From 32d742cf520678572c1328db9d29fb981f231dc0 Mon Sep 17 00:00:00 2001
From: guoweilkd <35251456+guoweilkd@users.noreply.github.com>
Date: Wed, 19 May 2021 19:27:09 +0800
Subject: [PATCH] fix encoded letter bug (#2252)

Co-authored-by: guowei15 <guowei15@xiaomi.com>
---
 src/draw/lv_draw_label.c |  6 +++---
 src/misc/lv_txt.c        | 12 ++++++++++--
 src/misc/lv_txt.h        | 11 +++++++++++
 src/widgets/lv_label.c   | 19 ++++++++-----------
 4 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/src/draw/lv_draw_label.c b/src/draw/lv_draw_label.c
index 23fab20f1..bc99cd577 100644
--- a/src/draw/lv_draw_label.c
+++ b/src/draw/lv_draw_label.c
@@ -261,9 +261,9 @@ LV_ATTRIBUTE_FAST_MEM void lv_draw_label(const lv_area_t * coords, const lv_area
 #endif
             }
 
-            uint32_t letter      = _lv_txt_encoded_next(bidi_txt, &i);
-            uint32_t letter_next = _lv_txt_encoded_next(&bidi_txt[i], NULL);
-
+            uint32_t letter;
+            uint32_t letter_next;
+            _lv_txt_encoded_letter_next_2(bidi_txt, &letter, &letter_next, &i);
             /*Handle the re-color command*/
             if((dsc->flag & LV_TEXT_FLAG_RECOLOR) != 0) {
                 if(letter == (uint32_t)LV_TXT_COLOR_CMD[0]) {
diff --git a/src/misc/lv_txt.c b/src/misc/lv_txt.c
index 9c400ce06..fa2bf0be9 100644
--- a/src/misc/lv_txt.c
+++ b/src/misc/lv_txt.c
@@ -366,8 +366,10 @@ lv_coord_t lv_txt_get_width(const char * txt, uint32_t length, const lv_font_t *
 
     if(length != 0) {
         while(i < length) {
-            uint32_t letter      = _lv_txt_encoded_next(txt, &i);
-            uint32_t letter_next = _lv_txt_encoded_next(&txt[i], NULL);
+            uint32_t letter;
+            uint32_t letter_next;
+            _lv_txt_encoded_letter_next_2(txt, &letter, &letter_next, &i);
+
             if((flag & LV_TEXT_FLAG_RECOLOR) != 0) {
                 if(_lv_txt_is_cmd(&cmd_state, letter) != false) {
                     continue;
@@ -525,6 +527,12 @@ char * _lv_txt_set_text_vfmt(const char * fmt, va_list ap)
     return text;
 }
 
+void _lv_txt_encoded_letter_next_2(const char * txt, uint32_t * letter, uint32_t * letter_next, uint32_t *ofs)
+{
+    *letter = _lv_txt_encoded_next(txt, ofs);
+    *letter_next = *letter != '\0' ? _lv_txt_encoded_next(&txt[*ofs], NULL) : 0;
+}
+
 #if LV_TXT_ENC == LV_TXT_ENC_UTF8
 /*******************************
  *   UTF-8 ENCODER/DECODER
diff --git a/src/misc/lv_txt.h b/src/misc/lv_txt.h
index 38c7e8a0e..c12bd1769 100644
--- a/src/misc/lv_txt.h
+++ b/src/misc/lv_txt.h
@@ -143,6 +143,17 @@ void _lv_txt_cut(char * txt, uint32_t pos, uint32_t len);
  */
 char * _lv_txt_set_text_vfmt(const char * fmt, va_list ap);
 
+/**
+ * Decode two encoded character from a string.
+ * @param txt pointer to '\0' terminated string
+ * @param letter the first decoded Unicode character or 0 on invalid data code
+ * @param letter_next the second decoded Unicode character or 0 on invalid data code
+ * @param ofs start index in 'txt' where to start.
+ *                After the call it will point to the next encoded char in 'txt'.
+ *                NULL to use txt[0] as index
+ */
+void _lv_txt_encoded_letter_next_2(const char * txt, uint32_t * letter, uint32_t * letter_next, uint32_t *ofs);
+
 /***************************************************************
  *  GLOBAL FUNCTION POINTERS FOR CHARACTER ENCODING INTERFACE
  ***************************************************************/
diff --git a/src/widgets/lv_label.c b/src/widgets/lv_label.c
index 4ff3e4578..d93817ec3 100644
--- a/src/widgets/lv_label.c
+++ b/src/widgets/lv_label.c
@@ -472,11 +472,11 @@ uint32_t lv_label_get_letter_on(const lv_obj_t * obj, lv_point_t * pos_in)
 
     if(new_line_start > 0) {
         while(i + line_start < new_line_start) {
-            /*Get the current letter.*/
-            uint32_t letter = _lv_txt_encoded_next(bidi_txt, &i);
-
-            /*Get the next letter too for kerning*/
-            uint32_t letter_next = _lv_txt_encoded_next(&bidi_txt[i], NULL);
+            /*Get the current letter and the next letter for kerning*/
+            /*Be careful 'i' already points to the next character*/
+            uint32_t letter;
+            uint32_t letter_next;
+            _lv_txt_encoded_letter_next_2(bidi_txt, &letter, &letter_next, &i);
 
             /*Handle the recolor command*/
             if((flag & LV_TEXT_FLAG_RECOLOR) != 0) {
@@ -575,12 +575,9 @@ bool lv_label_is_char_under_pos(const lv_obj_t * obj, lv_point_t * pos)
 
     if(new_line_start > 0) {
         while(i <= new_line_start - 1) {
-            /*Get the current letter
-             *Be careful 'i' already points to the next character*/
-            letter = _lv_txt_encoded_next(txt, &i);
-
-            /*Get the next letter for kerning*/
-            letter_next = _lv_txt_encoded_next(&txt[i], NULL);
+            /*Get the current letter and the next letter for kerning*/
+            /*Be careful 'i' already points to the next character*/
+            _lv_txt_encoded_letter_next_2(txt, &letter, &letter_next, &i);
 
             /*Handle the recolor command*/
             if((flag & LV_TEXT_FLAG_RECOLOR) != 0) {