:right-sidebar: True

Context
===================================================================

.. currentmodule:: gi.repository.Gst


.. versionadded:: 1.2




.. class:: Context(**kwargs)
   :no-contents-entry:






:obj:`~gi.repository.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
:func:`~gi.repository.Gst.Element.set_context`, which will then be propagated to all
child elements. Elements can handle these in :obj:`~gi.repository.Gst.ElementClass`\::set_context
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 :const:`~gi.repository.Gst.QueryType.CONTEXT` for the context
- Query upstream with :const:`~gi.repository.Gst.QueryType.CONTEXT` for the context
- Post a :const:`~gi.repository.Gst.MessageType.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 :const:`~gi.repository.Gst.MessageType.HAVE_CONTEXT` message
   on the bus.


Bins will catch :const:`~gi.repository.Gst.MessageType.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.

:obj:`~gi.repository.Gst.Context` can be persistent.
A persistent :obj:`~gi.repository.Gst.Context` is kept in elements when they reach
:const:`~gi.repository.Gst.State.NULL`, non-persistent ones will be removed.
Also, a non-persistent context won't override a previous persistent
context set to an element.


Constructors
------------

.. rst-class:: interim-class

.. class:: Context
   :no-index:


   .. classmethod:: new(context_type: str, persistent: bool) -> ~gi.repository.Gst.Context

      Creates a new context.


      .. versionadded:: 1.2





      :param context_type: Context type

      :param persistent: Persistent context








Methods
-------

.. rst-class:: interim-class

.. class:: Context
   :no-index:


   .. method:: get_context_type() -> str

      Gets the type of ``context``\.


      .. versionadded:: 1.2








   .. method:: get_structure() -> ~gi.repository.Gst.Structure

      Accesses the structure of the context.


      .. versionadded:: 1.2








   .. method:: has_context_type(context_type: str) -> bool

      Checks if ``context`` has ``context_type``\.


      .. versionadded:: 1.2





      :param context_type: Context type to check.




   .. method:: is_persistent() -> bool

      Checks if ``context`` is persistent.


      .. versionadded:: 1.2








   .. method:: writable_structure() -> ~gi.repository.Gst.Structure

      Gets a writable version of the structure.


      .. versionadded:: 1.2