comp_base.h

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// Copyright 2019-2023, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Helper implementation for native compositors.
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @author Lubosz Sarnecki <lubosz.sarnecki@collabora.com>
 * @ingroup comp_util
 */
 
#pragma once
 
#include "util/comp_sync.h"
#include "util/comp_swapchain.h"
 
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define COMP_MAX_LAYERS 16
 
/*!
 * A single layer.
 *
 * @ingroup comp_util
 * @see comp_layer_slot
 */
struct comp_layer
{
        /*!
         * Up to four compositor swapchains referenced per layer.
         *
         * Unused elements should be set to null.
         */
        struct comp_swapchain *sc_array[XRT_MAX_VIEWS * 2];
 
        /*!
         * All basic (trivially-serializable) data associated with a layer.
         */
        struct xrt_layer_data data;
};
 
/*!
 * A stack of layers.
 *
 * @ingroup comp_util
 * @see comp_base
 */
struct comp_layer_slot
{
        //! The per frame data.
        struct xrt_layer_frame_data data;
 
        //! All of the layers.
        struct comp_layer layers[COMP_MAX_LAYERS];
 
        //! Number of submitted layers.
        uint32_t layer_count;
 
        //! Special case one layer projection/projection-depth fast-path.
        bool one_projection_layer_fast_path;
 
        //! fov as reported by device for the current submit.
        struct xrt_fov fovs[XRT_MAX_VIEWS];
        //! absolute pose as reported by device for the current submit.
        struct xrt_pose poses[XRT_MAX_VIEWS];
};
 
/*!
 * A simple compositor base that handles a lot of things for you.
 *
 * Things it handles for you:
 * * App swapchains
 * * App fences
 * * Vulkan bundle (needed for swapchains and fences)
 * * Layer tracking, not @ref xrt_compositor::layer_commit
 * * Wait function, not @ref xrt_compositor::predict_frame
 *
 * Functions it does not handle:
 * * @ref xrt_compositor::begin_session
 * * @ref xrt_compositor::end_session
 * * @ref xrt_compositor::predict_frame
 * * @ref xrt_compositor::mark_frame
 * * @ref xrt_compositor::begin_frame
 * * @ref xrt_compositor::discard_frame
 * * @ref xrt_compositor::layer_commit
 * * @ref xrt_compositor::poll_events
 * * @ref xrt_compositor::destroy
 *
 * Partially implements @ref xrt_compositor_native, meant to serve as
 * the base of a main compositor implementation.
 *
 * @implements xrt_compositor_native
 * @ingroup comp_util
 */
struct comp_base
{
        //! Base native compositor.
        struct xrt_compositor_native base;
 
        //! Vulkan bundle of useful things, used by swapchain and fence.
        struct vk_bundle vk;
 
        //! For default @ref xrt_compositor::wait_frame.
        struct os_precise_sleeper sleeper;
 
        //! Swapchain garbage collector, used by swapchain, child class needs to call.
        struct comp_swapchain_shared cscs;
 
        //! We only need to track a single slot.
        struct comp_layer_slot slot;
};
 
 
/*
 *
 * Helper functions.
 *
 */
 
/*!
 * Convenience function to convert a xrt_compositor to a comp_base.
 *
 * @private @memberof comp_base
 */
static inline struct comp_base *
comp_base(struct xrt_compositor *xc)
{
        return (struct comp_base *)xc;
}
 
 
/*
 *
 * 'Exported' functions.
 *
 */
 
/*!
 * Inits all of the supported functions and structs, except @ref vk_bundle.
 *
 * The bundle needs to be initialised before any of the implemented functions
 * are call, but is not required to be initialised before this function is
 * called.
 *
 * @protected @memberof comp_base
 */
void
comp_base_init(struct comp_base *cb);
 
/*!
 * De-initialises all structs, except @ref vk_bundle.
 *
 * The bundle needs to be de-initialised by the sub-class.
 *
 * @private @memberof comp_base
 */
void
comp_base_fini(struct comp_base *cb);
 
 
#ifdef __cplusplus
}
#endif