GstStructure

GstStructure — Generic structure containing fields of names and values

Synopsis

#include <gst/gst.h>

struct              GstStructure;
gboolean            (*GstStructureForeachFunc)          (GQuark field_id,
                                                         const GValue *value,
                                                         gpointer user_data);
gboolean            (*GstStructureMapFunc)              (GQuark field_id,
                                                         GValue *value,
                                                         gpointer user_data);
GstStructure *      gst_structure_empty_new             (const gchar *name);
GstStructure *      gst_structure_id_empty_new          (GQuark quark);
GstStructure *      gst_structure_new                   (const gchar *name,
                                                         const gchar *firstfield,
                                                         ...);
GstStructure *      gst_structure_new_valist            (const gchar *name,
                                                         const gchar *firstfield,
                                                         va_list varargs);
GstStructure *      gst_structure_id_new                (GQuark name_quark,
                                                         GQuark field_quark,
                                                         ...);
GstStructure *      gst_structure_copy                  (const GstStructure *structure);
void                gst_structure_free                  (GstStructure *structure);
const gchar *       gst_structure_get_name              (const GstStructure *structure);
gboolean            gst_structure_has_name              (const GstStructure *structure,
                                                         const gchar *name);
void                gst_structure_set_name              (GstStructure *structure,
                                                         const gchar *name);
GQuark              gst_structure_get_name_id           (const GstStructure *structure);
gboolean            gst_structure_id_get                (const GstStructure *structure,
                                                         GQuark first_field_id,
                                                         ...);
gboolean            gst_structure_id_get_valist         (const GstStructure *structure,
                                                         GQuark first_field_id,
                                                         va_list args);
const GValue *      gst_structure_id_get_value          (const GstStructure *structure,
                                                         GQuark field);
void                gst_structure_id_set_value          (GstStructure *structure,
                                                         GQuark field,
                                                         const GValue *value);
void                gst_structure_id_take_value         (GstStructure *structure,
                                                         GQuark field,
                                                         GValue *value);
gboolean            gst_structure_get                   (const GstStructure *structure,
                                                         const char *first_fieldname,
                                                         ...);
gboolean            gst_structure_get_valist            (const GstStructure *structure,
                                                         const char *first_fieldname,
                                                         va_list args);
const GValue *      gst_structure_get_value             (const GstStructure *structure,
                                                         const gchar *fieldname);
void                gst_structure_set_value             (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         const GValue *value);
void                gst_structure_take_value            (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GValue *value);
void                gst_structure_set                   (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         ...);
void                gst_structure_set_valist            (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         va_list varargs);
void                gst_structure_id_set                (GstStructure *structure,
                                                         GQuark fieldname,
                                                         ...);
void                gst_structure_id_set_valist         (GstStructure *structure,
                                                         GQuark fieldname,
                                                         va_list varargs);
void                gst_structure_remove_field          (GstStructure *structure,
                                                         const gchar *fieldname);
void                gst_structure_remove_fields         (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         ...);
void                gst_structure_remove_fields_valist  (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         va_list varargs);
void                gst_structure_remove_all_fields     (GstStructure *structure);
GType               gst_structure_get_field_type        (const GstStructure *structure,
                                                         const gchar *fieldname);
gboolean            gst_structure_foreach               (const GstStructure *structure,
                                                         GstStructureForeachFunc func,
                                                         gpointer user_data);
gint                gst_structure_n_fields              (const GstStructure *structure);
gboolean            gst_structure_has_field             (const GstStructure *structure,
                                                         const gchar *fieldname);
gboolean            gst_structure_has_field_typed       (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GType type);
gboolean            gst_structure_is_equal              (const GstStructure *structure1,
                                                         const GstStructure *structure2);
gboolean            gst_structure_is_subset             (const GstStructure *subset,
                                                         const GstStructure *superset);
gboolean            gst_structure_can_intersect         (const GstStructure *struct1,
                                                         const GstStructure *struct2);
GstStructure *      gst_structure_intersect             (const GstStructure *struct1,
                                                         const GstStructure *struct2);
gboolean            gst_structure_id_has_field          (const GstStructure *structure,
                                                         GQuark field);
gboolean            gst_structure_id_has_field_typed    (const GstStructure *structure,
                                                         GQuark field,
                                                         GType type);
gboolean            gst_structure_get_boolean           (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gboolean *value);
gboolean            gst_structure_get_int               (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gint *value);
gboolean            gst_structure_get_uint              (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         guint *value);
gboolean            gst_structure_get_fourcc            (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         guint32 *value);
gboolean            gst_structure_get_double            (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gdouble *value);
const gchar *       gst_structure_get_string            (const GstStructure *structure,
                                                         const gchar *fieldname);
gboolean            gst_structure_get_date              (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GDate **value);
gboolean            gst_structure_get_date_time         (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GstDateTime **value);
gboolean            gst_structure_get_clock_time        (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GstClockTime *value);
gboolean            gst_structure_get_enum              (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GType enumtype,
                                                         gint *value);
gboolean            gst_structure_get_fraction          (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gint *value_numerator,
                                                         gint *value_denominator);
gboolean            gst_structure_map_in_place          (GstStructure *structure,
                                                         GstStructureMapFunc func,
                                                         gpointer user_data);
const gchar *       gst_structure_nth_field_name        (const GstStructure *structure,
                                                         guint index);
void                gst_structure_set_parent_refcount   (GstStructure *structure,
                                                         gint *refcount);
gchar *             gst_structure_to_string             (const GstStructure *structure);
GstStructure *      gst_structure_from_string           (const gchar *string,
                                                         gchar **end);
gboolean            gst_structure_fixate_field_nearest_int
                                                        (GstStructure *structure,
                                                         const char *field_name,
                                                         int target);
gboolean            gst_structure_fixate_field_nearest_double
                                                        (GstStructure *structure,
                                                         const char *field_name,
                                                         double target);
gboolean            gst_structure_fixate_field_nearest_fraction
                                                        (GstStructure *structure,
                                                         const char *field_name,
                                                         const gint target_numerator,
                                                         const gint target_denominator);
gboolean            gst_structure_fixate_field_boolean  (GstStructure *structure,
                                                         const char *field_name,
                                                         gboolean target);
gboolean            gst_structure_fixate_field_string   (GstStructure *structure,
                                                         const char *field_name,
                                                         const gchar *target);

