Package org.freedesktop.gstreamer.gst

Class Context

java.lang.Object

io.github.jwharm.javagi.base.ProxyInstance

org.freedesktop.gstreamer.gst.Context

All Implemented Interfaces:

Proxy

@Generated("io.github.jwharm.JavaGI")
public class Context
extends ProxyInstance

GstContext 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 GstElementClass::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:

1. Check if the element already has a context 2. Query downstream with QueryType.CONTEXT for the context 3. Query upstream with QueryType.CONTEXT for the context 4. Post a MessageType.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 MessageType.HAVE_CONTEXT message on the bus.

Bins will catch 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.

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

Constructor Summary

Constructors

Constructor	Description
Context(MemorySegment address)	Create a Context proxy instance for the provided memory address.
Context(String contextType, boolean persistent)	Creates a new context.

Method Summary

Modifier and Type	Method	Description
Context	copy()	Creates a copy of the context.
String	getContextType()	Gets the type of this Context.
Structure	getStructure()	Accesses the structure of the context.
static Type	getType()	Get the GType of the Context class
boolean	hasContextType(String contextType)	Checks if this Context has contextType.
boolean	isPersistent()	Checks if this Context is persistent.
Context	ref()	Convenience macro to increase the reference count of the context.
static boolean	replace(Out<Context> oldContext, @Nullable Context newContext)	Modifies a pointer to a GstContext to point to a different GstContext.
void	unref()	Convenience macro to decrease the reference count of the context, possibly freeing it.
Structure	writableStructure()	Gets a writable version of the structure.

Methods inherited from class io.github.jwharm.javagi.base.ProxyInstance

equals, handle, hashCode

Methods inherited from class java.lang.Object

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

Constructor Details

Context

public Context(MemorySegment address)

Create a Context proxy instance for the provided memory address.

Parameters:

address - the memory address of the native object

Context

public Context(String contextType,
 boolean persistent)

Creates a new context.

Parameters:

contextType - Context type

persistent - Persistent context

Method Details

getType

public static Type getType()

Get the GType of the Context class

Returns:

the GType

replace

public static boolean replace(Out<Context> oldContext,
 @Nullable
 @Nullable Context newContext)

Modifies a pointer to a GstContext to point to a different GstContext. The modification is done atomically (so this is useful for ensuring thread safety in some cases), and the reference counts are updated appropriately (the old context is unreffed, the new one is reffed).

Either newContext or the GstContext pointed to by oldContext may be null.

Parameters:

oldContext - pointer to a pointer to a GstContext to be replaced.

newContext - pointer to a GstContext that will replace the context pointed to by oldContext.

Returns:

true if newContext was different from oldContext

copy

public Context copy()

Creates a copy of the context. Returns a copy of the context.

Returns:

a new copy of this Context.

MT safe

getContextType

public String getContextType()

Gets the type of this Context.

Returns:

The type of the context.

getStructure

public Structure getStructure()

Accesses the structure of the context.

Returns:

The structure of the context. The structure is still owned by the context, which means that you should not modify it, free it and that the pointer becomes invalid when you free the context.

hasContextType

public boolean hasContextType(String contextType)

Checks if this Context has contextType.

Parameters:

contextType - Context type to check.

Returns:

true if this Context has contextType.

isPersistent

public boolean isPersistent()

Checks if this Context is persistent.

Returns:

true if the context is persistent.

ref

public Context ref()

Convenience macro to increase the reference count of the context.

Returns:

this Context (for convenience when doing assignments)

unref

public void unref()

Convenience macro to decrease the reference count of the context, possibly freeing it.

writableStructure

public Structure writableStructure()

Gets 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 this Context is writable.