A class used to perform queries on pads and elements. More...

#include <gstreamermm/query.h>

Inheritance diagram for Gst::Query:

[legend]

Public Member Functions
void	reference () const
	Increment the reference count for this object. More...

void	unreference () const
	Decrement the reference count for this object. More...

GstQuery*	gobj ()
	Provides access to the underlying C instance. More...

const GstQuery*	gobj () const
	Provides access to the underlying C instance. More...

GstQuery*	gobj_copy () const
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

	Query ()=delete

	Query (const Query&)=delete

Query&	operator= (const Query&)=delete

Glib::RefPtr< Gst::Query >	create_writable ()
	Makes a writable query from the given query. More...

Gst::Structure	get_structure () const
	Get the structure of a query. More...

QueryType	get_query_type () const
	Get the Gst::QueryType of the query. More...

Glib::RefPtr< Gst::Query >	copy ()
	Copies the given query using the copy function of the parent Gst::Structure. More...

Public Member Functions inherited from Gst::MiniObject
void	reference () const
	Increment the reference count for this object. More...

void	unreference () const
	Decrement the reference count for this object. More...

GstMiniObject*	gobj ()
	Provides access to the underlying C instance. More...

const GstMiniObject*	gobj () const
	Provides access to the underlying C instance. More...

GstMiniObject*	gobj_copy () const
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

	MiniObject ()=delete

	MiniObject (const MiniObject&)=delete

MiniObject&	operator= (const MiniObject&)=delete

	~MiniObject ()

guint	get_flags () const

void	set_flags (const guint& value)

gint	get_refcount () const

gint	get_lockstate () const

bool	lock (LockFlags flags)
	Lock the mini-object with the specified access mode in flags. More...

void	unlock (LockFlags flags)
	Unlock the mini-object with the specified access mode in flags. More...

bool	is_writable () const
	If mini_object has the LOCKABLE flag set, check if the current EXCLUSIVE lock on object is the only one, this means that changes to the object will not be visible to any other object. More...

Glib::RefPtr< MiniObject >	create_writable ()
	Checks if a mini-object is writable. More...

void	set_qdata (GQuark quark, QuarkData* data)
	This sets an opaque, named pointer on a miniobject. More...

QuarkData*	get_qdata (GQuark quark) const
	This function gets back user data pointers stored via set_qdata(). More...

QuarkData*	steal_qdata (GQuark quark)
	This function gets back user data pointers stored via set_qdata() and removes the data from object without invoking its destroy() function (if any was set). More...

void	add_finalize_notifier (const SlotFinalizer& slot)
	Adds notifier when mini object is finalized. More...

void	remove_finalize_notifier ()
	Remove finalize notifier. More...

Static Public Member Functions
static Glib::RefPtr< Gst::Query >	create_buffering (Gst::Format format)
	Constructs a new query object for querying the buffering status of a stream. More...

static Glib::RefPtr< Gst::Query >	create_allocation (Glib::RefPtr< Gst::Caps > caps, bool need_pool)
	Constructs a new query object for querying the allocation properties. More...

static Glib::RefPtr< Gst::Query >	create_uri ()
	Constructs a new query URI query object. More...

static Glib::RefPtr< Gst::Query >	create_scheduling ()
	Constructs a new query object for querying the scheduling properties. More...

static Glib::RefPtr< Gst::Query >	create_drain ()
	Constructs a new query object for querying the drain state. More...

static Glib::RefPtr< Gst::Query >	create_custom (Gst::QueryType type, const Gst::Structure& structure)
	Constructs a new custom query object. More...

static Glib::RefPtr< Gst::Query >	create_convert (Gst::Format format, gint64 value, Gst::Format dest_format)
	Constructs a new convert query object. More...

static Glib::RefPtr< Gst::Query >	create_position (Gst::Format format)
	Constructs a new query stream position query object. More...

static Glib::RefPtr< Gst::Query >	create_duration (Gst::Format format)
	Constructs a new stream duration query object to query in the given format. More...

static Glib::RefPtr< Gst::Query >	create_latency ()
	Constructs a new latency query object. More...

static Glib::RefPtr< Gst::Query >	create_seeking (Gst::Format format)
	Constructs a new query object for querying seeking properties of the stream. More...

static Glib::RefPtr< Gst::Query >	create_formats ()
	Constructs a new query object for querying formats of the stream. More...

static Glib::RefPtr< Gst::Query >	create_segment (Gst::Format format)
	Constructs a new segment query object. More...

static Glib::RefPtr< Gst::Query >	create_caps (Glib::RefPtr< Gst::Caps > filter)
	Constructs a new query object for querying the caps. More...

static Glib::RefPtr< Gst::Query >	create_accept_caps (Glib::RefPtr< Gst::Caps > filter)
	Constructs a new query object for querying if filter are accepted. More...