Description

A GstStructure is a collection of key/value pairs. The keys are expressed as GQuarks and the values can be of any GType.

In addition to the key/value pairs, a GstStructure also has a name. The name starts with a letter and can be folled by letters, numbers and any of "/-_.:".

GstStructure is used by various GStreamer subsystems to store information in a flexible and extensible way. A GstStructure does not have a refcount because it usually is part of a higher level object such as GstCaps. It provides a means to enforce mutability using the refcount of the parent with the gst_structure_set_parent_refcount() method.

A GstStructure can be created with gst_structure_empty_new() or gst_structure_new(), which both take a name and an optional set of key/value pairs along with the types of the values.

Field values can be changed with gst_structure_set_value() or gst_structure_set().

Field values can be retrieved with gst_structure_get_value() or the more convenient gst_structure_get_*() functions.

Fields can be removed with gst_structure_remove_field() or gst_structure_remove_fields().

Strings in structures must be ASCII or UTF-8 encoded. Other encodings are not allowed. Strings must not be empty either, but may be NULL.

Last reviewed on 2009-06-08 (0.10.23)

Details

struct GstStructure

struct GstStructure {
  GType type;
};

The GstStructure object. Most fields are private.

GType type;

the GType of a structure

GstStructureForeachFunc ()

gboolean            (*GstStructureForeachFunc)          (GQuark field_id,
                                                         const GValue *value,
                                                         gpointer user_data);

A function that will be called in gst_structure_foreach(). The function may not modify value.

field_id :

the GQuark of the field name

value :

the GValue of the field

user_data :

user data

Returns :

TRUE if the foreach operation should continue, FALSE if the foreach operation should stop with FALSE.

