Object: Context

Detailed Description

Defines the Context Object Interface.

The OpenVX context is the object domain for all OpenVX objects. All data objects live in the context as well as all framework objects. The OpenVX context keeps reference counts on all objects and must do garbage collection during its deconstruction to free lost references. While multiple clients may connect to the OpenVX context, all data are private in that the references referring to data objects are given only to the creating party.

Modules
	Memory import type constants.
	An enumeration of memory import types.
	The termination criteria list.
	The memory accessor hint flags.
	The memory accessor hint flags. These enumeration values are used to indicate desired system behavior, not the User intent. For example: these can be interpretted as hints to the system about cache operations or marshalling operations.
	The Round Policy Enumeration.
	The Round Policy Enumeration.

Macros
#define	VX_MAX_IMPLEMENTATION_NAME   (64)
	Defines the length of the implementation name string, including the trailing zero [R01651].

Typedefs
typedef struct _vx_context *	vx_context
	An opaque reference to the implementation context. More...

Functions
vx_context VX_API_CALL	vxCreateContext (void)
	Creates a vx_context. More...
vx_context VX_API_CALL	vxGetContext (vx_reference reference)
	Retrieves the context from any reference from within a context. More...
vx_status VX_API_CALL	vxQueryContext (vx_context context, vx_enum attribute, void *ptr, vx_size size)
	Queries the context for some specific information. More...
vx_status VX_API_CALL	vxReleaseContext (vx_context *context)
	Releases the OpenVX object context. More...
vx_status VX_API_CALL	vxSetContextAttribute (vx_context context, vx_enum attribute, const void *ptr, vx_size size)
	Sets an attribute on the context. More...

Typedef Documentation

vx_context

typedef struct _vx_context* vx_context

An opaque reference to the implementation context.

See also

vxCreateContext

Definition at line 226 of file vx_types.h.

Function Documentation

vxCreateContext()

vx_context VX_API_CALL vxCreateContext

(

void

)

Creates a vx_context.

This creates a top-level object context for OpenVX [R00444].

Note

This is required to do anything else.

Returns

The reference to the implementation context vx_context [R00445]. Any possible errors preventing a successful creation should be checked using vxGetStatus [R00446].

Postcondition

vxReleaseContext

vxReleaseContext()

vx_status VX_API_CALL vxReleaseContext

(

vx_context *

context

)

Releases the OpenVX object context.

All reference counted objects are garbage-collected by the return of this call. No calls are possible using the parameter context after the context has been released until a new reference from vxCreateContext is returned [R00447]. All outstanding references to OpenVX objects from this context are invalid after this call.

Parameters

[in]

context

The pointer to the reference to the context [R00448].

Postcondition

After returning from this function the reference is zeroed [R00449].

Returns

A The vx_status Constants value.

Return values

VX_SUCCESS	No errors; any other value indicates failure [R00450].
VX_ERROR_INVALID_REFERENCE	context is not a valid vx_context reference.

Precondition

vxCreateContext

vxGetContext()

vx_context VX_API_CALL vxGetContext

(

vx_reference

reference

)

Retrieves the context from any reference from within a context.

Parameters

[in]

reference

The reference from which to extract the context [R00451].

Returns

The overall context that created the particular reference [R00452]. Any possible errors preventing a successful completion of this function should be checked using vxGetStatus [R00453].

vxQueryContext()

vx_status VX_API_CALL vxQueryContext	(	vx_context	context,
		vx_enum	attribute,
		void *	ptr,
		vx_size	size
	)

Queries the context for some specific information.

Parameters

[in]	context	The reference to the context [R00454].
[in]	attribute	The attribute to query. Use a Context Attribute Constants [R00455].
[out]	ptr	The location at which to store the resulting value [R00456].
[in]	size	The size in bytes of the container to which ptr points [R00457].

Returns

A The vx_status Constants value.

Return values

VX_SUCCESS	No errors; any other value indicates failure [R00458].
VX_ERROR_INVALID_REFERENCE	context is not a valid vx_context reference.
VX_ERROR_INVALID_PARAMETERS	If any of the other parameters are incorrect.
VX_ERROR_NOT_SUPPORTED	If the attribute is not supported on this implementation.

vxSetContextAttribute()

vx_status VX_API_CALL vxSetContextAttribute	(	vx_context	context,
		vx_enum	attribute,
		const void *	ptr,
		vx_size	size
	)

Sets an attribute on the context.

Parameters

[in]	context	The handle to the overall context [R00459].
[in]	attribute	The attribute to set from Context Attribute Constants [R00460].
[in]	ptr	The pointer to the data to which to set the attribute [R00461].
[in]	size	The size in bytes of the data to which ptr points [R00462].

Returns

A The vx_status Constants value.

Return values

VX_SUCCESS	No errors; any other value indicates failure [R00463].
VX_ERROR_INVALID_REFERENCE	context is not a valid vx_context reference.
VX_ERROR_INVALID_PARAMETERS	If any of the other parameters are incorrect.
VX_ERROR_NOT_SUPPORTED	If the attribute is not settable.