gstreamer/gst/gstcontext.h

/* GStreamer
 * Copyright (C) 2013 Collabora Ltd.
 *   Author: Sebastian Dröge <sebastian.droege@collabora.co.uk>
 * Copyright (C) 2013 Sebastian Dröge <slomo@circular-chaos.org>
 *
 * gstcontext.h: Header for GstContext subsystem
 *
 * 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.
 */

#ifndef __GST_CONTEXT_H__
#define __GST_CONTEXT_H__

#include <glib.h>

G_BEGIN_DECLS

typedef struct _GstContext GstContext;

#include <gst/gstminiobject.h>
#include <gst/gststructure.h>

GST_EXPORT GType _gst_context_type;

#define GST_TYPE_CONTEXT                         (_gst_context_type)
#define GST_IS_CONTEXT(obj)                      (GST_IS_MINI_OBJECT_TYPE (obj, GST_TYPE_CONTEXT))
#define GST_CONTEXT_CAST(obj)                    ((GstContext*)(obj))
#define GST_CONTEXT(obj)                         (GST_CONTEXT_CAST(obj))



GType           gst_context_get_type            (void);


/* refcounting */
/**
 * gst_context_ref:
 * @context: the context to ref
 *
 * Convenience macro to increase the reference count of the context.
 *
 * Returns: @context (for convenience when doing assignments)
 */
static inline GstContext *
gst_context_ref (GstContext * context)
{
  return (GstContext *) gst_mini_object_ref (GST_MINI_OBJECT_CAST (context));
}

/**
 * gst_context_unref:
 * @context: the context to unref
 *
 * Convenience macro to decrease the reference count of the context, possibly
 * freeing it.
 */
static inline void
gst_context_unref (GstContext * context)
{
  gst_mini_object_unref (GST_MINI_OBJECT_CAST (context));
}

/* copy context */
/**
 * gst_context_copy:
 * @context: the context to copy
 *
 * Creates a copy of the context. Returns a copy of the context.
 *
 * Returns: (transfer full): a new copy of @context.
 *
 * MT safe
 */
static inline GstContext *
gst_context_copy (const GstContext * context)
{
  return GST_CONTEXT_CAST (gst_mini_object_copy (GST_MINI_OBJECT_CONST_CAST (context)));
}

/**
 * gst_context_is_writable:
 * @context: a #GstContext
 *
 * Tests if you can safely write into a context's structure or validly
 * modify the seqnum and timestamp fields.
 */
#define         gst_context_is_writable(context)     gst_mini_object_is_writable (GST_MINI_OBJECT_CAST (context))
/**
 * gst_context_make_writable:
 * @context: (transfer full): the context to make writable
 *
 * Checks if a context is writable. If not, a writable copy is made and
 * returned.
 *
 * Returns: (transfer full): a context (possibly a duplicate) that is writable.
 *
 * MT safe
 */
#define         gst_context_make_writable(context)  GST_CONTEXT_CAST (gst_mini_object_make_writable (GST_MINI_OBJECT_CAST (context)))
/**
 * gst_context_replace:
 * @old_context: (inout) (transfer full): pointer to a pointer to a #GstContext
 *     to be replaced.
 * @new_context: (allow-none) (transfer none): pointer to a #GstContext that will
 *     replace the context pointed to by @old_context.
 *
 * Modifies a pointer to a #GstContext to point to a different #GstContext. The
 * modification is done atomically (so this is useful for ensuring thread safety
 * in some cases), and the reference counts are updated appropriately (the old
 * context is unreffed, the new one is reffed).
 *
 * Either @new_context or the #GstContext pointed to by @old_context may be %NULL.
 *
 * Returns: %TRUE if @new_context was different from @old_context
 */
static inline gboolean
gst_context_replace (GstContext **old_context, GstContext *new_context)
{
  return gst_mini_object_replace ((GstMiniObject **) old_context, (GstMiniObject *) new_context);
}

GstContext *          gst_context_new                      (const gchar * context_type,
                                                            gboolean persistent) G_GNUC_MALLOC;

const gchar *         gst_context_get_context_type         (const GstContext * context);
gboolean              gst_context_has_context_type         (const GstContext * context, const gchar * context_type);
const GstStructure *  gst_context_get_structure            (const GstContext * context);
GstStructure *        gst_context_writable_structure       (GstContext * context);

gboolean              gst_context_is_persistent            (const GstContext * context);

G_END_DECLS

#endif /* __GST_CONTEXT_H__ */