GstMiniObject

GstMiniObject — Lightweight base class for the GStreamer object hierarchy

Synopsis


#include <gst/gst.h>


                    GstMiniObject;
enum                GstMiniObjectFlags;
GstMiniObject*      (*GstMiniObjectCopyFunction)        (const GstMiniObject *obj);
void                (*GstMiniObjectFinalizeFunction)    (GstMiniObject *obj);
#define             GST_MINI_OBJECT_FLAGS               (obj)
#define             GST_MINI_OBJECT_FLAG_IS_SET         (obj,flag)
#define             GST_MINI_OBJECT_FLAG_SET            (obj,flag)
#define             GST_MINI_OBJECT_FLAG_UNSET          (obj,flag)
#define             GST_MINI_OBJECT_REFCOUNT            (obj)
#define             GST_MINI_OBJECT_REFCOUNT_VALUE      (obj)
GstMiniObject*      gst_mini_object_new                 (GType type);
GstMiniObject*      gst_mini_object_copy                (const GstMiniObject *mini_object);
gboolean            gst_mini_object_is_writable         (const GstMiniObject *mini_object);
GstMiniObject*      gst_mini_object_make_writable       (GstMiniObject *mini_object);
GstMiniObject*      gst_mini_object_ref                 (GstMiniObject *mini_object);
void                gst_mini_object_unref               (GstMiniObject *mini_object);
void                gst_mini_object_replace             (GstMiniObject **olddata,
                                                         GstMiniObject *newdata);
GParamSpec*         gst_param_spec_mini_object          (const char *name,
                                                         const char *nick,
                                                         const char *blurb,
                                                         GType object_type,
                                                         GParamFlags flags);
void                gst_value_set_mini_object           (GValue *value,
                                                         GstMiniObject *mini_object);
void                gst_value_take_mini_object          (GValue *value,
                                                         GstMiniObject *mini_object);
GstMiniObject*      gst_value_get_mini_object           (const GValue *value);


Description

GstMiniObject is a baseclass like GObject, but has been stripped down of features to be fast and small. It offers sub-classing and ref-counting in the same way as GObject does. It has no properties and no signal-support though.

Last reviewed on 2005-11-23 (0.9.5)

Details

GstMiniObject

typedef struct {
  GTypeInstance instance;
  gint refcount;
  guint flags;
} GstMiniObject;

Base class for refcounted lightweight objects.

GTypeInstance instance; type instance
gint refcount; atomic refcount
guint flags; extra flags.

enum GstMiniObjectFlags

typedef enum
{
  GST_MINI_OBJECT_FLAG_READONLY = (1<<0),
  /* padding */
  GST_MINI_OBJECT_FLAG_LAST = (1<<4)
} GstMiniObjectFlags;

Flags for the padtemplate

GST_MINI_OBJECT_FLAG_READONLY is the miniobject readonly or writable
GST_MINI_OBJECT_FLAG_LAST first flag that can be used by subclasses.

GstMiniObjectCopyFunction ()

GstMiniObject*      (*GstMiniObjectCopyFunction)        (const GstMiniObject *obj);

Virtual function prototype for methods to create copies of instances.

obj : MiniObject to copy
Returns : reference to cloned instance.

GstMiniObjectFinalizeFunction ()

void                (*GstMiniObjectFinalizeFunction)    (GstMiniObject *obj);

Virtual function prototype for methods to free ressources used by mini-objects. Subclasses of the mini object are allowed to revive the passed object by doing a gst_mini_object_ref(). If the object is not revived after the finalize function, the memory associated with the object is freed.

obj : MiniObject to finalize

GST_MINI_OBJECT_FLAGS()

#define GST_MINI_OBJECT_FLAGS(obj)  (GST_MINI_OBJECT_CAST(obj)->flags)

This macro returns the entire set of flags for the mini-object.

obj : MiniObject to return flags for.

GST_MINI_OBJECT_FLAG_IS_SET()

#define GST_MINI_OBJECT_FLAG_IS_SET(obj,flag)        !!(GST_MINI_OBJECT_FLAGS (obj) & (flag))

This macro checks to see if the given flag is set.

obj : MiniObject to check for flags.
flag : Flag to check for

GST_MINI_OBJECT_FLAG_SET()

#define GST_MINI_OBJECT_FLAG_SET(obj,flag)           (GST_MINI_OBJECT_FLAGS (obj) |= (flag))

This macro sets the given bits.

obj : MiniObject to set flag in.
flag : Flag to set, can by any number of bits in guint32.