GstStructureMapFunc ()

gboolean            (*GstStructureMapFunc)              (GQuark field_id,
                                                         GValue *value,
                                                         gpointer user_data);

A function that will be called in gst_structure_map_in_place(). The function may modify value.

field_id :

the GQuark of the field name

value :

the GValue of the field

user_data :

user data

Returns :

TRUE if the map operation should continue, FALSE if the map operation should stop with FALSE.

gst_structure_empty_new ()

GstStructure *      gst_structure_empty_new             (const gchar *name);

Creates a new, empty GstStructure with the given name.

See gst_structure_set_name() for constraints on the name parameter.

Free-function: gst_structure_free

name :

name of new structure

Returns :

a new, empty GstStructure. [transfer full]

gst_structure_id_empty_new ()

GstStructure *      gst_structure_id_empty_new          (GQuark quark);

Creates a new, empty GstStructure with the given name as a GQuark.

Free-function: gst_structure_free

quark :

name of new structure

Returns :

a new, empty GstStructure. [transfer full]

gst_structure_new ()

GstStructure *      gst_structure_new                   (const gchar *name,
                                                         const gchar *firstfield,
                                                         ...);

Creates a new GstStructure with the given name. Parses the list of variable arguments and sets fields to the values listed. Variable arguments should be passed as field name, field type, and value. Last variable argument should be NULL.

Free-function: gst_structure_free

name :

name of new structure

firstfield :

name of first field to set

... :

additional arguments

Returns :

a new GstStructure. [transfer full]

gst_structure_new_valist ()

GstStructure *      gst_structure_new_valist            (const gchar *name,
                                                         const gchar *firstfield,
                                                         va_list varargs);

Creates a new GstStructure with the given name. Structure fields are set according to the varargs in a manner similar to gst_structure_new().

See gst_structure_set_name() for constraints on the name parameter.

Free-function: gst_structure_free

name :

name of new structure

firstfield :

name of first field to set

varargs :

variable argument list

Returns :

a new GstStructure. [transfer full]

gst_structure_id_new ()

GstStructure *      gst_structure_id_new                (GQuark name_quark,
                                                         GQuark field_quark,
                                                         ...);

Creates a new GstStructure with the given name as a GQuark, followed by fieldname quark, GType, argument(s) "triplets" in the same format as gst_structure_id_set(). Basically a convenience wrapper around gst_structure_id_empty_new() and gst_structure_id_set().

The last variable argument must be NULL (or 0).

Free-function: gst_structure_free

name_quark :

name of new structure

field_quark :

the GQuark for the name of the field to set

... :

variable arguments

Returns :

a new GstStructure. [transfer full]

Since 0.10.24


gst_structure_copy ()

GstStructure *      gst_structure_copy                  (const GstStructure *structure);

Duplicates a GstStructure and all its fields and values.

Free-function: gst_structure_free

structure :

a GstStructure to duplicate

Returns :

a new GstStructure. [transfer none]

gst_structure_free ()

void                gst_structure_free                  (GstStructure *structure);

Frees a GstStructure and all its fields and values. The structure must not have a parent when this function is called.

structure :

the GstStructure to free. [in][transfer full]

gst_structure_get_name ()

const gchar *       gst_structure_get_name              (const GstStructure *structure);

Get the name of structure as a string.

structure :

a GstStructure

Returns :

the name of the structure.

gst_structure_has_name ()

gboolean            gst_structure_has_name              (const GstStructure *structure,
                                                         const gchar *name);

Checks if the structure has the given name

structure :

a GstStructure

name :

structure name to check for

Returns :

TRUE if name matches the name of the structure.

gst_structure_set_name ()

void                gst_structure_set_name              (GstStructure *structure,
                                                         const gchar *name);

Sets the name of the structure to the given name. The string provided is copied before being used. It must not be empty, start with a letter and can be followed by letters, numbers and any of "/-_.:".

structure :

a GstStructure

name :

the new name of the structure

gst_structure_get_name_id ()

GQuark              gst_structure_get_name_id           (const GstStructure *structure);