Protected Member Functions
void	operator delete (void*, std::size_t)

Protected Member Functions inherited from Gst::MiniObject
void	operator delete (void*, std::size_t)

Static Protected Member Functions
template<class QueryType >
static Glib::RefPtr< QueryType >	wrap (GstQuery* query, bool take_copy=false)

Related Functions
(Note that these are not member functions.)
Glib::RefPtr< Gst::Query >	wrap (GstQuery* object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Related Functions inherited from Gst::MiniObject
Glib::RefPtr< Gst::MiniObject >	wrap (GstMiniObject* object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Additional Inherited Members
Public Types inherited from Gst::MiniObject
typedef sigc::slot< void >	SlotFinalizer

Detailed Description

A class used to perform queries on pads and elements.

Queries can be performed on pads (gst_pad_query()) and elements (gst_element_query()). Please note that some queries might need a running pipeline to work.

Queries can be created using the gst_query_new_*() functions. Query values can be set using gst_query_set_*(), and parsed using gst_query_parse_*() helpers.

The following example shows how to query the duration of a pipeline:

Glib::RefPtr<Gst::Query> query = Gst::QueryDuration::create(Gst::FORMAT_TIME);
bool res = pipeline->query(query);
if(res)
{
 gint64 duration = Glib::RefPtr<Gst::QueryDuration>::cast_dynamic(query)->parse();
 ...
}

Constructor & Destructor Documentation

◆ Query() [1/2]

Gst::Query::Query ( )

delete

◆ Query() [2/2]

Gst::Query::Query ( const Query& )

delete

Member Function Documentation

◆ copy()

Glib::RefPtr<Gst::Query> Gst::Query::copy ( )

Copies the given query using the copy function of the parent Gst::Structure.

Free-function: gst_query_unref

Returns: A new copy of q.

◆ create_accept_caps()

static Glib::RefPtr<Gst::Query> Gst::Query::create_accept_caps ( Glib::RefPtr< Gst::Caps > filter )

static

Constructs a new query object for querying if filter are accepted.

Free-function: gst_query_unref

Parameters

filter A fixed Gst::Caps.

Returns: A new Gst::Query.

◆ create_allocation()

static Glib::RefPtr<Gst::Query> Gst::Query::create_allocation	(	Glib::RefPtr< Gst::Caps >	caps,
		bool	need_pool
	)

static

Constructs a new query object for querying the allocation properties.

Free-function: gst_query_unref

Parameters

caps	The negotiated caps.
need_pool	Return a pool.

Returns: A new Gst::Query.

◆ create_buffering()

static Glib::RefPtr<Gst::Query> Gst::Query::create_buffering ( Gst::Format format )

static

Constructs a new query object for querying the buffering status of a stream.

Free-function: gst_query_unref

Parameters

format The default Gst::Format for the new query.

Returns: A new Gst::Query.

◆ create_caps()

static Glib::RefPtr<Gst::Query> Gst::Query::create_caps ( Glib::RefPtr< Gst::Caps > filter )

static

Constructs a new query object for querying the caps.

The CAPS query should return the allowable caps for a pad in the context of the element's state, its link to other elements, and the devices or files it has opened. These caps must be a subset of the pad template caps. In the nullptr state with no links, the CAPS query should ideally return the same caps as the pad template. In rare circumstances, an object property can affect the caps returned by the CAPS query, but this is discouraged.

For most filters, the caps returned by CAPS query is directly affected by the allowed caps on other pads. For demuxers and decoders, the caps returned by the srcpad's getcaps function is directly related to the stream data. Again, the CAPS query should return the most specific caps it reasonably can, since this helps with autoplugging.

The filter is used to restrict the result caps, only the caps matching filter should be returned from the CAPS query. Specifying a filter might greatly reduce the amount of processing an element needs to do.

Free-function: gst_query_unref

Parameters

filter A filter.

Returns: A new Gst::Query.

◆ create_convert()

static Glib::RefPtr<Gst::Query> Gst::Query::create_convert	(	Gst::Format	format,
		gint64	value,
		Gst::Format	dest_format
	)

static

Constructs a new convert query object.

Use unref() when done with it. A convert query is used to ask for a conversion between one format and another.

Free-function: gst_query_unref

Parameters

format	The source Gst::Format for the new query.
value	The value to convert.
dest_format	The target Gst::Format.

Returns: A Gst::Query.

◆ create_custom()

static Glib::RefPtr<Gst::Query> Gst::Query::create_custom	(	Gst::QueryType	type,
		const Gst::Structure&	structure
	)

static

Constructs a new custom query object.

Use unref() when done with it.

Free-function: gst_query_unref

Parameters

type	The query type.
structure	A structure for the query.

Returns: A new Gst::Query.

◆ create_drain()

static Glib::RefPtr<Gst::Query> Gst::Query::create_drain ( )

static

Constructs a new query object for querying the drain state.

Free-function: gst_query_unref

Returns: A new Gst::Query.

◆ create_duration()

static Glib::RefPtr<Gst::Query> Gst::Query::create_duration ( Gst::Format format )

static

Constructs a new stream duration query object to query in the given format.

