oxr_input_transform.h

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// Copyright 2018-2020, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Defines ways of performing (possibly multi-step) conversions of input
 * data.
 * @author Rylie Pavlik <rylie.pavlik@collabora.com>
 * @ingroup oxr_input_transform
 */
 
#pragma once
 
#include "xrt/xrt_device.h"
#include "oxr_objects.h"
 
// we need no platform-specific defines from OpenXR.
#include "openxr/openxr.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
struct oxr_logger;
struct oxr_sink_logger;
struct oxr_action;
struct oxr_action_cache;
 
/*!
 * @defgroup oxr_input_transform OpenXR input transformation
 *
 *
 * @ingroup oxr_input
 * @{
 */
 
/*!
 * Tag for the input transform
 *
 * @see oxr_input_transform
 */
enum oxr_input_transform_type
{
        /*!
         * Invalid value, so that zero-initialization without further assignment
         * is caught.
         */
        INPUT_TRANSFORM_INVALID = 0,
 
        /*!
         * Do not modify the input.
         *
         * This is only used as the root/head transform, to set the initial
         * type.
         */
        INPUT_TRANSFORM_IDENTITY,
 
        /*!
         * Get the X component of a 2D float input of any range.
         */
        INPUT_TRANSFORM_VEC2_GET_X,
 
        /*!
         * Get the Y component of a 2D float input of any range.
         */
        INPUT_TRANSFORM_VEC2_GET_Y,
 
        /*!
         * Apply a threshold to any 1D float input to make a bool.
         *
         * This transform type has data:
         *
         * @see oxr_input_transform_threshold_data
         */
        INPUT_TRANSFORM_THRESHOLD,
 
        /*!
         * Convert a bool to some range of 1D float input.
         *
         * This transform type has data:
         *
         * @see oxr_input_transform_bool_to_vec1_data
         */
        INPUT_TRANSFORM_BOOL_TO_VEC1,
 
        /*!
         * Interpret a 2D joystick or trackpad as a dpad.
         *
         * This transform type has data:
         *
         * @see oxr_input_transform_dpad_data
         */
        INPUT_TRANSFORM_DPAD,
};
 
struct oxr_input_transform;
/*!
 * Data required for INPUT_TRANSFORM_THRESHOLD
 */
struct oxr_input_transform_threshold_data
{
        //! The "greater-than" threshold value
        float threshold;
 
        //! If true, values greater than `threshold` are false instead of
        //! true
        bool invert;
};
 
/*!
 * Data required for INPUT_TRANSFORM_BOOL_TO_VEC1
 * @see oxr_input_transform
 * @see INPUT_TRANSFORM_BOOL_TO_VEC1
 */
struct oxr_input_transform_bool_to_vec1_data
{
        //! Value produced if bool is true.
        float true_val;
 
        //! Value produced if bool is false.
        float false_val;
};
 
/*!
 * Data required for INPUT_TRANSFORM_DPAD
 * @see oxr_input_transform
 * @see INPUT_TRANSFORM_DPAD
 */
struct oxr_input_transform_dpad_data
{
        enum oxr_dpad_region bound_region;
        enum oxr_dpad_region active_regions;
        struct oxr_dpad_settings settings;
        enum xrt_input_type activation_input_type;
        struct xrt_input *activation_input;
        bool already_active;
};
 
/*!
 * Variant type for input transforms.
 *
 * Some values for @p type do not have any additional data in the union
 */
struct oxr_input_transform
{
        /*!
         * The type of this transform.
         *
         * Some values imply that a member of oxr_input_transform::data is
         * populated.
         */
        enum oxr_input_transform_type type;
 
        //! The type output by this transform.
        enum xrt_input_type result_type;
 
        union {
                /*!
                 * Populated when oxr_input_transform::type is
                 * INPUT_TRANSFORM_THRESHOLD
                 */
                struct oxr_input_transform_threshold_data threshold;
                /*!
                 * Populated when oxr_input_transform::type is
                 * INPUT_TRANSFORM_BOOL_TO_VEC1
                 */
                struct oxr_input_transform_bool_to_vec1_data bool_to_vec1;
                /*!
                 * Populated when oxr_input_transform::type is
                 * INPUT_TRANSFORM_DPAD
                 */
                struct oxr_input_transform_dpad_data dpad_state;
        } data;
};
 
/*!
 * An input value enum with the associated tag required to interpret it.
 */
struct oxr_input_value_tagged
{
        enum xrt_input_type type;
        union xrt_input_value value;
};
 
/*!
 * Destroy an array of input transforms.
 *
 * Performs null check and sets to NULL.
 *
 * @public @memberof oxr_input_transform
 */
void
oxr_input_transform_destroy(struct oxr_input_transform **transform_ptr);
 
/*!
 * Apply an array of input transforms.
 *
 * @param[in] transforms An array of input transforms
 * @param[in] transform_count The number of elements in @p transform
 * @param[in] input The input value and type
 * @param[out] out The transformed value and type
 *
 * @returns false if there was a type mismatch
 * @public @memberof oxr_input_transform
 */
bool
oxr_input_transform_process(struct oxr_input_transform *transforms,
                            size_t transform_count,
                            const struct oxr_input_value_tagged *input,
                            struct oxr_input_value_tagged *out);
 
/*!
 * Allocate an identity transform serving as the root/head of the transform
 * chain.
 *
 * Usually called automatically by @ref oxr_input_transform_create_chain
 *
 * @param[in,out] transform A pointer to the @ref oxr_input_transform struct to
 * initialize.
 * @param[in] input_type The native input type from the device
 *
 * @public @memberof oxr_input_transform
 */
bool
oxr_input_transform_init_root(struct oxr_input_transform *transform, enum xrt_input_type input_type);
 