Get the name of structure as a GQuark.

structure :

a GstStructure

Returns :

the quark representing the name of the structure.

gst_structure_id_get ()

gboolean            gst_structure_id_get                (const GstStructure *structure,
                                                         GQuark first_field_id,
                                                         ...);

Parses the variable arguments and reads fields from structure accordingly. Variable arguments should be in the form field id quark, field type (as a GType), pointer(s) to a variable(s) to hold the return value(s). The last variable argument should be NULL (technically it should be a 0 quark, but we require NULL so compilers that support it can check for the NULL terminator and warn if it's not there).

This function is just like gst_structure_get() only that it is slightly more efficient since it saves the string-to-quark lookup in the global quark hashtable.

For refcounted (mini)objects you will receive a new reference which you must release with a suitable _unref() when no longer needed. For strings and boxed types you will receive a copy which you will need to release with either g_free() or the suitable function for the boxed type.

structure :

a GstStructure

first_field_id :

the quark of the first field to read

... :

variable arguments

Returns :

FALSE if there was a problem reading any of the fields (e.g. because the field requested did not exist, or was of a type other than the type specified), otherwise TRUE.

Since 0.10.24


gst_structure_id_get_valist ()

gboolean            gst_structure_id_get_valist         (const GstStructure *structure,
                                                         GQuark first_field_id,
                                                         va_list args);

Parses the variable arguments and reads fields from structure accordingly. valist-variant of gst_structure_id_get(). Look at the documentation of gst_structure_id_get() for more details.

structure :

a GstStructure

first_field_id :

the quark of the first field to read

args :

variable arguments

Returns :

TRUE, or FALSE if there was a problem reading any of the fields

Since 0.10.24


gst_structure_id_get_value ()

const GValue *      gst_structure_id_get_value          (const GstStructure *structure,
                                                         GQuark field);

Get the value of the field with GQuark field.

structure :

a GstStructure

field :

the GQuark of the field to get

Returns :

the GValue corresponding to the field with the given name identifier.

gst_structure_id_set_value ()

void                gst_structure_id_set_value          (GstStructure *structure,
                                                         GQuark field,
                                                         const GValue *value);

Sets the field with the given GQuark field to value. If the field does not exist, it is created. If the field exists, the previous value is replaced and freed.

structure :

a GstStructure

field :

a GQuark representing a field

value :

the new value of the field

gst_structure_id_take_value ()

void                gst_structure_id_take_value         (GstStructure *structure,
                                                         GQuark field,
                                                         GValue *value);

Sets the field with the given GQuark field to value. If the field does not exist, it is created. If the field exists, the previous value is replaced and freed.

structure :

a GstStructure

field :

a GQuark representing a field

value :

the new value of the field. [transfer full]

Since 0.10.31


gst_structure_get ()

gboolean            gst_structure_get                   (const GstStructure *structure,
                                                         const char *first_fieldname,
                                                         ...);

Parses the variable arguments and reads fields from structure accordingly. Variable arguments should be in the form field name, field type (as a GType), pointer(s) to a variable(s) to hold the return value(s). The last variable argument should be NULL.

For refcounted (mini)objects you will receive a new reference which you must release with a suitable _unref() when no longer needed. For strings and boxed types you will receive a copy which you will need to release with either g_free() or the suitable function for the boxed type.

structure :

a GstStructure

first_fieldname :

the name of the first field to read

... :

variable arguments

Returns :

FALSE if there was a problem reading any of the fields (e.g. because the field requested did not exist, or was of a type other than the type specified), otherwise TRUE.

