org.freedesktop.gstreamer

Class Context

java.lang.Object

org.freedesktop.gstreamer.glib.NativeObject

org.freedesktop.gstreamer.glib.RefCountedObject

org.freedesktop.gstreamer.MiniObject

org.freedesktop.gstreamer.Context

All Implemented Interfaces:

AutoCloseable

public class Context
extends MiniObject

Lightweight objects to represent element contexts.

See upstream documentation at https://gstreamer.freedesktop.org/documentation/gstreamer/gstcontext.html

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 Element.setContext(Context), which will then be propagated to all child elements. Elements can handle these in Element.setContext(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:

1. Check if the element already has a context
2. Query downstream with GST_QUERY_CONTEXT for the context
3. Query upstream* with GST_QUERY_CONTEXT for the context
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
5. 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.

Contexts can be persistent. A persistent context is kept in elements when they reach , non-persistent ones will be removed. Also, a non-persistent context won't override a previous persistent context set to an element.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	Context.Handle

Nested classes/interfaces inherited from class org.freedesktop.gstreamer.glib.NativeObject

NativeObject.Initializer, NativeObject.TypeProvider, NativeObject.TypeRegistration<T extends NativeObject>

Field Summary

Fields

Modifier and Type	Field and Description
static String	GTYPE_NAME

Constructor Summary

Constructors

Constructor and Description
Context(String contextType)
Context(String context_type, boolean persistent) Create a new context.

Method Summary

Modifier and Type	Method and Description
String	getContextType() Get the type of this context.
Structure	getStructure() Access the structure of the context.
Structure	getWritableStructure() Get a writable version of the structure.

Methods inherited from class org.freedesktop.gstreamer.MiniObject

copy, getRefCount, isWritable, makeWritable

Methods inherited from class org.freedesktop.gstreamer.glib.NativeObject

close, disown, dispose, equals, getPointer, getRawPointer, hashCode, invalidate, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

GTYPE_NAME

public static final String GTYPE_NAME

See Also:

Constant Field Values

Constructor Detail

Context

public Context(String contextType)

Context

public Context(String context_type,
               boolean persistent)

Create a new context.

Method Detail

getStructure

public Structure getStructure()

Access the structure of the context.

Returns:

The structure of this context. The structure is still owned by this context, which means that you should not modify it and not dispose of it.

getWritableStructure

public Structure getWritableStructure()

Get a writable version of the structure.

Returns:

The structure of this context. The structure is still owned by the context, which means that you should not dispose of it.

getContextType

public String getContextType()

Get the type of this context.

Returns:

The type of this context.