Structure

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 filled 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, #GstMessage, #GstEvent, #GstQuery. It provides a means to enforce mutability using the refcount of the parent with the gst.structure.Structure.setParentRefcount method.

A #GstStructure can be created with gst.structure.Structure.newEmpty or gst.structure.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.Structure.setValue or gst.structure.Structure.set.

Field values can be retrieved with gst.structure.Structure.getValue or the more convenient gst_structure_get_*() functions.

Fields can be removed with gst.structure.Structure.removeField or gst.structure.Structure.removeFields.

Strings in structures must be ASCII or UTF-8 encoded. Other encodings are not allowed. Strings may be null however.

The serialization format

GstStructure serialization format serialize the GstStructure name, keys/GType/values in a comma separated list with the structure name as first field without value followed by separated key/value pairs in the form key=value, for example:

a-structure, key=value
`

The values type will be inferred if not explicitly specified with the (GTypeName)value syntax, for example the following struct will have one field called 'is-string' which has the string 'true' as a value:

a-struct, field-is-string=(string)true, field-is-boolean=true

*Note*: without specifying (string), field-is-string` type would have been inferred as boolean.

*Note*: we specified (string) as a type even if gchararray is the actual GType name as for convenience some well known types have been aliased or abbreviated.

To avoid specifying the type, you can give some hints to the "type system". For example to specify a value as a double, you should add a decimal (ie. 1 is an harfbuzz.types.int while 1.0 is a double).

*Note*: when a structure is serialized with #gst_structure_to_string, all values are explicitly typed.

Some types have special delimiters:

GstValueArray are inside curly brackets ({ and }). For example a-structure, array={1, 2, 3}
Ranges are inside brackets ([ and ]). For example `a-structure, range=[1, 6, 2]` 1 being the min value, 6 the maximum and 2 the step. To specify a #GST_TYPE_INT64_RANGE you need to explicitly specify it like: a-structure, a-int64-range=(gint64) [1, 5]
GstValueList are inside "less and greater than" (< and >). For example `a-structure, list=<1, 2, 3>

Structures are delimited either by a null character \0 or a semicolon ; the latter allowing to store multiple structures in the same string (see #GstCaps).

Quotes are used as "default" delimiters and can be used around any types that don't use other delimiters (for example a-struct, i=(int)"1"). They are use to allow adding spaces or special characters (such as delimiters, semicolumns, etc..) inside strings and you can use backslashes \ to escape characters inside them, for example:

a-struct, special="\"{[(;)]}\" can be used inside quotes"

They also allow for nested structure, such as:

a-struct, nested=(GstStructure)"nested-struct, nested=true"

Since 1.20, nested structures and caps can be specified using brackets ([ and ]), for example:

a-struct, nested=[nested-struct, nested=true]

> *note*: gst.structure.Structure.toString_ won't use that syntax for backward > compatibility reason, gst.structure.Structure.serializeFull has been added for > that purpose.

class Structure : Boxed {

static gst.structure.Structure fromString(string string_, string end);

static gst.structure.Structure newEmpty(string name);

static gst.structure.Structure newFromString(string string_);

static gst.structure.Structure newIdEmpty(glib.types.Quark quark);

bool canIntersect(gst.structure.Structure struct2);

gst.structure.Structure copy();

void filterAndMapInPlace(gst.types.StructureFilterMapFunc func);

void fixate();

bool fixateField(string fieldName);

bool fixateFieldBoolean(string fieldName, bool target);

bool fixateFieldNearestDouble(string fieldName, double target);

bool fixateFieldNearestFraction(string fieldName, int targetNumerator, int targetDenominator);

bool fixateFieldNearestInt(string fieldName, int target);

bool fixateFieldString(string fieldName, string target);

bool foreach_(gst.types.StructureForeachFunc func);

bool getArray(string fieldname, gobject.value_array.ValueArray array);

bool getBoolean(string fieldname, bool value);

bool getClockTime(string fieldname, gst.types.ClockTime value);

bool getDate(string fieldname, glib.date.Date value);

bool getDateTime(string fieldname, gst.date_time.DateTime value);

bool getDouble(string fieldname, double value);

bool getEnum(string fieldname, gobject.types.GType enumtype, int value);

gobject.types.GType getFieldType(string fieldname);

bool getFlags(string fieldname, gobject.types.GType flagsType, uint value);

bool getFlagset(string fieldname, uint valueFlags, uint valueMask);

bool getFraction(string fieldname, int valueNumerator, int valueDenominator);

bool getInt(string fieldname, int value);

bool getInt64(string fieldname, long value);

bool getList(string fieldname, gobject.value_array.ValueArray array);

string getName();

glib.types.Quark getNameId();

