feat(dropdown): add lv_dropdown_get_option_index

src/widgets/lv_dropdown.c

@@ -398,6 +398,26 @@ void lv_dropdown_get_selected_str(const lv_obj_t * obj, char * buf, uint32_t buf
     buf[c] = '\0';
 }
 
+int32_t lv_dropdown_get_option_index(lv_obj_t * obj, const char * option)
+{
+    const char * opts = lv_dropdown_get_options(obj);
+    uint32_t char_i = 0;
+    uint32_t opt_i = 0;
+    const char * start = opts;
+
+    while(start[char_i] != '\0') {
+        for(char_i = 0; (start[char_i] != '\n') && (start[char_i] != '\0'); char_i++);
+
+        if(memcmp(start, option, LV_MIN(strlen(option), char_i)) == 0) return opt_i;
+        start = &start[char_i];
+        if(start[0] == '\n') start++;
+        opt_i++;
+    }
+
+    return -1;
+}
+
+
 const char * lv_dropdown_get_symbol(lv_obj_t * obj)
 {
     LV_ASSERT_OBJ(obj, MY_CLASS);

src/widgets/lv_dropdown.h

@@ -189,6 +189,14 @@ uint16_t lv_dropdown_get_option_cnt(const lv_obj_t * obj);
  */
 void lv_dropdown_get_selected_str(const lv_obj_t * obj, char * buf, uint32_t buf_size);
 
+/**
+ * Get the index of an option.
+ * @param obj       pointer to drop-down object
+ * @param option    an option as string
+ * @return          index of `option` in the list of all options. -1 if not found.
+ */
+int32_t lv_dropdown_get_option_index(lv_obj_t * obj, const char * option);
+
 /**
  * Get the symbol on the drop-down list. Typically a down caret or arrow.
  * @param obj       pointer to drop-down list object