Since 0.10.24


gst_structure_get_valist ()

gboolean            gst_structure_get_valist            (const GstStructure *structure,
                                                         const char *first_fieldname,
                                                         va_list args);

Parses the variable arguments and reads fields from structure accordingly. valist-variant of gst_structure_get(). Look at the documentation of gst_structure_get() for more details.

structure :

a GstStructure

first_fieldname :

the name of the first field to read

args :

variable arguments

Returns :

TRUE, or FALSE if there was a problem reading any of the fields

Since 0.10.24


gst_structure_get_value ()

const GValue *      gst_structure_get_value             (const GstStructure *structure,
                                                         const gchar *fieldname);

Get the value of the field with name fieldname.

structure :

a GstStructure

fieldname :

the name of the field to get

Returns :

the GValue corresponding to the field with the given name.

gst_structure_set_value ()

void                gst_structure_set_value             (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         const GValue *value);

Sets the field with the given name field to value. If the field does not exist, it is created. If the field exists, the previous value is replaced and freed.

structure :

a GstStructure

fieldname :

the name of the field to set

value :

the new value of the field

gst_structure_take_value ()

void                gst_structure_take_value            (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GValue *value);

Sets the field with the given name field to value. If the field does not exist, it is created. If the field exists, the previous value is replaced and freed. The function will take ownership of value.

structure :

a GstStructure

fieldname :

the name of the field to set

value :

the new value of the field. [transfer full]

Since 0.10.31


gst_structure_set ()

void                gst_structure_set                   (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         ...);

Parses the variable arguments and sets fields accordingly. Variable arguments should be in the form field name, field type (as a GType), value(s). The last variable argument should be NULL.

structure :

a GstStructure

fieldname :

the name of the field to set

... :

variable arguments

gst_structure_set_valist ()

void                gst_structure_set_valist            (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         va_list varargs);

va_list form of gst_structure_set().

structure :

a GstStructure

fieldname :

the name of the field to set

varargs :

variable arguments

gst_structure_id_set ()

void                gst_structure_id_set                (GstStructure *structure,
                                                         GQuark fieldname,
                                                         ...);

Identical to gst_structure_set, except that field names are passed using the GQuark for the field name. This allows more efficient setting of the structure if the caller already knows the associated quark values. The last variable argument must be NULL.

structure :

a GstStructure

fieldname :

the GQuark for the name of the field to set

... :

variable arguments

Since 0.10.10


gst_structure_id_set_valist ()

void                gst_structure_id_set_valist         (GstStructure *structure,
                                                         GQuark fieldname,
                                                         va_list varargs);

va_list form of gst_structure_id_set().

structure :

a GstStructure

fieldname :

the name of the field to set

varargs :

variable arguments

Since 0.10.10


gst_structure_remove_field ()

void                gst_structure_remove_field          (GstStructure *structure,
                                                         const gchar *fieldname);

Removes the field with the given name. If the field with the given name does not exist, the structure is unchanged.

structure :

a GstStructure

fieldname :

the name of the field to remove

gst_structure_remove_fields ()

void                gst_structure_remove_fields         (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         ...);

Removes the fields with the given names. If a field does not exist, the argument is ignored.

structure :

a GstStructure

fieldname :

the name of the field to remove

... :

NULL-terminated list of more fieldnames to remove

gst_structure_remove_fields_valist ()

void                gst_structure_remove_fields_valist  (GstStructure *structure,
                                                         const gchar *fieldname,
                                                         va_list varargs);

va_list form of gst_structure_remove_fields().

structure :

a GstStructure

fieldname :

the name of the field to remove

varargs :

NULL-terminated list of more fieldnames to remove

gst_structure_remove_all_fields ()

void                gst_structure_remove_all_fields     (GstStructure *structure);

Removes all fields in a GstStructure.

structure :

a GstStructure

gst_structure_get_field_type ()

GType               gst_structure_get_field_type        (const GstStructure *structure,
                                                         const gchar *fieldname);

Finds the field with the given name, and returns the type of the value it contains. If the field is not found, G_TYPE_INVALID is returned.

structure :

a GstStructure

fieldname :

the name of the field

Returns :

the GValue of the field

gst_structure_foreach ()

gboolean            gst_structure_foreach               (const GstStructure *structure,
                                                         GstStructureForeachFunc func,
                                                         gpointer user_data);

Calls the provided function once for each field in the GstStructure. The function must not modify the fields. Also see gst_structure_map_in_place().

