found:
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{
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g_warning ("no property %s in object %s", name,
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(GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
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return;
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}
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cant_copy:
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{
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g_warning ("error copying value %s in object %s: %s", pspec->name,
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(GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""), error);
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g_value_unset (&value);
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return;
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}
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}
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/**
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* gst_child_proxy_get:
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* @object: the parent object
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* @first_property_name: name of the first property to get
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* @...: return location for the first property, followed optionally by more name/return location pairs, followed by %NULL
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*
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* Gets properties of the parent object and its children.
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*/
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void
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gst_child_proxy_get (GstChildProxy * object, const gchar * first_property_name,
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...)
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{
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va_list var_args;
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g_return_if_fail (GST_IS_CHILD_PROXY (object));
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va_start (var_args, first_property_name);
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gst_child_proxy_get_valist (object, first_property_name, var_args);
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va_end (var_args);
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}
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/**
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* gst_child_proxy_set_property:
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* @object: the parent object
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* @name: name of the property to set
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* @value: new #GValue for the property
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*
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* Sets a single property using the GstChildProxy mechanism.
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*/
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void
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gst_child_proxy_set_property (GstChildProxy * object, const gchar * name,
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const GValue * value)
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{
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GParamSpec *pspec;
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GObject *target;
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g_return_if_fail (GST_IS_CHILD_PROXY (object));
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g_return_if_fail (name != NULL);
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g_return_if_fail (G_IS_VALUE (value));
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if (!gst_child_proxy_lookup (object, name, &target, &pspec))
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goto not_found;
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g_object_set_property (target, pspec->name, value);
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g_object_unref (target);
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return;
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not_found:
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{
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g_warning ("cannot set property %s on object %s", name,
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(GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
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return;
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}
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}
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/**
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* gst_child_proxy_set_valist:
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* @object: the parent object
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* @first_property_name: name of the first property to set
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* @var_args: value for the first property, followed optionally by more name/value pairs, followed by %NULL
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*
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* Sets properties of the parent object and its children.
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*/
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void
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gst_child_proxy_set_valist (GstChildProxy * object,
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const gchar * first_property_name, va_list var_args)
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{
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const gchar *name;
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gchar *error = NULL;
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GValue value = { 0, };
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GParamSpec *pspec;
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GObject *target;
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g_return_if_fail (GST_IS_CHILD_PROXY (object));
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name = first_property_name;
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/* iterate over pairs */
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while (name) {
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if (!gst_child_proxy_lookup (object, name, &target, &pspec))
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goto not_found;
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G_VALUE_COLLECT_INIT (&value, pspec->value_type, var_args,
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G_VALUE_NOCOPY_CONTENTS, &error);
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if (error)
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goto cant_copy;
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g_object_set_property (target, pspec->name, &value);
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g_object_unref (target);
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g_value_unset (&value);
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name = va_arg (var_args, gchar *);
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}
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return;
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not_found:
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{
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g_warning ("no property %s in object %s", name,
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(GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
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return;
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}
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cant_copy:
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{
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g_warning ("error copying value %s in object %s: %s", pspec->name,
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(GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""), error);
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g_value_unset (&value);
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g_object_unref (target);
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g_free (error);
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return;
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}
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}
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/**
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* gst_child_proxy_set:
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* @object: the parent object
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* @first_property_name: name of the first property to set
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* @...: value for the first property, followed optionally by more name/value pairs, followed by %NULL
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*
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* Sets properties of the parent object and its children.
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*/
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void
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gst_child_proxy_set (GstChildProxy * object, const gchar * first_property_name,
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...)
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{
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va_list var_args;
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g_return_if_fail (GST_IS_CHILD_PROXY (object));
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va_start (var_args, first_property_name);
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gst_child_proxy_set_valist (object, first_property_name, var_args);
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va_end (var_args);
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}
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/**
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* gst_child_proxy_child_added:
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* @parent: the parent object
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* @child: the newly added child
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* @name: the name of the new child
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*
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* Emits the "child-added" signal.
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*/
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void
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gst_child_proxy_child_added (GstChildProxy * parent, GObject * child,
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const gchar * name)
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{
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g_signal_emit (parent, signals[CHILD_ADDED], 0, child, name);
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}
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/**
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* gst_child_proxy_child_removed:
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* @parent: the parent object
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* @child: the removed child
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* @name: the name of the old child
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*
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* Emits the "child-removed" signal.
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*/
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void
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gst_child_proxy_child_removed (GstChildProxy * parent, GObject * child,
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const gchar * name)
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{
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g_signal_emit (parent, signals[CHILD_REMOVED], 0, child, name);
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}
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/* gobject methods */
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static void
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gst_child_proxy_class_init (gpointer g_class, gpointer class_data)
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{
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GstChildProxyInterface *iface = (GstChildProxyInterface *) g_class;
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iface->get_child_by_name = gst_child_proxy_default_get_child_by_name;
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}
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static void
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gst_child_proxy_base_init (gpointer g_class)
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{
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static gboolean initialized = FALSE;
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if (!initialized) {
|
|
/* create interface signals and properties here. */
|
|
/**
|
|
* GstChildProxy::child-added:
|
|
* @child_proxy: the #GstChildProxy
|
|
* @object: the #GObject that was added
|
|
* @name: the name of the new child
|
|
*
|
|
* Will be emitted after the @object was added to the @child_proxy.
|
|
*/
|
|
signals[CHILD_ADDED] =
|
|
g_signal_new ("child-added", G_TYPE_FROM_CLASS (g_class),
|
|
G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GstChildProxyInterface,
|
|
child_added), NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE,
|
|
2, G_TYPE_OBJECT, G_TYPE_STRING);
|
|
|
|
/**
|
|
* GstChildProxy::child-removed:
|
|
* @child_proxy: the #GstChildProxy
|
|
* @object: the #GObject that was removed
|
|
* @name: the name of the old child
|
|
*
|
|
* Will be emitted after the @object was removed from the @child_proxy.
|
|
*/
|
|
signals[CHILD_REMOVED] =
|
|
g_signal_new ("child-removed", G_TYPE_FROM_CLASS (g_class),
|
|
G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GstChildProxyInterface,
|
|
child_removed), NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE,
|
|
2, G_TYPE_OBJECT, G_TYPE_STRING);
|
|
|
|
initialized = TRUE;
|
|
}
|
|
}
|
|
|
|
GType
|
|
gst_child_proxy_get_type (void)
|
|
{
|
|
static volatile gsize type = 0;
|
|
|
|
if (g_once_init_enter (&type)) {
|
|
GType _type;
|
|
static const GTypeInfo info = {
|
|
sizeof (GstChildProxyInterface),
|
|
gst_child_proxy_base_init, /* base_init */
|
|
NULL, /* base_finalize */
|
|
gst_child_proxy_class_init, /* class_init */
|
|
NULL, /* class_finalize */
|
|
NULL, /* class_data */
|
|
0,
|
|
0, /* n_preallocs */
|
|
NULL /* instance_init */
|
|
};
|
|
|
|
_type =
|
|
g_type_register_static (G_TYPE_INTERFACE, "GstChildProxy", &info, 0);
|
|
|
|
g_type_interface_add_prerequisite (_type, G_TYPE_OBJECT);
|
|
g_once_init_leave (&type, (gsize) _type);
|
|
}
|
|
return type;
|
|
}
|