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/*
* Copyright (C) 2010 Nokia Corporation.
* Copyright (C) 2012, 2013 Intel Corporation.
*
* Authors: Arun Raghavan <arun.raghavan@collabora.co.uk>
* Krzesimir Nowak <krnowak@openismus.com>
*
* 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, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/**
* SECTION:gupnp-dlna-metadata-extractor
* @short_description: Base class for extracting metadata for given
* media.
*
* #GUPnPDLNAMetadataExtractor is used by #GUPnPDLNAProfileGuesser to
* get needed metadata for profile matching. This class itself does
* not implement any metadata extraction features. For that it is
* expected to provide a plugin which:
* - Provides a #GUPnPDLNAMetadataExtractor subclass implementation.
* - Exports a <function>gupnp_dlna_get_default_extractor</function>() which
* takes no parameters and returns a #GUPnPDLNAMetadataExtractor.
*
* #GModule is used for loading the plugin, so #GModule's features can
* be used also (like exporting <function>g_module_check_init</function>() to
* initialize the multimedia framework used for extracting metadata).
*
* Default plugin directory and default plugin file is set during
* configuration stage, but it can be overriden during runtime by
* setting respectively <envar>GUPNP_DLNA_METADATA_BACKEND</envar> and
* <envar>GUPNP_DLNA_METADATA_BACKEND_DIR</envar> environment variables before
* the plugin is loaded (i.e. before #GUPnPDLNAProfileGuesser is used for
* guessing profile).
*
* The <envar>GUPNP_DLNA_METADATA_BACKEND</envar> environment variable should
* hold a name like <userinput>"gstreamer"</userinput>, so
* <filename>libgstreamer.so</filename> will be loaded. For determining a
* plugin filename g_module_build_path() is used.
*
* If subclassing #GUPnPDLNAMetadataExtractor then also
* #GUPnPDLNAInformation, #GUPnPDLNAAudioInformation,
* #GUPnPDLNAContainerInformation, #GUPnPDLNAImageInformation and
* #GUPnPDLNAVideoInformation have to be subclassed as well.
*/
#include "gupnp-dlna-metadata-extractor.h"
enum {
DONE,
SIGNAL_LAST
};
static guint signals[SIGNAL_LAST];
struct _GUPnPDLNAMetadataExtractorPrivate {
gpointer placeholder;
};
typedef struct _GUPnPDLNAMetadataExtractorPrivate
GUPnPDLNAMetadataExtractorPrivate;
G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GUPnPDLNAMetadataExtractor,
gupnp_dlna_metadata_extractor,
G_TYPE_OBJECT)
static void
gupnp_dlna_metadata_extractor_class_init
(GUPnPDLNAMetadataExtractorClass *extractor_class)
{
extractor_class->extract_async = NULL;
extractor_class->extract_sync = NULL;
/**
* GUPnPDLNAMetadataExtractor::done:
* @extractor: The #GUPnPDLNAMetadataExtractor.
* @info: (transfer none): The results as #GUPnPDLNAInformation.
* @error: (allow-none) (transfer none): Contains details of
* the error if discovery fails, otherwise is %NULL.
*
* Will be emitted when all information on a URI could be
* discovered.
*/
signals[DONE] =
g_signal_new ("done",
G_TYPE_FROM_CLASS (extractor_class),
G_SIGNAL_RUN_LAST,
0,
NULL,
NULL,
g_cclosure_marshal_generic,
G_TYPE_NONE,
2,
GUPNP_TYPE_DLNA_INFORMATION,
G_TYPE_ERROR);
}
static void
gupnp_dlna_metadata_extractor_init (GUPnPDLNAMetadataExtractor *self)
{
}
/**
* gupnp_dlna_metadata_extractor_extract_async:
* @extractor: #GUPnPDLNAMetadataExtractor object to use for discovery
* @uri: URI to gather metadata for
* @timeout_in_ms: Timeout in miliseconds.
* @error: A #GError.
*
* Queues @uri for metadata discovery. When discovery is completed,
* the ::done signal is emitted on @extractor.
*
* Returns: %TRUE if @uri was successfully queued, %FALSE otherwise.
*/
gboolean
gupnp_dlna_metadata_extractor_extract_async
(GUPnPDLNAMetadataExtractor *extractor,
const gchar *uri,
guint timeout_in_ms,
GError **error)
{
GUPnPDLNAMetadataExtractorClass *extractor_class;
g_return_val_if_fail (GUPNP_DLNA_IS_METADATA_EXTRACTOR (extractor),
FALSE);
g_return_val_if_fail (uri != NULL, FALSE);
extractor_class = GUPNP_DLNA_METADATA_EXTRACTOR_GET_CLASS (extractor);
g_return_val_if_fail (GUPNP_DLNA_IS_METADATA_EXTRACTOR_CLASS
(extractor_class),
FALSE);
g_return_val_if_fail (extractor_class->extract_async != NULL, FALSE);
return extractor_class->extract_async (extractor,
uri,
timeout_in_ms,
error);
}
/**
* gupnp_dlna_metadata_extractor_extract_sync:
* @extractor: #GUPnPDLNAMetadataExtractor object to use for discovery
* @uri: URI to gather metadata for
* @timeout_in_ms: Timeout in miliseconds.
* @error: A #GError.
*
* Discovers synchronously metadata of given @uri.
*
* Returns: (transfer full) : A #GUPnPDLNAInformation object if discovery succeeded,
* otherwise %NULL.
*/
GUPnPDLNAInformation *
gupnp_dlna_metadata_extractor_extract_sync
(GUPnPDLNAMetadataExtractor *extractor,
const gchar *uri,
guint timeout_in_ms,
GError **error)
{
GUPnPDLNAMetadataExtractorClass *extractor_class;
g_return_val_if_fail (GUPNP_DLNA_IS_METADATA_EXTRACTOR (extractor),
NULL);
g_return_val_if_fail (uri != NULL, NULL);
extractor_class = GUPNP_DLNA_METADATA_EXTRACTOR_GET_CLASS (extractor);
g_return_val_if_fail (GUPNP_DLNA_IS_METADATA_EXTRACTOR_CLASS
(extractor_class),
NULL);
g_return_val_if_fail (extractor_class->extract_async != NULL, NULL);
return extractor_class->extract_sync (extractor,
uri,
timeout_in_ms,
error);
}
/**
* gupnp_dlna_metadata_extractor_emit_done:
* @extractor: A #GUPnPDLNAMetadataExtractor object.
* @info: (transfer none): A #GUPnPDLNAInformation about discovered URI.
* @error: (allow-none) (transfer none): A #GError.
*
* Emits ::done signal. This function is intended to be used by
* subclasses of #GUPnPDLNAMetadataExtractor. It is required to always
* pass a meaningful @info, even in case of error. That way a receiver
* of this signal can know which URI discovery failed by using
* gupnp_dlna_information_get_uri().
*/
void
gupnp_dlna_metadata_extractor_emit_done (GUPnPDLNAMetadataExtractor *extractor,
GUPnPDLNAInformation *info,
GError *error)
{
g_return_if_fail (GUPNP_DLNA_IS_METADATA_EXTRACTOR (extractor));
g_return_if_fail (GUPNP_DLNA_IS_INFORMATION (info));
g_signal_emit (extractor, signals[DONE], 0, info, error);
}
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