structure :

a GstStructure

func :

a function to call for each field. [scope call]

user_data :

private data. [closure]

Returns :

TRUE if the supplied function returns TRUE For each of the fields, FALSE otherwise.

gst_structure_n_fields ()

gint                gst_structure_n_fields              (const GstStructure *structure);

Get the number of fields in the structure.

structure :

a GstStructure

Returns :

the number of fields in the structure

gst_structure_has_field ()

gboolean            gst_structure_has_field             (const GstStructure *structure,
                                                         const gchar *fieldname);

Check if structure contains a field named fieldname.

structure :

a GstStructure

fieldname :

the name of a field

Returns :

TRUE if the structure contains a field with the given name

gst_structure_has_field_typed ()

gboolean            gst_structure_has_field_typed       (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GType type);

Check if structure contains a field named fieldname and with GType type.

structure :

a GstStructure

fieldname :

the name of a field

type :

the type of a value

Returns :

TRUE if the structure contains a field with the given name and type

gst_structure_is_equal ()

gboolean            gst_structure_is_equal              (const GstStructure *structure1,
                                                         const GstStructure *structure2);

Tests if the two GstStructure are equal.

structure1 :

a GstStructure.

structure2 :

a GstStructure.

Returns :

TRUE if the two structures have the same name and field.

Since 0.10.36


gst_structure_is_subset ()

gboolean            gst_structure_is_subset             (const GstStructure *subset,
                                                         const GstStructure *superset);

Checks if subset is a subset of superset, i.e. has the same structure name and for all fields that are existing in superset, subset has a value that is a subset of the value in superset.

subset :

a GstStructure

superset :

a potentially greater GstStructure

Returns :

TRUE if subset is a subset of superset

Since 0.10.36


gst_structure_can_intersect ()

gboolean            gst_structure_can_intersect         (const GstStructure *struct1,
                                                         const GstStructure *struct2);

Tries intersecting struct1 and struct2 and reports whether the result would not be empty.

struct1 :

a GstStructure

struct2 :

a GstStructure

Returns :

TRUE if intersection would not be empty

Since 0.10.36


gst_structure_intersect ()

GstStructure *      gst_structure_intersect             (const GstStructure *struct1,
                                                         const GstStructure *struct2);

Interesects struct1 and struct2 and returns the intersection.

struct1 :

a GstStructure

struct2 :

a GstStructure

Returns :

Intersection of struct1 and struct2

Since 0.10.36


gst_structure_id_has_field ()

gboolean            gst_structure_id_has_field          (const GstStructure *structure,
                                                         GQuark field);

Check if structure contains a field named field.

structure :

a GstStructure

field :

GQuark of the field name

Returns :

TRUE if the structure contains a field with the given name

Since 0.10.26


gst_structure_id_has_field_typed ()

gboolean            gst_structure_id_has_field_typed    (const GstStructure *structure,
                                                         GQuark field,
                                                         GType type);

Check if structure contains a field named field and with GType type.

structure :

a GstStructure

field :

GQuark of the field name

type :

the type of a value

Returns :

TRUE if the structure contains a field with the given name and type

Since 0.10.26


gst_structure_get_boolean ()

gboolean            gst_structure_get_boolean           (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gboolean *value);

Sets the boolean pointed to by value corresponding to the value of the given field. Caller is responsible for making sure the field exists and has the correct type.

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to a gboolean to set. [out]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a boolean, this function returns FALSE.

gst_structure_get_int ()

gboolean            gst_structure_get_int               (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gint *value);

Sets the int pointed to by value corresponding to the value of the given field. Caller is responsible for making sure the field exists and has the correct type.

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to an int to set. [out]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain an int, this function returns FALSE.

gst_structure_get_uint ()

gboolean            gst_structure_get_uint              (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         guint *value);

Sets the uint pointed to by value corresponding to the value of the given field. Caller is responsible for making sure the field exists and has the correct type.

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to a uint to set. [out]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a uint, this function returns FALSE.

