add log interface (lv_log) but still there are no log messages added

lv_conf_templ.h

@@ -86,6 +86,16 @@
 #define LV_ATTRIBUTE_TASK_HANDLER             /* Define a custom attribute to `lv_task_handler` function */
 #define LV_COMPILER_VLA_SUPPORTED    1        /* 1: Variable length array is supported*/
 
+/*Log settings*/
+#define USE_LV_LOG		1	/*Enable/disable the log module*/
+#if USE_LV_LOG
+#define LV_LOG_INFO		0	/*1: Log a lot of runtime information*/
+#define LV_LOG_WARN		0	/*1: Log is something unexpected happens but succesfully handled*/
+#define LV_LOG_ERROR	1	/*1: Log critical error*/
+#define LV_LOG_USER		1	/*1: Log user defined/user level things */
+#define LV_LOG_PRINTF	0	/*1: Print the log with 'printf'; 0: user need to register a callback*/
+#endif  /*USE_LV_LOG*/
+
 /*================
  *  THEME USAGE
  *================*/

lv_core/lv_obj.c

@@ -62,6 +62,10 @@ static lv_ll_t scr_ll;                 /*Linked list of screens*/
  */
 void lv_init(void)
 {
+#if USE_LV_LOG
+	lv_log_add(LV_LOG_LEVEL_INFO, __FILE__, __LINE__, "lv_init called");
+#endif
+
     /*Initialize the lv_misc modules*/
     lv_mem_init();
     lv_task_init();
@@ -101,6 +105,10 @@ void lv_init(void)
     /*Init the input device handling*/
     lv_indev_init();
 #endif
+
+#if USE_LV_LOG
+    lv_log_add(LV_LOG_LEVEL_INFO, __FILE__, __LINE__, "lv_init finished");
+#endif
 }
 
 /*--------------------

lv_core/lv_obj.h

@@ -21,6 +21,7 @@ extern "C" {
 #include "../lv_misc/lv_mem.h"
 #include "../lv_misc/lv_ll.h"
 #include "../lv_misc/lv_color.h"
+#include "../lv_misc/lv_log.h"
 
 /*********************
  *      DEFINES

lv_misc/lv_log.c

@@ -0,0 +1,80 @@
+/**
+ * @file lv_log.c
+ *
+ */
+
+/*********************
+ *      INCLUDES
+ *********************/
+#include "lv_log.h"
+#if USE_LV_LOG
+
+#if LV_LOG_PRINTF
+#include <string.h>
+#endif
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ *  STATIC PROTOTYPES
+ **********************/
+
+/**********************
+ *  STATIC VARIABLES
+ **********************/
+static void (*print_cb)(lv_log_level_t , const char *, uint32_t ,  const char *);
+
+/**********************
+ *      MACROS
+ **********************/
+
+/**********************
+ *   GLOBAL FUNCTIONS
+ **********************/
+
+/**
+ * Register custom print (or anything else) function to call when log is added
+ * @param f a function pointer:
+ *          `void my_print (lv_log_level_t level, const char * file, uint32_t line, const char * dsc)`
+ */
+void lv_log_register_print(void f(lv_log_level_t , const char *, uint32_t ,  const char *))
+{
+	print_cb = f;
+}
+
+/**
+ * Add a log
+ * @param level the level of log. (From `lv_log_level_t` enum)
+ * @param file name of the file when the log added
+ * @param line line number in the source code where the log added
+ * @param dsc description of the log
+ */
+void lv_log_add(lv_log_level_t level, const char * file, uint32_t line, const char * dsc)
+{
+	if(level >= _LV_LOG_LEVEL_NUM) return;		/*Invalid level*/
+
+	if((level == LV_LOG_LEVEL_INFO && LV_LOG_INFO)  ||
+	   (level == LV_LOG_LEVEL_WARN && LV_LOG_WARN)  ||
+	   (level == LV_LOG_LEVEL_ERROR && LV_LOG_ERROR) ||
+	   (level == LV_LOG_LEVEL_USER && LV_LOG_USER))
+	{
+
+#if LV_LOG_PRINTF
+		static const char * lvl_prefix[] = {"Info", "Warn", "Error", "User"};
+		printf("%s %s:%d:   %s\n", lvl_prefix[level], file, line, dsc);
+#else
+		if(print_cb) print_cb(level, file, line, dsc);
+#endif
+	}
+}
+
+/**********************
+ *   STATIC FUNCTIONS
+ **********************/
+
+#endif /*USE_LV_LOG*/

lv_misc/lv_log.h

@@ -0,0 +1,74 @@
+/**
+ * @file lv_log.h
+ *
+ */
+
+#ifndef LV_LOG_H
+#define LV_LOG_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*********************
+ *      INCLUDES
+ *********************/
+#include "../../lv_conf.h"
+#include <stdint.h>
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/*Possible log level. For compatibility declare it independently from `USE_LV_LOG`*/
+typedef enum
+{
+	LV_LOG_LEVEL_INFO = 0,
+	LV_LOG_LEVEL_WARN,
+	LV_LOG_LEVEL_ERROR,
+	LV_LOG_LEVEL_USER,
+	_LV_LOG_LEVEL_NUM
+}lv_log_level_t;
+
+#if USE_LV_LOG
+
+/**********************
+ * GLOBAL PROTOTYPES
+ **********************/
+
+/**
+ * Register custom print (or anything else) function to call when log is added
+ * @param f a function pointer:
+ *          `void my_print (lv_log_level_t level, const char * file, uint32_t line, const char * dsc)`
+ */
+void lv_log_register_print(void f(lv_log_level_t , const char *, uint32_t ,  const char *));
+
+/**
+ * Add a log
+ * @param level the level of log. (From `lv_log_level_t` enum)
+ * @param file name of the file when the log added
+ * @param line line number in the source code where the log added
+ * @param dsc description of the log
+ */
+void lv_log_add(lv_log_level_t level, const char * file, uint32_t line, const char * dsc);
+
+/**********************
+ *      MACROS
+ **********************/
+
+#else /*USE_LV_LOG*/
+
+/*Do nothing if `USE_LV_LOG  0`*/
+#define lv_log_add(level, file, line, dsc) {;}
+
+#endif /*USE_LV_LOG*/
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /*LV_LOG_H*/