/* GStreamer

 * Copyright (C) 2021 Collabora Ltd.

 *   Author: Nicolas Dufresne <nicolas.dufresne@collabora.com>

 *

 * 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., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "gstvideocodecalphameta.h"

/**

 * SECTION:gstvideocodecalphameta

 * @title: GstVideoCodecAlphaMeta

 * @short_description: GstMeta that can carry an extra buffer holding  an

 * encoded a frame whith luma that can be used as an alpha channel.

 *

 * This meta is primarily for internal use in GStreamer elements to support

 * VP8/VP9 transparent video stored into WebM or Matroska containers, or

 * transparent static AV1 images. Nothing prevents you from using this meta

 * for custom purposes, but it generally can't be used to easily to add support

 * for alpha channels to CODECs or formats that don't support that out of the

 * box.

 *

 * Since: 1.20

 */

/**

 * gst_video_codec_alpha_meta_api_get_type:

 *

 * Returns: #GType for the #GstVideoCodecAlphaMeta structure.

 *

 * Since: 1.20

 */

GType

gst_video_codec_alpha_meta_api_get_type (void)

{

  static GType type = 0;

  static const gchar *tags[] = { GST_META_TAG_VIDEO_STR, NULL };

  if (g_once_init_enter (&type)) {

    GType _type =

        gst_meta_api_type_register ("GstVideoCodecAlphaMetaAPI", tags);

    g_once_init_leave (&type, _type);

  }

  return type;

}

static gboolean

gst_video_codec_alpha_meta_transform (GstBuffer * dest,

    GstMeta * meta, GstBuffer * buffer, GQuark type, gpointer data)

{

  GstVideoCodecAlphaMeta *dmeta, *smeta;

  smeta = (GstVideoCodecAlphaMeta *) meta;

  if (GST_META_TRANSFORM_IS_COPY (type)) {

    dmeta =

        (GstVideoCodecAlphaMeta *) gst_buffer_add_meta (dest,

        GST_VIDEO_CODEC_ALPHA_META_INFO, NULL);

    if (!dmeta)

      return FALSE;

    dmeta->buffer = gst_buffer_ref (smeta->buffer);

  }

  return TRUE;

}

static gboolean

gst_video_codec_alpha_meta_init (GstMeta * meta, gpointer params,

    GstBuffer * buffer)

{

  GstVideoCodecAlphaMeta *ca_meta = (GstVideoCodecAlphaMeta *) meta;

  /* the buffer ownership is transfered to the Meta */

  ca_meta->buffer = (GstBuffer *) params;

  return TRUE;

}

static void

gst_video_codec_alpha_meta_free (GstMeta * meta, GstBuffer * buffer)

{

  GstVideoCodecAlphaMeta *ca_meta = (GstVideoCodecAlphaMeta *) meta;

  gst_clear_buffer (&ca_meta->buffer);

}

/**

 * gst_video_codec_alpha_meta_get_info:

 *

 * Returns: #GstMetaInfo pointer that describes #GstVideoCodecAlphaMeta.

 *

 * Since: 1.20

 */

const GstMetaInfo *

gst_video_codec_alpha_meta_get_info (void)

{

  static const GstMetaInfo *info = NULL;

  if (g_once_init_enter ((GstMetaInfo **) & info)) {

    const GstMetaInfo *meta =

        gst_meta_register (GST_VIDEO_CODEC_ALPHA_META_API_TYPE,

        "GstVideoCodecAlphaMeta",

        sizeof (GstVideoCodecAlphaMeta),

        gst_video_codec_alpha_meta_init,

        gst_video_codec_alpha_meta_free,

        gst_video_codec_alpha_meta_transform);

    g_once_init_leave ((GstMetaInfo **) & info, (GstMetaInfo *) meta);

  }

  return info;

}

/**

 * gst_buffer_add_video_codec_alpha_meta:

 * @buffer: (transfer none): a #GstBuffer

 * @alpha_buffer: (transfer full): a #GstBuffer

 *

 * Attaches a #GstVideoCodecAlphaMeta metadata to @buffer with

 * the given alpha buffer.

 *

 * Returns: (transfer none): the #GstVideoCodecAlphaMeta on @buffer.

 *

 * Since: 1.20

 */

GstVideoCodecAlphaMeta *

gst_buffer_add_video_codec_alpha_meta (GstBuffer * buffer,

    GstBuffer * alpha_buffer)

{

  GstVideoCodecAlphaMeta *meta;

  g_return_val_if_fail (buffer != NULL, NULL);

  g_return_val_if_fail (alpha_buffer != NULL, NULL);

  meta =

      (GstVideoCodecAlphaMeta *) gst_buffer_add_meta (buffer,

      GST_VIDEO_CODEC_ALPHA_META_INFO, alpha_buffer);

  return meta;

}