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design/context: add missing markup to function calls and gst keywords

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Reynaldo H. Verdejo Pinochet 2016-12-20 23:10:03 -08:00
parent 67fb7c7b94
commit 949c08b512
1 changed files with 12 additions and 12 deletions
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markdown/design/context.md
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@ -1,7 +1,7 @@
# Context # Context
GstContext is a container object, containing a type string and a generic `GstContext` is a container object, containing a type string and a generic
GstStructure. It is used to store and propagate context information in a `GstStructure`. It is used to store and propagate context information in a
pipeline, like device handles, display server connections and other pipeline, like device handles, display server connections and other
information that should be shared between multiple elements in a information that should be shared between multiple elements in a
pipeline. pipeline.
@ -22,40 +22,40 @@ Elements that need a specific context for their operation would do the
following steps until one succeeds: following steps until one succeeds:
1) Check if the element already has a context of the specific type, 1) Check if the element already has a context of the specific type,
i.e. it was previously set via gst_element_set_context(). i.e. it was previously set via `gst_element_set_context()`.
2) Query downstream with GST_QUERY_CONTEXT for the context and check if 2) Query downstream with `GST_QUERY_CONTEXT` for the context and check if
downstream already has a context of the specific type downstream already has a context of the specific type
3) Query upstream with GST_QUERY_CONTEXT for the context and check if 3) Query upstream with `GST_QUERY_CONTEXT` for the context and check if
upstream already has a context of the specific type upstream already has a context of the specific type
4) Post a GST_MESSAGE_NEED_CONTEXT message on the bus with the required 4) 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 context types and afterwards check if a usable context was set now
as in 1). The message could be handled by the parent bins of the as in 1). The message could be handled by the parent bins of the
element and the application. element and the application.
4) Create a context by itself and post a GST_MESSAGE_HAVE_CONTEXT message 4) Create a context by itself and post a `GST_MESSAGE_HAVE_CONTEXT` message
on the bus. on the bus.
Bins will propagate any context that is set on them to their child Bins will propagate any context that is set on them to their child
elements via gst\_element\_set\_context(). Even to elements added after elements via `gst_element_set_context()`. Even to elements added after
a given context has been set. a given context has been set.
Bins can handle the GST\_MESSAGE\_NEED\_CONTEXT message, can filter both Bins can handle the `GST_MESSAGE_NEED_CONTEXT` message, can filter both
messages and can also set different contexts for different pipeline messages and can also set different contexts for different pipeline
parts. parts.
## Applications ## Applications
Applications can set a specific context on a pipeline or elements inside Applications can set a specific context on a pipeline or elements inside
a pipeline with gst\_element\_set\_context(). a pipeline with `gst_element_set_context()`.
If an element inside the pipeline needs a specific context, it will post If an element inside the pipeline needs a specific context, it will post
a GST\_MESSAGE\_NEED\_CONTEXT message on the bus. The application can a `GST_MESSAGE_NEED_CONTEXT` message on the bus. The application can
now create a context of the requested type or pass an already existing now create a context of the requested type or pass an already existing
context to the element (or to the complete pipeline). context to the element (or to the complete pipeline).
Whenever an element creates a context internally it will post a Whenever an element creates a context internally it will post a
GST\_MESSAGE\_HAVE\_CONTEXT message on the bus. Bins will cache these `GST_MESSAGE_HAVE_CONTEXT` message on the bus. Bins will cache these
contexts and pass them to any future element that requests them. contexts and pass them to any future element that requests them.