/*!
 * Allocate a transform to get the X component of a Vec2.
 *
 * Usually called automatically by @ref oxr_input_transform_create_chain
 *
 * @param[in,out] transform A pointer to the @ref oxr_input_transform struct to
 * initialize.
 * @param[in] parent The preceding transform
 *
 * @pre parent->result_type is @ref XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE
 *
 * @public @memberof oxr_input_transform
 */
bool
oxr_input_transform_init_vec2_get_x(struct oxr_input_transform *transform, const struct oxr_input_transform *parent);
 
/*!
 * Allocate a transform to get the Y component of a Vec2.
 *
 * Usually called automatically by @ref oxr_input_transform_create_chain
 *
 * @param[in,out] transform A pointer to the @ref oxr_input_transform struct to
 * initialize.
 * @param[in] parent The preceding transform
 *
 * @pre parent->result_type is @ref XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE
 *
 * @public @memberof oxr_input_transform
 */
bool
oxr_input_transform_init_vec2_get_y(struct oxr_input_transform *transform, const struct oxr_input_transform *parent);
 
/*!
 * Allocate a transform to threshold a float to a bool.
 *
 * Usually called automatically by @ref oxr_input_transform_create_chain
 *
 * @param[in,out] transform A pointer to the @ref oxr_input_transform struct to
 * initialize.
 * @param[in] parent The preceding transform
 * @param[in] threshold Threshold value to use
 * @param[in] invert If true, condition is "value <= threshold" instead of
 * "value > threshold"
 *
 * @pre parent->result_type is @ref XRT_INPUT_TYPE_VEC1_ZERO_TO_ONE or
 * @ref XRT_INPUT_TYPE_VEC1_MINUS_ONE_TO_ONE
 *
 * @public @memberof oxr_input_transform
 */
bool
oxr_input_transform_init_threshold(struct oxr_input_transform *transform,
                                   const struct oxr_input_transform *parent,
                                   float threshold,
                                   bool invert);
 
/*!
 * Allocate a transform to turn a bool into an arbitrary 1D float.
 *
 * Usually called automatically by @ref oxr_input_transform_create_chain
 *
 * @param[in,out] transform A pointer to the @ref oxr_input_transform struct to
 * initialize.
 * @param[in] parent The preceding transform
 * @param[in] result_type Either XRT_INPUT_TYPE_VEC1_ZERO_TO_ONE or
 * XRT_INPUT_TYPE_VEC1_MINUS_ONE_TO_ONE
 * @param[in] true_val Value to return when true
 * @param[in] false_val Value to return when false
 *
 * @pre parent->result_type is XRT_INPUT_TYPE_BOOLEAN
 *
 * @public @memberof oxr_input_transform
 */
bool
oxr_input_transform_init_bool_to_vec1(struct oxr_input_transform *transform,
                                      const struct oxr_input_transform *parent,
                                      enum xrt_input_type result_type,
                                      float true_val,
                                      float false_val);
 
/*!
 * Create a transform array to convert @p input_type to @p result_type.
 *
 * @todo This should be configured using knowledge from the device as well as user options/policy.
 *
 * @param[in] log The logger
 * @param[in] slog The sink logger
 * @param[in] input_type The type of input received from the hardware
 * @param[in] result_type The type of input the application requested
 * @param[in] action_name The action name - used for error prints only
 * @param[in] bound_path_string The path name string that has been bound.
 * @param[out] out_transforms A pointer that will be populated with the output
 * array's address, or NULL.
 * @param[out] out_transform_count Where to populate the array size
 * @return false if not possible
 *
 * @relates oxr_input_transform
 */
bool
oxr_input_transform_create_chain(struct oxr_logger *log,
                                 struct oxr_sink_logger *slog,
                                 enum xrt_input_type input_type,
                                 XrActionType result_type,
                                 const char *action_name,
                                 const char *bound_path_string,
                                 struct oxr_input_transform **out_transforms,
                                 size_t *out_transform_count);
 
/*!
 * Create a transform array to process a 2D input plus activation input to a dpad.
 *
 * @param[in] log The logger
 * @param[in] slog The sink logger
 * @param[in] input_type The type of input received from the hardware
 * @param[in] result_type The type of input the application requested
 * @param[in] bound_path_string The path name string that has been bound.
 * @param[in] dpad_settings The dpad settings provided by the application
 * as a binding modification. NULL means use the defaults as per the spec.
 * @param[in] dpad_region The dpad region associated with this binding
 * @param[in] activation_input_type The type of the activation input
 * @param[in] activation_input The activation input, i.e. the input used
 * to determine when the emulated dpad buttons should activate
 * @param[out] out_transforms A pointer that will be populated with the output
 * array's address, or NULL.
 * @param[out] out_transform_count Where to populate the array size
 * @return false if not possible
 *
 * @relates oxr_input_transform
 */
bool
oxr_input_transform_create_chain_dpad(struct oxr_logger *log,
                                      struct oxr_sink_logger *slog,
                                      enum xrt_input_type input_type,
                                      XrActionType result_type,
                                      const char *bound_path_string,
                                      struct oxr_dpad_binding_modification *dpad_binding_modification,
                                      enum oxr_dpad_region dpad_region,
                                      enum xrt_input_type activation_input_type,
                                      struct xrt_input *activation_input,
                                      struct oxr_input_transform **out_transforms,
                                      size_t *out_transform_count);
 
/*!
 * @}
 */
 
 
#ifdef __cplusplus
}
#endif