string getString(string fieldname);

bool getUint(string fieldname, uint value);

bool getUint64(string fieldname, ulong value);

gobject.value.Value getValue(string fieldname);

bool hasField(string fieldname);

bool hasFieldTyped(string fieldname, gobject.types.GType type);

bool hasName(string name);

gobject.value.Value idGetValue(glib.types.Quark field);

bool idHasField(glib.types.Quark field);

bool idHasFieldTyped(glib.types.Quark field, gobject.types.GType type);

void idSetValue(glib.types.Quark field, gobject.value.Value value);

void idTakeValue(glib.types.Quark field, gobject.value.Value value);

gst.structure.Structure intersect(gst.structure.Structure struct2);

bool isEqual(gst.structure.Structure structure2);

bool isSubset(gst.structure.Structure superset);

bool mapInPlace(gst.types.StructureMapFunc func);

int nFields();

string nthFieldName(uint index);

void removeAllFields();

void removeField(string fieldname);

string serialize(gst.types.SerializeFlags flags);

string serializeFull(gst.types.SerializeFlags flags);

void setArray(string fieldname, gobject.value_array.ValueArray array);

void setList(string fieldname, gobject.value_array.ValueArray array);

void setName(string name);

void setValue(string fieldname, gobject.value.Value value);

void takeValue(string fieldname, gobject.value.Value value);

string toString_();

static bool take(gst.structure.Structure oldstrPtr, gst.structure.Structure newstr);