GST_MINI_OBJECT_FLAG_UNSET()

#define GST_MINI_OBJECT_FLAG_UNSET(obj,flag)         (GST_MINI_OBJECT_FLAGS (obj) &= ~(flag))

This macro usets the given bits.

obj : MiniObject to unset flag in.
flag : Flag to set, must be a single bit in guint32.

GST_MINI_OBJECT_REFCOUNT()

#define GST_MINI_OBJECT_REFCOUNT(obj)           ((GST_MINI_OBJECT_CAST(obj))->refcount)

Get access to the reference count field of the mini-object.

obj : a GstMiniObject

GST_MINI_OBJECT_REFCOUNT_VALUE()

#define GST_MINI_OBJECT_REFCOUNT_VALUE(obj)     (g_atomic_int_get (&(GST_MINI_OBJECT_CAST(obj))->refcount))

Get the reference count value of the mini-object.

obj : a GstMiniObject

gst_mini_object_new ()

GstMiniObject*      gst_mini_object_new                 (GType type);

Creates a new mini-object of the desired type.

MT safe

type : the GType of the mini-object to create
Returns : the new mini-object.

gst_mini_object_copy ()

GstMiniObject*      gst_mini_object_copy                (const GstMiniObject *mini_object);

Creates a copy of the mini-object.

MT safe

mini_object : the mini-object to copy
Returns : the new mini-object.

gst_mini_object_is_writable ()

gboolean            gst_mini_object_is_writable         (const GstMiniObject *mini_object);

Checks if a mini-object is writable. A mini-object is writable if the reference count is one and the GST_MINI_OBJECT_FLAG_READONLY flag is not set. Modification of a mini-object should only be done after verifying that it is writable.

MT safe

mini_object : the mini-object to check
Returns : TRUE if the object is writable.

gst_mini_object_make_writable ()

GstMiniObject*      gst_mini_object_make_writable       (GstMiniObject *mini_object);

Checks if a mini-object is writable. If not, a writeable copy is made and returned. This gives away the reference to the original mini object, and returns a reference to the new object.

MT safe

mini_object : the mini-object to make writable
Returns : a mini-object (possibly the same pointer) that is writable.

gst_mini_object_ref ()

GstMiniObject*      gst_mini_object_ref                 (GstMiniObject *mini_object);

Increase the reference count of the mini-object.

Note that the refcount affects the writeability of mini-object, see gst_mini_object_is_writable(). It is important to note that keeping additional references to GstMiniObject instances can potentially increase the number of memcpy operations in a pipeline, especially if the minibject is a GstBuffer.

mini_object : the mini-object
Returns : the mini-object.

gst_mini_object_unref ()

void                gst_mini_object_unref               (GstMiniObject *mini_object);

Decreases the reference count of the mini-object, possibly freeing the mini-object.

mini_object : the mini-object

gst_mini_object_replace ()

void                gst_mini_object_replace             (GstMiniObject **olddata,
                                                         GstMiniObject *newdata);

Modifies a pointer to point to a new mini-object. The modification is done atomically, and the reference counts are updated correctly. Either newdata and the value pointed to by olddata may be NULL.

olddata : pointer to a pointer to a mini-object to be replaced
newdata : pointer to new mini-object

gst_param_spec_mini_object ()

GParamSpec*         gst_param_spec_mini_object          (const char *name,
                                                         const char *nick,
                                                         const char *blurb,
                                                         GType object_type,
                                                         GParamFlags flags);

Creates a new GParamSpec instance that hold GstMiniObject references.

name : the canonical name of the property
nick : the nickname of the property
blurb : a short description of the property
object_type : the GstMiniObjectType for the property
flags : a combination of GParamFlags
Returns : a newly allocated GParamSpec instance

gst_value_set_mini_object ()

void                gst_value_set_mini_object           (GValue *value,
                                                         GstMiniObject *mini_object);

Set the contents of a GST_TYPE_MINI_OBJECT derived GValue to mini_object. The caller retains ownership of the reference.

value : a valid GValue of GST_TYPE_MINI_OBJECT derived type
mini_object : mini object value to set

gst_value_take_mini_object ()

void                gst_value_take_mini_object          (GValue *value,
                                                         GstMiniObject *mini_object);

Set the contents of a GST_TYPE_MINI_OBJECT derived GValue to mini_object. Takes over the ownership of the caller's reference to mini_object; the caller doesn't have to unref it any more.

value : a valid GValue of GST_TYPE_MINI_OBJECT derived type
mini_object : mini object value to take

gst_value_get_mini_object ()

GstMiniObject*      gst_value_get_mini_object           (const GValue *value);

Get the contents of a GST_TYPE_MINI_OBJECT derived GValue. Does not increase the refcount of the returned object.

value : a valid GValue of GST_TYPE_MINI_OBJECT derived type
Returns : mini object contents of value