Since 0.10.15


gst_structure_get_fourcc ()

gboolean            gst_structure_get_fourcc            (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         guint32 *value);

Sets the Fourcc pointed to by value corresponding to the value of the given field. Caller is responsible for making sure the field exists and has the correct type.

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to a 32bit unsigned int to set. [out]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a fourcc, this function returns FALSE.

gst_structure_get_double ()

gboolean            gst_structure_get_double            (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gdouble *value);

Sets the double pointed to by value corresponding to the value of the given field. Caller is responsible for making sure the field exists and has the correct type.

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to a gdouble to set. [out]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a double, this function returns FALSE.

gst_structure_get_string ()

const gchar *       gst_structure_get_string            (const GstStructure *structure,
                                                         const gchar *fieldname);

Finds the field corresponding to fieldname, and returns the string contained in the field's value. Caller is responsible for making sure the field exists and has the correct type.

The string should not be modified, and remains valid until the next call to a gst_structure_*() function with the given structure.

structure :

a GstStructure

fieldname :

the name of a field

Returns :

a pointer to the string or NULL when the field did not exist or did not contain a string.

gst_structure_get_date ()

gboolean            gst_structure_get_date              (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GDate **value);

Sets the date pointed to by value corresponding to the date of the given field. Caller is responsible for making sure the field exists and has the correct type.

On success value will point to a newly-allocated copy of the date which should be freed with g_date_free() when no longer needed (note: this is inconsistent with e.g. gst_structure_get_string() which doesn't return a copy of the string).

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to a GDate to set. [out callee-allocates]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a data, this function returns FALSE.

gst_structure_get_date_time ()

gboolean            gst_structure_get_date_time         (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GstDateTime **value);

Sets the datetime pointed to by value corresponding to the datetime of the given field. Caller is responsible for making sure the field exists and has the correct type.

On success value will point to a reference of the datetime which should be unreffed with gst_date_time_unref() when no longer needed (note: this is inconsistent with e.g. gst_structure_get_string() which doesn't return a copy of the string).

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to a GstDateTime to set. [out callee-allocates]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a data, this function returns FALSE.

Since 0.10.31


gst_structure_get_clock_time ()

gboolean            gst_structure_get_clock_time        (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GstClockTime *value);

Sets the clock time pointed to by value corresponding to the clock time of the given field. Caller is responsible for making sure the field exists and has the correct type.

structure :

a GstStructure

fieldname :

the name of a field

value :

a pointer to a GstClockTime to set. [out]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a GstClockTime, this function returns FALSE.

gst_structure_get_enum ()

gboolean            gst_structure_get_enum              (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         GType enumtype,
                                                         gint *value);

Sets the int pointed to by value corresponding to the value of the given field. Caller is responsible for making sure the field exists, has the correct type and that the enumtype is correct.

structure :

a GstStructure

fieldname :

the name of a field

enumtype :

the enum type of a field

value :

a pointer to an int to set. [out]

Returns :

TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain an enum of the given type, this function returns FALSE.

gst_structure_get_fraction ()

gboolean            gst_structure_get_fraction          (const GstStructure *structure,
                                                         const gchar *fieldname,
                                                         gint *value_numerator,
                                                         gint *value_denominator);

Sets the integers pointed to by value_numerator and value_denominator corresponding to the value of the given field. Caller is responsible for making sure the field exists and has the correct type.

structure :

a GstStructure

fieldname :

the name of a field

value_numerator :

a pointer to an int to set. [out]

value_denominator :

a pointer to an int to set. [out]

Returns :

TRUE if the values could be set correctly. If there was no field with fieldname or the existing field did not contain a GstFraction, this function returns FALSE.

gst_structure_map_in_place ()

gboolean            gst_structure_map_in_place          (GstStructure *structure,
                                                         GstStructureMapFunc func,
                                                         gpointer user_data);

Calls the provided function once for each field in the GstStructure. In contrast to gst_structure_foreach(), the function may modify but not delete the fields. The structure must be mutable.

structure :

a GstStructure

func :

a function to call for each field. [scope call]

user_data :

private data. [closure]

Returns :