}

Members

Functions

canIntersect bool canIntersect(gst.structure.Structure struct2): Tries intersecting struct1 and struct2 and reports whether the result would not be empty.
copy gst.structure.Structure copy(): Duplicates a #GstStructure and all its fields and values.
filterAndMapInPlace void filterAndMapInPlace(gst.types.StructureFilterMapFunc func): Calls the provided function once for each field in the #GstStructure. In contrast to gst.structure.Structure.foreach_, the function may modify the fields. In contrast to gst.structure.Structure.mapInPlace, the field is removed from the structure if false is returned from the function. The structure must be mutable.
fixate void fixate(): Fixate all values in structure using gst.global.valueFixate. structure will be modified in-place and should be writable.
fixateField bool fixateField(string fieldName): Fixates a #GstStructure by changing the given field with its fixated value.
fixateFieldBoolean bool fixateFieldBoolean(string fieldName, bool target): Fixates a #GstStructure by changing the given field_name field to the given target boolean if that field is not fixed yet.
fixateFieldNearestDouble bool fixateFieldNearestDouble(string fieldName, double target): Fixates a #GstStructure by changing the given field to the nearest double to target that is a subset of the existing field.
fixateFieldNearestFraction bool fixateFieldNearestFraction(string fieldName, int targetNumerator, int targetDenominator): 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.
fixateFieldNearestInt bool fixateFieldNearestInt(string fieldName, int target): Fixates a #GstStructure by changing the given field to the nearest integer to target that is a subset of the existing field.
fixateFieldString bool fixateFieldString(string fieldName, string target): Fixates a #GstStructure by changing the given field_name field to the given target string if that field is not fixed yet.
foreach_ bool foreach_(gst.types.StructureForeachFunc func): Calls the provided function once for each field in the #GstStructure. The function must not modify the fields. Also see gst.structure.Structure.mapInPlace and gst.structure.Structure.filterAndMapInPlace.
getArray bool getArray(string fieldname, gobject.value_array.ValueArray array): This is useful in language bindings where unknown #GValue types are not supported. This function will convert the GST_TYPE_ARRAY into a newly allocated #GValueArray and return it through array. Be aware that this is slower then getting the #GValue directly.
getBoolean bool getBoolean(string fieldname, bool 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.
getClockTime bool getClockTime(string fieldname, gst.types.ClockTime 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.
getDate bool getDate(string fieldname, glib.date.Date 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.
getDateTime bool getDateTime(string fieldname, gst.date_time.DateTime 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.
getDouble bool getDouble(string fieldname, double 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.
getEnum bool getEnum(string fieldname, gobject.types.GType enumtype, int 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.
getFieldType gobject.types.GType getFieldType(string 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.
getFlags bool getFlags(string fieldname, gobject.types.GType flagsType, uint value): Sets the unsigned 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 flagstype is correct.
getFlagset bool getFlagset(string fieldname, uint valueFlags, uint valueMask): Read the GstFlagSet flags and mask out of the structure into the provided pointers.
getFraction bool getFraction(string fieldname, int valueNumerator, int valueDenominator): 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.
getInt bool getInt(string fieldname, int 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.
getInt64 bool getInt64(string fieldname, long value): Sets the #gint64 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.
getList bool getList(string fieldname, gobject.value_array.ValueArray array): This is useful in language bindings where unknown #GValue types are not supported. This function will convert the GST_TYPE_LIST into a newly allocated GValueArray and return it through array. Be aware that this is slower then getting the #GValue directly.
getName string getName(): Get the name of structure as a string.
getNameId glib.types.Quark getNameId(): Get the name of structure as a GQuark.
getString string getString(string 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.
getUint bool getUint(string fieldname, uint 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.
getUint64 bool getUint64(string fieldname, ulong value): Sets the #guint64 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.
getValue gobject.value.Value getValue(string fieldname): Get the value of the field with name fieldname.
hasField bool hasField(string fieldname): Check if structure contains a field named fieldname.
hasFieldTyped bool hasFieldTyped(string fieldname, gobject.types.GType type): Check if structure contains a field named fieldname and with GType type.
hasName bool hasName(string name): Checks if the structure has the given name
idGetValue gobject.value.Value idGetValue(glib.types.Quark field): Get the value of the field with GQuark field.
idHasField bool idHasField(glib.types.Quark field): Check if structure contains a field named field.
idHasFieldTyped bool idHasFieldTyped(glib.types.Quark field, gobject.types.GType type): Check if structure contains a field named field and with GType type.
idSetValue void idSetValue(glib.types.Quark field, gobject.value.Value 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.
idTakeValue void idTakeValue(glib.types.Quark field, gobject.value.Value 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.
intersect gst.structure.Structure intersect(gst.structure.Structure struct2): Intersects struct1 and struct2 and returns the intersection.
isEqual bool isEqual(gst.structure.Structure structure2): Tests if the two #GstStructure are equal.
isSubset bool isSubset(gst.structure.Structure 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.
mapInPlace bool mapInPlace(gst.types.StructureMapFunc func): Calls the provided function once for each field in the #GstStructure. In contrast to gst.structure.Structure.foreach_, the function may modify but not delete the fields. The structure must be mutable.
nFields int nFields(): Get the number of fields in the structure.
nthFieldName string nthFieldName(uint index): Get the name of the given field number, counting from 0 onwards.
removeAllFields void removeAllFields(): Removes all fields in a GstStructure.
removeField void removeField(string fieldname): Removes the field with the given name. If the field with the given name does not exist, the structure is unchanged.
serialize string serialize(gst.types.SerializeFlags flags): Converts structure to a human-readable string representation.
serializeFull string serializeFull(gst.types.SerializeFlags flags): Alias for gst.structure.Structure.serialize but with nullable annotation because it can return null when gst.types.SerializeFlags.Strict flag is set.
setArray void setArray(string fieldname, gobject.value_array.ValueArray array): This is useful in language bindings where unknown GValue types are not supported. This function will convert a array to GST_TYPE_ARRAY and set the field specified by fieldname. Be aware that this is slower then using GST_TYPE_ARRAY in a #GValue directly.
setList void setList(string fieldname, gobject.value_array.ValueArray array): This is useful in language bindings where unknown GValue types are not supported. This function will convert a array to GST_TYPE_LIST and set the field specified by fieldname. Be aware that this is slower then using GST_TYPE_LIST in a #GValue directly.
setName void setName(string 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 "/-_.:".
setValue void setValue(string fieldname, gobject.value.Value 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.
takeValue void takeValue(string fieldname, gobject.value.Value 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.
toString_ string toString_(): Converts structure to a human-readable string representation.

Static functions

fromString gst.structure.Structure fromString(string string_, string 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.
newEmpty gst.structure.Structure newEmpty(string name): Creates a new, empty #GstStructure with the given name.
newFromString gst.structure.Structure newFromString(string string_): 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.
newIdEmpty gst.structure.Structure newIdEmpty(glib.types.Quark quark): Creates a new, empty #GstStructure with the given name as a GQuark.
take bool take(gst.structure.Structure oldstrPtr, gst.structure.Structure newstr): Atomically modifies a pointer to point to a new structure. The #GstStructure oldstr_ptr is pointing to is freed and newstr is taken ownership over.

Inherited Members

From Boxed

cInstancePtr void* cInstancePtr;: Pointer to the C boxed value
getType GType getType(): Get the GType of this boxed type.
gType GType gType [@property getter]: Boxed GType property.
self Boxed self(): Convenience method to return this cast to a type. For use in D with statements.
copy_ void* copy_(): Make a copy of the wrapped C boxed data.
boxedCopy void* boxedCopy(void* cBoxed): Copy a C boxed value using g_boxed_copy.
boxedFree void boxedFree(void* cBoxed): Free a C boxed value using g_boxed_free.

gst structure classes

Structure