fix(API): keep font struct lv_font_fmt_txt_kern_pair_t public (#6625)

src/font/lv_font_fmt_txt.h

@@ -108,6 +108,21 @@ typedef struct {
     lv_font_fmt_txt_cmap_type_t type;
 } lv_font_fmt_txt_cmap_t;
 
+/** A simple mapping of kern values from pairs*/
+typedef struct {
+    /*To get a kern value of two code points:
+       1. Get the `glyph_id_left` and `glyph_id_right` from `lv_font_fmt_txt_cmap_t
+       2. for(i = 0; i < pair_cnt * 2; i += 2)
+             if(glyph_ids[i] == glyph_id_left &&
+                glyph_ids[i+1] == glyph_id_right)
+                 return values[i / 2];
+     */
+    const void * glyph_ids;
+    const int8_t * values;
+    uint32_t pair_cnt   : 30;
+    uint32_t glyph_ids_size : 2;    /*0: `glyph_ids` is stored as `uint8_t`; 1: as `uint16_t`*/
+} lv_font_fmt_txt_kern_pair_t;
+
 /** More complex but more optimal class based kern value storage*/
 typedef struct {
     /*To get a kern value of two code points:

src/font/lv_font_fmt_txt_private.h

@@ -24,21 +24,6 @@ extern "C" {
  *      TYPEDEFS
  **********************/
 
-/** A simple mapping of kern values from pairs*/
-struct lv_font_fmt_txt_kern_pair_t {
-    /*To get a kern value of two code points:
-       1. Get the `glyph_id_left` and `glyph_id_right` from `lv_font_fmt_txt_cmap_t
-       2. for(i = 0; i < pair_cnt * 2; i += 2)
-             if(glyph_ids[i] == glyph_id_left &&
-                glyph_ids[i+1] == glyph_id_right)
-                 return values[i / 2];
-     */
-    const void * glyph_ids;
-    const int8_t * values;
-    uint32_t pair_cnt   : 30;
-    uint32_t glyph_ids_size : 2;    /*0: `glyph_ids` is stored as `uint8_t`; 1: as `uint16_t`*/
-};
-
 #if LV_USE_FONT_COMPRESSED
 typedef enum {
     RLE_STATE_SINGLE = 0,

src/misc/lv_types.h

@@ -169,8 +169,6 @@ typedef struct lv_cover_check_info_t lv_cover_check_info_t;
 
 typedef struct lv_obj_spec_attr_t lv_obj_spec_attr_t;
 
-typedef struct lv_font_fmt_txt_kern_pair_t lv_font_fmt_txt_kern_pair_t;
-
 typedef struct lv_image_t lv_image_t;
 
 typedef struct lv_animimg_t lv_animimg_t;

tests/src/test_cases/test_font_loader.c

@@ -9,7 +9,6 @@
 
 #if LV_BUILD_TEST
 #include "../../lvgl.h"
-#include "../../lvgl_private.h"
 
 #include "unity/unity.h"