TRUE if the supplied function returns TRUE For each of the fields, FALSE otherwise.

gst_structure_nth_field_name ()

const gchar *       gst_structure_nth_field_name        (const GstStructure *structure,
                                                         guint index);

Get the name of the given field number, counting from 0 onwards.

structure :

a GstStructure

index :

the index to get the name of

Returns :

the name of the given field number

gst_structure_set_parent_refcount ()

void                gst_structure_set_parent_refcount   (GstStructure *structure,
                                                         gint *refcount);

Sets the parent_refcount field of GstStructure. This field is used to determine whether a structure is mutable or not. This function should only be called by code implementing parent objects of GstStructure, as described in the MT Refcounting section of the design documents.

structure :

a GstStructure

refcount :

a pointer to the parent's refcount. [in]

gst_structure_to_string ()

gchar *             gst_structure_to_string             (const GstStructure *structure);

Converts structure to a human-readable string representation.

For debugging purposes its easier to do something like this:

1
GST_LOG ("structure is %" GST_PTR_FORMAT, structure);

This prints the structure in human readble form.

Free-function: g_free

structure :

a GstStructure

Returns :

(transfer full)L a pointer to string allocated by g_malloc(). g_free() after usage.

gst_structure_from_string ()

GstStructure *      gst_structure_from_string           (const gchar *string,
                                                         gchar **end);

Creates a GstStructure from a string representation. If end is not NULL, a pointer to the place inside the given string where parsing ended will be returned.

Free-function: gst_structure_free

string :

a string representation of a GstStructure.

end :

pointer to store the end of the string in. [out][allow-none]

Returns :

a new GstStructure or NULL when the string could not be parsed. Free with gst_structure_free() after use. [transfer full]

gst_structure_fixate_field_nearest_int ()

gboolean            gst_structure_fixate_field_nearest_int
                                                        (GstStructure *structure,
                                                         const char *field_name,
                                                         int target);

Fixates a GstStructure by changing the given field to the nearest integer to target that is a subset of the existing field.

structure :

a GstStructure

field_name :

a field in structure

target :

the target value of the fixation

Returns :

TRUE if the structure could be fixated

gst_structure_fixate_field_nearest_double ()

gboolean            gst_structure_fixate_field_nearest_double
                                                        (GstStructure *structure,
                                                         const char *field_name,
                                                         double target);

Fixates a GstStructure by changing the given field to the nearest double to target that is a subset of the existing field.

structure :

a GstStructure

field_name :

a field in structure

target :

the target value of the fixation

Returns :

TRUE if the structure could be fixated

gst_structure_fixate_field_nearest_fraction ()

gboolean            gst_structure_fixate_field_nearest_fraction
                                                        (GstStructure *structure,
                                                         const char *field_name,
                                                         const gint target_numerator,
                                                         const gint target_denominator);

Fixates a GstStructure by changing the given field to the nearest fraction to target_numerator/target_denominator that is a subset of the existing field.

structure :

a GstStructure

field_name :

a field in structure

target_numerator :

The numerator of the target value of the fixation

target_denominator :

The denominator of the target value of the fixation

Returns :

TRUE if the structure could be fixated

gst_structure_fixate_field_boolean ()

gboolean            gst_structure_fixate_field_boolean  (GstStructure *structure,
                                                         const char *field_name,
                                                         gboolean target);

Fixates a GstStructure by changing the given field_name field to the given target boolean if that field is not fixed yet.

structure :

a GstStructure

field_name :

a field in structure

target :

the target value of the fixation

Returns :

TRUE if the structure could be fixated

gst_structure_fixate_field_string ()

gboolean            gst_structure_fixate_field_string   (GstStructure *structure,
                                                         const char *field_name,
                                                         const gchar *target);

Fixates a GstStructure by changing the given field_name field to the given target string if that field is not fixed yet.

structure :

a GstStructure

field_name :

a field in structure

target :

the target value of the fixation

Returns :

TRUE if the structure could be fixated

Since 0.10.30

See Also

GstCaps, GstMessage, GstEvent, GstQuery