font: add user data

lv_conf_template.h

@@ -259,6 +259,9 @@ typedef void * lv_indev_drv_user_data_t;            /*Type of user data in the i
 
 #define LV_FONT_DEFAULT        &lv_font_dejavu_20     /*Always set a default font from the built-in fonts*/
 
+/*Declare the type of the user data of fonts (can be e.g. `void *`, `int`, `struct`)*/
+typedef void * lv_font_user_data_t;
+
 /*=================
  *  Text settings
  *=================*/

src/lv_core/lv_refr.c

@@ -167,8 +167,7 @@ void lv_disp_refr_task(lv_task_t * task)
             /* With true double buffering the flushing should be only the address change of the
              * current frame buffer. Wait until the address change is ready and copy the changed
              * content to the other frame buffer (new active VDB) to keep the buffers synchronized*/
-            while(vdb->flushing)
-                ;
+            while(vdb->flushing);
 
             uint8_t * buf_act = (uint8_t *)vdb->buf_act;
             uint8_t * buf_ina = (uint8_t *)vdb->buf_act == vdb->buf1 ? vdb->buf2 : vdb->buf1;

src/lv_misc/lv_font.h

@@ -66,6 +66,9 @@ typedef struct _lv_font_struct
     uint8_t line_height;      /*The real line height where any text fits*/
     uint8_t base_line;        /*Base line measured from the top of the line_height*/
     void * dsc;               /*Store implementation specific data here*/
+#if LV_USE_USER_DATA
+    lv_font_user_data_t user_data;
+#endif
 } lv_font_t;
 
 /**********************