monado/src/xrt/state_trackers/oxr/oxr_chain.h
Ryan Pavlik fa8047fed3 st/oxr: Add oxr_chain.h header
This should replace all manual poking of the next chain.
Prefer the macros over the functions since they'll do your casting for you.
2019-06-03 22:52:28 +00:00

95 lines
2.2 KiB
C

// Copyright 2019, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
* @file
* @brief Utilities for accessing members in an OpenXR structure chain.
* @author Ryan Pavlik <ryan.pavlik@collabora.com>
*/
#pragma once
#include <xrt/xrt_openxr_includes.h>
#ifdef __cplusplus
extern "C" {
#endif
/*!
* @ingroup oxr_api
* @{
*/
/*!
* Finds an input struct of the given type in a next-chain.
*
* Returns NULL if nothing matching is found.
*
* Prefer using OXR_GET_INPUT_FROM_CHAIN() instead, since it includes the
* casting.
*/
static inline XrBaseInStructure const*
oxr_find_input_in_chain(const void* ptr, XrStructureType desired)
{
while (ptr != NULL) {
XrBaseInStructure const* base = (XrBaseInStructure const*)ptr;
if (base->type == desired) {
return base;
}
ptr = base->next;
}
return NULL;
}
/*!
* Finds an input struct of the given type in a next-chain and casts it as
* desired.
*
* Returns NULL if nothing matching is found.
*
* Note: There is no protection here to ensure that STRUCTURE_TYPE_ENUM (an
* XrStructureType value) and TYPE (a type name) actually match!
*/
#define OXR_GET_INPUT_FROM_CHAIN(PTR, STRUCTURE_TYPE_ENUM, TYPE) \
((TYPE const*)oxr_find_input_in_chain(PTR, STRUCTURE_TYPE_ENUM))
/*!
* Finds an output struct of the given type in a next-chain.
*
* Returns NULL if nothing matching is found.
*
* Prefer using OXR_GET_OUTPUT_FROM_CHAIN() instead, since it includes the
* casting.
*/
static inline XrBaseOutStructure*
oxr_find_output_in_chain(void* ptr, XrStructureType desired)
{
while (ptr != NULL) {
XrBaseOutStructure* base = (XrBaseOutStructure*)ptr;
if (base->type == desired) {
return base;
}
ptr = base->next;
}
return NULL;
}
/*!
* Finds an output struct of the given type in a next-chain and casts it as
* desired.
*
* Returns NULL if nothing matching is found.
*
* Note: There is no protection here to ensure that STRUCTURE_TYPE_ENUM (an
* XrStructureType value) and TYPE (a type name) actually match!
*/
#define OXR_GET_OUTPUT_FROM_CHAIN(PTR, STRUCTURE_TYPE_ENUM, TYPE) \
((TYPE*)oxr_find_output_in_chain(PTR, STRUCTURE_TYPE_ENUM))
/*!
* @}
*/
#ifdef __cplusplus
}
#endif