ra8_touch_cal.h

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#pragma once
 
#ifdef __cplusplus
extern "C" {
#endif
 
#include <stddef.h>
#include <stdint.h>
 
#include "ra8_err.h"
 
/* ===========================================================================
 * Compile-time limits
 * ===========================================================================
 */

typedef enum : uint8_t {
  k_ra8_touch_cal_n_targets       = 5U,  
  k_ra8_touch_cal_min_targets     = 3U,  
  k_ra8_touch_cal_max_targets     = 5U,  
  k_ra8_touch_cal_blob_size       = 36U, 
  k_ra8_touch_cal_storage_version = 1U,  
} ra8_touch_cal_limits_t;

typedef enum : uint8_t {
  k_ra8_touch_cal_off_magic    = 0U,  
  k_ra8_touch_cal_off_version  = 4U,  
  k_ra8_touch_cal_off_reserved = 5U,  
  k_ra8_touch_cal_off_coeffs   = 8U,  
  k_ra8_touch_cal_off_crc32    = 32U, 
} ra8_touch_cal_layout_t;

typedef enum : uint8_t {
  k_ra8_touch_cal_magic_b0 = 0x54U, 
  k_ra8_touch_cal_magic_b1 = 0x43U, 
  k_ra8_touch_cal_magic_b2 = 0x41U, 
  k_ra8_touch_cal_magic_b3 = 0x4CU, 
} ra8_touch_cal_magic_t;
 
/* ===========================================================================
 * Public types
 * ===========================================================================
 */

typedef struct {
  int32_t x; 
  int32_t y; 
} ra8_touch_cal_point_t;

typedef struct {
  float a; 
  float b; 
  float c; 
  float d; 
  float e; 
  float f; 
} ra8_touch_cal_matrix_t;

typedef ra8_err_t (*ra8_touch_cal_draw_target_fn_t)(void* ctx, ra8_touch_cal_point_t target);

typedef ra8_err_t (*ra8_touch_cal_read_raw_fn_t)(void* ctx, ra8_touch_cal_point_t* out_raw);

typedef struct {
  uint16_t                       screen_width;  
  uint16_t                       screen_height; 
  uint16_t                       inset_px;      
  ra8_touch_cal_draw_target_fn_t draw_target;   
  void*                          draw_ctx;      
  ra8_touch_cal_read_raw_fn_t    read_raw;      
  void*                          read_ctx;      
} ra8_touch_cal_run_cfg_t;
 
/* ===========================================================================
 * Public API
 * ===========================================================================
 */

[[nodiscard]] ra8_err_t ra8_touch_cal_compute(const ra8_touch_cal_point_t* raw,
                                              const ra8_touch_cal_point_t* screen,
                                              uint8_t                      n,
                                              ra8_touch_cal_matrix_t*      out_mtx);

[[nodiscard]] ra8_err_t ra8_touch_cal_run(const ra8_touch_cal_run_cfg_t* cfg,
                                          ra8_touch_cal_matrix_t*        out_matrix);

[[nodiscard]] ra8_err_t ra8_touch_cal_apply(ra8_touch_cal_point_t         raw,
                                            const ra8_touch_cal_matrix_t* matrix,
                                            uint16_t                      screen_width,
                                            uint16_t                      screen_height,
                                            ra8_touch_cal_point_t*        out_screen);

[[nodiscard]] ra8_err_t
ra8_touch_cal_save(const ra8_touch_cal_matrix_t* matrix, uint8_t* dst, size_t dst_size);

[[nodiscard]] ra8_err_t
ra8_touch_cal_load(const uint8_t* src, size_t src_size, ra8_touch_cal_matrix_t* out_matrix);
 
#ifdef __cplusplus
}
#endif