Lightweight objects to represent element contexts. More...

#include <gstreamermm/context.h>

Inheritance diagram for Gst::Context:

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...

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

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

GstContext*	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...

	Context ()=delete

	Context (const Context&)=delete

Context&	operator= (const Context&)=delete

Glib::RefPtr< Gst::Context >	copy () const
	Creates a copy of the context. More...

Glib::ustring	get_context_type () const
	Get the type of context. More...

bool	has_context_type (const Glib::ustring& context_type) const
	Checks if context has context_type. More...

bool	is_persistent () const
	Check if context is persistent. More...

Gst::Structure	writable_structure () const
	Get a writable version of the 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::Context >	create (const Glib::ustring& context_type, bool persistent)
	Create a new context. 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)

Related Functions
(Note that these are not member functions.)
Glib::RefPtr< Gst::Context >	wrap (GstContext* 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

Lightweight objects to represent element contexts.

Gst::Context is a container object used to store contexts like a device context, a display server connection and similar concepts that should be shared between multiple elements.

Applications can set a context on a complete pipeline by using Gst::Element::set_context(), which will then be propagated to all child elements. Elements can handle these in Gst::Element::set_context_vfunc() and merge them with the context information they already have.

When an element needs a context it will do the following actions in this order until one step succeeds:

Check if the element already has a context
Query downstream with Gst::QUERY_CONTEXT for the context
Query upstream with Gst::QUERY_CONTEXT for the context
Post a Gst::MESSAGE_NEED_CONTEXT message on the bus with the required context types and afterwards check if a usable context was set now
Create a context by itself and post a Gst::MESSAGE_HAVE_CONTEXT message on the bus.

Bins will catch Gst::MESSAGE_NEED_CONTEXT messages and will set any previously known context on the element that asks for it if possible. Otherwise the application should provide one if it can.

Last reviewed on 2016-05-16 (1.8.0)

Since: 1.2

Constructor & Destructor Documentation

◆ Context() [1/2]

Gst::Context::Context ( )

delete

◆ Context() [2/2]

Gst::Context::Context ( const Context& )

delete

Member Function Documentation

◆ copy()

Glib::RefPtr<Gst::Context> Gst::Context::copy ( ) const

Creates a copy of the context.

Returns a copy of the context.

Returns: A new copy of context.

MT safe.

◆ create()

static Glib::RefPtr<Gst::Context> Gst::Context::create	(	const Glib::ustring &	context_type,
		bool	persistent
	)

static

Create a new context.

Parameters

context_type	Context type.
persistent	Persistent context.

Returns: The new context.

◆ get_context_type()

Glib::ustring Gst::Context::get_context_type ( ) const

Get the type of context.

Returns: The type of the context.

◆ gobj() [1/2]

GstContext* Gst::Context::gobj ( )

Provides access to the underlying C instance.

◆ gobj() [2/2]

const GstContext* Gst::Context::gobj ( ) const

Provides access to the underlying C instance.

◆ gobj_copy()

GstContext* Gst::Context::gobj_copy ( ) const

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

◆ has_context_type()

bool Gst::Context::has_context_type ( const Glib::ustring & context_type ) const

Checks if context has context_type.

Parameters

context_type Context type to check.

Returns: true if context has context_type.

◆ is_persistent()

bool Gst::Context::is_persistent ( ) const

Check if context is persistent.

Returns: true if the context is persistent.

◆ operator delete()

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

protected

◆ operator=()

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

delete

◆ reference()

void Gst::Context::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::Context::unreference ( ) const

Decrement the reference count for this object.

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

◆ writable_structure()

Gst::Structure Gst::Context::writable_structure ( ) const

Get a writable version of the structure.

Returns: The structure of the context. The structure is still owned by the context, which means that you should not free it and that the pointer becomes invalid when you free the context. This function checks if context is writable.

Friends And Related Function Documentation

◆ wrap()

Glib::RefPtr< Gst::Context > wrap	(	GstContext *	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

Related Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Context() [1/2]

◆ Context() [2/2]

Member Function Documentation

◆ copy()

◆ create()

◆ get_context_type()

◆ gobj() [1/2]

◆ gobj() [2/2]

◆ gobj_copy()

◆ has_context_type()

◆ is_persistent()

◆ operator delete()

◆ operator=()

◆ reference()

◆ unreference()

◆ writable_structure()

Friends And Related Function Documentation

◆ wrap()