Use unref() when done with it. A duration query will give the total length of the stream.

Free-function: gst_query_unref

Parameters

format The Gst::Format for this duration query.

Returns: A new Gst::Query.

◆ create_formats()

static Glib::RefPtr<Gst::Query> Gst::Query::create_formats ( )

static

Constructs a new query object for querying formats of the stream.

Free-function: gst_query_unref

Returns: A new Gst::Query.

◆ create_latency()

static Glib::RefPtr<Gst::Query> Gst::Query::create_latency ( )

static

Constructs a new latency query object.

Use unref() when done with it. A latency query is usually performed by sinks to compensate for additional latency introduced by elements in the pipeline.

Free-function: gst_query_unref

Returns: A Gst::Query.

◆ create_position()

static Glib::RefPtr<Gst::Query> Gst::Query::create_position ( Gst::Format format )

static

Constructs a new query stream position query object.

Use unref() when done with it. A position query is used to query the current position of playback in the streams, in some format.

Free-function: gst_query_unref

Parameters

format The default Gst::Format for the new query.

Returns: A new Gst::Query.

◆ create_scheduling()

static Glib::RefPtr<Gst::Query> Gst::Query::create_scheduling ( )

static

Constructs a new query object for querying the scheduling properties.

Free-function: gst_query_unref

Returns: A new Gst::Query.

◆ create_seeking()

static Glib::RefPtr<Gst::Query> Gst::Query::create_seeking ( Gst::Format format )

static

Constructs a new query object for querying seeking properties of the stream.

Free-function: gst_query_unref

Parameters

format The default Gst::Format for the new query.

Returns: A new Gst::Query.

◆ create_segment()

static Glib::RefPtr<Gst::Query> Gst::Query::create_segment ( Gst::Format format )

static

Constructs a new segment query object.

Use unref() when done with it. A segment query is used to discover information about the currently configured segment for playback.

Free-function: gst_query_unref

Parameters

format The Gst::Format for the new query.

Returns: A new Gst::Query.

◆ create_uri()

static Glib::RefPtr<Gst::Query> Gst::Query::create_uri ( )

static

Constructs a new query URI query object.

Use unref() when done with it. An URI query is used to query the current URI that is used by the source or sink.

Free-function: gst_query_unref

Returns: A new Gst::Query.

◆ create_writable()

Glib::RefPtr<Gst::Query> Gst::Query::create_writable ( )

Makes a writable query from the given query.

Returns: A Gst::Query (possibly the same pointer) that is writable.

◆ get_query_type()

QueryType Gst::Query::get_query_type ( ) const

Get the Gst::QueryType of the query.

◆ get_structure()

Gst::Structure Gst::Query::get_structure ( ) const

Get the structure of a query.

Returns: The Gst::Structure of the query. The structure is still owned by the query and will therefore be freed when the query is unreffed.

◆ gobj() [1/2]

GstQuery* Gst::Query::gobj ( )

Provides access to the underlying C instance.

◆ gobj() [2/2]

const GstQuery* Gst::Query::gobj ( ) const

Provides access to the underlying C instance.

◆ gobj_copy()

GstQuery* Gst::Query::gobj_copy ( ) const

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

◆ operator delete()

void Gst::Query::operator delete	(	void *	,
		std::size_t
	)

protected

◆ operator=()

Query& Gst::Query::operator= ( const Query& )

delete

◆ reference()

void Gst::Query::reference ( ) const

Increment the reference count for this object.

You should never need to do this manually - use the object via a RefPtr instead.

◆ unreference()

void Gst::Query::unreference ( ) const

Decrement the reference count for this object.

You should never need to do this manually - use the object via a RefPtr instead.

◆ wrap()

template <class QueryType >

static Glib::RefPtr<QueryType> Gst::Query::wrap	(	GstQuery *	query,
		bool	take_copy = `false`
	)

inlinestaticprotected

Friends And Related Function Documentation

◆ wrap()

Glib::RefPtr< Gst::Query > wrap	(	GstQuery *	object,
		bool	take_copy = `false`
	)

Parameters

object	The C instance.
take_copy	False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns: A C++ instance that wraps this C instance.

Public Member Functions

Static Public Member Functions

Protected Member Functions

Static Protected Member Functions

Related Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Query() [1/2]

◆ Query() [2/2]

Member Function Documentation

◆ copy()

◆ create_accept_caps()

◆ create_allocation()

◆ create_buffering()

◆ create_caps()

◆ create_convert()

◆ create_custom()

◆ create_drain()

◆ create_duration()

◆ create_formats()

◆ create_latency()

◆ create_position()

◆ create_scheduling()

◆ create_seeking()

◆ create_segment()

◆ create_uri()

◆ create_writable()

◆ get_query_type()

◆ get_structure()

◆ gobj() [1/2]

◆ gobj() [2/2]

◆ gobj_copy()

◆ operator delete()

◆ operator=()

◆ reference()

◆ unreference()

◆ wrap()

Friends And Related Function Documentation

◆ wrap()